92 black max 150 3800 WOT

[Sailormike22]

Hey all. Been getting closer on my 92 procraft 200 combo but could use a little help. I have read thru hundreds of topics but now it's time to start my own.
as the above says my 150 just won't get above 4k and im not sure where to look next. Here is a run down on what's been done so far..

Compression 115-117 on all 6
New CDI switch boxes
New CDI trigger
New CDI stator
Fresh plugs
Carbs cleaned
new water pump
New t-stats
And more
primer bulb is full and hard when wide open

The last thing I did was the stator, before that it would cough, and bog down at about 2k. With new stator it runs nice and smooth but only at 38-4k?
Should I go thru the carbs again? Going to check my link and sync this afternoon but I'm a little confused about the high side timing. Should it be 18 or 22 when on the hose?
Also wondering about the prop. The 92 procraft 200 combo is a HEAVY boat. 1900 lbs on spec sheet. Add 2 people, full bait tank, and beer I'm probably at 2500 lbs. It currently has the 21p laser 2 prop. Should I try a 19p? Or look elsewhere?

Thanks for any help..
Mike

[bullet123]

Probably a link and sync issue. Make sure carbs open the whole way and even. make sure trigger is advancing the proper distance and at the right time. 22max timing on on #1. do you still have oil injection and retard boxes on?

[Sailormike22]

Thanks for the response.
When you say "at the right time" can you clarify?
And yes, oil injection is gone and so is the idle stabilizer.

[bullet123]

Do you have a mercury manual?

[Sailormike22]

123 Yes, I have a manual. It was a free download, 800+ pages but it appears to be the factory manual.
Triple checked link and sync, re plumbed bleed lines per manual, re cleaned carbs (they were spotless the first time I tore them down and still are, although I did set them about 1/16" proud of bowl face) , WOT timing 22 degrees static, more new plugs. All this made no improvement.
Since one of the things I haven't done is the fuel pump I tore it apart today and will pick up a kit tomorrow. But I couldn't see anything wrong with it....

[Sailormike22]

Bit of an update. Since my last post I found out ALL my coils are bad! Didn't pay any attention to them since the all fired and looked like decent spark. Turns out they were all shorted and cracked ��. The rest of coils and wires should be in today.
BUT. Here's the real kicker! Something told me to check the jets so I just checked the ones I could get to easy and the mains on the top are .054 and .096! What the !!! So I checked the vents and they were both .046. This is weird, so I checked the next one and they were all different.
So now it looks like I need to order a whole set of jets!
Should I stick with what the manual says is stock for the WMH 1? Or any other suggestions
Thanks

[Merc 2.5]

Any mods done? Runnin airbox?

[Sailormike22]

I don't have any history on the boat. But the best I can tell it's all stock apart from maintenance items

[Merc 2.5]

If the air box is on it, I'd prob go 1 size bigger on the mains and keep rest factory. Mainly because of thses days fuels ain't as gud. Maybe sumone will back me up on this. If airbox is gone then u will need raise couple sizes

[Sailormike22]

Yes, airbox is on and stock

[Merc 2.5]

Go back what the merc man says or size bigger .002 on the mains

[Sailormike22]

Thanks Merc 2.5, will do
Just curious, is there any reason for someone to run two different size mains (.054/.096) ? I know I did not mix them up so had to be a P.O. somewhere down the line
Also, can someone confirm that I'm looking at the correct jet sizes in the book? Here is what I'm seeing ( top line in spec sheet)

421587

421588

421592

421586

Sorry about the pics. I'm better at turning wrenches than I am at computers

[Merc 2.5]

Ya kinda wiered all over. I see a wmh 1a 2a 2a. Should had been a 3a. Dnt guess that really matter but sounds like u need go by book and put correct jets n correct places,

[Merc 2.5]

Is the mains only jets messed with?

[Bruce2]

This is directly out of a Mercury oem manual...

421593

[Fishwhisper]

I would think changing out the clear fuel line that is inserted into the black fuel line and fastened with a zip tie would be a good idea too.

[rock]

Ya might wanna consider getting a set of number drills to see, in fact, what they really are. I have seen so many drilled out over the years I wouldn't even think of trusting what is stamped on them. That is of course unless you have already confirmed the size. There is no reason for anyone to use 2 jets in the same carb that far apart in size.

