Mercury 150 black max identification

**Merc 2.5** · 12-23-2021, 09:30 PM

Originally Posted by SJD1974

When adding stuffers, do I need to change anything else with compression going up, such as running premium gas which I already do?

No need , also when I did the carbs and reeds. I left the vertical intake. Performed great. It's wild how much they choked the 150 down with carbs alone. Do u have a base # for performance b4 u do the swap ? If so u will b able tell exactly how much more mph u get etc

**SJD1974** · 12-24-2021, 02:17 PM

I don't have a base number. We have a issue with it getting up to speed say 53-55 but it would fall back to 43 or so and then speed back up randomly. We also had a issue with it running cold. That's when I decided not to run until I got that figured out. So for now we're replacing both switch boxes, putting CC reed's and putting on a 5.5 setback manual Jack plate and getting the motor at the correct height. Then I can get a base number and go from there. I have removed the black idle box and the oil injection and all its components.
Going to pull the carbs apart and go through them. Check the floats to make sure they haven't soaked up gas. Will to much fuel cause it to run cold? I have tested the thermostats they open at about 140.

**SJD1974** · 12-24-2021, 02:31 PM

I also replaced the poppet diaphragm and gasket. Has anyone ever seen the spring for the poppet get weak and open prematurely? I have cold water coming from the line circled in red at the bottom of the picture while on muffs immediately after it has been started. I had it disconnected from the thermostat lines so i could tell what was coming from it, didn't want the other water mixed with it so i could figure out what it was. Does the water from this line effect the running temperature of the motor?

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**SJD1974** · 12-24-2021, 04:08 PM

I hope to do the carbs once i find out how it runs. Will i be able to get out 60 out of this motor, our boat fully loaded weighs 1950 with people and .......... Just from your experience i ask this.

**rgsauger** · 12-24-2021, 10:21 PM

Not sure if you'll see 60 mph but should definitely be in the 50's...which I think is whole lot faster than you were, right?

**SJD1974** · 12-25-2021, 06:54 AM

Our best with this boat has been 54 and she was still pulling, had to slow down for no-wake zone. It ran like that for a couple of days for us. That was wright after i did the link and sync and adjusted the timing up to 19 by ear. Was running warm, close to hot side at that time which it never did before i made the changes. It changed when we replaced the impeller and i backed the timing off a little. Never ran warm again and would not go any faster than 50 and didn't get much above 5500 rpms and this was with the Quick Silver laser 2 21 pitch prop on which as you put it sucks monkey balls. LOL. This is all before any of the changes we are going to make. Adding 5.5 setback jack plate, CC reeds, moving motor up from 5.5 pad to prop center, going to go up 2 holes to about 3.5 pad to prop center, removing oil injection and idle control black box, we also removed about 100 lbs from boat in unneeded equipment, replacing both ignition box's with these https://www.amazon.com/dp/B0000AYZ7L/?coliid=IKG2M3F3HED5T&colid=36PDYLTPPW21R&psc=1&ref_=lv_ov_lig_dp_it. and finally adjust the timing up to 23* from 19. With all these changes i hope we can get another 5 or 6 mph out of her, fingers crossed.
Is there a better place to get the switch box's from?

**SJD1974** · 12-25-2021, 08:33 AM

Merry Christmas all

**Merc 2.5** · 12-25-2021, 03:41 PM

Originally Posted by SJD1974

I hope to do the carbs once i find out how it runs. Will i be able to get out 60 out of this motor, our boat fully loaded weighs 1950 with people and .......... Just from your experience i ask this.

Really depends on weight of the boat. My 150 was on a 15ft bass hull then and it went over 60. Urs being 18ft , not sure bout weight , idk it may be close to knocking on 60s door anyway. That's also with the right setup , if setup not right nothin gonna help much

**SJD1974** · 12-25-2021, 04:41 PM

Well we have weighed our boat with all its contents for tournament, She comes in at 1700 + 400 for passengers=2100. I plan to have the setup on this boat down to its best. My son will be out on his own with it in a few years and it has to be at its best!!!!!!! He is learning on the way through this so he will be able to take care things himself if he has to. Its nice to have a weigh scale down the road.

