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Fuel delivery gremlin

J

Junr78

Member
Anyone ever have an issue where your fuel pump doesn't seem to move as much fuel as you think it should? New engine build, all new parts, pulsed from the valve cover..the motor runs but it seems to cut out at higher rpm..I feel like it's a fuel delivery issue, the fuel line doesn't seem to fill up like it should or does on other similar builds.. the fuel pump is new and i have tried 2 others with same results...thanks in advance for any input!
 
Pull the pulse line off of the pulse end of the fuel pump, put another fuel line on there that you can pulse with your mouth. Pull the fuel line off at the fuel pump, going to the carburetor and put a rag under there. with your mouth pulse the fuel pump, and if you have a nice pulse coming out of that pump, you don’t have a problem. Also, if you tried other pumps and you have the same problem, my guess is you do not have a fuel pump Problem.
 
Thanks dynodon.. I've kinda ruled out the pump as being the actual problem simply because the issue persists with other pumps, just not sure what else would cause the weak fuel delivery tho..
 
Arc racing has a video on pump mounting and he talked about locations that don't work as well for the pulse line. Check his utube video.
 
If you can do a leak down on the engine to make sure that you have enough vacuum in the engine to work the fuel pump properly off the valve cover that’ll give you an idea whether you have a problem there or not. Nice thing about a leak down you’re going to find out how your rings are and how both of your valves are and how your head gasket is
 
Which side of the pump is it? Delivery from tank? Or pump to carb? Have you switched fuel filters? Some flow better than others.
 
Colt sr said:
Which side of the pump is it? Delivery from tank? Or pump to carb? Have you switched fuel filters? Some flow better than others.
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I have not tried a different filter but can try taking it out to see if the flow increases. ..based on visual inspection it's both sides of the pump.. My other build I'm comparing it to will move fuel freely through the lines by just pulling slowly on the pull cord..this motor won't even move fuel until the motor is running and at that its very minimal
 
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Junr78 said:
I have not tried a different filter but can try taking it out to see if the flow increases. ..based on visual inspection it's both sides of the pump.. My other build I'm comparing it to will move fuel freely through the lines by just pulling slowly on the pull cord..this motor won't even move fuel until the motor is running and at that its very minimal
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Check filter first then check tank for blockages.
 
Thanks everyone for the ideas on things to check..im just getting around to getting it fixed...ended up being the reed valve in the valve cover, it was open to much wasn't sealing.
 
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