Merc. 225 EFI 3.0L 2-Stroke Spark Plugs

[CNC_Guy]

Rudy, get out you Hoser!

[Chaz]

Put a toque on if you know what that is.

I'm still tryin to figure out what all that white clumpy stuff is on the ground, every time it rain's up there ..

Ifin ya never cleaned that screen , chances are it's way past due ..

[Rudy]

It's Thanksgivings here so a little cheer is called for. Today is nice and sunny but it's about 30f but then I live in the mountains at a ski resort so it's supposed to be getting cold. But down on the ocean today it would be very pleasant. I know Chaz you hate Champion plugs but I just received an email from Mercury Outboard Customer Assistance and they think it is RFI on the ECM and that I should at least try the QL77CC plugs. But I will also have a look at the VST screen and also make sure there is no fuel coming out of the VST vent.

[Rudy]

Okay Chaz you were right about changing spark plugs the champions didn't make a difference. It still ran rich and wouldn't reach wot. and when I got to my cottage after 30 miles, idling through the bay it was rough and almost stalling and black smoke out the rear. Prior to the run I checked the VST screen it was clean and made sure no gas was coming out of the VST vent. I would also like to add that the day of my test if the air temp. and MAP sensors weren't working the ECM default setting should have perform properly as it was around 32f outside and of coarse at sea level which are the default settings. This now still leaves me with the head temp. sensors and perhaps the fuel pulse pump diaphragm which I have read could get a small hole in it allowing fuel to leak into the crank but at the same time wouldn't that effect the performance of the pump and not pull enough vacuum? What are your thoughts on the Brucato ACU for $1000. or the

Mercury 250 EFI Outboard MAGNUM Dyno-Boost Boat Performance Chip

$200?

[Rudy]

I am glad to be able to finely close this chat on my running rich fouling plugs thing. My problem after putting a DDT to test all my sensors and finding them all working properly it turned out to be a clogged fuel regulator screen. This caused the fuel pressure to run at 60 psi instead of the 42-45 psi for normal pressure. Since the fuel injection is a timed action the higher psi allowed too much fuel at all RPMs. I hope this can help others that have the same problem.

[texsurf]

Hello, I am having the same problem as you.. Where is the fuel regulator screen located??? Thanks

[Rudy]

Hi texsurf the fuel reg on the 250 efi is on the left side above the fuel filter with only 2 screws holding it inplace there is a hose with only a zap strap on it which I cut and remove the hose and the pressure reg just comes straight up with o-rings to seal it very easy. take it out and the screen is on the bottom.

[tjones99]

Rudy, Chaz and all… Huge thanks for this thread. Rudy, thanks for taking the time to followup and post your solution.

I have a 2002 Mercury 225 EFI used for water skiing. Lately been running rough at idle. Running great pulling skiers, but feeling like fuel consumption is higher than normal (hard to tell with water skiing, we burn a lot of fuel in a weekend and don’t really pay attention but it just “feels” like its using more than normal)

Sometimes it would idle OK, not good, just OK… sometimes really rough, sometimes stall. Didn’t matter hot or cold. Often smokes a LOT on startup… more than it used to for sure.

Was just looking this up to see where I should look and ran across this thread. Noting all the places I have to go and came to the regulator part… hmmm… dead simple to remove and check… It is located on the top of the VST or Vapor Seperator Tank hase a thin line connected to it and a dimple in the top and two screws holding in place. (full removal: remove cowling, pop off plastic flywheel cover, one screw on the front to lift off the air intake cover to get access to the two Philips/slot head screws that hold the regulator in place and popped it out. Did not remove the cable tie on the hose to the regulator, was able to life the regulator up and out the front to get full access to it)

Here is a picture of the VST with regulator circled.


Here is a picture of a regulator and you can see the screen areas. Not exactly like mine but close enough.



When I pulled it out I was expecting a screen still in the hole under the regulator but it was part of the regulator. I looked at it and thought it looked fine. Then I poked it gently with my Philips screwdriver and the nice “even” dark colour MOVED and revealed a clear looking nylon screen underneath. I swear it looked like a nice thick “lint” covering all sections of the screen. The nylon screen looks fragile so I used a gentle toothbrush and some naptha (Coleman fuel AKA lighter fluid) to clean it. I have not had a chance to test it but looking at what was under there that was certainly a problem that HAD to be addressed.

