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

beady said:

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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Have you checked codes yet, see if you have #12

Ricko1966 said:

Have you checked codes yet, see if you have #12

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There is no check engine light. The ALDL connector must have a pin that sends +12v out to a reader. If I knew which pin I could hook up a light.

beady said:

There is no check engine light. The ALDL connector must have a pin that sends +12v out to a reader. If I knew which pin I could hook up a light.

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Aldl link pins a and b short with a piece of wire. Check engine light should blink like Morse code one long flash 2 short flashes repeat. You should have a 12 check it. Have pin and paper ready in case there are others.

Ricko1966 said:

Aldl link pins an and b short with a piece of wire. Check engine light should blink like Morse code one long flash 2 short flashes repeat. You should have a 12 check it. Have pin and paper ready in case there are others.

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The truck physically has no check engine light. Not no light flashes, there is no light actually present on the vehicle, so I can’t short pins and get a light that is not physically there to flash.

I have felt up behind the speedo and there are openings, but no bulb, no bulb holder, no wires.

Ricko1966 said:

Aldl link pins a and b short with a piece of wire. Check engine light should blink like Morse code one long flash 2 short flashes repeat. You should have a 12 check it. Have pin and paper ready in case there are others.

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I built a device to pull and reset the blink codes on my w124 Mercedes, I bet it might work fit this. Looks like pin 4 is the data out, I’ll look into that more.

Or I could get a cheapy flash reader, but I was looking at Amazon and they seemed hit or miss. One might say “73 to 95 chevy” and the reviews would have ppl saying “doesn’t work on my 1988 Chevy xxxx”….

beady said:

The truck physically has no check engine light. Not no light flashes, there is no light actually present on the vehicle, so I can’t short pins and get a light that is not physically there to flash.

I have felt up behind the speedo and there are openings, but no bulb, no bulb holder, no wires.

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Search for a pin out for the ecm on your truck. I think it's #g is for check engine light. Hook an analog meter there and watch the needle sweeps,or an led test light. Ground the other end of course. Maybe able to use a regular test light. Whenever I'm dealing with ECM my default is analog meter or led trying g to be as safe as possible with ecm.

Ricko1966 said:

Search for a pin out for the ecm on your truck. I think it's #g is for check engine light. Hook an analog meter there and watch the needle sweeps,or a led test light. Ground the other end of course. Maybe able to use a regular test light. Whenever I'm dealing with ECM my default is analog meter or led trying g to be as safe as possible with ecm.

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Yeah, I’m a little leery of frying the ecu. I have a fluke that has a simulated analog output (bar graph on the bottom of the screen), I’d think it’s pretty well buffered to stop you damaging things you are taking readings of. If the pulses are pretty slow I should be able to watch the digital output too and watch it swing from 0-5v.

Thanks

if it is the original cluster and the wiring hasn't been hacked to pieces there is a check engine light. on my 1990, it is bottom right on speedometer i think. it could be different on yours. use Chart A1 to diagnose the lack of a check engine light. it could be a bad bulb or maybe a PO got tired of looking at the light on if there was an issue and pulled the bulb. you might also check both ECM fuses. if one of them is popped, also no check engine light and no start. ECM1 also controls the injectors....but a few other random things also, like VSS on my 1990. but if it ran after starting on fluid, it is probably not ECMB fuse, because that is the main lower to the ECM. but could be ECM1.

if the fuses check out, I'm still putting my bet on the ICM....you have a noid light I think, and chart A4 will diagnose the lack of injector action. I bet you find out in test #1 that the ICM is bad given what you have posted so far.

but always diagnose the lack of check engine light and get it working before moving on to the rest of the diagnostics.

beady said:

The truck physically has no check engine light. Not no light flashes, there is no light actually present on the vehicle, so I can’t short pins and get a light that is not physically there to flash.

I have felt up behind the speedo and there are openings, but no bulb, no bulb holder, no wires.

