1998 Mercury Promax 300 Fuel Delivery Issue? [Archive] - Scream And Fly Powerboat and High Performance Powerboating Discussion Forums

Basnova

02-19-2020, 11:30 PM

I took my boat for an easy run today, as part of my regimen of running it every 45 days or so during winters here on Folsom Lake, CA. I was simply cruising it at 4000 rpms, give or take. No WOT bursts or anything. It was running smooth for about 10 minutes, then suddenly surged two or three times, then suddenly cut out. Upon restarting it, it started and idled for a few seconds, then died again. On the third try, it did not catch at all. It almost feels like it ran out of gas, even though I had 3/4 of a tank from a fill-up before winter, with Marine Stabil added.

I previously ran it in January, and it ran fine. The boat is garaged year round, so it is not exposed to the elements unless I'm out on the water.

Upon launching today, I squeezed the primer bulb as I normally do, and it initially felt soft as usual, and firmed up as I primed. But, later, after the engine cut out, I squeezed it to see if I had gas in the line, and it seemed quite firm, almost too firm. Not firm like hardened rubber, but as if it had quite a bit of pressure in it. FWIW, the bulb and some lines were replaced about two years ago, so they're good, but I thought I would mentioned how the bulb seemed over pressurized in case it might be a clue.

Is it possible that a fuel filter can cause something like this? Last time it was changed was two years ago. If I recall correctly, my filter looks similar to an oil filter for a car. Do I just unscrew the thing to remove it, or must I relieve fuel pressure somehow before removing it? Is there something specific that I should look at on the filter? Like can it be emptied or something to see if might be clogged?

Any tips on how to test the fuel pump? Or anything else I might look at that might be simple enough to at least determine what might be wrong, like line connections, or...? This time of year is so inconvenient for taking it somewhere, as I suspect a back log of people trying to get their boats ready for spring fishing.

I'm pretty good with cars, but have always had this motor serviced professionally, aside from real simple things, but I'd be willing to get my hands a bit dirty so resolve this.

Thanks in advance.

half fast

02-20-2020, 08:37 AM

If it has the merc grey fuel line feeding the motor , I would check to see if the inner wall has released from the outer wall causing a restriction in fuel flow. hf...

billybob

02-20-2020, 10:50 AM

He is correct, sounds like fuel line is coming apart internally. Not uncommon at all. I have never heard of a 1998 300 promax. Don,t just replace fuel line, probably pieces are stuck in fuel system.

Basnova

02-20-2020, 11:34 AM

Thanks for the replies, guys. Am I correct in assuming that the firm primer bulb pressure is a clue? I had lines replaced two years ago, which is why I am asking. I also assume I would need to disconnect the lines and look in them. Do I need to relieve pressure before doing so, and if so, any tips in that regard? I have a service manual, and regarding the fuel filter, it just says to remove it when talking about inspecting or replacing it, but makes no mention of relieving fuel pressure. On my Vette and Suburban, any fuel line disconnects call for relieving pressure, which is why I ask.
@half fast (https://www.screamandfly.com/member.php?u=377): sounds like you speak from experience here. If I go look at it, and don't see any Grey lines, because they were recently replaced, would they still be something suspect to you?
@billybob (https://www.screamandfly.com/member.php?u=8482): wouldn't pieces get caught in the fuel filter? Also, do you mean you never heard of a Promax 300, or didn't know they made one in 1998?

Dave Strong

02-20-2020, 01:34 PM

Try running it on a 5 gal remote thank with a known good primer ball and fuel line, check valves in those balls can do strange things.

Dave

Basnova

02-20-2020, 02:01 PM

Try running it on a 5 gal remote thank with a known good primer ball and fuel line, check valves in those balls can do strange things.

DaveThanks for that suggestion, Dave, good idea. Do you happen to know if there is a special procedure for relieving fule line pressure before disconnecting lines?

Dave Strong

02-20-2020, 02:59 PM

Thanks for that suggestion, Dave, good idea. Do you happen to know if there is a special procedure for relieving fule line pressure before disconnecting lines?

