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Poor performance after fuel pump rebuild

N

NaymzJaymz

Contributing Member
Hello,
My latest issue has to do with my attempt to rebuild the fuel pump on my 1980 Evinrude 25 HP motor (model #E25RCSA). I used Sierra kit #18-7820. When I finish reassembling it the motor fired right up and ran fine for a few minutes and died. I pulsed the bulb again and refired it and it ran great at moderate throttle for about ten minutes before it died again. When I remove the bolt screw at the bottom of the carb only a small trickle came out. In other words, no gas. Any ideas what I did wrong? All the gakets only go on one way. I put it together exactly as I took it apart. Why did the unit run for ten minutes the second time I fired it if the pumps not working? The fuel pump in the parts catalog at the top of this page doesn't include an exploded view of the actual pump. Was I wrong to try and rebuild it? The old diaphram and the gaskets were all in pretty bad shape, so it probably needed to be replaced. At least it didn't die before. I may mention that there is a small section of clear tubing in the fuel line I was using, and I never saw any interuption in fuel up to the pump. As I've said before, I'm no mechanic, and I usually have to do it wrong the first time. Any help would be appreciated. Thanks
 
Thanks for this link, Davie, I will check it out. Meanwhile, I just loosened the screws all the screws and then tightened them back down, and now it works. Thanks again.
 
I am really pulling my hair out over this one. I notice in the link that daviet gave me that these are fickle pumps and maybe I shouldn't have messed with it(my pump is a different style than the one in the link).The motor runs fine, and at times I gently pull the fuel line off the pump and the fuel is shooting out. Then it will suddenly die and there is no fuel in the carb. Sometimes it runs for 5 minutes and sometimes for 10 minutes or so. I'll mention again that I used the Sierra rebuild kit. This is a major supplier. Perhaps I should buy the new Sierra pump in the parts catalog at the top of the page. It seemed so simple to unsrew two flat pates and put new gaskets and a diaphram in. What could I have done wrong? Why does it work for a while before it dies if I rebuilt it wrong? I've tried two different fuel tanks. Maybe there's no exploded view of the pump in the parts catalog because it's better just to buy a new pump. Any more help you gentlemen could treat me to would be greatly appreciated.
 
I have used the sierra kits before without problems.
To eliminate the fuel pump, can you set the fuel tank higher than the engine and let the fuel gravity feed to the carb, bypass the pump and start the engine. Will it run properly with gravity feed? If it does it sounds like you have a pump problem, might save your sanity to just go ahead and get a complete pump.
 
I had a similar problem with a 79 25hp. Turned out the fuel line running from the fuel pump to the carb had been replaced and was a shade too long. The fuel line made a 90 degree turn up to the bottom of the carb and the excess length made the line crimp there. No way I could see the crimp but a simple shortening of the line fixed my problem.
 
I notice in the link that daviet gave me that these are fickle pumps and maybe I shouldn't have messed with it(my pump is a different style than the one in the link).The motor runs fine, and at times I gently pull the fuel line off the pump and the fuel is shooting out. Then it will suddenly die and there is no fuel in the carb. Sometimes it runs for 5 minutes and sometimes for 10 minutes or so. I'll mention again that I used the Sierra rebuild kit.
 
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