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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29534
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Chevrolet K3500 4x4 I have a 1996 Chevy 3500 dump truck with

Customer Question

I have a 1996 Chevy 3500 dump truck with the 6.5 turbo diesel. I have been having a problem with supplying fuel to the motor. Sometimes its a hard start, but the real problem is that sometimes when driving the truck just starts to bog down and lose power and I find that even with the accelerator pedal fully pressed it won't gain speed, eventually I have to pull over and it'll idle rough for a few seconds before dying completely. When this first started happening I thought it was air in the line because my rear fuel tank has a pinhole in it, but then I discovered that because that tank is missing a part that reads the fuel level the truck doesn't even draw off of it, so I'm really only running off the front tank. For a while when this happened I would bleed the fuel line with the valve on the front of the motor, again I did this thinking that there was air in the line. Well that did seem to help get me going again for a while but now the problem is getting worse and more frequent and bleeding the line seems to have no effect whatsoever. Now the truck has died and I can't get it going for longer than a about 2 seconds. I am no mechanic and I've had one place tell me I might need a new lift pump or injector pump, to the tune of $2000 at least and they said probably even more. I would really appreciate any suggestions as I cannot afford to just throw money at it, but it is my only work truck and customers are waiting plus snow will be here before I know it and I do snow removal. PLEASE HELP!
Submitted: 6 years ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 6 years ago.

Welcome, and thanks for using Just Answer. I am Cam, and I will do my best to assist you. When you are finished please click on accept only if you are satisfied. I don't get paid unless you do.Please do not accept if you cannot leave positive feedback. I don't know if you are a tech or a just working on your own vehicle so we may have to fine tune the answer. I only know as much about your problem as you have told me in your post, so my answers will be based on what you tell me so please add all the details you can. About your vehicle, is the lift pump running? These use a lift pump to supply fuel to the engine, and the pressure is 4-7 psi. Basically if you have it running or cranking, you should be able to open the top of the filter and fuel should come out. If not then look at the lift pump on the frame rail. Take the electrical connector apart and see if there is feul in there. If so, replace that lift pump.


Customer: replied 6 years ago.
No I'm not a tech. I don't know where the lift pump is or what it looks like. The truck will not run for longer than a couple seconds, and even that takes A LOT of cranking and pedal pumping, but yes it does crank.
Expert:  GM Tech (Cam) replied 6 years ago.

It looks like an inline filter in the fuel line inside of the drivers frame rail but with a couple wires coming out of it. Check that as I suggested and lets see what you find.


Customer: replied 6 years ago.
Thanks, XXXXX XXXXX said check the filter first, right? Where can I find the fuel filter?
Expert:  GM Tech (Cam) replied 6 years ago.

Fuel filter is back of the engine at the top.

It has a black ring and a small black valve on it.


Customer: replied 6 years ago.
Ok, I'll check it out thanks for your help. It'll be a couple hours before I'm back at my computer.
Expert:  GM Tech (Cam) replied 6 years ago.

You can reply at any time for follow up information regarding this issue, even after you accept my answer and I will reply.

Customer: replied 6 years ago.
I was not able to unscrew or in any way remove the filter as a whole. I did remove the black valve on top and found fuel inside.
Expert:  GM Tech (Cam) replied 6 years ago.

Did fuel come out when you were cranking?


Customer: replied 6 years ago.
I wasn't able to crank it as the batteries are now about dead from cranking. I just unscrewed that little cap and saw fuel.
Expert:  GM Tech (Cam) replied 6 years ago.

Fuel must come shooting out, it sounds like the lift pump is not running. It is a plunger pump. makes a rapid clicking when it is working. Check for power and ground at the pump when cranking the engine. It sounds like your injection pump is out.


Customer: replied 6 years ago.

I do hear a clicking?vibrating noise when I turn the key to allow the glow plugs to warm up, if thats what youre talking about, however when the "wait to start" light goes off on the dash the clicking stops.

So just to make sure I'm clear, in your last response it seems like youre telling me to replace both the lift pump and the injection pump. Would you suggest one before the other based on cost and ease and see if that fixes the problem, or just do them both now?

Thank you so much for your help.

Expert:  GM Tech (Cam) replied 6 years ago.

That is not the same and the lift pump will run when it is cranking. Take the black cover off on the right side of the firewall under the hood. There is a sealed fuse holder there with 2 wires. TAke the cover off and jump power to the fuse and see if the pump runs. If not then the lift pump is bad.

I am not suggesting you replace anything yet until we confirm the pressure, and if the lift pump is bad, then we replace ONLY the lift pump to start with. I don't like Shotgun diagnosis (repalce all knowing one of the parts will fix it).

Customer: replied 6 years ago.

Sorry it took me so long to reply. I had to put a booster pack on the truck to get it going, it still didn't crank strong at all so I guess I need to remove the batteries and have them charged, they are only a month or so old. But yes, when I was cranking fuel did come out the top of the filter. So I guess I need to replace the injector pump then? I didn't remove the lift pump because fuel did come out of the filter.

Expert:  GM Tech (Cam) replied 6 years ago.

Measure the pressure of the lift pump to be sure, and replace that fuel filter, the large ring is threaded, take it off to get the filter out.