Rock

[Merc 2.5]

Ya might wanna consider getting a set of number drills to see, in fact, what they really are. I have seen so many drilled out over the years I wouldn't even think of trusting what is stamped on them. That is of course unless you have already confirmed the size. There is no reason for anyone to use 2 jets in the same carb that far apart in size.

Rock

This is so true. Unless u pull then out of a pack new ,they r not to b trusted unless measured. I have drilled sum myself but I keep those in a separate bag labeled now.

[Sailormike22]

This is so true. Unless u pull then out of a pack new ,they r not to b trusted unless measured. I have drilled sum myself but I keep those in a separate bag labeled now.

I was thinking about that. I have a new set of # drills and will double check the sizes with that, maybe I can use some of the jets if they check out ok. Measuring with calipers quickly turned into a waste of time lol.

[Sailormike22]

Is the mains only jets messed with?
It looks like all are whacked?!
These #'s are before checking with drills

421670

421671

Carb #3 is same as #2

Also, can I just eliminate the backdraft/bowl vent all together an all carbs? Or maybe use the .096 in that spot?

Thanks everyone

[bullet123]

.096 is too large for a 150. Probably fouling plugs on the cylinders being fed by those carbs. I run WH-46s on a highly modified 2.5 200 and .088 is my largest jet. I have some spare jets. Let me know what sizes you need and I will see if I have them.

[Merc 2.5]

It is crazy how you 96 in the mains. I'n order to drill a 96 jet for a 150 I'm thinkin it would need be soldered up then drilled to rite size. Maybe sumone was missing sum jets and just threw sum n it to try run it. Not sure. The stamp on the jets same as on the paper?

[Sailormike22]

Yeah, it was stamped correct!
Update, think I figured out what's going on. These are wmh 1 and 2 from a 1990 which is supposed to have .062/.064 mains, .044/.044 prog air, .040/.044 idle air, and .080/.084 back draft

The motor is a 1992 that is SUPPOSED to have wmh 13's the book calls for .064 main, .048 prog, .050 idle and (.096) back draft!
Other thing that's weird is I have the emulsion cap/plug that is supposed to be in the wmh 13 and not the tube style that the wmh 1 and 2 show??
Anyway, yesterday I juggled things around and now have .068 in main, .056 idle, .070 prog, one .096 back draft.
Took it to the ramp, it was blowing too hard for a test ride, and it did MUCH better. It stumbled a bit coming off idle and only got to 4k, but it STAYED there instead of surging. I suspect it will rev higher when not tied to the trailer.
At least I feel like I'm on the right track, after replacing the entire ignition system (it was all bad) I'm ready to go fishing!
A little tweeting on the jets and I should be good, fingers crossed!

Thanks for all the help. I'll let you know what happens when the weather clears

[Merc 2.5]

Almost all the carb motors I've ever owned had a stumble on 1st startup/blastoff of the day. I think it's got alot to do with gas and oil in carb bowls from the previous run. After the initial blastoff prob wont do it again rest of the day. Thus is just my experience over the yrs, also seem to be the 135/150hp that always done it the worst,

[nitro_rat]

A lot of times there isn’t enough cooling at idle speeds. If you’re launching the boat and idling through a no wake zone, when you first punch it the poppit dumps and lets a surge of cold water hit the cylinders. This is many times the cause of that stumble. It can also result in what is often mistaken for a “cold sieze” in extreme cases!

Mercury never did sort out the cooling on these motors. If you look at an old 2.0 or 2.4 you will see the boss down by the poppit that was the original thermostat location. When this failed to flow enough water in pre-production testing the ‘stats were moved to the heads as a stopgap. The patch stuck and all through the development of the V6 the cooling system was tweaked here or there but it never really was “fixed!”

[Sailormike22]

Thanks for the explanation, makes complete sense and certainly something I can live with.
Got it out yesterday and it did GREAT!! ���� can't tell how good it felt to throw the hammer down kind it actually come out of the hole and turn 5300@45 mph!!!
The only problem was it ran real rich, at idle, at first and by the time I got back an hour later it wouldn't stay running at idle, like it was too lean at that point? Remember, my idle air jet is about .015 bigger than it should be (supposed to bo .040) if any one has a few .040 Or .044 laying around?? Can't find any in stock anywhere. Don't want to run too lean at this point.
I'm guessing the thermal air valve is what caused this and that I should adjust mixture with TAV disconnected? I'm too close to melt anything at this point.