No real pressure just the fuel in the line.

Dave

JR IN JAX

02-25-2020, 04:53 PM

I had a stalling problem with my 1 year old 300XS so I replaced all of my fuel lines with ethanol proof linerless and then installed a fuel pump rebuild kit that I ordered online. After 40+ hours since, it has only stalled 1 time.

Basnova

02-25-2020, 05:01 PM

Seeing as how my fuel filter is mounted right on my engine, I checked that first, since it's the last thing in the fuel line, aside from a very short hose from there to the motor. Although the filter was installed in 2016, when I unscrewed it, it was full of fuel, and the fuel looked clean. When I looked inside the filter, it looks brand spanking new.

I'm suspecting it's the fuel pump. I see two wires going to to it. I was thinking maybe I should put a voltmeter on those contact points to see if it's even getting any power. Maybe I should see if I can find a line on the output side of it, and disconnect it to see if it's pumping at all. I'll take a pic of the fuel pump so you guys can see it. It's definitely different-looking, being mounted to the block of the motor rather than in-line somewhere.

JR IN JAX

02-25-2020, 05:14 PM

I rebuilt the Diaphragm fuel lift pulse pump, not the electric VST pump.

Basnova

02-25-2020, 05:59 PM

I rebuilt the Diaphragm fuel lift pulse pump, not the electric VST pump.Thanks for the clarification. Please excuse my ignorance, but does my motor also have both of these?

JR IN JAX

02-25-2020, 06:27 PM

Thanks for the clarification. Please excuse my ignorance, but does my motor also have both of these?

Yes, there is a flat diaphragm pulse pump that lifts the fuel from the tank and fills the VST tank. The VST electric pump boosts the fuel at high pressure to the injectors. The pulse pump has a fuel line the connects to the tank.

Many modify theirs with a boat mounted electric pump that takes the place of both pumps.

Basnova

02-25-2020, 08:54 PM

Yes, there is a flat diaphragm pulse pump that lifts the fuel from the tank and fills the VST tank. The VST electric pump boosts the fuel at high pressure to the injectors. The pulse pump has a fuel line the connects to the tank.

Many modify theirs with a boat mounted electric pump that takes the place of both pumps.Thanks for that. What I must be seeing on the side of the engine block is the VST. I don't see anything else inline prior to that, and certainly don't see anything in the tank. I'll post a pic of the thing on the side of the block.

JR IN JAX

02-25-2020, 10:19 PM

Basnova

02-25-2020, 10:56 PM

Mercury Mercruiser Marine - PUMP KIT-FUEL (#14360A78)
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.perfprotech.com%2Fmercury-marine-parts-catalog%2Fumodel%2F5333&psig=AOvVaw08HHpzp0ecS7Olq9wiDEQ5&ust=1582772753713000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCODe2JGe7ucCFQAAAAAdAAAAABAv
Thank you for that. Unfortunately, I don't think that's my problem. From what I can see, that unit is before the fuel filter, and since my fuel filter is full, I think the little unit is fine. I thought this behemoth was the fuel pump, which is after the fuel filter:
459365
If this isn't the fuel pump, what is this?

Dave Strong

02-26-2020, 10:47 AM

Thats the VST, fuel pump is in there at the ft of the unit.

Dave

Basnova

02-26-2020, 12:50 PM

What does VST stand for, Vapor Separator Tank, or something along those lines? Anyone have experience testing or R&R'ing one of these?

Dave Strong

02-26-2020, 02:21 PM

Not sure about 3.0L but 2.5 has a pressure port to check regulated press. If you take it apart you will need a new o-ring to seal the top, they enlarge when removed and will not fit.

Dave

Basnova

02-26-2020, 04:46 PM

Yes, I see a Schrader valve on one of the ports, so it must be the same. When you say an o-ring, are you talking about a seal for the entire top of the tank, or do you mean where the schrader valve inserts on the top of the tank?

