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Dead ECM replacement

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Offline aaron74

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Dead ECM replacement
« on: April 15, 2008, 07:02:03 PM »
I spent part of the day head scratching over a Sunrunner with a dead ECM.  The story is during a tune-up someone had taken the distributor out of the truck and replaced it with a new one.  This person did not mark anything before removing the disty, nor did they note the firing order ... nothing. 

The short version is TDC #1 cylinder, replace disty ... still no run.  But strangely, if you started it with a little propane sniff it would run fine (that's how the timing got set) it would run just fine.  Turn it off though and no start. 

Time to head scratch and consider taking up smoking again (no beer available!)  This is when I find out that it wasn't running before the "tune-up" (previous to this I just thought this was a routine tune-up gone horribly wrong!)

Next, check engine light which goes on with key but after jumper no flashing.  The man comes with a reader and no response from ECU ... conclusion, dead ECU. 

So, can anyone tell their experience of Motoguy's lifetime guarantee ECU's?  That is what I have recommended to my friends but if you tell me that was bad I will tell them to try something else. 
I used to be indecisive but now, I'm not so sure.

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Offline Digger

  • 1991
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  • Gender: Male
  • 1996 Suzuki X-90 4X4
Re: Dead ECM replacement
« Reply #1 on: April 15, 2008, 07:47:14 PM »
So it would run on propane vapor. Did you have to keep feeding it propane to keep it running or would it stay running after just getting it started on propane? If it would stay running on it's own after just getting it started, sounds to me like possibly a bad wire connection, bad fuel relay or bad fuel pump. Possibly the injector isn't getting power(like because of a bad ECM). The main harness connector behind the left tail light is known to corrode and cause problems like the one you describe. What year is the Sunrunner? When you have someone turn the key on, can you hear the fuel pump running in the tank?

I have chased a similar problem before and mine ended up being the ECM, but along the way I learned of several different things that can cause what you are describing...
Had a cool sig pic till I changed the text... sigh...
90 Tracker: "Silver", 2" BL, 1-1/2" Coil Spacers, Strut mount flip, Calmini Header, Winch, 31" Swamper radials, Sold.
98 Suzuki X-90: Calmini 2" Sus, 1-1/4" whl spcrs, 2" Exhaust, Cobra Safari Bar, Neon, Sold.
96 Suzuki X-90: Mostly stock daily driver(for now)

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Offline aaron74

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Re: Dead ECM replacement
« Reply #2 on: April 15, 2008, 08:16:37 PM »
Hi Digger,

Sorry, 92 Sunrunner.  Would start on the propane and then continue running without additional propane.   

I only got the call after one of them had pulled the disty out without marking anything and was assuming it was running before that.  Now, that I know it was dead before the "tune-up," this is another whole kettle of fish and I am not getting signed on for any more. 

After I couldn't get a response from the ECM, they called a guy in with a reader.  He was really surprised that he couldn't get a response with his equipment and then proceeded to the jumper test. 

This is the first time I have seen behaviour like this where it runs fine once started but otherwise dead.  I agree it could be a short and am willing to pass it on but the only person I have to pass it on to is the one who pulled the distributor without any regard to timing.  Frankly, I would say that they have bitten off more than I can chew again. 

I will tell him to check the main harness connector and listen for the pump but I was hoping the reader being unable to raise the ECM was fairly smoking gun.  I don't want to advise them to buy parts that may not fix the problem but they have been leading me on a bit (by not telling me the truth in the first place - I know that he is sheepish about having done the wrong thing) but I really don't have time for this and don't really want to extend my involvement by having them call me back for more directions. 

This post is even turning into a book ...

Thanks,

Aaron
I used to be indecisive but now, I'm not so sure.

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Offline Digger

  • 1991
  • 1
  • Gender: Male
  • 1996 Suzuki X-90 4X4
Re: Dead ECM replacement
« Reply #3 on: April 15, 2008, 08:52:00 PM »
That really sounds like a fuel delivery problem. It still might be ecm, especially since the reader didn't pick anything up. But then again being that it's a 92, I wasn't aware there was a reader out there that could read it... Sounds like a dead pump, either gone bad or not getting power due to bad connection, bad relay or bad ecm...
Had a cool sig pic till I changed the text... sigh...
90 Tracker: "Silver", 2" BL, 1-1/2" Coil Spacers, Strut mount flip, Calmini Header, Winch, 31" Swamper radials, Sold.
98 Suzuki X-90: Calmini 2" Sus, 1-1/4" whl spcrs, 2" Exhaust, Cobra Safari Bar, Neon, Sold.
96 Suzuki X-90: Mostly stock daily driver(for now)

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Offline aaron74

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Re: Dead ECM replacement
« Reply #4 on: April 15, 2008, 10:28:22 PM »
Hi Digger,

Well, the pump comes on every time.  In fact, they replaced the pump and didn't tighten the lines so well so it is leaking up a storm.  Pumping fuel like mad anyway.  The back of the truck is full of water though so I told them to check the harness connectors before they just changed the ECM.  I think they are on the right track. They also did the jumper again and still no flashing. 

Thanks for your time,

Aaron
I used to be indecisive but now, I'm not so sure.