Went to fire up the Scout tonight.... put the battery back in it, turn the key and let the fuel pressure build, crank it, but no fire. Pulled the air cleaner and I am not getting a squirty squirty from the injectors (GM TBI, 1227747). Checked all my fuses.... all good. I wanted to see if it was getting fire, so I dribbled a little gas down the throttle bores. Hit the key and she fires right up, but dies as soon as the gas it burned off.

Thought I'd check to see if it logged any codes, so I jumpered the A&B terminal on the diagnotic port and it won't even go into diagnostic mode. The CEL just stays lit with the key in the on position. I fiddled with the jumper for about 15 minutes with no change.... the ECM just won't go into diagnostic mode.

She ran fine several months ago when I fired it up.... but now I got nothing. It got dark on me so I called it a night. Next thing I'm going to try is to put 12V straight to the injectors to make sure they're working.

Since the injectors are grounded through the ECM and the ECM won't go into diagnostic mode, I'm thinking the ECM might have died. :confused::confused: I have to admit that this system has worked so well that I haven't had to jack with in 5 years and I've forgotten so much about them that I feel a little dumb. :emb:

Open to any and all ideas or suggestions.

Are you wired with a start enable relay? It will supply ground for the injectors.

Are you wired with a start enable relay? It will supply ground for the injectors.

Don't believe that I am. Pretty much wired straight from the 747 pinouts off the web and the ones I used do not include such a relay. The injectors do not squirt while cranking or in the run position.

You hear the fuel pump cycle on for the first couple seconds of key on?

oh, and binderplanet faq's work wonders.

make sure you have fuel pressure, i had a 747 loose the ability to turn on the pump (kinda my fault after borrowing fuel from the 80) and had to wire the pump relay directly to the ignition circuit.

I don't know what a start enable relay is, but the injectors should be getting +12 anytime the key is on from a relay, then the two other wires going directly to the ecm.

You hear the fuel pump cycle on for the first couple seconds of key on?

oh, and binderplanet faq's work wonders.

make sure you have fuel pressure, i had a 747 loose the ability to turn on the pump (kinda my fault after borrowing fuel from the 80) and had to wire the pump relay directly to the ignition circuit.

I don't know what a start enable relay is, but the injectors should be getting +12 anytime the key is on from a relay, then the two other wires going directly to the ecm.

Yes... I have fuel pressure. I have a gauge and it builds full pressure.

well, it will run without the ecm being powered. the est gives 0 timing untill 3k or so then advances to something, without a computer present.

but if you are getting ses light, id assume the ecm is getting power, just jank.

I don't suppose you have another ecm laying around to try?


Once you've checked +12 at the white and red injector wires IIRC, try grounding D14 and d16 and watch for fuel spraying.

If they spray, and i'd guess they should, the ecm is about the only thing that could go bad over time.

Had a similar issue with my 89 BBC TBI that I had swapped into an earlier Blazer. The fuel pump relay should provide an initial squirt for ignition but the fuel pump relies on an oil pressure switch to remain engaged after ignition.

The injection section of the ColoradoK5 board can sort you out. user
dyeager535 knows as much about these systems as anyone I have found on any of the boards. link: http://coloradok5.com/forums/forumdisplay.php?f=81

Todd don't you have a spare ECM to just plug in and try it? If it won't go into ALDL mode I would think that there's something wrong with the ECM..

Went to fire up the Scout tonight.... put the battery back in it, turn the key and let the fuel pressure build, crank it, but no fire. Pulled the air cleaner and I am not getting a squirty squirty from the injectors (GM TBI, 1227747). Checked all my fuses.... all good. I wanted to see if it was getting fire, so I dribbled a little gas down the throttle bores. Hit the key and she fires right up, but dies as soon as the gas it burned off.

Thought I'd check to see if it logged any codes, so I jumpered the A&B terminal on the diagnotic port and it won't even go into diagnostic mode. The CEL just stays lit with the key in the on position. I fiddled with the jumper for about 15 minutes with no change.... the ECM just won't go into diagnostic mode.

She ran fine several months ago when I fired it up.... but now I got nothing. It got dark on me so I called it a night. Next thing I'm going to try is to put 12V straight to the injectors to make sure they're working.

Since the injectors are grounded through the ECM and the ECM won't go into diagnostic mode, I'm thinking the ECM might have died. :confused::confused: I have to admit that this system has worked so well that I haven't had to jack with in 5 years and I've forgotten so much about them that I feel a little dumb. :emb:

Open to any and all ideas or suggestions.

Basic stuff, did you on/off the key several times to make sure fuel is all the way to the tbi? (since it hasn't run in several months) Did you jumper the ecm before turning on the key?

It sounds weird for the ecm to just randomly die, I'm thinking there's something else. I read that the pump is working, so maybe a rodent got in and chewed some wires, injectors, start signal wire, or the fuel pump signal wire maybe?

well, it will run without the ecm being powered. the est gives 0 timing untill 3k or so then advances to something, without a computer present.


How??

How??

x2, the injectors arnt the only things controlled by the ecu, you shouldnt be able to do anything without the magic silver box.

How??

x2, the injectors arnt the only things controlled by the ecu, you shouldnt be able to do anything without the magic silver box.

The est fires the coil @ 0* until it receives a signal from the ecu to do otherwise.

