Engine refuses to go full throttle

[fmjnax]

If it's not one thing, it's another. I have been fighting a lean sneeze at idle. Everything was fine otherwise. I decided to pull the carbs and soak them for a few days to try and fix that problem. I reassembled and headed to the lake.

Everything was going as normal and we idled/slow trolled around the cove to see how it was going. Sneeze was gone! I punched it to get on plane and the boat bogged down and died. Wouldn't stay running unless I held the choke and it wouldn't go above 5mph.

So I held the choke and headed for shore. Beached it and pulled the cover. Nothing seemed out of place. My choke solenoid has a red lever (I guess for manual start). I turned it to the other position and sure enough, she ran. I headed out to deep water and idle/troll was good... or so I thought. Something didn't sound right, but I thought it was because the cowl was off. Punched it to WOT and... it didn't want to go. It would go about 6mph and no more. Every 5-10 seconds it would go high RPM like it wanted to hit full throttle but it would immediately bog down. While the throttle lever was on full, I reached back to the bulb. Still hard and good. If I pumped it, the RPM's would increase but not even close to full.

Headed back to shore and noticed something I didn't the first time. One of the barbs on the choke solenoid was broken off and the hose dangling. Fuel was constantly squirting (which I now know was because I turned the red choke lever to manual... which is also why the motor would idle without holding the choke... and probably why the motor sounded odd. So I pulled out the trolling motor and headed to the ramp.

Such an interesting evening. Anyway, would the broken barb on the choke cause this problem? My gut tells me that the motor was starving for fuel. Why, I don't know. When I reassembled the carbs, I did the blow test upside down and rightside up to make sure the float was seating properly, which both were. I made sure all passages were clean and free. The only thing I did different, which I wonder could be a problem, is I used a gasket compound on the bowl gaskets. Don't ask why I thought to do that as the old gaskets are still practically brand new. I was careful not to put too much or block any passages, but I wonder if tightening down squeezed some out and may have blocked a passage (just my luck!).

Suggestions, thoughts, ideas?

The motor is a 1984 Johnson V4 115, but it has parts on it from other model years (previous owner Frankensteined it).

 

[fmjnax]

Sorry for the lack of formatting. Posting from my phone and it seems to have dropped paragraph breaks.

 

[emdsapmgr]

If the fuel primer is in the "run" position, the broken primer hose barb will only be a problem when you choke the engine. That system is sealed when normally running, except when the engine is choked. When choked, it will leak fuel pressure and fuel which could deprive the carbs of some needed fuel (not a lot, but some.) If you were starting the engine cold and tried to periodically choke the engine to keep it running (first minute or so) that could be part of the lean sneeze you note prior to the engine fully warming up. One carb would be running lean when cold. If you are running the fuel primer in the "service" position, the system can leak fuel all the time the engine is running (fuel system is pressurized.) That engine must be run with the fuel primer in the "run" position only. If the engine still does not run properly, it's likely the problem is unrelated to the fuel primer system. Most of your time thus far appears to be with the fuel system. Have you checked to see if you have spark on all 4 plugwires when the engine is fully warmed up? Possible it's only running on 3 cyls. It's hard to tell the difference between 3 and 4 cyls firing when that engine is idling. Gasket sealer is not required on the carb bowl gaskets, but I doubt that is contributing to your running problem.

 

[fmjnax]

Spark is good and strong across all 4 cylinders. Spark plugs are new as of last weekend. Compression is also good. The boat ran fine last weekend (aside from the lean sneeze). The only thing different is that I apparently broke the choke faceplate and I used a gasket compound on the bowl gaskets. What's strange to me is that the boat idle and trolled around perfectly fine right off the trailer. As soon as I went WOT, it bogged and died. From that point on, it would only run while choked and never at WOT.

 

[fmjnax]

Ok, so I think I may have been right about the gasket compound. Even though I used a minimal amount (or so I thought) and let it sit overnight before tightening, it squeezed out. Apparently gas dissolves the stuff and turns it to a goop, too. Pulled the carbs, removed the bowl, and this is what I found. Jets were plugged, the float appeared to be plugged, and the stuff was everywhere in the bowls. I cleaned out as much as I could and the carbs are now soaking in some Berryman's. I won't know for sure if this was the culprit until next weekend, but I'm at least 90% certain. It's clear to see how fuel flow might have been impeded.

 

[fmjnax]

It's been a while since I've been able to get out on the water, but I was able to this past Friday. Suspicions confirmed, using the gasket compound was a huge mistake. With it all cleaned out and the choke plate replaced, the problem was gone. Good to go in that aspect.

 

[fireman57]

Only gaskets on a carb and heads. No sealer at all.