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3.4 wont turn over


gp90se

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Just dropped the 3.4 into the grand prix, its getting spark and fuel in the cylinders, but wont turn over, the timing belt is new and the wiring is good, we tryed starting fluid but 2 no avail. it wants 2 start but it just keeps cranking.

 

ideas?

-Jeff

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hmmm..... ECM problem? o.o

 

try checking your wiring.... or, in the golve box (I think) check the ecm fuse, or the Engine fuse (do w-bodies have one? O_o)

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if that went, i wouldnt have spark, correct?

 

Yeah, you wuld not get spark if the Crankshaft Position is toast.

If you're getting fuel & spark, it's something with incorrect timing, injector, or bad ECM.

Are you running the donor DOHC ECM?

Is there a gas smell like the car is flooding?

 

- Erik

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the engine is a 95, the wiring is from a 91 and that ecu was bad, pats extra 1 with the 91 chip seemed 2 make everything rung right (spark fuel and air)

 

doesnt smell like gas.

it really wants 2 go, its got 2 be not getting enough fuel.

 

-Jeff

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it has:

 

fuel in cyls

injectors pulsing

cams are timed correct(my car is right here as a reference)

strong spark

good module and coils

crank sensor tested good

wiring has been gone over 2x

all the sensors save tps and cts have been replaced w/ new or almost new known working ones

tps checked out w/ ohm meter

cts same

 

i ran thru the "vehicle cranks but will not start" section of the gm factory service manual and this gd thing should be running according to the general.

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problem found:

 

rings are wiped out, the gas is running right down the cylinders past the rings into the oil. apparently the motor sat for a while before it was shipped, it looked like it came out of a junkyard motor pile to be honest.

 

so the rings are gone, cyls probably need bored, in general it needs a complete rebuild. compression is on the very poor side of the scale

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problem found:

so the rings are gone, cyls probably need bored, in general it needs a complete rebuild. compression is on the very poor side of the scale

 

 

if you have no piston rings, you won't have very good compression ;)

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I saw this motor it sat out of the car for about a week. and it ran when it was removed. Which ECM did you use and which harness did you use. will need a 95 harness to work a 95 ECM. How do you know the rings are bad? Did you change the oil and smell it?

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yes, the oil, which we put in fresh, reaked of gasoline after 10 sec of cranking.

 

i have a feeling this was NOT the engine that was sold to jeff, because it had a hacked up harness banded to it and was filthy, corroded to hell and back(peeling paint on the cam covers from corrosion), covered in mud and wood chips.

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we got 1 off of a 91 3.4 in the junkyard, went thru each wire and used the ECM chip for that year. the injectors were all firing and each cylinder was getting spark, but like pat said, after 10 seconds of cranking, the oil smelled like gas.

 

-Jeff

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Well jeff, sounds like you have a cat by the tail. I could be wrong but it looks like you have two different fuel platforms. 95 sfi w/ cam sensor to fire the injectors on the motor and 91 mpi on the ecm. Don’t know how compatible these would be? The injectors are different but its probably just #.

 

I would check timing with a timing light to eliminate ignition timing as an issue. Make sure every wire lights the light. Compression test, what are the numbers. You might try pinching of the fuel pressure line and see if it starts. If it does I would suspect injectors or regulator. The way you describe it you have to much fuel. Good luck.

 

jud

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the harness and ecm and sensors are all from a 91. this eliminates the cam position sensor from the equation. this would make the engine start and run as if it were a 91 - believe me because i've done this quite a few times to quite a few cars, i'm running a 94 harness and sensors on the 91 3.4 in my car right now and have done several swaps for local cars. harness is good, we had spark at the proper time and fuel at the proper time, but as jeff said above the oil smells like a gasoline tank after just 10 seconds of trying to start it.

 

jeff's car now has the factory 3.1 back in and he is gone. just to verify everything a leakdown test will be performed shortly and a head will be pulled to inspect the cylinder walls and rings(will be inspected by an ASE cert 20yr mechanic)

 

the engine arrived with plug wire o-rings missing and water down all the plug holes, and had a couple plugs that were not tight. before removing the plugs i used a shop vac to take the water out of the plug holes, blew them out with the compressor, and let them air dry the little leftover moisture for a day. when the plugs were pulled a few had wet threads and firing tips leading me to believe there was water in the cyls for a little while at least, any water is enough to rust the cylinder walls and wipe out rings.

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Guest Anonymous

I think I'd be getting my money back on that deal. Sounds like someone didn't give a good description of the motor's condition prior to purchase.

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it does not sound like the same motor that came out of the 95. The motor looked like it was in great condition when he pulled it. I was there and helped do it. I dont think it is the same motor

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Pat will be getting the VIN number off the block as soon as it can be found, we he finds that, we'll know if its the right motor, if it isnt, the junkyard screwed both of us. if it is, sum1 left the engine outside for what looks to be weeks, we shall soon find out, i hope.

 

-Jeff

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brian, the engine that showed up, well, the junkyard has stacks of junk engines laying out for the scrap man that look cleaner and less corroded. this is why i suspect something went awry between when sailor77 dropped it off to send and it got here.

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