Question-------------------------
Followup To
Question -
I have a 91 Chevy 1500 with a 350 standard shift. I have been having trouble getting it started to the point of having to prime the TBI. I have replaced the fuel pump filter plugs rotor and cap but nothing has helped. When the truck gets running it runs great. Can you help?
Answer -
Hi Bert,
First make sure the pump is running when you turn the key to run.
Then you might want to check the throttle position sensor, and the temperature sensor.
Here is a great discussion about the temp sensor.
http://www.chevytalk.org/threads/showthreaded.php?Cat=0&Number=1366279
Van
PS...join that forum while you are there. It is free, and a great site for Chevy Lovers.
I put both of these parts on and it did not change anything.... Do you have any other ideas?
Bert
AnswerHi Bert,
I suggested you check those items, not replace them. They can be tested, and I hate to see people just throw money at a problem, even though it occasionally catches the problem.
The way you say yours does, makes me think the fuel pump isn't running by relay power, but by oil pressure power. There is an oil pressure switch that provides power to the fuel pump once oil pressure builds to 4 PSi.
Now, don't replace that switch. If that is what's happening, the switch is ok.
That is why I asked if the pump runs when you turn the key to run. It should come on and run for two or three seconds.
If it doesn't, then there are a couple possibilities, but check it first.
If the pump does run, I personally would like to test the pressure, to see if it is up to spec.
If the pressure is correct, and there is spark, which I assume there is if it starts with a prime, then I would look at the control system for the injectors.
It is remotely possible you are getting some vapor lock in the injectors from heat soak, so if the pump does run with the switch in run, try cycling it to run for three seconds, off a few, run for three, etc. and see if that will circulate some fuel through to cool them.
There is a hot start module for some of the larger engines just for that reason, that runs the fuel pump for seven seconds.
Any sign of running hot?
Van