Dave Strong

02-26-2020, 04:51 PM

Seal for the top of the VST. Sit down when you price it.:rolleyes:

Dave

Basnova

02-26-2020, 05:25 PM

Are you talking about this part number? GASKET (#98-8M6002520)

GASKET (#98-8M6002520) (https://www.perfprotech.com/gasket-kit-8m6002520/product/524773)

GASKET (#98-8M6002520) (https://www.perfprotech.com/gasket-kit-8m6002520/product/524773)

Dave Strong

02-27-2020, 03:06 PM

Basnova

02-29-2020, 11:54 PM

I finally got some time to eyeball the fuel lines, and can see there is new grey hose before and after the primer bulb. This must be what a shop installed when they replaced my bulb and some hose a few years ago.

The other day I spoke to the mechanic who rebuilt my lower end a couple of years ago. Like what you guys have already mentioned, he said there's a big problem with the new style fuel hose. When I told him I had some grey hose, he said that's the worst hose. He said he's been seeing two year old boats where their hoses are collapsing. He also said that even though I have fuel in my filter, it doesn't mean anything, and that that hose could indeed be my problem, and said that would be absolutely what he would look at first, just like you guys said.

There are some zip ties holding some hoses on, but where the grey hose connects, there some of these clamps pictured in the graphic below. Can someone please tell me how to remove this clamp? There appears to be a little tab that fits into a slot, and is bent down, in what appears to be a position so it can't slip back through the slot. Am I supposed to bend that little tab and somehow maneuver that tab back out of the slot? And, once I get it off, will I be able to put it back on, or should I use zip ties, or hose clamps, or...?

Also, if this ends up being my problem, or I want to test with a gas can and a different hose and bulb altogether, where do I get hose that doesn't have that inner wall like the new hose does?

459678

Dave Strong

03-01-2020, 11:17 AM

Those clamps are one use only and need the correct tool to install.

Dave

Basnova

03-01-2020, 11:37 AM

How do you get them off, and what can I use in their place, if anything?

Basnova

03-01-2020, 11:39 AM

And, can I use regular fuel line from an auto parts store, if I find a problem with that Grey line?

Basnova

03-01-2020, 03:19 PM

OK, spent the time necessary to troubleshoot. First thing I did was have someone turn the key to the ON position to see if I even hear the fuel pump in the VST. Nothing, no sound at all. Next, I hooked a multi-meter to the positive and negative terminals of the VST pump. Good continuity. Switched multi-meter to 20v setting, and turned key. Saw 12.3 volts, but heard nothing. Obviously the pump is not working. Went onto Crowley Marine site, and it says fuel pump is Part# 809088T and it's $769! Is that for real? even worse, it's not longer available. Anyone have any thoughts for me now?

Basnova

03-01-2020, 04:14 PM

Dave, thanks for pointing me to that o-ring seal number. I just ordered one, and also found a pump for the VST, which I just ordered. Now, all I need to do is find those clamps and the tool for it.

JR IN JAX

03-01-2020, 07:50 PM

I replaced the one-time clamps with some Aviation spec-grade clamps from West Marine. They are not cheap but work well.

Basnova

03-01-2020, 08:36 PM

OK, I'll check them out. I don't care how much they cost, as I only need a few. I wish I knew what sizes I need. I have two hoses with right angle bends coming from VST to brass housing with Schrader valve on it, which I assume or high pressure fuel hoses. They are stamped with 7.94mm. There is another hose of a similar size connected to a brass fitting at the back of the VST that has what looks like a special type of black zip tie. Then, underneath there is a tiny clear oil hose that also has that special zip tie, but it's tiny!

Basnova

03-01-2020, 09:09 PM

What do you guys think of these in place of the stock Oetiker clamps?
https://www.amazon.com/dp/B07VSFB3Q1?tag=viglink22381-20&th=1

JR IN JAX

03-02-2020, 09:51 AM

I might buy both sizes to make sure since they are so cheap.

