‘87 454 TBI, NO Fuel spray, HAS fuel pressure, has 12v @ injectors, has spark

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beady

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Drove the truck for an hour to pick up my kids Sunday. Turned truck off, kids put their stuff in, daughter went to start truck literally 2 mins after I turned it off and it would crank fine, but not a hint of fire. Ended up having to get it towed home.

There is ZERO fuel from the injectors when cranking and the tips are bone dry. There is 10+ psig of fuel pressure downstream of the fuel filter and you can hear the pump running in the tank.

There is +12v at one pin of each injector connector with the key ON.

There is NO pulse from the injector wires (using a timing light clipped to leads).

There IS spark at the spark plug wires.

Ecm B fuse looks fine.

What do I check next?

Thanks
 
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Ricko1966

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Will it run and Rev up if you put a couple of tablespoons of fuel down the throttle body. Have you checked for codes? Have checked all fuses?
 
Strick

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Check the module in the distributor. It controls injector pulse.
 
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Strick said:
Check the module in the distributor. It controls injector pulse.
Click to expand...

agree - you could run through the diagnostics, but it sure sounds like the ICM based on having spark and fuel pressure.
 
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I thought ecm controlled spark at cranking speed ignition module took over above 400 rpm. That's why I said see if would Rev with fuel down the throttle body. If it has spark at crank but loses it above 400 rpm I'd be looking at module. And I said check codes, looking for a tps malfunction. If tps thinks he's in clear flood he won't get fuel but will get spark.
 
Last edited:
beady

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Ricko1966 said:
I thought ecm controlled spark at cranking speed ignition module took over above 400 rpm. That's why I said see if would Rev with fuel down the throttle body. If it has spark at crank but loses it above 400 rpm I'd be looking at module. And I said check codes, looking for a tps malfunction. If tps thinks he's in clear flood he won't get fuel but will get spark.
Click to expand...
Will check in a bit. One other clue that I’m looking into now is there are no interior lights or headlights either.

Pulled and metered every fuse, all read intact.
 
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beady said:
Will check in a bit. One other clue that I’m looking into now is there are no interior lights or headlights either.

Pulled and metered every fuse, all read intact.
Click to expand...
You need to check the fuses in the box. Check for power on both sides,a burnt fuse will only have power on one side. But a fuse with no power on either side is still a problem,not the fuse it self,but a problem with that circuit.
 
beady

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Ricko1966 said:
I thought ecm controlled spark at cranking speed ignition module took over above 400 rpm. That's why I said see if would Rev with fuel down the throttle body. If it has spark at crank but loses it above 400 rpm I'd be looking at module. And I said check codes, looking for a tps malfunction. If tps thinks he's in clear flood he won't get fuel but will get spark.
Click to expand...
Runs fine on starting fluid.
 
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gmbellew

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Ricko1966 said:
I thought ecm controlled spark at cranking speed ignition module took over above 400 rpm. That's why I said see if would Rev with fuel down the throttle body. If it has spark at crank but loses it above 400 rpm I'd be looking at module. And I said check codes, looking for a tps malfunction. If tps thinks he's in clear flood he won't get fuel but will get spark.
Click to expand...

I believe it is the reverse - 400rpm and below the ICM is controling the timing and above 400rpm the ECM is controling the timing.
 
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gmbellew

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beady said:
Runs fine on starting fluid.
Click to expand...

I'd run through the diagnostics to be sure (i think you need chart A4 from the emissions and drivability manual). but my money is still on the ICM being bad.
 
beady

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gmbellew said:
I'd run through the diagnostics to be sure (i think you need chart A4 from the emissions and drivability manual). but my money is still on the ICM being bad.
Click to expand...
You wouldn’t happen to have that handy, or a link?

I just found a site with service manuals, but it only has 1986 and 1988. Not sure which is more in line with 1987 since that seemed to be the year things changed.

http://forum.73-87chevytrucks.com/s...204905f8377e59c61d6fb891e28d90d&topic=30115.0

Thanks
 
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Usually when the ICM module goes bad you lose both spark and injector pulse - if it runs off of starting fluid/bit of gas dribbled into the TB then you can rule out the pickup in the distributor and probably the ICM as the problem. The way the injectors work is they have +12 on them continually, and the ECM pulses the ground side to trigger them. Since you have pressure and +12 on the injectors, I'd start checking to make sure your ECM is playing nice. If you've also lost power to other in-cab systems, that could be impacting the power to your ECM and no ECM=no go. Does your Service Engine light come on when you turn the key on? If so, can you jumper the holes on the ALDL connector and check for errors?
 
beady

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YakkoWarner said:
Usually when the ICM module goes bad you lose both spark and injector pulse - if it runs off of starting fluid/bit of gas dribbled into the TB then you can rule out the pickup in the distributor and probably the ICM as the problem. The way the injectors work is they have +12 on them continually, and the ECM pulses the ground side to trigger them. Since you have pressure and +12 on the injectors, I'd start checking to make sure your ECM is playing nice. If you've also lost power to other in-cab systems, that could be impacting the power to your ECM and no ECM=no go. Does your Service Engine light come on when you turn the key on? If so, can you jumper the holes on the ALDL connector and check for errors?
Click to expand...
I removed and put back the main battery ground and the lights, etc., came back. Still zero fuel spray.

There is no check engine light (at least that I can see when ignition is turned to ON or feeling behind dash for a loose bulb. I have the bezel off and am going to pull the cluster to see what I see, and troubleshoot the speedometer at the same time.
 
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