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g huns
Anonymous Poster
gthunsberger@fourway.net
May 28, 2009, 2:45 PM
Post #1 of 5
(4547 views)
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I have a 98 Olds mini van with the trusty 3400 V6. The van just turned 180K but the motor has only 60K. I just replaced the head gasket 2500 miles ago, drove it 500+ miles over Memorial Day weekend, and today it stated acting up. It spits, sputters, jerks and then dies when driving down the road. It will start up again and idle but if I give it gas it misfires and dies. Sat there and scratched my head a few minutes and it started up and I drove home with no problem. Went out later and drove it, same thing. This time I took my fuel pressure gauge and OBD II code scanner. Fuel pressure is never under 40 psi and no codes to be scanned. I can't believe a computer controlled engine can run this bad and not throw a code. It reminds my of how my Bonneville ran when the crank sensor was bad but that spit out a code right away. Any suggestions?
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Loren Champlain Sr
Veteran
/ Moderator
May 28, 2009, 3:26 PM
Post #2 of 5
(4536 views)
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Re: GM 3400 misfires
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g huns; First, what type of a scanner are you using? Is it just a code puller? This vehicle has misfire detection and should be storing at least a misfire code and setting a check engine light if it's doing what it 'sounds like' from here. Do you have any valve train noise? Any overheating?
Fuel pressure spec is 41-47psi. If you are at 40psi, that's not enough. 40 is enough for it to 'run', but not enough to handle much of a demand. Just for grins, check/replace the fuel filter and retest.
Most parts stores will retrieved trouble codes for free. Post any codes you get and we can go from there.
Loren
SW Washington
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g huns
Anonymous Poster
May 28, 2009, 3:39 PM
Post #3 of 5
(4535 views)
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Re: GM 3400 misfires
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I have an OBDII scanner. It scans for regular code as well as misfires etc. I got none out of it. The service engine light has not come on at all.
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Guest
Anonymous Poster
May 28, 2009, 5:17 PM
Post #4 of 5
(4528 views)
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Re: GM 3400 misfires
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Just checked fuel pressure again. 38 psi at idle 36 under load. Unhooked the vacuum line to the fuel pressure regulator and it jumps to 47 psi. Is this normal?
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Loren Champlain Sr
Veteran
/ Moderator
May 28, 2009, 5:23 PM
Post #5 of 5
(4525 views)
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Re: GM 3400 misfires
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Yes; With the pressure regulator unplugged, it goes full rich. Your fuel pressure specs are too low.
Loren
SW Washington
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