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87 ECM No injector signal by rodgertoilman
Started on: 04-12-2012 03:15 AM
Replies: 13 (228 views)
Last post by: Carcenomy on 05-13-2012 07:47 AM
rodgertoilman
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04-12-2012 03:15 AM Click Here to See the Profile for rodgertoilmanClick Here to Email rodgertoilmanSend a Private Message to rodgertoilmanEdit/Delete MessageReply w/QuoteDirect Link to This Post

My 84 with 87 engine is still under restoration just needing the paint job . I have been able to start and run the engine to move the car around the workshop but suddenly
i have an engine turns but refuses to run situation . I have squirted raw fuel down the throat and it runs up till i stop squirting ,so i tested with a noid light and no signal at the injector tested the wire from ECU to injector for continuity all good. Is a new ECU the recomended fix ? i could have fried the injector trying to get it to pulse by applying 12v direct to it so i'm happy to replace it.A new ECU i will need to import from the mother land of Fiero and i see they come less the Prom could my Prom be dead too??

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fgt1988
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04-12-2012 06:29 AM Click Here to See the Profile for fgt1988Click Here to Email fgt1988Send a Private Message to fgt1988Edit/Delete MessageReply w/QuoteDirect Link to This Post

no offense bec im not good at fuel issues but have you tried to plug in a fuel pressure guage to see if you have fuel pressure while the engine is idling? bec messing with injectors, i would rule out that first. 2nd, i ve heard 12V before on injectors and it did not harm it but it could.. just a thought.......either way the cra should still idle even if u don't have all 6 inj firing up and i find it hard that u fried them all..... keep checking and hopefully someone will come out with a fresher mind than me. it is still too early for me..

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rodgertoilman
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04-12-2012 08:10 AM Click Here to See the Profile for rodgertoilmanClick Here to Email rodgertoilmanSend a Private Message to rodgertoilmanEdit/Delete MessageReply w/QuoteDirect Link to This Post

Yes i do have fuel pressure. And its a 4cylinder Duke DIS Ignition

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phonedawgz
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04-12-2012 08:42 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post

You need to do some checks before replacing anything.

1 - Does the ECM still properly operate the fuel pump relay? When you turn the key to on does the relay come on for two seconds and then turn off? Perhaps you have jumpered the fuel pump power to run it.

2 - Does the Service Engine Soon light come on - Key on engine off? It should. If the answer is no for 1 & 2 then check to make sure the ECM is getting power. If you have a disconnect connector near the power distribution posts, is that connector plugged together? That is the ECM reset connector.



3 - If the answer to 1 and 2 was yes, then check to see when you just bump the starter, does the fuel pump relay come on again for two seconds and then turn off again right away? It should. This lets you know if the ECM is getting ignition pulses from the ICM.

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theogre
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04-12-2012 08:53 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post

make sure dis-ecm wiring is good... 87 service manual, download http://www.fieronews.net/fusion/downloads.php
Likely a dead ECM.
ECM "wear out" from overheating. Not enough air to cool off. Get a new ECM and remove some insulation.
See my cave, ECM heat in ECM section.

+ doing that makes things in storage box cool to.

Injector likely is fine. You may have blown a fuse messing around. Injector signal is ECM switch to ground, Not 12v...

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firejo24
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04-12-2012 01:04 PM Click Here to See the Profile for firejo24Send a Private Message to firejo24Edit/Delete MessageReply w/QuoteDirect Link to This Post

The ECM needs to see that the engine is turning over before it will fire the injectors. While I agree that checking for fuel pressure is a good idea, if a noid light showed no pulsing, and the injector has power, then you’re on the right track. However, a noid light won’t show an injector pulsing if the power to the injector isn’t there. So, check to make sure there is power on the red wire at the injector (with it disconnected). If not, you have a problem with the injector getting power and that’s where you need to start (fuse?). If you have power and still no noid light, check for spark. If the ignition is not working and not sending a signal to the ECM the ECM won’t pulse the injector.

One thing you might try doing is downloading the repair manual for the car and follow the “no start” flow chart. It will guide you to check all the systems needed for the car to run.

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rodgertoilman
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04-13-2012 01:49 AM Click Here to See the Profile for rodgertoilmanClick Here to Email rodgertoilmanSend a Private Message to rodgertoilmanEdit/Delete MessageReply w/QuoteDirect Link to This Post

ECM must be powered up as the engine will run if fuel" bottle feed "down the throat ,yes fuel pump runs. Don't think ECM would over heat as its only been run for a few minutes to move the frame around the yard .Yes the red injector wire has 12v.

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phonedawgz
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04-13-2012 07:29 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by rodgertoilman:

ECM must be powered up as the engine will run if fuel" bottle feed "down the throat ,yes fuel pump runs.....


No that is an incorrect statement. The engine will run without an ECM is fuel is fed into the throttle body. The ignition will work without the ECM. After the engine starts turning over 400 RPM the ECM will take over the ignition advance. But until you reach 400 RPM the ECM is not used for ignition.

That is why I was asking about the other tasks the ECM also does to see if the ECM is functioning.

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rodgertoilman
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04-13-2012 06:16 PM Click Here to See the Profile for rodgertoilmanClick Here to Email rodgertoilmanSend a Private Message to rodgertoilmanEdit/Delete MessageReply w/QuoteDirect Link to This Post

Thanks for the help will go do more tests

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rodgertoilman
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04-19-2012 05:20 AM Click Here to See the Profile for rodgertoilmanClick Here to Email rodgertoilmanSend a Private Message to rodgertoilmanEdit/Delete MessageReply w/QuoteDirect Link to This Post

Well the plot thickens, had a young non mechanic guy in my garage and was telling of my no start problem and he finds the red feed wire from the power distribution disconected just like Ogre suggested. So lets throw the battery in and plug in the ECM and try for a start. Fired a few shots then flooded, fuel is now pouring from the injector all the time the ign is on. Disconnected the injector plug and fitted in the noid light its lit up all the time no flashs. Is my circuit467 grounded somewhere?
And yes i have the 87 service manual on my PC

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Carcenomy
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04-19-2012 07:53 AM Click Here to See the Profile for CarcenomyClick Here to visit Carcenomy's HomePageSend a Private Message to CarcenomyEdit/Delete MessageReply w/QuoteDirect Link to This Post

Didn't I tell you to check the wiring again?

I'll come over some time in the weekend and we'll have a bit of a poke around.

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[This message has been edited by Carcenomy (edited 04-19-2012).]

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phonedawgz
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04-19-2012 09:40 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post

Unplug the wires from the ECM. If the injector stops spewing fuel, then your ECM did indeed get fried.

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Carcenomy
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04-21-2012 12:49 AM Click Here to See the Profile for CarcenomyClick Here to visit Carcenomy's HomePageSend a Private Message to CarcenomyEdit/Delete MessageReply w/QuoteDirect Link to This Post

Checked continuity and voltages everywhere, short is in the ECM. Time for a new computer.

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Carcenomy
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05-13-2012 07:47 AM Click Here to See the Profile for CarcenomyClick Here to visit Carcenomy's HomePageSend a Private Message to CarcenomyEdit/Delete MessageReply w/QuoteDirect Link to This Post

Thought I'd give this a quick bump since the issue is resolved.

ECM appears to have shorted its injector driver, was holding the injector open. Snapperhead sorted us a replacement. Plugged it in, and the Duke fired up first go. Happy ending!

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