That may just have been a 15 minute job that saves me a fortune in fuel and makes things run a lot smoother… can't wait to test it and see...

[Chaz]

Seven year old thread .. LOL
Lets see , 1 filter in the boat . 1 filter hangin off the VST . 6 injector filters .. yea 8 filters ..
Deff gonna need the 9th one under the regulator …

If anyone is concerned about R.F.F'in with the ignition box .. then put some good spiral wound plug wires on .. instead of 20 year old .. straight wire cored dry rots ..

BR8HS plugs are $1.90 each .. you can throw away 4 sets, for what one set of skinny wire plugs cost ..

Ifinya buy the -10 NGK plugs. It doesn't mean that there are 10 in a box .. It means that they are pre gapped to .03937 or 1 mm . Big gap , 20 year old wires .. yea , might make a lil R.F. noise … LOL
Close the gap on any plug you choose (BR8HS) down to .028 - .030 and change em every year along with your water pump impeller ..

Chaz = thinkin, Merc won't say .. yea we sold them motors with the wrong wires and no R.F. filter in the ign box , so we gonna make ya buy $ 8.00 a piece plugs to try and cover our early mistake's .. I like the shuffle dance the Merc tech czar's do when I tell them that …

[tjones99]

Seven year old thread .. LOL
Lets see , 1 filter in the boat . 1 filter hangin off the VST . 6 injector filters .. yea 8 filters ..
Deff gonna need the 9th one under the regulator …

I admit it sounds silly... but then again, there was mine absolutely plugged with "something" and I have a water seperating filter in the boat and one hanging off the VST...

So on the subject of spark plugs... Whats your theory in suggesting changing the plugs every year? I admit that I typically use a plug forever until it actually fails. Yes, I check the gap. Yes if they look bad I will change them and if that soon looks bad I will try to figure out the root cause. But if a plug comes out nice toasty brown in colour and otherwise clean doesn't the "if it ain't broke don't fix it" saying come into play?

That was what my father taught me and as I grow older I am learning that a LOT of what my father taught me that was WRONG when I was younger turns out to actually be right as I get older... but thats just the way kids are I think... And I am asking you not to be contrary, but in hopes of learning still even as I grow older...

And even though I am new to this forum, from comments I read and from this thread alone you are a source of information so thank you Chaz.

[Chaz]

Jones ,
I look at it like this ..
It took 20 years to clog that little filter . Yes I know that it's better to clog it up instead of the little basket on top of each injector , have it go lean and kill the motor. However I don't think it's a good idea to let the motor go for 20 years without being serviced ..
Most people do lower unit oil , water pump , plugs , fresh gas and injector cleaning once a year. It's a good habit to get into .
When I was a kid , I "had to reuse" old plugs. My dad thought anything that burned gas was only meant to drive back and forth to work , anything more than that was a waste of money. As a kid in He11's kitchen , he stood in line for a bowl of hot water with a piece of ham in it during the crash of 1929 . Sadly the horror of that never left him , but I wasn't about to let that hold me back from my love of motorsports ..
Part of that was to learn early on that the plugs are "the window" of what's going on in the combustion cycle . And the only way to see .. was with a fresh plug . By the time the tip has turned paper bag brown or cinnamon colored .. the hydrocarbon ring at the base has been covered up . So it doesn't bother me to buy 5 or 10 boxes of plugs at a time and "arrive" at a tune up . Which might call for a #7 in one hole , a #8 in three holes and #9's in the bottom two holes. I never think I can tell the motor what it want's .. I've learned to let it tell me what it want's .. we get along much better that way ..

[tjones99]

100% agree that spark plugs are the window into the health of the motor... which is why I figured if they looked fine just keep monitoring and looking for change... I will ponder your approach...

I suspect I am shy of that approach because once (and only once) when I changed plugs I actually got a bad plug right out of the package and thats not something you really expect and it caused grief for a while because I really wasn't expecting that...