InjectorService

03-02-2020, 10:57 AM

Basnova

03-02-2020, 01:31 PM

Why don't you go buy an Oetiker clamp kit like the one below? Did you figure out your pump issue? Order a new pump?

https://www.amazon.com/Proster-Single-Stepless-Stainless-Crimper/dp/B07KPGW9X8/ref=sr_1_3?keywords=otiker+clamp+kit&qid=1583164536&sr=8-3Yes, I was actually thinking I should just do it like the factory did. Because I don't need that many clamps, I was looking at this similar kit:
https://www.amazon.com/dp/B07MX9DKNK/?coliid=I2I560PU40VNP4&colid=4XO8XFUVVB9A&psc=1&ref_=lv_ov_lig_dp_it

But, I wish there was a kit like that came with both top and side jaws. Having never used this type of tool before, I don't know if the top jaw is good enough for this, and future, applications. Do you think the top jaw is all I need for the fuel line clamps on the top front of the VST?

And, yes, it appears the VST fuel pump is not responding. I attached a voltmeter to the terminals, and turned the key. 12 volts indeed reached the terminals, but the pump doesn't turn on. I ordered a pump and VST o-ring seal, and am now trying to find Oetiker clamps and tool, large and small fuel line zip ties that will all need to be cut off to remove the VST from side of the motor.

Basnova

03-02-2020, 01:33 PM

I might buy both sizes to make sure since they are so cheap.I think I'm just going to go with the Oetiker clamps, like the factory did. I think those other ones are going to be a tight fit in this application.

InjectorService

03-02-2020, 01:51 PM

I have both the tool with the front and side pincers, 99% of the time the front only ones would work. I wouldn't let that be your deciding factor. In a pinch side cutters work as well, but definitely not as nice.

Edit: Hose zip ties if you were looking for some.
https://www.amazon.com/Hose-Clamp-Style-Black-Cable/dp/B00NV7IU0Q/ref=sr_1_4?keywords=hose+zip+ties&qid=1583175132&sr=8-4

Dave Strong

03-02-2020, 02:24 PM

Basnova

03-02-2020, 02:36 PM

I also need a tiny size for the tiny oil line to my VST. I think it must be the 4" model, because I can't find anything other than 8" or 4" online. I'll use my micrometer to verify size based on listed specs for the 4". Amazon doesn't seem to have the 4" model, so I'll need to get them on eBay or from an online retailer. The 8" size is also cheaper on other sites, so much as I'd prefer to buy from Amazon, I'll have to look elsewhere.

Dave Strong

03-02-2020, 03:14 PM

The Pico number for the small clamp zip ties is 7164-0-C.

Dave

Basnova

03-02-2020, 06:19 PM

The Pico number for the small clamp zip ties is 7164-0-C.

DaveThanks again, Dave. That confirms it. That model number is for the 4" size. Now I know to order the 8" and the 4". Both sizes can be had for about $10 for 50-100 of each through many retailers, but it's crazy I need to order that many when I only need one of each! :eek:

Basnova

03-03-2020, 10:24 AM

Looks like I was wrong about the zip ties. I measured the strap width with a micrometer, and they are both .18" wide, which means they are the 8" model, even the one on the tiny oil hose. If anyone cares, they are Hellermann Tyson part number CTT60R. I found some folks selling smaller quantities on eBay, so instead of having to buy 100, I was able to buy a 25 pack.

I also ordered the Oetiker Clamps and Tool kit, to help ensure I put everything back the way it was designed. After all, who am I to rethink a design that's worked flawlessly for all these years, right?

When mic'ing the small oil hose, I noticed a bit of oil seepage from where the hose is zip tied to the brass fitting on the bottom rear of the VST. A shop did service the VST several years ago. Is it possible they used a zip tie there, when it originally came with an Oetiker clamp? I wouldn't think they would do that seeing as they must've replaced the Oetiker clamps on the high pressure fuel lines when they reassembled the VST. Or, does that simply mean the zip tie on the oil hose is too loose? Or, should I replace that zip tie with an Oetiker clamp? I don't think it has high pressure there, but I thought I'd ask in case one of you knew what Mercury originally used there, or isf anyone has experience with this, and think I should use a clamp there instead.

