GMC Sierra 3500 Extended Cab Pick-up

2003 GMC Sierra 3500 Extended Cab Pick-up Engine Stalling When driving When warm 

My dad is stuck in Arizona pulling a heavy load on a trailer. The problem started a few weeks back, before he was pulling the trailer, but it has gotten really bad in the past day.
The pattern has been that, while driving, the engine will quit. He lets it sit for 20-30 minutes, and it will start up again and run. The time between stalls has gotten shorter--as bad as 0.7 miles!
He has tried having the fuel filter changed. The mechanic checked the fuel pump at the time, and it had good pressure. Any other ideas?

Hi,
I am assuming this is a gas engine, 6.0?

The ideal thing to do is to have a fuel pressure guage on the truck when it fails to start. A fuel pump can cut in and out like that, especially if there is a bad connector on the line that is overheating and losing contact.

The next question is whether the tachometer drops to 0 immediately when the truck starts to die. If it is gradual, then it is most likely not spark related. If it flicks to 0 like the key was turned off, then you may have a bad crank sensor. They tend to be temperature sensative.

I assume the check engine light is not on. If it is on, have the coded checked.

These trucks have habit of stalling at stops because of dirty throttle bodies. However, this would not affect high speed driving.

Hope this helps,
Dale

I finally raised my dad on his cell phone, so here is more info.

First, I was mistaken on the model: it is a 2001 Sierra 2500 with a 6000 Series gas engine.

He has been able to figure out that the engine will die under two conditions: full throttle and idle (though it does not die every time at these conditions--it is inconsistent). There isn't a gas tank level associated with the behavior; it happens all the time.

If he is running wide open, sometimes he can play with the throttle as it is dying and get the engine to catch again. If he is idling and the engine misses, there is nothing he can do to recover it. The tach shows gradually dropping RPMs...500,400,...100,50, sputtering, then it dies.

The check engine light has not been on in the past month when the problem was gradually manifesting itself, but it did come on today after it said the engine was low on coolant. He checked the coolant level, and it was fine, but the light hasn't gone away.

He is in hill country now, so there is not much way he can avoid full throttle. When he is faced with a hill, he has to let it sit for three minutes, go wide open for 30 seconds until it quits, take his tenth of a mile of progress, and repeat the process. He is trying to coax it in to Flagstaff to the dealership.

As for the throttle body, he had looked a it earlier today and found it pretty dirty and unable to open and close all the way. He WD-40ed it and got it loosened up. This helped the problem, but did not cure it.

I think that covers your questions. I'd appreciate any help you could lend us. Thanks -Sam

These trucks have their share of fuel pump problems. It stems from a design error in the fuel pump assembly.
Have him listen to determine if the fuel pump runs during the no start.
Also have him listen for the normal clicking of the relays underhood during the no start.

Unfortunately there is nothing he can really do other than be prepared to explain the situation when he reaches the dealer.

You should consider recommending he has it towed in to be safe. Many insurance policies will reimburse (some plans only partially) the tow charge.

Thanks for the response. (By the way, he made it into Flagstaff.) I have just one more question though....

Is there an easy way to tell a fuel pressure regulator problem from a fuel pump problem? Or is that what you described in listening to it during the no-start (if the fuel pump sounds OK, it must be the regulator)?

Any additional info you have about the fuel pump design error would be nice, but is not required.

Thanks!

Glad he made it safely.

The main problem is poor wiring in the pump assembly. I had images saved but can't find them now.

The regulator simply keeps fuel pressure at a predetermined pressure. Usually when they fail fuel pressure goes high. This typically results in a rich running condition. This is harmful for fuel economy and exhaust emmissions. At idle excessive fuel could stall the engine. But not at wide open throttle. What you may be thinking of is a fuel pump relay. What this does is provide power to the pump. Whenever the relay malfunctioned power would be lost to pump. No power to the pump no fuel.

If the fuel pump don't run as it should fuel pressure is lost completely or drops off enough that the engine won't run.

Let us know what the dealer finds. I'm curious exactly what the problem was.

1998 GMC Sierra 3500 Extended Cab Pick-up Heating / Cooling System   

1998 gmc desel how to change heater blower motor

Hello, Disconnect the negative battery cable. Remove the glove box from the instrument panel. Remove the front screw from the right door sill plate. Remove the right kick panel trim. Disconnect the electrical connectors from the powertrain control module (PCM) as needed. Remove the PCM and mounting bracket. Disconnect the electrical connector from the blower motor. Remove the bolt from the right lower instrument panel support. Remove the blower motor cover. Remove the blower motor cooling tube. Remove the blower motor flange mounting screws. Carefully pull the blower motor forward in order to avoid distorting the fan and pry back on the right side of the instrument panel as necessary to remove the blower motor.

Upon reassembly guide the blower motor into position . Avoid catching the fan on any protruding parts. Continue reassembly in reverse order of removal. Test the blower motor operation.

Take your time to avoid injury.

Roger

1991 GMC Sierra 3500 Extended Cab Pick-up Ignition System Making Noise When accelerating Always

had to replace the engine, wire that connected to knock sensor somehow got cut off and have been unable to find. it does not have a esc mounted on the intake manifold so I guess it is built into the distributor. There are 4 wires going into the distributor coming from the computer. one is a white wire, I cut this wire and spliced the sensor in, knock stopped, but I'm now getting "service engine soon" light. How do I get the sensor wired up to the right wire coming from the computer?

Is this the first time the service engine soon light appeared? It wouldn't be a bad idea to pull the troublecodes, just in case there is more than one thing wrong here.

Here is a site with free diagrams and troublecode information. A bit unfriendly to navigate, but free is nice.

http://www.e-toolbox.com/ads

Does this help?

I have already done that and got a code number 42, I disconnected the wire and reset the code and the light went off. The valves started chattering again so I spliced the wire in again and the valve noise stopped but the light came on again with the same code. The truck has a 4L80E transmission. The white wire comes from the # D11 terminal on the PCM. My guess is it is hooked up to the wrong terminal.

First off, sorry for the delay.

The knock sensor wire should be dark blue at the PCM.

If you go to
http://www.e-toolbox.com/ads

Enter vehicle info.
Then select Repair Procedures.

Once this page loads click 'Search' in the top left hand corner. Type 'knock' (and only knock) in the search. Then click 'Testing' for a diagram (click to enlarge).

If this isn't enough, give me engine size and I'll see what I can find.

Good luck

I guess I'm confused, the items you said look at shows the knock sensor's dark blue wire coming from the terminal B15. my PCM does not have a B15. It has A1-12, B1-12, c1-16 and d1-16. This seems to be a simple problem, but I haven't been able to solve it.
Thanks for your efforts and suggestions, what do you think we can do next?

Email me

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