Question-------------------------
Followup To
Question -
My truck runs great but while I am driving, it just shuts off. I am able to crank it back up after 1- 5 tries. Before it shuts off, I hit the accelerator and it does nothing, the engine won't wind up or anything.
This problem has been going on for about a year. I had it put on the computer and the oxygen sensors came up, I replaced it 3- 4 times. Then the catalytic converter and the fuel pump were replaced, still no change. Do you have any suggestions. I had it placed on computer again and nothing comes up. Whan it shuts off and I turn it back on again I have no problems but sometimes it goes off 3-4 times in one trip.
Answer -
Hi Joe,
First you will need to find out if it is spark related, or fuel related.
Sounds like your fuel pump may be quitting for some reason.
Whether it is the pump itself, or control system is the question.
But it could be that the pump is fine, and you loose spark.
So when it happens, listen for the pump running in the tank. it should run for two to three seconds after the key is turned to run.
Then check to see if there is spark at the plug wires.
Van
Update and further information:
Today it shut off 5 times. The fuel pump was replaced last year when I fisrt started going through this. The pump at the time was very loud and I didn't want t o take any chances. The Oxygen sensors came up on the computer they hooked it up to. It was replaced several times. Then the CAT came up. When I replaced it, it ran fine for several months without a problem. Then all of a sudden it began again and quite frequent. They instructed me to use a fuel injector cleaner with every fill up. The first time I used it, The truck started to bog and had loss of power right away. This continued for a couple of hours and then it was fine. I still experienced the shut off at least once in every trip. Today was the 3rd time I filled and used the cleaner.
It was checked for the spark a couple of months ago and was fine. I even did a tune up and replaced all wires and plugs as a precaution.
AnswerHi Joe,
Fuel sounds like the problem for sure.
I would first change the filter. It should be in a clip in the frame, under the drivers seat area.
While I had the filter disconnected, I would catch some gas from the rear line in a clean quart jar, and set it aside. A little later look at it to see if there is water in the bottom, and / or dirt, rust, etc.
After installing the new filter, connect a pressure tester, prefferably in a manner that will let you read the gauge while driving. Go for a ride, and see if the pressure stays up to specs.
A throttle body engine should have 13 to 14 PSI. Multi point injectors should be much higher. I believe about 45 PSI, but I am not positive. At any rate, that pressure needs to stay up there.
I have had the little hose inside the tank, where the pump connects to the line, split, and only allow about 7 PSI to be maintained. The rest just sprayed out inside the tank. The truck ran, but no power, and wouldn't do much above idle.
If yours runs good sometimes, I doubt that would be the problem, but I have also seen the electric connections through the tank unit loose, and work intermittently. If you had the pump replaced at a dealer, they probably replaced that complete unit, and should have charged three or four hundred dollars for parts.
But the attached pressure gauge will tell if loss of pressure is the problem. You Defanitely want the pressure to stay up till after the engine is shut off.
If it drops causing the engine to shut off, then it will be necessary to trace out if it is a control problem, an electrical problem, or a pump problem.
There is a relay and a oil pressure switch that supply power to the pump. Either should run it, but there are two systems for redundency. Al song as there is oil pressure in the engine, the pump should run, even with the key off.
An ignition switch is another possible problem.
Good luck,
Van
