pump or regulator

[zpd307]

got the buick going last night, put new front bearings and brakes. changed oil and fuel filter. took it out to test everything out. the car starts and idles normally. but, while driving and bringing up the boost quickly the motor misfired right away. gradually bringing it up, it started misfiring at around 7 psi. i got home and hooked up a fuel pressure gauge. after initial fuel prime, guage went immediately back to zero. with the motor running, 30 psi-vacuum on, 38- vacuum off. while in park and reving the motor, the psi will go down to almost 20. the pump is a walboro and the regulator is a stock appearing adjustable. both are 3 to 4 four years old. there are no visible fuel leaks. i am leaning towards the pump going south. but i am not ruling out the regulator either. if it is the pump, what what reliable alternative do i have in that price range.

 

[DailyDrifter]

When you take the vac line off was there any fuel in it? Could be a faulty check valve in the pump. Also could be bad regulator. You need some type of restriction to have psi hold, you dont. I would lean towards the pump first.

 

[zpd307]

the regulator was dry. with it not holding pressure, i know there are several factors- check ball in the pump, a leak somewhere, regulator, and leaky injectors. as far as the injectors, they were replaced almost six years ago and it does start and idle fine. so i think that is out. i have no fuel leaks, so i think that is out. the losing pressure as the speeds increases has got me leaning towards the pump, but i am still unsure if that would qualify as a faulty regulator.

 

[DailyDrifter]

Sounds like the pump

 

[GN owner]

Same Problem

Turned out to be the fuel pump was bad on my car. Also the short piece of hose that connects the fuel pump to the fuel line inside the tank was the wrong kind of hose material. The hose material became sponge-like and was split down the center and was leaking fuel. Thus the loss of fuel pressure as soon as the engine was turned off.

 

[zpd307]

i was wondering about that myself. no slow leak, instant no pressure. but i didnt think that hose would give out.