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Old 08-30-2009, 02:07 PM   #1
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Join Date: Oct 2007
Location: Tucson, Arizona
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Car: 1987 Z28 Camaro
Engine: 5.7 performance crate motor/TPI
Transmission: 700R4
Axle/Gears: Stock posi

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Car will start but wont idle or stay running

Ok...I've got a 91 firebird that was sitting for about a year until we decided
we wanted to get it running again. We put a fuel pump (Carter) in it, fuel filter, starter and cleaned the injectors out and it was running fine and passed emissions until about a week later it wouldn't restart one morning. I found that the starter relay wasn't sending signal to the starter so we bypassed it and got it to crank. Now the injectors are not spraying and these are the things that we know are good based off switching them out with known good parts.

-Injectors
-ECM
-Wires from ECM to injectors (verified continuity between ECM and injectors)
-Injectors have constant power
-Ignition Control Module
-TPS
-Vats (is sending 5 volt reference to ECM when cranking)
-Fuel pressure (11 psi when cranking)

Anyone have any ideas why the injectors wont stay pulsing. They prime when ignition is turned on but will only pule every once in a while once started. (gas pedal has to be pumped to keep it running)

Any ideas would be great. Thxs
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Old 08-30-2009, 02:34 PM   #2
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Car: 91 Trans Am 'vert
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Re: Car will start but wont idle or stay running

Since it's a 91, I'm assuming the car is fuel injected. Is it TPI or TBI? Since I think that you should be getting a lot more than 11 psi (40-45ish?). I'm no expert... but that's what I heard.
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Old 08-30-2009, 03:55 PM   #3
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Car: 1987 Z28 Camaro
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Re: Car will start but wont idle or stay running

Sorry I guess I should have put that. It is a 305 TBI

We hooked up the fuel pressure gauge to the 91 RS Camaro that we have that has a 305 TBI in it as well and fuel pressure in it was only 11 PSI. As far as I know it is only supposed to be between 10-13 PSI.
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Old 08-30-2009, 03:56 PM   #4
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Re: Car will start but wont idle or stay running

Oh ok, since fuel pressure for the TPI's is like 40-45 psi. My mistake
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Old 08-30-2009, 08:08 PM   #5
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Car: 1987 Z28 Camaro
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Re: Car will start but wont idle or stay running

Update

Swapped distributors and it still did not make a difference. Injectors aren't seeing a ground from ECM. Anyone have an ECM ground location layout?
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Old 08-31-2009, 08:40 PM   #6
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Car: 1987 Z28 Camaro
Engine: 5.7 performance crate motor/TPI
Transmission: 700R4
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Re: Car will start but wont idle or stay running

Found what pins are the ground for the ECM and found the ECM has good grounds. So so far these are the things that I know that are good or have swapped to see that they are good

-Fuel pressure (10 PSI when cranking)
-Oil pressure (goes to about 15 psi when cranking)
-Injectors (swapped with another 91 TBI camaro)
-Injectors have constant 12 volt power
-Distributor as well as ignition module
-Wires from ECM to injectors (all 4 have continuity)
-TPS
-VATS (is sending 5 volt reference to ECM when key turned on)
-Key (we have tried both keys we have)
-Fuel pump (carter fuel pump as installed and working fine)
-ECM (put in another car and it ran fine)

Car was running fine till it was filled up with gas then parked. We found we had to jump the starter relay to get it to crank so I don't know what is wrong with that. I believe the only function of the starter relay is to allow power to starter when VATs ground relay.

Anyone have any ideas why the ECM wont send a ground to injectors? I'm running out of things to check. It is a 91 firebird with a 305 TBI

Last edited by THE87IROCZ; 08-31-2009 at 08:41 PM. Reason: spelling
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Old 09-02-2009, 12:18 AM   #7
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Re: Car will start but wont idle or stay running

Found wires to ignition were broke. Replaced ignition cylinder and car started right up. Guess VATS module will act normal even if it doesn't detect the right key.
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Old 04-11-2010, 08:01 PM   #8
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Car: 1985 Camaro & 1994 Camaro
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Re: Car will start but wont idle or stay running

Quote:
Originally Posted by THE87IROCZ View Post
Found wires to ignition were broke. Replaced ignition cylinder and car started right up. Guess VATS module will act normal even if it doesn't detect the right key.


Hello. I have an 85 camaro that is doing alot of the same things yours was doing to you. Mine has a 2.8L V6 but it turns and turns over but when it finally starts it dies as soon as you let go of the key. You said you had to change the ignition cylinder, do you mean where the key goes? Mine was at a mechanic getting the clutch changed out and he noticed that you had to nearly break the key turning it so hard before it would make contact and start, so he said he for an extra $20 he would adjust something in the steering column to make it get contact sooner. Well, he did but now I notice I don't have the accessory option when you turn the key backwards from the lock position. Would what he did cause my problems! Any help would be greatly appreciated! You could reply to cannon12@suddenlink.net if that would be easier for you! Thank you for your time!
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Old 04-11-2010, 11:57 PM   #9
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Engine: 305 TBI
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Re: Car will start but wont idle or stay running

sounds like he over adjusted the Ign. switch. It's located on top of the steering column about half way down. (The electrical part) with a rod that comes down from the ignition tumbler (where the key goes)
Might need to be re adjusted or replaced.
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Old 04-12-2010, 02:45 PM   #10
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Car: 1985 Camaro & 1994 Camaro
Engine: 85 - 2.8L to 5.7L, 94 - 3.4L
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Re: Car will start but wont idle or stay running

Quote:
Originally Posted by Fuzzman17 View Post
sounds like he over adjusted the Ign. switch. It's located on top of the steering column about half way down. (The electrical part) with a rod that comes down from the ignition tumbler (where the key goes)
Might need to be re adjusted or replaced.


Thanks. Thats what I am hoping it is. I have replaced alot of parts during this problem. I'll probably end up having to take it to mechanic anyway before its all said and done. But I'll try the ignition switch first. I'll post back once I get it in!
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