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83 305 crossfire no start when hot

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Old 10-11-2018, 05:47 PM
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83 305 crossfire no start when hot

I am currently working on a 83 305 Z28 camaro. When its cold it starts fine When its hot it won't start at all. There is no injector pulse. I have replaced the coil pickup, module, rotor, & in cap coil...any help would be appreciated TIA
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Old 10-11-2018, 08:34 PM
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Re: 83 305 crossfire no start when hot

When this occurs. Have you unplugged both injectors and checked for pulse. Iirc the injectors should be 2.5ohms .
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Old 10-15-2018, 02:21 PM
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Re: 83 305 crossfire no start when hot

Originally Posted by Tuned Performance View Post
When this occurs. Have you unplugged both injectors and checked for pulse. Iirc the injectors should be 2.5ohms .
Noid lite does not blink on either injector
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Old 10-15-2018, 02:24 PM
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Re: 83 305 crossfire no start when hot

Originally Posted by jbrodder View Post
Noid lite does not blink on either injector
Replaced coil pickup, module, coil, fuel pump, fuel pump relay. Going to replace electronic spark control module tomorrow
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Old 10-15-2018, 03:52 PM
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Re: 83 305 crossfire no start when hot

no 2 second pulse of fuel pump when hot. if I shoot a small shot of ether into tbi it fires right up
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Old 10-16-2018, 04:03 PM
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Re: 83 305 crossfire no start when hot

Few questions, what do you mean exactly by "when hot"? How "hot"? How long does it take to get to "hot"? Will it stop running when it reaches "hot" or just not start back? At what temperature will it re-start?
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Old 10-16-2018, 08:50 PM
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Re: 83 305 crossfire no start when hot

It starts fine cold, if you drive it for 20 to 30 minutes & shut it off it will not start until it cools down. By hot I mean operating temp. It doesn’t go over 190 degrees. When you try to restart it it turns over finre. There is no injector pulse but there is spark at the plugs. If you give it a little shot of ether it’s starts right up. Also I do not see a 2 second fuel pump run.
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Old 10-17-2018, 01:00 PM
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Re: 83 305 crossfire no start when hot

Have you checked/replaced the temp sensor? The one for the ECM, not the gauge on the dash (maybe it's sending a freaked out reading to the computer after it gets hot). Also verify there is 12 volts reading at both injector plugs (red on one and white on other I think), those go to the injector fuses. Should be hot with ignition switch in on position. Obviously they will test fine when it WILL start, but what about when it WON'T? Also did you get a value for the resistance at the injectors themselves as Tuned Performance stated? I would recommend a cold ohms reading as well as another after the engine gets to temp.

Last edited by jstadmud; 10-17-2018 at 02:51 PM.
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Old 10-17-2018, 02:56 PM
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Re: 83 305 crossfire no start when hot

If you flash the check engine light, are there any codes present?
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Old 10-21-2018, 10:53 AM
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Re: 83 305 crossfire no start when hot

No codes present.removed covering from wires back to firewall to check for bad or broken wire...nothing. This vehicle has only 40k miles on it.
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Old 10-21-2018, 08:05 PM
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Re: 83 305 crossfire no start when hot

sounds like an ECM problem to me,but there are a few things to check before subbing out the ECM with another one, remove and reinstall the fuses-over several decades,an oxide film forms between the tinned copper blades of the fuse and the brass contacts of the fuse panel causing a high resistance connection-remove/reinstall restores proper contact.Do the same with ECM plugs as same thing can happen there.Injectors receive battery power with ignition on ,ECM grounds the other side to "fire"injectors,so next time fails to fire injectors, check for power to injectors and ECM.CFI 'vettes use same ECM as 3G,'82 ECMs are bigger than '83,but plug in and work the same as long as proper '82 chip used.
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Old 10-22-2018, 07:23 AM
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Re: 83 305 crossfire no start when hot

Thanx for the info. I will try that
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Old 10-22-2018, 05:26 PM
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Re: 83 305 crossfire no start when hot

Before going as far as swapping the ECM, I would pull the board out and inspect (with a magnifying glass) the circuits and soldered joints for any signs of overheating or damage.
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Old 10-24-2018, 05:26 PM
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Re: 83 305 crossfire no start when hot

Changed all the fuses in the fuse panel. Pulled the computer out, pulled the board, looked it over, had a few spots that looked like corrosion. I took a stainless steel tooth brush & brushed the area & the corrosion went away. While I was in there I noticed there was a hypertech unit plugged into the prom. Could that be at fault? Thanx in advance for your help.
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Old 10-25-2018, 11:56 AM
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Re: 83 305 crossfire no start when hot

I have no experience with Hypertech chips, so I can't say good or bad either way.

But I did find this explanation of its function in another thread:

WHAT IS A PROM?
A PROM is a removable memory chip located within an ECM. PROM stands for
Programmable Read Only Memory. This memory chip contains the vehicle
characteristic information, as well as memory tables for such functions as spark timing,
fuel control, emission control strategy, etc. The information contained within the PROM
memory chip can be thought of as an instruction manual written for the ECM. Without
the proper PROM chip, an ECM may not function as intended for a specific vehicle
application. Also, if certain driveability concerns are traced back to the PROM, a new
updated PROM may be released calling for the removal of the old PROM followed by
the installation of the updated version.

I would imagine it could create all sorts of problems if it were to start malfunctioning from time to time...

...
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Old 10-25-2018, 12:06 PM
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Re: 83 305 crossfire no start when hot

If the prom was bad you should experience a rapidly flashing check engine light. Or it might throw a code 41 or 51.
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Old 10-25-2018, 01:33 PM
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Re: 83 305 crossfire no start when hot

yes I checked the code it comes up 12. Called Hypertech suport & they said if chip was bad it either wouldn't start at all & would give a 51 code.another dead end.Thanx for the input if you guys think of anything else all help is appreciated. Thanx
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Old 11-06-2018, 09:31 AM
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Re: 83 305 crossfire no start when hot

Check starter motor. The starter motor probably has gone bad.
I have the same problem. I tried to put an alluminium heat shield (piece of metal around motor) but in vain.
Coil field is badly affected by heat. This is a singn of wear out for starter.
My suggestion is buying a new starter.
Its my next move, too.

Last edited by katrav8; 11-06-2018 at 09:34 AM.
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Old 11-06-2018, 12:51 PM
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Re: 83 305 crossfire no start when hot

what would the starter have to do with no injector pulse when at operating temp? I sent computer out they found a couple of weak solder joints &repaired them. reinstalled computer same thing, no start when warm. running out of things to check & replace. has to be something simple I would think. Any more suggestions??? thanx in advance for your time.....JB
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