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1994 gmc safari ext minivan


gwk007's Avatar
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Join Date: May 2002
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06-16-03, 02:30 PM   #1  
1994 gmc safari ext minivan

i have a 1994 gmc safari ext minivan with 130,000 miles, automatic, 2 wheel drive, 4.3 v-6 tbi.
i recently had a catalytic conv., muffler, tune-up with plugs, wires, cap, rotor, fuel filter, air filter and pcv. it wants to pull down on hills. when i get it up to normal operating speed say 60-70 mph it seems to be in a strain. it will get to that speed pretty much ok but it seems to be in a strain. there is no check engine light coming on. also on cold start sometimes it will go dead immediately and second try is usually ok. i was wondering does it sound like an O2 sensor or maybe a map sensor. any help will be appreciated. also when the air-conditioner is off it seems to perform a little better. and when i depress the accelerator to the for the passing gear kicks in ok.
thanks,
gwk007

 
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06-16-03, 03:29 PM   #2  
Joe_F
Does it feel like the tranny is slipping? How's the fuel pressure?

 
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06-17-03, 10:42 AM   #3  
thanks joe as always you seem to be bailing us out. the transmission seems to be ok. i haven't checked the fuel pressure yet. can i check it some where other than under the dog house?
the reason i asked about the O2 or the map sensor was i read about some of the functions of those sensors and was wondering if maybe that could be it. i also read about checking those by using a volt meter and reading a certain voltage and at a certain rpm.
thanks,
gary

 
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06-17-03, 10:52 AM   #4  
Joe_F
Well, the proper way is to use a scanner to read the various sensors and their outputs and compare them to spec. For instance, you can pull the vacuum from a MAP sensor and compare it to the test specs to determine if it is bad or not. With a hand vacuum pump and the spec, it's quite easy.

You will throw parts at the problem without following logic. Start with my "The Basics" and autolibrary.org for test procedures on the various parts.

The fuel pressure is checked with a gauge (rented from Autozone if you don't own one) at the fuel pressure port from under the hood or doghouse.

 
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06-17-03, 05:17 PM   #5  
thanks joe, you're right. it is always best to test. i will try the pressure test first.
thanks

 
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