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throttle body turns but no fire

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Old Sep 1, 2012 | 10:13 PM
  #1  
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Car: 1986 Trans am
Engine: tuned port 305 LB9
Transmission: 700r4
Axle/Gears: .323
throttle body turns but no fire

My 91 camaro with a 350 throttle body suddlenly stopped wanting to crank yesterday. it will turn and turn but never crank fule pump is good i even put gas directly in throttle body and stilol no spark. please help

thanks,andrew
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Old Sep 1, 2012 | 10:15 PM
  #2  
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From: Sussex County, NJ
Car: 1994 Z28
Engine: 355 LT1
Transmission: T56
Axle/Gears: 3.42
Re: throttle body turns but no fire

got power to the coil/distributor?
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Old Sep 3, 2012 | 10:40 AM
  #3  
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Car: 1986 Trans am
Engine: tuned port 305 LB9
Transmission: 700r4
Axle/Gears: .323
Re: throttle body turns but no fire

Originally Posted by zraffz
got power to the coil/distributor?

I've replaced the ECM because i've had problems with it in the past, but it still wont fire. And how would I check if there is power to the coil?
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Old Sep 3, 2012 | 02:26 PM
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Car: 1986 Trans am
Engine: tuned port 305 LB9
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Axle/Gears: .323
Re: throttle body turns but no fire

well I took the spark plug out to check for a spark and there was no spark. while checking for a spark the engine turned over and began to run so i killed it put the plug back in and started it again. i ran it for about 10 minutes with no problem, and killed it and cranked it about 7 or 8 times without problem. So i took it and drove it for about a mile and killed it. now it is doing the same as it was before just turns and turns with no fire.
any ideas? please help.
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Old Sep 3, 2012 | 09:57 PM
  #5  
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From: Sussex County, NJ
Car: 1994 Z28
Engine: 355 LT1
Transmission: T56
Axle/Gears: 3.42
Re: throttle body turns but no fire

Your red power wire running to your distributor should have 12 volts. Make sure the black wire (ground) is properly grounded.
If you have power running into your distributor but don't have any spark, it's something inside your distributor (bad module, rotor, cap, coil--on HEI units).

Of course this is assuming your spark plugs are clean/properly gapped and your wires aren't damaged.

Try a little spurt of ether just to ensure it isn't a fuel issue.


I was actually just finishing up putting a small block in my s10 today and thought I had lost spark. I went crazy, only had it running for about 15 minutes. Tore the distributor apart to inspect the weights, springs, cap, rotor, coil, checked for power. Realized my aftermarket ignition box wasn't grounded too well. Regrounded it and still didn't get it to fire.
Started taking plugs out and noticed they were all extremely fouled (I hadn't had time to tune it and it was running EXTREMELY rich to the point the plugs weren't igniting).

Last edited by zraffz; Sep 3, 2012 at 10:00 PM.
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Old Sep 3, 2012 | 10:25 PM
  #6  
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Car: 1986 Trans am
Engine: tuned port 305 LB9
Transmission: 700r4
Axle/Gears: .323
Re: throttle body turns but no fire

that actually may be it because i havnt gotten it tuned yet and it idles high and downshifts out of overdrive like it doesnt know what to do. and i will check the wires tomorrow and let you know how it goes thank you!!
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Old Sep 3, 2012 | 10:32 PM
  #7  
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From: Sussex County, NJ
Car: 1994 Z28
Engine: 355 LT1
Transmission: T56
Axle/Gears: 3.42
Re: throttle body turns but no fire

It would take a lot to foul a set of plugs on a properly running motor. Mine were caused by unadjusted fuel floats and idle mixture screws. (I got the carb used and I assume someone seriously tweaked it).
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Old Sep 3, 2012 | 10:48 PM
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Car: 1986 Trans am
Engine: tuned port 305 LB9
Transmission: 700r4
Axle/Gears: .323
Re: throttle body turns but no fire

ok but would you have any idea why it cranked when i took the plug out? just luck or maybe the plugs were drowned in fuel or maybe not enough air into the engine?
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Old Sep 3, 2012 | 11:51 PM
  #9  
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From: Glen Park, NY
Car: 1987 IROC-Z
Engine: TPIS II Supercharged w/Nitrous
Transmission: 700R4 Probuilt
Axle/Gears: 3:73 Richmond 12 Bolt
Re: throttle body turns but no fire

