1997 GMC Truck Engine Starting problems due to fuel system

HDOUGN

MEMBER
1997 GMC TRUCK
V8
4WD
AUTOMATIC
175,000 MILES

My 97 GMC K1500 -Z71- pickup truck has the 5.7L V8 and has been progressively difficult starting to the point I now have to spray starter fluid on the air filter to get it to actually run. Otherwise it only turns over and over like it hasn't got any fuel. However, once its running I can drive it without any notice of any problems - never getting any check engine light error codes. I've tested its fuel pressure and it doesn't remain constant after the engine has been shut off with a noticeable bleed off after only 5 minutes or so. But it does rise again to the sprecifications shown its supposed to have once I turn on the ignition without actually cranking it over.
So, do I have possibly a malfunctioning fuel regulator / intake manifold gasket leak, or should I go directly to changing out the fuel pump assembly in the gas tank which is supposedly exactly what a dealer tech said to me is what's usually found wrong when a GMC vehicle has a bleedoff of fuel pressure?

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,254 POSTS

The tech is most likely correct. However, have you checked the pressure when the engine is running and determine of the regulator is doing its job?

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Thursday, September 24th, 2009 AT 7:48 PM

SFLYBOY

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5 POSTS

I have the exact same problem. What ended up being the solution?

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Friday, April 1st, 2011 AT 6:43 AM

JACOBANDNICKOLAS

MECHANIC
108,254 POSTS

Make sure the pressure is within the spec when it won't start. Check to see if the fuel filter is partially plugged. I have seen many that are weak, won't start the car (at times), but once the car is started, it will keep going.

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Tuesday, May 31st, 2011 AT 6:31 PM

SFLYBOY

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5 POSTS

It turned out to be a bad throttle position sensor. I replaced it and it runs grate!

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Wednesday, June 1st, 2011 AT 5:24 AM

HDOUGN

MEMBER
2 POSTS

For the record, it required lifting the truckbed 24 inches off the fuel tank to access removal of wiring harness and fuel-lines from the pump; thoroughly cleaning old gasket off once pump removed, and thoroughly tightening the new pump/lockring/gas-lines. It's run troublefree since, except for having to remove the gastank again within 6 months to replace a rusted-through brake line. But that's another different problem needing a full size hydraulic vehicle lift in a garage to work underneath the whole shebang.