Regarding opening the VST, is it simply a matter of unscrewing those Phillips head screws that hold the top on, and lifting straight up? And, is it simply a matter of swapping out the pump, once opened? I mean, nothing's going to just spring apart, or anything, right? Any tips for me? Like is that VST full of fuel and oil that I have to worry about or anything like that?

Thanks again to everyone that's posted on this thread. You have all been most helpful.

InjectorService

03-03-2020, 01:51 PM

Basnova

03-03-2020, 06:07 PM

Drain the VST by using the flat head screws on the bottom of the tank. Pull the philips screws out, lift straight up. Might need to remove the VST mounting bolts depending on space available for lifting up. Nothing will spring out.
Thank you for the instructions.

As for the zip ties, I think you might be going a little deep into it.
Not trying to overthink anything, but since I've not really worked on an outboard motor before (this motor has been quite the reliable workhorse since I got it new in 1998), I want to make sure I have all my ducks in a row so I don't find myself in a position where I end up waiting for something else I need to order later.

If your talking the zip tie on the back upper brass 90 degree fitting, take it off clean up the brass barb check the hose for cracks.On my VST, there is a brass fitting on the back bottom. Connected to that is a clear 1/4"(?) hose that is filled with oil. That hose looks like it's had oil seeping down it for quite some time. Not enough to drip off and puddle in the cowling or anything, but definitely wet. That's why I was wondering if that zip tie should have an Oetiker ear clamp on it instead.

Dave Strong

03-03-2020, 06:39 PM

On the clear oil feed hose just use a clamp type zip tie and tension gun to install it. May find the metal clamp will ut the hose when you crimp it.

Dave

Basnova

03-07-2020, 11:14 PM

I thought I'd post an update in case someone else runs into this:

If you recall, I had power to the fuel pump when I turned the ignition switch, but the fuel pump did not run. So, I ordered a new fuel pump. Thinking it's possible that something got lodged in the fuel pump, preventing it from turning, I thought I'd try hooking up some power wires in reverse, positive to negative/negative to positive, to see if a reversal might dislodge the debris. So, I bypassed the ignition switch with wires directly from the battery. But, before powering in reverse, I tested the pump with the direct wires. Lo and behold, the fuel pump came on! I then tested voltage to the fuel pump wires coming from the harness again, saw 12.3 volts just like before. I then hooked them back up, and turned the key. Nothing. I disconnected the harness wires again, and hooked up the direct wires again, and VOILA! The pump ran again. I must've tried this 10 times, each time thinking I must not be doing something right. Completely perplexed, I hooked up the harness wires again, and of course the pump didn't run. I then hooked the direct wires as well, and the pump did not run this time. WTF?

Then, I did something different. Having only the harness wires connected and the key on, I started turning the nuts on the posts of the pump. I did the positive terminal first with no change, but when I put some counter-clockwise torque on the negative post nut, like you would normally do when unscrewing the nut, the pump came on. The nut never broke free, but the post twisted ever so slightly. I then put clockwise torque on the nut, and the pump stopped. Back and forth I went a few times, and each time I put counter-clockwise torque on the nut without breaking it loose, the pump would come on.

I disassembled the VST, thinking maybe the extension post on the fuel pump where it goes through the VST top might be loose, but it was not. Obviously, there was something losing continuity inside the pump. So, I replaced the pump.

Good news is that I now have a spare VST seal (o-ring), as I did not have to replace it. I did note what you guys said about it being tough to try to maintain the shape of the o-ring when removing the top, but the top to my VST came off and most of the o-ring stayed in its recess. It still had a light coat of grease on it, so I was able to set it back in the recess where it stayed when I put it back together.

I consider myself fortunate to have discovered the intermittent continuity break, because not knowing what was happening can drive you nuts, and I hate just throwing parts at problems without knowing what is really wrong, 'cause that can end up costing you a lot of money. I'm also glad that Mercury discontinued the fuel pump, because if they still had them I would have paid $769 for a $70 pump! Holy sh|t, talk about price gouging!

