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2004 Avalanche Crank, but no start

pvnova73

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Jan 20, 2007
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I had not started my 2004 Avalanche for about a month and now it won't start anymore. I've often gone this interval or longer without issue. I actually did get it to start and run for about a minute this morning, then it stalled out. I got it started again and it only ran for a few seconds and then stalled and could not be started. I checked fuel pressure at the test point on the fuel rail immediately after the fuel pump primes. Pressure gets to 40-45psi and then dwindles to about 30psi in about 30 seconds. Pressure continues to drop slowly thereafter. When trying to start the engine, the needle flutters between 50-55psi, but the engine will not start. Prior to all of the above, I had noticed the truck would occasionally stall about 10-15 minutes into a short trip. I could always restart it without issue and the problem would not typically recur thereafter.

Do the above conditions sound like a bad fuel pump? My pressure readings seem borderline, maybe passable, and I had changed the fuel pump about 6 years ago and swapped in an AC Delco pump, so it seems like it should have lasted longer. Are there any other checks I should do before replacing the fuel pump? I wanted to check to see if there is anything else I should test first since the fuel pump is a pain to change. Would bad (old) fuel give me the same problems?
 

Wingo

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Apr 28, 2022
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Could try replacing the regulator, they go bad often I hear. It's a 5 minute swap. It's possible you are getting leakdown after the pump primes and it's not keeping the pressure up as it's supposed to. Stuck injector could do that too, does the oil smell like gas?

Also, do you have spark? Crank position sensor may be bad also.
 
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pvnova73

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Jan 20, 2007
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My '04 does not have the fuel pressure regulator mounted on the fuel rail like some of the older models do. The fact that it started and ran briefly implies I have spark, but I will check in more detail. The truck has not thrown any codes, but maybe the crank position sensor is still a possibility. Aren't there typically codes associated with a bad crank position sensor?
 
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pvnova73

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Jan 20, 2007
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I did some more checks. I checked for spark using a harbor freight spark checker light that you put in line between the spark plug wire and spark plug. The checker blinked when the vehicle was trying to start. It wasn't very bright, but I've never used it before now, so I have nothing to compare it to. My oil does smell like gas. I know I definitely have some fuel pressure, I just don't know if it is enough to start the car. What else should I check?

Edit: The truck has 250k miles on it and is only used occasionally, so that may be the reason for the oil smelling like gas.
 
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Wingo

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Apr 28, 2022
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I'm no mechanic, I usually have to bumble my way through things and I'm often wrong. But if an injector is stuck open, I think it leaks fuel into the cylinder when it's turned off, that may be why it smells like gas in the oil. I have no clue how to test that. I only responded because I'm tracking down a similar issue with my 2002 2500 avalanche and I had a couple ideas.

If you have spark that should be good. I would assume a crank sensor would trigger a code I suppose.
 

ygmn

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Sounds like pump issue since pressure drops.

might be due to sitting in old fuel for long time.

Worth removing and checking it out.
 

EXT4ME

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If you suspect a badly leaking fuel injector that's bad enough to drain gas into the crankcase, I am thinking pulling each spark plug and checking for raw fuel on the plugs and in the cylinders.
 
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