1995 Silverado Fuel delivery problem

MasterEvilAce · September 18, 2006

Have a 1995 Silverado 2500 series diesel. There seems to be an intermittent fuel delivery problem. The truck will just act as if it's starving for fuel, then it will die out, and won't start for 30 minutes to 1 hour.

I believe the fuel pump is on the driver side, underneath the door and towards the center of the truck, on the frame. It looks like a fuel filter, but has two wires going to it. Is this correct? I'm trying to see if the fuel pump is the problem, I checked for voltage at the plug, and there doesn't seem to be anything. I've even unplugged it completely and the truck still starts, so now I'm not sure what to think.

Does anybody have any insight?

95Sierra2500 · September 18, 2006

Sounds like you're vapor-locking. My dad's old diesel used to do that alot...but I can't remember what the fix was.

dizzy · September 19, 2006

Sounds like that is the filter, but I could be wrong. Are you sure there are wires going to it? On a gas rig that is the location for the in-line fuel filter and the pump itself is located inside the gas tank.

Unless that is a booster pump, you should have many more filters than gas.

I'd check all fuel filters and water seperators.

MasterEvilAce · September 19, 2006

It definitely has wires going to it.

This is what a few sites show as the fuel pump.

http://www.partsamerica.com/product_images...g/mst/e3309.jpg

And that's what it looks like. However, it doesn't make any noise at all with the key on. And even unplugged the engine still runs.

dizzy · September 19, 2006

yeah I believe ya on the wires, could very well be the "booster" pump, the injector pump on your diesel should be on the engine itself.

I installed a Holly Pro Injection TBI kit once it has a pump like you show but even smaller and it put out 38PSI pressure.

I replaced the filter on my 2000 Silverado (also gas, not diesel) and it took this Fram G3727 in-line filter (notice the absence of wires).

There is a Delco on ebay for about $105 bucks:

http://cgi.ebay.com/ebaymotors/CHEV-GMC-FU...sspagenameZWDVW

95Sierra2500 · September 19, 2006

Guys, he stated in his first post that he's got a diesel, which, IIRC they mounted the main filter on the firewall. That definately sounds like the booster pump, and it sounds like it's getting too hot after a while and shorting out.

MasterEvilAce · September 19, 2006

Explain? So there are two fuel pumps? One at the engine, and the other on the frame rail?

So technically the booster could be unplugged and the truck would still run, right?

95Sierra2500 · September 19, 2006

Not necessarily. Remember that your diesel operates at a MUCH higher fuel pressure than a gasoline engine, especially if you've still got the old mechanical injection system (I really don't know if you do). So if you don't have enough fuel pressure, your engine wouldn't get enough fuel squirted into the cylinders and the truck would stall.

MasterEvilAce · October 6, 2006

Did some other research.. When we just hot-wire the pump to the battery, it runs and everything. Some guide online mentioned that the pump is activated by the oil pressure switch. If the switch is bad, the pump won't run, whatever. Does anybody know where the wires go from this pump? Again: It's on the framerail, underneath the driver door, towards the center of the truck.

I want to trace these wires , and just disconnect them and wire them to the ignition, so when the key is on, the pump runs. Where is the oil pressure switch, and do the wires run directly from that, or does the switch go to a relay, and then the relay goes to the pump? I need this info ASAP.

The more descriptive, the better. Even a wiring diagram would be better than anything. All wires seem to disappear into a harness, so it's tough.