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Discussion Starter · #1 ·
please help 86 buick gn when starting warm or cold crank and cranks ( about 5- 8 second crank times)and them back fires it runs fine after starts only has problem when starting... any clues thanks glen
 

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When you first turn the key to Run, the fuel pump should run for about two seconds, then cut off. Does it?

If not, the fuel pump relay is probably bad and the car is running on the back up circuit which does not turn on until the car has been cranked long enuf to build up oil pressure greater than 4 psi.
 

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Welcome! Now, lets get to basics first! What do you have for a scan tool? What are your TPS IAC Cam sensor doing? Have you done any reading at GNTTYPYPE.org yet? Spring cleaning done? Any upgrades done to the car? What chip? Injectors? Etc etc etc. So tell us what you have car wise, scan tool wise, knowledge wise? Cheers!
 

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Discussion Starter · #4 ·
i have an otc 2000 for my scan tool, atr double pumper, red's 100 chip, green stripe injectors, and a new te-44 turbo
(old stock turbo smoked real bad)
 

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Do you have an adjustable fuel pressure regulator or a guage to read fuel pressure? If not they are a great start to diagnose fuel related problems. Also, a modern chip from Eric @ Turbotweak burned for your setup would be a good start! Now, what about what Steve mentioned?
 

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Discussion Starter · #6 ·
i adj the tps .46 it was at .40 this helps alot it starts up fine cold, but it still has hard time when hot, im going to put injetor cleaner in and new wires and new plugs and see it this helps, fuel pressure is 35lbs at ideal with vacuume hose off.
 

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unfortunately, tps change has nothing to do with that....unless you go pass .46 and then it will idle very fast because a number greater than .46 tells the ecm that the car is not idling.

There is no difference in starting, idling, or whatever between .34 and .46.
 

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Thanks for the initial post, Steve. I think this is the problem with my intermittent startup issue. I'll verify by listening for the fuel-pump cuton and all that jazz you spoke of in post 2!! :cheers: :yup:
 

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Discussion Starter · #9 ·
i took the car to a local and he put it on a engine tester, he said that every thing looked good, he said it might be the crank sensor going bad with long crank engine times, if so is it easy to change crank sensor?
 

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Do you have a hotwire kit and does the pump shut off after a couple seconds like Steve asked?
It sounds like you're "flooding" it if the pump doesn't shut off after KOEO.
 

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very highly unlikely that it is the crank sensor...they tend to work, or not work.

Most likely possibilities are the fuel pump relay is bad, or, the injectors are old, dirty, tired, or defective, and are dribbling fuel out when the key is turned off-thereby flooding the engine.

One has to to do some detective work to find the problem.

A) does the fuel pump come on a run for two seconds when you turn the key on? (or does the fuel pressure immediately jump up when you turn the key on?)

B) does the fuel pressure stay up after turning the engine off for at least 30 minutes?

c) have you pulled the plugs about 15 minutes after shutting the engine down to see if they are wet from fuel?

D) Does the oil smell like gasoline?
 

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Discussion Starter · #15 ·
fuel pressure builds up very fast, took plugs out look great, no smell of gas at all, holds pressure for more then 20 minutes when car is turned off
 

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Has anyone been in the engine on this car? A buddy of mine did the cam on his T and I'm not sure what he was smoking when he set the cam sensor but it was way out and his car did exactly what your describing yours as doing.
 

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Discussion Starter · #17 ·
no one inside engine, it's just been getting worse, i'm going to do full tune-up on it this week, what sucks is when it's running it's like a bat out of hell!
 

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You might follow up on what Craig suggested and pop the top on the cam sensor and make sure the interupter wheel is still fixed in place...also make sure the body of the sensor is not loose and has turned a bit.

Won't hurt to look at the crank sensor and make sure it is not loose in its bracket, either. :)
 

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Discussion Starter · #19 · (Edited)
re-did the pump test... turned on key and the pressure went up tp 40 psi, did not start the car, held pressure at 40 psi for more then 30 minutes is 40 psi too high???... is this saying the injectors are ok and are not leaking? i have green strip disk injectors
my next thing to do is look at the crank sensor and see if it oily and then adj the cam sensor... this is killing me :confused: :confused: :( :crazy:
 

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Discussion Starter · #20 ·
ck'd coil 13.8k all 3 ..... put the otc2000 on it and o2 sensor is about .700
block learn 160 int is 138
 
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