97 tahoe had to start after sitting for a few hours

[bautino95]

I put the fuel pressure gauge on. I have 50 -60psi but noticed that while cranking the engine to start the psi drops to 40-45 psi the builds back to 50-60 again when I stop. I think this drop in pressure while cranking is my problem. because I found that if I just tap the key over a few time its more likely to start then just cranking it over longer. BTW the fuel pump was replaced last year. what do you guys think. thanks.

[RainRider]

http://www.automotiveforums.com/vbul...d.php?t=693112

pertinent info there

Luck with it,
Rain

[klinn]

When was the last time the fuel filter was replaced? The injectors need alot of fuel pressure to open, that low of fuel pressure while cranking most likely will not opoen them. That either means restriction of low pressure. In other words, partially clogged filter, or weak fuel pump.

[glenncof]

I assume engine turns over but doesn't fire so battery voltage is good.

There is a relay under the hood, if it is going bad it will work as you describe (turn key several times). My starter relay failed in that manner. There is supposed to be a test wire in the harness where you can monitor fuel pump voltage or run fuel pump directly. I measure the voltage off the relay pins.

Swap suspect relay with another one (match p/n on relays) on non-critical circuit like AC.

The pumps are known to fail, my 1997 did at 125K. Just stopped on highway. AND dealer replaced it AND it failed AGAIN. They claim the "connector was melted" due to fuel filter (which was only 20-30K miles old).
There is a history of bad connectors on the stock pump. Do Google on p/n and "bad connector".

[MT-2500]

You fuel pressure is to low.
A cold start requires full pressure for injector to squirt fuel.
Even a couple of lbs low can give a slow hard start cold.
If fuel filter does not help you need to run a good fuel pressure test.
If CSI injection. 60/66 lbs of fuel pressure
If SFI injection. specs are 56/62
Hard to start cold.
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.
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 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.
MT