QuestionHello,
Recently, I have been having problems with my truck suddenly dying. I could be driving down the road and the engine will quit. After waiting 10 minutes or so, it will start again. The problem is becoming more and more persistent. When the truck died out today, I was across the street from my mechanic. He scanned the system, however, there were no error codes showing. I was able to driver off. When I pulled into work, the truck died again and there it sits. The truck currently has approximately 260,000 kms (155,000 miles) and I had a new starter installed last month. The truck is a crew-cab, automatic transmission and a/c. I feel that with the engine simply dying out, that there could be a fuel pump problem. Any thoughts?
Thank you.
AnswerGregg,
Yes it can be the fuel system. It could also be the electronics on the injection pump. Or both.
First, make certain that the fuel filter is not restricted. If it has been a while since the filter was replaced, replace it again. After the vehicle is running again, perform the follwing test:
At idle, open the fuel filter bleed valve. Fuel should come out and the engine should run for at least 30 seconds without any trouble. If no fuel comes out, or the engine stalls, the lift (transfer) pump is not working.
If the lift pump is not working, it is usually due to the oil pressure switch (OPS). The power for the lift pump is run through a set of contacts in the oil pressure switch so that loss of oil pressure stops the transfer of fuel (safety device). GM did not provide an OPS with contacts heavy enough to carry the current that is required by the lift pump. Over time, the OPS goes bad (replacement OPS units are not any more durable than GM's switch).
Sometimes, the lift pump is also bad. If it refuses to pump fuel, after replacing a bad OPS, the lift pump has to be replaced.
Lastly, GM warranted the injection pump and its electronics for 11 years or 120,000 miles. When the electronics on the side of the injection pump (a black plastic housing that is about the size of a deck of playing cards) starts to fail, it does not set any diagnostic codes. The engine stalls when hot and there seems to be no pattern to it.
The cure is to buy another PMD (Pump Mounted Driver, also called FSD for Fuel Solenoid Driver) and mount it on a heatsink away from the engine. Extension cables and heatsinks come in kits from aftermarket suppliers. Some owners mount the PMD/heatsink out behind the bumper. Others have installed it in the incoming air duct to the engine. The PMD on the injection pump is abandoned in place and only the cable connecting to it has to be removed to allow the extension cable to be plugged into it.
Otherwise, the intake manifold has to come off to allow for PMD replacement, and the replacement (also be affected by engine heat over time) will eventually fail.
You can find these kits and parts on eBay and from companies like www.heathdiesel.com or www.kennedydiesel.com. Another vendor, www.usdiesel.com, in Montana, was dishonest with me a few years ago. I would avoid them. Heath Diesel offers a seven year warranty on a replacement PMD, if I recall correctly. I have done business with John Kennedy at Kennedy Diesel. He is honest and helpful.
