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Pontiac Repair/93 Pontiac Trans Sport


QUESTION: Hello I am pulling my hair out on this one lol My sister has a 93 trans sport and she said it wasn't running and most thought it was the fuel pump and said it would cost her 600.00 over rated lol so I drove 2 1/2 hours one way to change the  furl pump but when I got there and checked it out  it was running GREAT , I drive it around and at times hard started it over and over!! I changed the air filter cuz it was clogged and the fuel filter changed it ran great all day and the next day as well but the 3 rd she said it stopped  running again ! I am not sure what it is I was thinking maybe the map senor or fuel pressure reg , any help ? ASAP

ANSWER: Hi Dave you need to figure out what it's missing and go from there. you need fuel,sprak ans compression for it to run. I doubt it's a compression issue that would mean some sort of mechanical problem with the engine and you said it ran fine. so it's missing fuel or spark.  you can as a quick check take the pressure tap tap off and push down on the Schrader valve and see if you get a good shot of fuel do that second. first pull 2 spark plug wires off the same ignition coil and have someone crank the car over you should see spark jump across the tower of the coil. They have to be on the SAME coil or you will not likely see it jump. if you have spark try it on the other 2 coils and make sure all 3 do it. if you have no spark you either have a bad ground connection somewhere for the engine or a bad crank position sensor or ignition module hard to say the MOST likely cause for a no spark on that engine is a crank sensor but ther are lengthy tests to do to verify if the ignition module is getting the signal to fire off the coils. second test is the fuel test do not do that first and then try the spark test because you can light off the gas vapor. so do the fuel test second. if you don't get a good shot out your missing fuel pressure.

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QUESTION: i am sure it has spark , and she says she dowsnt hear the fuel pump when this happens , but when I was down there the pump and everything was working fine it ran all day for me and then after I left it ran fine for her the next day but on the 3rd it did the same thing I guess wouldnt start and she says again she doesnt hear the pump , but I know these pumps go out they dont work then dont work

ANSWER: could be a bad fuel pump relay which is either on the fire wall on the inner fender well. depending on the year there was a "Prime" wire that would hang out of the wire harness it's either a red wire or a grey wire  right around that model year is when they stopped having that wire. if indeed it does have that prime wire if you run 12V to that wire the pump should run if it does the relay is bad or the ecm is not firing off the relay.  the prime wire is past the relay so if the pump still doesn't run it either is a bad pump or a bad ground wire going to the pump. you can also unplug the harness going to the tank and the body side of the harness which goes to the tank you can check for power and ground at that connector. go across the grey wire and the heavier gauge black wire which is for the pump. put a test light across those 2 ckts and key on the light should light for about 1 second which is a pre prime. and then again once the engine is cranked it should have power the whole time your cranking the engine.

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QUESTION: where would the prime wire be ?

if it has it, it will be in the main engine harness neat the fuel pump relay Like I said before that is around the time where it may or may not be ther. so don't spend a lot of time looking if you don't see it it's not there. it only hangs out of the harness by maybe 2"  

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Todd Puccio


General auto repair,electrical issues,driveability issues,anti-lock brakes,SIR systems,HVAC,engine performance,Gm specific. I have worked at my current dealership since the 1990 model year anything much older than that I have limited exposure to. I do not have very much transmission experience so those question you may want to ask of another expert. When you send me a question let me know the exact make/model/engine and year for the car or suv you have it makes it easier to answer the questions that way. If your happy with the answer I gave you please feel free to Donate. This is a free service to you and I am not compensated at all by this web site. I have 22 years of experience to share with you and my knowledge wasn't free to me. I had to pay for my education.


Experience in the area: I have been a technician in GM dealerships for over 22 years and I am a ASE master technician. I work at a Buick and GMC truck store Previously I worked at a Pontiac GMC store for 18 years. I Served a a lead technician when dealership was on a team system. I just recently moved to a Buick,Hummer,Saab Store when my franchise was purchased by this dealership. Organizations: ASE master technician


Education/Credentials:High school diploma,2 year vocational school degree 2 year college degree. Associates degree in applied sciences (auto technology)Awards and Honors: GMC master technician

Awards and Honors
Master GMC truck technician Master ASE technician in 9 categories

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