Since the est gets it power from the coil/ign relay, it will fire the coil with the ecu unplugged.

The only events that the 747 can handle doing fast is the firing of the injectors.

The est fires the coil @ 0* until it receives a signal from the ecu to do otherwise.

Since the est gets it power from the coil/ign relay, it will fire the coil with the ecu unplugged.

The only events that the 747 can handle doing fast is the firing of the injectors.

But how do the injectors squirt when the ecm is unplugged?

Your getting off topic here. You can pull the chip and it will run on limp home mode. Pulling the ECM is just like pulling the battery. i.e nothing will happen.

Step 1. Do you hear the pump whine ( assume yes as you have flue pressure. )
Step 2 unplug ECM from harness and then plug it back in. ( could just need a reset)
Step 3 Drink a beer as this is hard work when it's hot outside.
Step 4 Since all Scouts are rust buckets, double check the FI grounding location/s.
Step 5 do the voltage checks with the key off and the key on. blow up the PDF to like 200% to read the fine print. I've found Dave's doc to be very helpful.

click here (http://www.binderplanet.com/forums/attachment.php?attachmentid=17757&d=1149799931)


edit, Grounding the injector with the key on should prove the injector works, just don't have a cigar burning

1. Call camo

2. Check the green wire

3. blah blah blah your a newbie, blah blah blah no your a newbie...

4. You have a bad ground!

1. Call camo

2. Check the green wire

3. blah blah blah your a newbie, blah blah blah no your a newbie...

4. You have a bad ground!

Camo is the answer? I thought Jesus was the answer. :confused:

But how do the injectors squirt when the ecm is unplugged?

They don't, he poured gas in it.

Camo is the answer? I thought Jesus was the answer. :confused:On Pirate camo is the answer..,. :flipoff2:

So what did you find out? And remember the old test light can fool you when its a bad ground, or one that is completed by a relay.

Haven't had time to mess with it. Probably won't have a chance to fool with it until after the weekend.

well, it will run without the ecm being powered.

How do the injectors squirt?
They don't, he poured gas in it.

Well then, I guess it doesn't run without an ecm.

Well then, I guess it doesn't run without an ecm.

his does, and that is why.

Came home a little early after a dental appointment and mess around with the Scout some more. I directly grounded the injectors and they did not squirt. On another board, Bill suggested stuck injectors.... turn out he was right. A couple of taps with a screwdriver handle and they started working. Fired up the engine and it purred along at high idle. After a few minutes, it warmed up and came down off of high idle. Since the power had been removed from the ECM, it lost all the "learned" data. It slowed way down and the "stall saver" had to catch it a few times before it settled down to a nice slow slightly lopy idle. No CEL during the entire run.

Now what's weird is that the ECM will still no go into diagnostic mode when A and B on the data port are shorted. If I turn the key on (unshorted) the CEL lights and stays lit until the engine is started. If I short the data port, the CEL blinks once and then stays lit until the engine is started. I'm going to short those two wires by backprobing the terminals at the ECM to see if it's something in my wiring to the data port.

By the way the engine is acting, it seems to me like the ECM is working fine, but I don't have a data cable or a laptop at the moment to hook it up to it.

his does, and that is why.

Start doesn't equal run.

Went back out and shorted the diagnostic terminal by backprobing the ECM connector. Work like it should. Traced the problem down a bad connection in the diagnostic signal wire (A9). Works fine now... no codes.

So are you finally going to get off your ass and install all of those parts in your spare bedroom? Or just making room in the driveway for another project?

Neither.... my lips got numb from making the vrrroooom vrroooom motor sound, so I wanted to hear it run for real. :flipoff2:





































I like to start it up every now and again to keep it limber. I slacked off on that since I didn't have any oil in the trans, rangebox or t-case. I couldn't put oil in the t-case until I got around to sealing up the PTO cover. Squeezing a tube of gasket maker and turning six bolt while laying on my back seemed like a lot of work :flipoff2: so it didn't get done for a while. I finally got off my ass and flat on my back got that taken care of so I could start it. Guess I waited too long, since it sat long enough for the injectors to stick on it. :homer:

While filling the t-cases, I did manage to squirt a shot of gear lube straight into my eye. Gear lube is great for gears, but not that great for "dry-eye".... I recommend the old standby for that - Visine.

Neither.... my lips got numb from making the vrrroooom vrroooom motor sound, so I wanted to hear it run for real. :flipoff2:

While filling the t-cases, I did manage to squirt a shot of gear lube straight into my eye. Gear lube is great for gears, but not that great for "dry-eye".... I recommend the old standby for that - Visine.

Well there are so many crude things that come to mind about your lips being numb but since I am at work I will refrain. Still pretty funny.

I feel your pain about the oil in the eye. Mine was only 30w since my spotter forgot to tell me about the big rock in the middle of the trail that punctured the oil pan on the last outing. Epoxy is still holding strong. Have not fixed it yet.

While filling the t-cases, I did manage to squirt a shot of gear lube straight into my eye. Gear lube is great for gears, but not that great for "dry-eye".... I recommend the old standby for that - Visine.

Did Ben Stein give you some Clear Eyes?

YouTube - Ben Stein - Clear Eyes commercial (http://www.youtube.com/watch?v=RcH-3d-BZn4)