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98 GMC Sierra 4.3 V6 "cold start problem"


1DubiousDan
09-22-2008, 07:11 PM
Hi Folks,

I am having trouble starting my truck (with 150K) when it has not been operated for over 4 hours (sometimes less) it cranks with plenty of power it just seems like it is not getting fuel. Once I get the truck started it runs excellent and does not have any power problems other then an occasional power buildup when passing sometimes resulting in a hard shift that will break the rear end loose (chirp the tires). I have tested the fuel pump (pressure check 60 psi) and I have visually inspected the truck for fuel leaks and checked the vacuum lines as well. Everything appears to be ok... any suggestions on possible causes? I am looking to sell the vehicle and this is a real problem :banghead: .

Work done on the truck within the last 25K:
New fuel pump
New fuel Filter
Tune up
Regular oil changes
Professional fuel system treatment (whatever that means)

2000CAYukon
09-22-2008, 08:55 PM
What does the fuel pressure do when you turn the engine off?

//2000CAYukon

1DubiousDan
09-23-2008, 02:24 AM
It holds initially then drops down to about 55-57 psi, is that normal or is that a sign of a malfunction?

2000CAYukon
09-23-2008, 10:53 AM
It holds initially then drops down to about 55-57 psi, is that normal or is that a sign of a malfunction?

How long did you watch the pressure for? This looks normal.

Since you have a pressure gauge, you should see what the pressure is when it is hard to start just to make sure it is not a fuel related issue.

If you have access to a scan tool, you should see what value the ECT sensor is reporting. The engine needs more fuel when cold and if the ECT is incorrect, it might not get enough fuel to start.

//2000CAYukon

dexterthedog
09-27-2008, 06:28 AM
Does your truck have a Throttle body injection system?
Not sure about anything as new as a '98 but the earlier '90's had a module in the distributor which controlled fuel while the key was in the start position. Fuel after it was running was controlled from another module on the firewall. Mine would not start at all but would run fine with a splash of gas into the T.B. to get it going.

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