Carburetor Troubleshooting

[BradMph]

This is a basic troubleshooter sheet for a Carburetor.
16428
(click image to expand)

[maxdsm]

Nice thanks ,
Question for ya , My fuel pressure on the regulator jumps from 3 and 5 Back and forth while running is that normal? I stuck with using a mechanical fuel pump and holly fuel pressure regulator.

[pennyman1]

is that input or output pressure? Input can vary on motor speed, output should not vary unless the pump output is weak and can't keep up with demand.

[maxdsm]

Yes that would be input pressure . Thanks pennyman just checking to see if that is right.

[BradMph]

Hey Max why have regulator on a stock pump? Usually those are pretty much setup to run as is. Are you regulating a Weber with the mechanical pump?
I also was going to say your pump is pulsating the gauge but as fast as it pumps, the gauge shouldn't fluctuate like that. Your gauge is prior the pump if I read your input pressure answer correctly. If regulating a Weber, I would think that the regulator and gauge would be after the mechanical pump or just before the carb so it will give a better reading on how much it is feeding the carb. I'm not sure if this will stress the pump diaphram either, by causing it to build up pressure behind a regulator.

[pennyman1]

it will stress the pump diaphragm and blow the pump sooner or later. It depends on how old the pump is.