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1992 Evinrude 60hp struggles at WOT

J

jspeciale

New member
I recently rebuilt the carbs and installed a new fuel pump on my 1992 60hp Evinrude. Since doing these changes the motor will loose RPM then surge at 3/4 and WOT, it repeats this until it sounds like it's going to shut off so I throttle down and it runs fine. It will get on plane just fine, then about 5-10 seconds after it starts doing it again. I can pump the gas valve by hand and it goes back to normal for a few seconds and then back to surging.

I checked all the gas lines and took the carbs apart again, don't see anything obvious. The VRO2 was originally replaced with a OMC #318374 fuel pump. I took the old pump apart and was going to rebuild it but could not find a gasket kit or a new one that matched the part number. I bought a #438559 pump, could it be sized wrong or disfunctional out of the box?

I never had issues with the motor acting like this until I did the recent work. My next step is replacing the hose and valve from the gas tank to the motor, if that doesn't work I will get another pump. Is there a cross reference # for a replacement 318374 pump? Is the 438559 appropriate for my motor? Is there a way to test this fuel pump? Are there other possible reasons for the motor acting this way?
Your help is greatly appreciated. Thank you
 
You should have full speed while pumping the sqeeze bulb, that would then be a supply issue like fuel pump then. If bulb won't help when it is pumped and becomes hard, then I would suspect partially restricted main jets. Did you just blow through them or did you physically clean to original and correct opening size? This is often the problem. Another thing, if the sqeeze bulb won't pump up properly and get solid, then there is a restriction at the fuel tank, or perhaps a vacuum leak between the bulb and the tank. That includes the vertical tube/pipe inside the tank.
 
At full speed if I pump ball it doesn't surge or bog. I installed brand new fuel pump and completely took apart carbs took jets out and cleaned them. The bulb pumps up, I wouldn't say hard as a rock. If I pump it while boat is sitting in my garage and check it an hour later it seems to lose pressure, is that normal? As I said all worked until the new fuel pump was installed. Is there a possibility the fuel pump does isn't the correct one? Is there a way to test the pump to see if there is an issue with it? I know it sends fuel through, but not enough at full speed
 
So the pump was installed and the problem began? It ran fine before the pump replacement? May sound like a foolish question, but why was the pump replaced? Did it have symptoms coming on that were similar to what you have now? No it shouldn't loose pressure while in the garage and the motor is vertical. If the motor is tilted, the fuel will bleed past the float needle and loose pressure as the fuel drips out. Unlikely it's the wrong pump unless it's got a smaller fitting on the intake side. The best way to test the pump by the process of elimination. Factors like engine compression, fuel tank issues.....inadequate venting, vacuum leak...etc..., defective squeeze bulb, defective fuel supply line, dirty fuel filter, and contaminated fuel......all to be factors when determining the health of the fuel pump.
 
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I was going to clean the pump and replace the gaskets on the pump as general maintenance but couldn't find the ones to match OMC #318374. So I bought a new pump and installed it. It may have bogged down once or twice over the last couple years but nothing like is happening now. I will the gas tank and try a different fuel line and new bulb.
 
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