You are saying that you checked your plugs and they are fuel saturated. Sounds like you need to change all your plugs.. Don't try the old trick of spraying them down with brake cleaner and burning off any remaining fuel.. Get new ones. Are you getting good spark currently?
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Old Sep 4, 2012 | 12:35 AM
  #10  
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Car: 1986 Trans am
Engine: tuned port 305 LB9
Transmission: 700r4
Axle/Gears: .323
Re: throttle body turns but no fire

nope. when i took the plug out and tried to crank it it had no spark at all then it fired up and they were all running fine. it wont crank right now. it just turns again and again. but a friend told me it is most likely the coil so i was going to replace that tomorrow morning and see if it got me anywhere.
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Old Sep 4, 2012 | 01:29 AM
  #11  
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From: Glen Park, NY
Car: 1987 IROC-Z
Engine: TPIS II Supercharged w/Nitrous
Transmission: 700R4 Probuilt
Axle/Gears: 3:73 Richmond 12 Bolt
Re: throttle body turns but no fire

Originally Posted by Wormdog13
nope. when i took the plug out and tried to crank it it had no spark at all then it fired up and they were all running fine. it wont crank right now. it just turns again and again. but a friend told me it is most likely the coil so i was going to replace that tomorrow morning and see if it got me anywhere.
Have you changed your pickup coil in the Distrib?

Does your car have the ECM fuse? Is it blown?

What is the year / make / engine size, I will upload wiring schematics
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Old Sep 4, 2012 | 01:49 AM
  #12  
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From: Glen Park, NY
Car: 1987 IROC-Z
Engine: TPIS II Supercharged w/Nitrous
Transmission: 700R4 Probuilt
Axle/Gears: 3:73 Richmond 12 Bolt
Re: throttle body turns but no fire

Here are the schematics for your year...
Attached Files
File Type: pdf
85346202.pdf (49.8 KB, 98 views)
File Type: pdf
85346205.pdf (45.2 KB, 88 views)
File Type: pdf
85346206.pdf (46.6 KB, 94 views)
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Old Sep 4, 2012 | 01:57 AM
  #13  
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Car: 1986 Trans am
Engine: tuned port 305 LB9
Transmission: 700r4
Axle/Gears: .323
Re: throttle body turns but no fire

i have no idea if it has an ECM fuse where would it be located?
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Old Sep 4, 2012 | 08:51 AM
  #14  
ibmtech's Avatar
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From: Glen Park, NY
Car: 1987 IROC-Z
Engine: TPIS II Supercharged w/Nitrous
Transmission: 700R4 Probuilt
Axle/Gears: 3:73 Richmond 12 Bolt
Re: throttle body turns but no fire

Originally Posted by Wormdog13
i have no idea if it has an ECM fuse where would it be located?
If you look at the 8534602.pdf at the ECM Connector A10 from the ECM to the top of the screen there is a BRN (Brown) wire that goes to the HOT N START you can see the 3 amp CRANK FUSE.. That is what I would be looking for... The fuse is normally located close to the battery but I am not 100% sure because of the difference in years.. Mine was located on the inner fender behind the battery in a weather pack connector.

Last edited by ibmtech; Sep 4, 2012 at 08:57 AM. Reason: Found Schematic Location
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Old Sep 4, 2012 | 04:43 PM
  #15  
Wormdog13's Avatar
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Car: 1986 Trans am
Engine: tuned port 305 LB9
Transmission: 700r4
Axle/Gears: .323
Re: throttle body turns but no fire

i couldnt find it haha. but i went back and took the plug out again and it started up fine and ran but when i drove it it wanted to die after about a mile and then it did die and wouldnt crank.
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