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94’ Johnson fast strike 150 J150glerv

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Baxter83

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Ok, I’m stumped.

From cold my engine fires right up and purrs like a kitten. It’ll idle and/or run for just long enough to get warmed up then bog down like it’s starved for fuel. I had a similar issue last year that ended up being the power pack, so assuming (like a dummy) I just got a bad pack that didn’t last I swapped it with another new one, but it didn’t clear it up. So from there I’ve checked compression which is good on all 6, I’ve checked fire on all 6 and it’s good. I also put the muffs on it to try to replicate the problem in the drive which was successful, and I still had good fire on all 6 (I thought it might be going into a limo/safety/whatever mode and killing some cylinders). This tells me it’s fuel. I have the vro oil system, but have had it disconnected and plugged off for years. Here’s where I’m stumped. Why would I be getting a fuel issue when it’s warm only? Carb bowls warping and making floats stick closed? Am I starting off looking at the right stuff?
 
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Have you tried pumping the fuel bulb when it starts to bog down? That would let you know if it is the fuel pump.

And be sure your gas tank vent is not blocked or closed off.
 
You can actually just loosen the gas cap, to vent the tank. If that fixes the issue then your vent is most likely plugged.
 
Alright, I took the cap off and thought you might have nailed it, but after a little while of idling I noticed the idle change sound (like from a cammed up 350 to just pop pop pop pop pop) then it died. Before it died I tried unplugging temp sensors in hopes that maybe one of them is bad, but nothing changed. I could touch the heads (not for long), but don’t think it’s actually getting hot though I don’t have a temp gun to know for certain.

So I fired it up prior to this, then turned the engine off for a minute, then fired it back up again and got an alarm. Beep….beep….beep….beep. Not a solid alarm. Isn’t that dealing with fuel flow?
 
Pretty sure a beep every second or so is VRO oil restriction. Solid beep is overheating OR fuel restriction. Beep every 20 seconds is low on oil.
 
riopga said:
Pretty sure a beep every second or so is VRO oil restriction. Solid beep is overheating OR fuel restriction. Beep every 20 seconds is low on oil.
Click to expand...

It’s a beep every second or two, but I’ve had the vro disconnected and plugged for several years.

I ordered a service manual yesterday, so when it gets here I’ll find whatever I’m missing.
 
So I think that the issue is over-heat. I still haven't put the thermometer to it, but it feels hotter than I think it should at each head, plus it's been 3 years since the impeller was changed. I went to change it out, but realized while I was in there that the seals and whatnot need to be changed as well, so I'm waiting for them to get here as well as two new T-stats. I have already had the cylinder water intrusion problem with this block at the glue line and had it welded and re-machined/sleeved, and I'm not seeing that any of my cylinders or pistons have been steam cleaned, so I don't think that this is the issue again, but I'm still just stumped.
 
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Baxter83 said:
So I think that the issue is over-heat. I still haven't put the thermometer to it, but it feels hotter than I think it should at each head, plus it's been 3 years since the impeller was changed. I went to change it out, but realized while I was in there that the seals and whatnot need to be changed as well, so I'm waiting for them to get here as well as two new T-stats. I have already had the cylinder water intrusion problem with this block at the glue line and had it welded and re-machined/sleeved, and I'm not seeing that any of my cylinders or pistons have been steam cleaned, so I don't think that this is the issue again, but I'm still just stumped.
Click to expand...

So, the over heat wasn’t it. Still does it with temp sensors out of circuit. I went ahead and replaced the impeller, water pump housing gaskets, and thermostats anyway. The vacuum switch seems to be working. The other tan wire stuff seems to be working correctly, but the problem is still there. I did find that there’s a bolt on the lower port side carb plate that is backed out, so hoping that this is heating up, opening up for air, and causing it. Please chime in with opinions. I haven’t pulled the carbs yet.
 
Did you test the temp sensors by grounding them to set off horn? Even with a new impellor etc the internal passages can be blocked.

Are the carb bowls plastic? They can warp and allow air in. You can grind them down on sandpaper on a piece of glass to even them out.
 
riopga said:
Did you test the temp sensors by grounding them to set off horn? Even with a new impellor etc the internal passages can be blocked.

Are the carb bowls plastic? They can warp and allow air in. You can grind them down on sandpaper on a piece of glass to even them out.
Click to expand...

I did not ground out the sensors to test, but I did flow water with a garden hose through the head passages and through the thermostat passages and they were free of obstructions.
Yes, carb bowls are plastic. This will be my next step…
 
I haven't followed up on this post in a while, mainly because I still haven't figured it out, and also because I have embarrassingly overlooked some obvious stuff that some of you that commented mentioned. So, since the last post I have done the following...

1) Determined that it is a fuel delivery issue because pumping the bulb when it starts to change tone at idle will recover it and it will idle good again. (muff testing, not on water). Apparently I just had to put more effort into it than I was prior to answering that very first response to my thread... :/
2) Rebuilt the fuel pump with all new seals and diaphragm as well as thoroughly inspected it for cracks in the housing. It is good
3) Replaced the entire fuel line from the pickup tube in the tank all the way to the cowling as well as a new bulb.
4) Rebuilt all of the carbs and corrected any warping in the bowls. Also found a few of the little pressed in ball bearing things were leaking and fixed that.

So as of now I only have the primer and vapor separator left to examine more thoroughly and/or rebuild. I have already had all of the fuel lines off and inspected them, and they're good.

Question: Now that I know that it is dying due to fuel starvation and knowing what all I have changed out, does anybody have prior experience with vapor separator or primer solenoid problems that has caused this?
 
I could be wrong, but I think that the powerhead I have doesn't exactly match the model number on the transom tag. I think my problem the whole time was hose routing to the vapor separator pump and I hooked it all back up based on the model number on the tag, but according to the exploded views of parts on this site what I have better matches a 98'model ELxxxx. All I have to go by is the serial number on the block, but nobody can decipher it anymore. Anyway, I tested on the muffs late last week and it never starved for fuel after I switched some hoses around.
 
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