Logo
FULL SITE MENU

Fuel pump question

T

tthomp1334

Contributing Member
Should the fuel line from the fuel pump to carb hold pressure after you turn off the ignition.

Been having with engine bogging down after about 1/3 throttle under a load so I hooked up a pressure tester on the fuel line that goes from the pump to the carbs.

Could only get about two pounds of pressure at idle and hardly any at 1/2 throttle with no load on engine., kill engine and no pressure.

The pump has new gaskets and diaphragm.

Could it be bad check valve in the pump.

Thanks
Milton
 
There is absolutely no reason for pressure in there when motor is not running !!-----Do some more trouble shooting on other systems.-----Or perhaps open low speed mixture needles on carburetors 1/8th turn at a time and see if bogging goes away.---Yes it could be that simple !
 
Run the motor.------Then have an assistant operate the manual pump.-----If motor keeps running the fuel pump on the motor is defective.----These pumps are elegantly simple ( my opinion ) and it should be easy to figure out what is wrong.-----The pumps operate with pressure pulses from the crankcase so need to look into that too.----Could be issues with crankcase sealing !
 
The most I can get is 3 psi

New pump rebuild

Each cylinder has 125-130 psi

New fuel lines

New fuel filter

Have good positive and negative pressure from the crankcase

????

Milton
 
Have you tried opening the low speed mixture needles 1/8th turn at a time ?---That has proven to be a " no money spent fix " on many motors !----And what motor are you working on ?
 
Motor is a 1982 90 hp mercury

We had it at lake two times and ran perfect and the third time would not fire up at all.

Finally got it to run but will not run above about 1/3 throttle.

We first got it it would not run below half throttle, Installed new stater and it ran fine for a while.

Milton
 
Back
Top