**SJD1974** · 12-25-2021, 04:42 PM

By the way that is 3 passengers.

**SJD1974** · 12-25-2021, 04:52 PM

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Didn't even make it 5 miles down the road and he had to have a picture with his new boat

Surprisingly he has not said anything about a picture after all the polishing of everything. You have to wear sunglasses now to look at it in the sun.

**OnPad** · 12-26-2021, 05:00 AM

Your boat looks to be in good shape for it's age. It sounds like you and your son are stoked. I would of been thrilled to have something like that to fish with as a younger adult.
In order to achieve top performance and not damage your engine. You need to do your timing with a timing light. First step would be to index flywheel. A set of dial calibers works almost as good as the special adapter and dial gauge. There is some good threads on site explaining process.
A dva adapter and multimeter is invaluable in trouble shooting most electrical problems.
Your temp sender is usually mounted to the surface of the cylinder head. In all the mercs I own it's factory installed. All I had to do is hook up a gauge to the brown wire in harness up at the control box or dash.
My neighbor had the same boat with a 110 Johnson on it. Later repowered to a four stroke Yamaha 150.
I spent a bit of time fishing out of it with both power sources. It ran almost 50 with the johnson.
It ran close to 60 with the yamaha. It had a bad tendency to want to hop over 30mph with the yamaha on it. It was also one of the wettest boats I've been in.
Invest in some good rain gear and eye protection if your tournament fishing in foul weather.

**SJD1974** · 12-26-2021, 08:35 AM

It was the idle timing that i adjusted. I have since purchased a timing light to do WOT timing.
I am a machinist so i have no shortage of instruments.
I have a DMM as i used to be a diesel mechanic and had plenty electrical issues to trouble shoot.
As far as engine temp, we install water temp sender in the top of the engine where the water pressure line comes from and put in new gauges for both water temp and water pressure, gauges with number values on them, so i can actually see what things are at.
While i am operating the boat i like to know exactly my engine is doing!!!!!
I used the brown for my new sender and gauge but have been thinking i will run e separate wire the it and reconnect the brown to the temp sender in the head for the temp warning horn which i have told by a marine mechanic doesn't work.

We had a 17 ft Polar Craft powered by a 70 hp Evinrude four stroke that topped out at a solid 30mph that was the boat we had before this one for most of last years tournament season, for us that was a WET ride, we immediately purchased rain gear the first nasty weather tournament. We only had the Bass Tracker for three of our 27 tournaments, just enough to get to know it a little.
First trip out with it and we hit 54 MPH, my son was blown away almost literally. Through the time we had it out we found it would randomly run up in the low fifty's and then just drop back to mid to high forties and vise versa like somebody flipped on the nitro switch.
We never have been able to say we have a true base line or top speed.
We have been told by other boaters we fish with that if we bring the motor up we will gain a few mph with just that.
It is currently 5.5 inchs below pad, measuring pad to prop center.
I could tell you all the symptoms we are having and what are doing to fix them but that would be a lot. I dont believe you want to read all that. So i have just given a little.

Thanks for your info and i will definitely use it.

**SJD1974** · 12-26-2021, 12:10 PM

One quick question, when i purchase the CC reeds the sport model says 6500rpm, does that mean max rpm? And is possible i could go over 6500 with mods i may do in the future?
Thanks

**OnPad** · 12-26-2021, 02:19 PM

You can adjust your rpm with the prop you are using.
I had pretty good luck with a 25p laser on a mariner 150 (2.5L) mounted to a 16' champion ran in the low 60s. The laser prop is not that much different than a fury ( used on alot of new bass boats) just not as much blade area, and alot cheaper. Laser start having trouble when mounted high.
I wouldn't worry about your new reeds.