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-   -   Intermittent no start condition (https://classracer.com/classforum/showthread.php?t=49404)

Rich Biebel 09-19-2013 09:33 AM

Re: Intermittent no start condition
 
The sensor outputs a very low voltage and it would be millivolts......

A Fluke can read this accurately....

I just had some trouble with the ABS sensors in my GMC....

They do the same thing.......and can easily lose low speed output from rust building up under them. I found the info readily available online as to what they should read just by turning the wheels by hand......and a little work with a file and a wire brush.....and Viola....all better...

That was after I had already replaced both sensors and they were probably good.....

John Nechiporchik 09-19-2013 09:44 AM

Re: Intermittent no start condition
 
Mike/Joe/Kirk,
I did the test of the crank trigger as Joe stated. Simple and effective.
Next, I spoke to MSD and the tech rep indicated the ohms reading of the MSD pickup (test leads on purple and green wires) should be between 65 and 85 ohms. This is for the non magnetic pick-up.....magnets are in the wheel, not the sensor.

Will test mine tonight along with using my newly acquired noit light to test injectors.
Also got a few other areas to check (connections, grounds etc) tonight.

buzzinhalfdozen 09-19-2013 12:50 PM

Re: Intermittent no start condition
 
Rich , I believe there is a special coverage for the wheel speed sensors you can check with your local GM dealer as it varies year to year. We clean and apply a compound to the knuckle so rust doesn't redevelope. John, good deal testing this stuff is not hard at all, but does require a few items, sounds like you're on top of it. Joe Oh and sorry bout that wrong resistance spec, I was shooting from the hip on that, which is the spec GM uses withtheir sensors must have got stuck in my head.

Steve Williams 09-19-2013 05:20 PM

Re: Intermittent no start condition
 
Quote:

Originally Posted by Kirk Morgan (Post 400721)
I have been working on this stuff since it all started, Certified mech for 30 years. I went to a A/C Delco class many years ago and learned that the magnet type makes A/C voltage when cranking. I believe the spec is 3 volts. I can dig out my old books to confirm if needed. That will confirm signal strength which can cause intermittent problems.

Kirk

This is exactly what I was referring to when I spoke of voltages and weak signal.

John Nechiporchik 09-19-2013 08:54 PM

Re: Intermittent no start condition
 
FED 387....after testing every circuit I could test....it appears that the only logical conclusion I can come to is the coil is the problem, as you stated a few days ago.
Tonight, I checked the ohms on the crank trigger sender....78.2 (MSD said between 65-85)...OK
Tried to start....fired right up.
Repeated 2 more times and fired up.
4th. try....no start
Grounded coil wire (dist. end) to block in two different locations approx. 1/16 gap......no spark
Tried again about 15 minutes later....spark like 4th of July.
Replaced coil wire.....fired right up.

Gotta be the Friggin coil.....
Going to get one tomorrow.

John Nechiporchik 09-20-2013 09:31 AM

Re: Intermittent no start condition
 
Went through test process again this morning.
I believe when I tested the coil last night (metal screw in dist end of not) I did not have a proper connection.When I use a spark tester, it gives me a signal.
Throw out last nights test.
Tried to start car this AM....fires right up
Second try ...no start.
put spark tester on coil AND noid tester on injector simultaneously...Result...no start, spark at coil, NO light at noid tester.
Repeated several times same result.
HELP AGAIN!!

Rich Biebel 09-20-2013 11:29 AM

Re: Intermittent no start condition
 
John....It sounds to me as I said before.....You have an intermittent wire connection problem between the ECU and your MSD or possibly your battery connections to your ECU.

It has been to long for me to recall the exact wiring connections needed between the MSD and the Accel ECU.....

Accel still shows the wiring diagrams and tons of info on their website.



The ignition connector on the Accel unit and all the connections related to it are where I believe your trouble may be. Your ECU needs to be switched on and also gets a tach signal from the MSD....

Without actually seeing your car and wiring it's impossible to tell you how to fix it.

You have isolated the problem and now know it IS the injectors are not turning on and supplying fuel to the engine......so the ignition system is not the problem.....

Kirk Morgan 09-20-2013 11:33 AM

Re: Intermittent no start condition
 
Check for battery voltage in the injector harness when you have a no start condition.

Kirk

Rich Biebel 09-20-2013 11:58 AM

Re: Intermittent no start condition
 
This is for a Gen VII Accel ECU and may be helpfull

The connector labeled IGNITION is what powers up the ECU....

http://data.prestoliteperformance.co...ng_diagram.pdf


A lot of info available here..

http://info.accel-ignition.com/dfi/a...-download.html

John Boland 09-20-2013 08:05 PM

Re: Intermittent no start condition
 
The battery is something to consider before you spend real money. It could be failing in a way that it is generating electrical noise.


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