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#371 of 375 Re: 2008 Suburban same electrical problem [gmcustsvc] by gmlemon2

Dec 23, 2012 (12:10 pm)

Replying to: gmcustsvc (Dec 20, 2012 11:14 am)

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#372 of 375 1998 Chevrolet Tahoe Hard Start by kingdudley

Feb 06, 2013 (4:45 pm)

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• alanrs (Feb 06, 2013 11:11 pm)

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#373 of 375 Re: 1998 Chevrolet Tahoe Hard Start [kingdudley] by alanrs

Feb 06, 2013 (11:11 pm)

Replying to: kingdudley (Feb 06, 2013 4:45 pm)

Your truck should have the 5.7L "L31" V-8, with a Central Sequential Fuel Injection system. Here is a basic starting option: Instead of rotating the key to the "Start" spot when you first get into the Tahoe, turn it only to "Run". Wait several seconds while fuel pressure builds in the system, since the fuel pump will be activated until full pressure is achieved. Then, without turning the key off, go ahead and rotate the key into the "Start" detent.
 
If the motor starts immediately, what it will tell you is this: There is likely a loss of fuel pressure between the time that the motor is turned off, and you start it again. There may be a very slight leak (even inside the tank at the pump) in a line, or a check valve which is supposed to hold pressure between runs is failing. Unless there is an external leak, it is probably nothing to worry about, and it does not indicate an imminent fuel pump failure. Can you detect the odor of gasoline anywhere around the truck or in the engine compartment? A failing fuel injector system may allow the pressure loss from the fuel rail, and let gas trickle into the engine. If the oil on your dipstick smells strongly like gasoline, that is the likely culprit, and it should be repaired.
 
In the old days when the mechanical fuel pump was mounted to the side of engines, a leak could cause gas to quickly fill up the crank-case. The results were not good!
 
If it still requires the crank, wait, and crank again method before the engine will start, it just may indicate that the motor has lost some compression, and takes a few extra rotations to build sufficient cylinder pressure for combustion. That does not necessarily mean that the motor is nearing the end of it's life cycle, either. Some wear is always normal, considering how many miles each piston has traveled in its bore through a quarter of a million on the road. Basic calculations lead me to believe that each piston has probably traveled 99,000 miles, moving 3.5 inches up and down with each rotation of the crank!
 
A third option which comes to mind is that the fuel injectors are no longer producing as broad or well-atomized spray patterns as they did when they were newer. There are cleaners used through the fuel which can help, but the only real answer might be to service (replace) the injection system, not a task that is lightly undertaken. Note that the CSFI system is fully enclosed inside of the top intake manifold. There are many discussions regarding that system to be found on the 'net, and it would be good reading to further your understanding of how it works and what it looks like. There is at least one Multi-Port Fuel Injection system which can be utilized as a replacement, and there may be benefits in doing that conversion.
 
Typically, if the CSFI system is at fault, the engine will not run well at all, and fuel economy will suffer a lot. Still, if the motor runs well, but that system is indeed leaking raw fuel into the crank-case between engine runs, it may be necessary to do something about it. Understand that it will be expensive!
 
Good luck!

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#374 of 375 2000 Tahoe. Sudden loss of power. Fuel pump? by purplebeard

Mar 11, 2013 (7:42 pm)

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• alanrs (Mar 11, 2013 8:53 pm)

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#375 of 375 Re: 2000 Tahoe. Sudden loss of power. Fuel pump? [purplebeard] by alanrs

Mar 11, 2013 (8:53 pm)

Replying to: purplebeard (Mar 11, 2013 7:42 pm)

Certainly sounds like the pump to me. To confirm it, see if your local auto parts store lends tools (some do in my area) and use a fuel pressure tester.
When the pump failed on my Suburban, I had just left a business, headed for a freeway. The truck was stumbling and would not accelerate on the entrance ramp. I managed about two miles 50mph, and there was no power for acceleration. When I got off at the next exit, the engine quit while I coasted around the curve. As yours, it would sometimes restart but not run. The pump was it, and the replacement job is a BEAR!
 
Regarding what to look out for during the pump change: You might want to scan the "Chevrolet Suburban and Tahoe No Start Problems" and the "Chevy Suburban/Tahoe Rough Idle and Stalling" discussions. I know I posted the procedure I used somewhere in this forum, but can't find it right now. One partipant listed what he did, post #347 in the "No Start" thread. Because it was cold when I did the pump, and because it was old, I had to cut the large diameter filler hose which connects directly to the tank to get it off more easily. Be forewarned: Although less than 18" long, that hose is $150!!!