Thanks to everyone who chimed in on this thread. It really was helpful to me.

SUNKIST

03-08-2020, 07:25 AM

[U]what is the part no. And manufacturer for the replacement vst fuel pump priced at 70$.

460158

Basnova

03-08-2020, 12:19 PM

[U]what is the part no. And manufacturer for the replacement vst fuel pump priced at 70$.

460158
Quantum HFP-512. It was darned hard to figure out what might be a direct-fit replacement, and I ended up coming across it in their eBay store for $79.98. It wasn't even listed on their company website. I bought it on the spot because I was so thrilled to see it for 1000% less than $769, you know what I mean? But, after I bought it, I found it on Amazon for $69.98.
https://www.amazon.com/Strainer-Replacement-1997-2001-65L-13907-00-00-66K-13907-00-00/dp/B01FWUT4J0

One caveat: The Mercury diagram for my 1998 Promax 300 shows the equivalent of the blue strainer in the pic I linked to. However, upon disassembly of my VST, the fuel pump that was in there was fitted with the yellow strainer in the pic. The Quantum pump comes with both the blue and yellow strainers. That said, the little hook-like tab on the yellow one that came with the Quantum pump was molded in the wrong orientation, so I ended up reusing the strainer that was on my original. Thankfully, mine was in great shape, even after 22 years. I'm going to call them on Monday and report it. Perhaps they don't know about it, or mine was just a one-off mistake, I don't know.

460190

I thought I would just use the blue one like it shows in the Mercury parts diagram, but the blue one is a little taller than the yellow one, so I didn't know if I should have used it, like if it might cause a fit problem, or something. Do you happen to know if yours has the taller blue one?

SUNKIST

03-08-2020, 01:50 PM

I dont know but have the old pumps ....will check. There also 98 mercs

Basnova

03-10-2020, 01:57 PM

Spoke to the manufacturer of the pump yesterday. They recognized the issue, and are sending me the correct one. I speifically asked if all the models I got came with the "wrong" strainer, and they said "No", so it must've just been a one-off thing. That's good to know for everyone else that needs to replace their pumps.

Basnova

03-11-2020, 08:53 PM

Ran it on the lake today. Warmed it up well, then took an easy pass. Removed cowl, no leaks. Reinstalled cowl and did a WOT pass. Checked for leaks again, and still dry. Pushed it hard on a couple more WOT passes. Got to about 80 and scared the crap out of myself (I only have a bass boat fish-n-ski model that's designed more for fish then ski). I don't know how you guys go upwards of 80mph without peeing all over yourselves!

Drove it enough to eat about 13 gallons, which goes fast with this motor, but it ran strong. So far, so good with this fuel pump! Wooo-hooo!

PP28

07-13-2021, 07:49 AM

Great thread - I just had this exact same issue happen to one of my 1998 promax 300's this past weekend. I did the same checks and ended up determining the high pressure pump was not turning on. I verified I had power to the pump. However, I had to play around with the positive and negative terminals to get it to turn on.

Had a few questions - If I leave the existing pump (now operational) and it looses power while under load, is there any concern with leaning out the cylinders resulting in damage? Or will the entire engine just quite due to lack of fuel with no long term effect?

Also, I'm considering replacing the pump and I looked into the $70 fuel pump you purchased. It looks legit - how's it holding up? Anybody got concerns with 3rd party parts like these? How can the quality be the same while also being 10% the cost of OEM? Or is OEM just way overpriced?

Apperciate any feedback.

Basnova

07-13-2021, 08:42 AM

Sounds like you have the EXACT same problem I had, since twisting the terminal posts got the pump running again. Obviously that's a common way that they fail.

The new pump has been solid, and having a lifetime warranty doesn't hurt, either, which I hopefully won't need.