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I wonder if someone got tired of seeing it on all the time (or was attempting to get thru an inspection/sale) and just yanked it. See if you have a suspicious looking empty bulb holder swinging around loose up in there somewhere. Or some cut wires that go nowhere. A small mirror helps. I know my Suburban had quite a few "liberties" taken by the previous owners - mostly related to the stereo wiring and adding a custom center console that at one point hosted a VCR and small analog television. There are still a couple things up in there that don't appear on any factory wiring diagram that I have to wonder "what the you-know-what was THIS for".... My whole ALDL connector is just hanging loose but fortunately seems to still work.

I'm not having much luck figuring out which pins would mirror the absent Service Engine light. With a high quality digital meter you're unlikely to damage anything by testing voltage by itself since the internal impedance of the meter will still be very close to an open circuit as far as any of these old analog systems are concerned. I did find a reference to an indication that the Service Engine light always has 12V applied to it and the computer turns it on and off by completing the ground half of the circuit, but I am not 100% confident in that information. I am trying to find out which color wires should have gone from the ECU to the light, but no luck yet.

Alright, so I bought a good scan tool that can read some of the live data from the ECU as I figured that would be useful in the long run. And, it reads the codes as well. It’s an OTC 3211 (same as Bosch 1300 and Actron CP9690) and it doesn’t recognize that it is attached to the truck/ALDL port. Key is ON (not ACC), and no luck. I’ve tried seating/unseating the connector, key in multiple positions, different variations of powering up reader and when I turn key on, etc.

Any thoughts? Maybe this is an indication of something else going on? Damaged wiring to connector, or worse?

beady said:

Alright, so I bought a good scan tool that can read some of the live data from the ECU as I figured that would be useful in the long run. And, it reads the codes as well. It’s an OTC 3211 (same as Bosch 1300 and Actron CP9690) and it doesn’t recognize that it is attached to the truck/ALDL port. Key is ON (not ACC), and no luck. I’ve tried seating/unseating the connector, key in multiple positions, different variations of powering up reader and when I turn key on, etc.

Any thoughts? Maybe this is an indication of something else going on? Damaged wiring to connector, or worse?

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Where did you get the device (and roughly how much was it if you don't mind saying since I kind of need one too)???

If you're not getting readings at all, I'd hazard a guess that your ECU is either not powering on or is experiencing a problem. The ECU itself lives behind the glovebox - I would take the glovebox out and check all the connectors on it (there are 2 multipin connectors going into it, the unit itself is isolated from the body grounding intentionally).

YakkoWarner said:

Where did you get the device (and roughly how much was it if you don't mind saying since I kind of need one too)???

If you're not getting readings at all, I'd hazard a guess that your ECU is either not powering on or is experiencing a problem. The ECU itself lives behind the glovebox - I would take the glovebox out and check all the connectors on it (there are 2 multipin connectors going into it, the unit itself is isolated from the body grounding intentionally).

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It was about $250, apparently one of the only hand held tools that will read the ecu live data.

https://www.ebay.com/itm/235344132189


OK, so it was partially user error, even tho it has internal batteries and powers up, you MUST have the 12v adapter plugged into it also.

It works on my k2500 5.7 1993 fine and connects and reads the codes (says no codes found).

This is what it says on the 1987 after it connects. I tried several times with the same results. So……

Did you ever check the fuse circuits as on post #7. If you are missing a power to the ecm that would explain a lot.

Ricko1966 said:

Did you ever check the fuse circuits as on post #7. If you are missing a power to the ecm that would explain a lot.

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I pulled each fuse out of the block and individually checked each one using my meter in continuity check mode. I checked both ecu fuses again after that as well. I’ll check again.

Guess I’ll pull the glovebox and see if I can check the wires from ecu to the ALDL connector for continuity.

beady said:

I pulled each fuse out of the block and individually checked each one using my meter in continuity check mode. I checked both ecu fuses again after that as well. I’ll check again.

Guess I’ll pull the glovebox and see if I can check the wires from ecu to the ALDL connector for continuity.

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You need to check the fuses,in the box checking for power on both sides of the fuse Technically that's not checking the fuses it's checking the fuses and power to the circuit. But a good fuse with no power to it still won't get the job done.