silverado won't start....sometimes

[Glen A. Davis]

My 1999 4.3 won't start unless i put fuel in the throtle body, then it starts up and runs fine. My fuel psi is 63lb.s, fuel pump and filter is new. Has anyone heard of the key switch being faulty and not allowing the engine to start. sometimes all i need to do is turn the switch off and on a few times and it will start and run fine, HELP

[MT-2500]

Originally Posted by Glen A. Davis

My 1999 4.3 won't start unless i put fuel in the throtle body, then it starts up and runs fine. My fuel psi is 63lb.s, fuel pump and filter is new. Has anyone heard of the key switch being faulty and not allowing the engine to start. sometimes all i need to do is turn the switch off and on a few times and it will start and run fine, HELP

Welcome to AF on your first post.
You need to start a New thread with your problem.

Start a New thread and answer questions below for more help.
What brand of fuel pump did you install?

Is that 63 lbs pressure engine off key on or engine cranking or just 63 when you lip ke a couple times?

You need 64-65 lbs engine cranking fuel pressure to squirt injectors on a cold start.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 90 -100 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 90- 100 or more on yours.
And if it has a fast leak down after shut off you have a leak in system.
Post back all fuel pressure readings.