Regarding damage as a result of fuel running out, I personally think that can't be good for any engine, but I seem to recall reading somewhere, perhaps in the manual, that killing power to a fuel pump is how you ensure the motor is completely void of gas for storage, or something like that. Not sure what the end result would be if you that's done too many times because, as you've mentioned, it's basically like running a motor on too lean of a mixture, and that can't be all that good. A short burst of lean might be OK, but of you keep running that pump and it keeps dying due to vibration loosening up the bad terminal post, that is likely not good for the motor. Now that I've done it, my recommendation would be to replace your bad pump, because the job was quite simple. Just be careful removing those short, bent fuel hoses on the VST tank, as they would probably be impossible to find if you damage one.

PP28

07-13-2021, 08:49 AM

Thanks for the reply Basnova.

With regard to the replacement pump, can you confirm the Quantum model # you used? The Amazon link above takes me to a Quantum pump designed for replacement on Yamaha Ob's. How did you determine it is the correct one for the 98 promax 300 which I believe is Merc part # 808505T01.

Basnova

07-13-2021, 05:53 PM

If I remember correctly, different Mercury part numbers succeeded others for the fuel pump, but I don't remember exactly which number succeeded which. But, I will tell you that I was in your shoes with not much help, so I did my homework and research, and stumbled across the Quantum pump. I can't remember the exact sequence of events but at one point, I spoke to a product manager at Quantum who said that the same pump is used across so many models for so many manufacturers, it was hard for Quantum to list all the applications and have people find those appplications on the web. But, trust me, it's the correct pump and fit without a hitch, aside from the screen in the box being the wrong one, as I mentioned above in this thread. Although I used my old screen, Quantum did send me the correct screen later, but I didn't want to take the VST apart again, just to change the screen.

Check out this listing on Amazon. Same pump, different description. Note that the part number you referenced is in the description on this listing. Even though the description on this listing says for 1999 year model, it cross-references to the part numbers that fit yours and my 1998 Promax 300s.

https://www.amazon.com/Strainer-Replacement-Outboard-1999-2002-808505T01/dp/B01FWUT3VE

Chaz

07-13-2021, 09:30 PM

I'm also glad that Mercury discontinued the fuel pump, because if they still had them I would have paid $769 for a $70 pump! Holy sh|t, talk about price gouging!

Your not sposta know that ... :icon_bs:

Your not sposta tell that ... :icon_bs:

Mercury has their own pump plantation , they only pick from once a decade .. :icon_bs:

The $3.00 ea. that Mercury paid for a cheaper quality pump in bulk , is worth the additional $699 ............... in peace of mind ... :icon_bs:

Chaz = thinkin , if you have the right hose and hose barb fittings , you'll be good to 250 psi without crimps-clamps-fancy tie-wraps ... :)

Chaz = uses the puny red and black fuel pump wires coming out of the PCM to trigger a waterproof Bosch type relay ... no matter what pump is used ... :)

Wait till you price out an O-ring kit for the Laser box or cylinder head O-rings ... :eek: You'll be convinced they got a rubber tree plantation too .... :icon_bs:

Ask them or one of their lackeys' about price gouging , they will try to answer :o as they're running away :leaving: at full speed .... yes , FULL SPEED ... :D

Basnova

07-13-2021, 11:37 PM

Chaz, I'm curious as to why you don't just go direct to the pump; why do you use a relay? To clarify, I know what a relay is, but why not just run from the key switch, why use a relay? Thanks.

Chaz

07-14-2021, 08:19 AM

When you go "key up" ... your not going from the switch to the pump. Instead your telling the PCM's to cycle the fuel pump and read all the sensors , as well as activate the ign circuit. So when you engage the starter ... everybody's ready.

Ever notice that the fuel pump wires have gotten hot , stiff and the insolation has slightly melted together .. if not fully ? Pure sign that they are too small for the job. As they become less efficient , they will start to work on the plug at the box , then the driver inside the box.

If you give them a new job , like running the low side or a relay , that circuit will live a long and happy life. Then let something like a twin gang 14ga. run the pump.

https://i.imgur.com/7VOBht9l.jpg