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Jon89

Jon89 1/8/2019

1994 GMC Sonoma SL 4 Cyl 2.20L

Engine

Intermittent Stalling, Low Fuel Pressure. Why?

I've been having this issue for a few months now, has gotten progressively worse.
Vehicle stalls often while at low rpms, but can be driven fine if I keep rpms high. Happens more often while driving in the city, not at all while driving long distances in 4th gear at 50-60mph.
When it stalls engine still runs but I get no acceleration from gas pedal. Lights and radio also cut off. Downshifting to get rpms really high usually fixes this, otherwise it will usually start back up after a few minutes, sometimes it will not.
I replaced battery terminals, checked cable connections and have tested alternator, all are fine. I've also replaced the fuel filter which was pretty rough, was hard to get air through it.
Is this the fuel pump, sensor, or maybe the fuel line is clogged from the fuel filter getting so bad? I am on limited funds and this is my only vehicle, I'd like to be as sure as possible what the issue is before I have any work done, especially if it is an easy fix I could do.

1 Answer


Jimm

Jimm 1/8/2019

First step is to measure the fuel pressure at the outlet side of the fuel pump, and again at the engine fuel rail port. These two readings should be very similar. Fuel pressure should be between 41-47 psi while the pump is running with key key on and engine off. When the engine is running (at idle speed) the fuel pressure should read 31-44 psi.

If one of the measured fuel pressure points is low, then suspect a fuel system blockage, an internal or external leak, a faulty fuel pressure regulator, or a failed fuel pump.

Try these on-line parts resources; www.autopartsanything.com; www.partsgeek.com; www.Rockauto.com, www.stockwiseauto.com - to list only a few.

In fact, they (RockAuto) list the replacement fuel pump assembly from around $51.00, and the fuel pump strainer from around $1.40 each for your vehicle.

Fuel pump and housing assembly (in-tank) = AC DELCO part #EP378 {#25163468} GM Original Equipment - or it's equivalent
Fuel pump strainer = SPECTRA PREMIUM part #STR01 - or it's equivalent

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