Update: Hard start after sitting 2-3hrs.

[Gsragtop]

Good afternoon, I just picked up a 2004 Tahoe with 250,000+ miles. She runs fantastic, and just does not show her age. She is running a custom true duel exhaust with twin cats, but no mufflers and she sound SO GOOD.

This is my problem, this is not my daily driver and she will start fine after sitting for days. However she has an issue that seems to be getting worse. Like I said it will start right up even after sitting for days.. However is she sits for a few hours, she is very hard to start. Today I was afraid she would not start at all. She cranks fine, and once started she runs perfect without an check engine light.

Reading the forums, I see the regulator is a common issue but I don't think it's my issue as the truck will start fine if it only sits for 10-20 min. Also I do not see fuel leaking out of the regulator when I disconnect the vac line (although it does smell like gas when I sniff the end of the vac line). On an unrelated note I broke with 90 rubber vac elbow on the intake side where can I find a new one ??

Today when it gave me issues I pushed in the shraider valve on the fuel rail with a stick and found it pushing or pulling air. No fuel. Even after turning the key a few times. Eventually fuel came out, and a few tries after that she started.

I tried turning the key multiple times before cranking with no results. Usually you would hear the motor catch for a split second then nothing.

So what do you guys think, fuel pump, fuel injector, or what ??

 

[cmc76]

total shot in the dark, but if it were an older vehicle, i would be saying look for hot start issues. back in the day, some cars needed heat shields to keep exhaust heat off the starter. fuel is totally plausible, but the few day wait doesnt add up.

 

[bottomline2000]

have the fuel pressure checked there should be fuel in the rail once the pump cycles on. sounds like a bad fuel pump or a pump going bad. its fine when cold, but once the pump warms up it starts to get weaker hence the hard starts when warm. just another shot in the dark.

 

[Gsragtop]

have the fuel pressure checked there should be fuel in the rail once the pump cycles on. sounds like a bad fuel pump or a pump going bad. its fine when cold, but once the pump warms up it starts to get weaker hence the hard starts when warm. just another shot in the dark.

That was my thought, add to that maybe a leak at the pump back draining the line and that was my thought exactly. Now hypothetically speaking adding fuel should make a difference as more fuel should dispaite the heat better. However I don't want to add fuel and have the pump quit all together. Lol

 

[Wake]

The only time I ever experienced your situation was an 80s vehicle with leaky fuel injectors, they made hot starting hard. Cold start was easy because the fuel evaporated over time, but hot start was difficult.

Next time you try to hot start it put the pedal to the floor while cranking to allow max air and I believe it triggers the "clear flood mode" (no fuel injected). if it starts up easier then it is likely leaking fuel injectors. At your mileage, I'd think that would be the cause.

 

[Gsragtop]

Update:
So I got a fuel pressure gauge finally. And I'm thinking I have a bad fuel pressure regulator. Tell me what you think.

While cold, turned key and the pressure went right up to 50, truck started no problem and ran at a consistent 50psi.. Goosing the gas cause a split second drop in pressure with an immediate return to 50.. Turn the truck off and fuel pressure dropped immediately to 20, then slowly the rest of the way to zero. Turning the key pressure went right back to 50, but immediately dropped after the pump stopped running (did not start it that time).. Repeated this test a few times with the same results.

Removing the vac line from the regulator made no difference in psi at all.

Let truck run to operating temp, then let it sit for 2hrs and then turned key. No fuel pressure, in fact it took 4 turns of the key to start getting pressure then two more to get to 50.. After that running psi I was 53 and everything was the same.

Used a stop watch to measure psi drop this time 15 seconds from 50 to 20, 45 total seconds 20 to 10 and about 2 min total time to 0...


What do you think ???

 

[chevyv8]

what did you find out?

 

[Scottydoggs]

sounds like a beat pump to me. the whole no pressure deal reeks of it.

 

[Fless]

Next time you try to hot start it put the pedal to the floor while cranking to allow max air and I believe it triggers the "clear flood mode" (no fuel injected). if it starts up easier then it is likely leaking fuel injectors. At your mileage, I'd think that would be the cause.

^^^^^ Definitely something to try. And the pressure shouldn't be leaking down that fast. Depending on your particular engine and VIN, the working pressure might be low. Or not.