Cranks, no fuel, no spark

[Jppr26]

So here's a bit of back story, truck Is a 87 v20 custom deluxe TBI 350 4x4. I got the truck from a guys yard. It had been sitting 3 years. I cleaned up the distributor, oiled the cylinders put gas in it and drove it home. Since then I've replaced alot of parts that just needed replaced, I've put about 400+ miles on the truck and it started cutting out every now and then, then it just died and wouldn't start, I replaced the pickup coil and the coil and it fired right up and ran great for about 2 miles then died again and wouldn't start, and no codes. I've replaced all but the CPU, oil pressure sending unit, and the 02 sensor, checked fuses and I'm at a lose. My injectors are not spraying, my fuel pump is running. If I pore gas down the intake it will not fire, so I'm guessing that I'm not getting spark as well but I have not been able to visibly check yet as I cannot get a 2nd person to help quite yet

 

[bucket]

Ignition module. Even if you replaced it, that doesn't mean it's not the problem. But no fuel, no spark is slmoal always a failed module.

 

[Jppr26]

Wife got home and cranked while I checked for spark and no go, reading through my Chilton book it was looking like the icm but its fairly new so I've been hesitant about changing one but ended up in town this evening so I bought a new one. If this dont work is there a relay or fuseable link somewhere

 

[bucket]

There's usually a couple IGN/ECM type fuses in the panel under the dash.

And more than once I've seen a new module fail within a day.

 

[Jppr26]

So installed the new module, and I got fuel spray but no spark. Also got code 42, checked the black and tan wire connector that you disconnect to set the timing and it was plugged in and fine. I had replaced my pickup coil recently an wondering if I should have replaced the magnet on the shaft as well

 

[chengny]

So installed the new module, and I got fuel spray but no spark. Also got code 42, checked the black and tan wire connector that you disconnect to set the timing and it was plugged in and fine. I had replaced my pickup coil recently an wondering if I should have replaced the magnet on the shaft as well

Code 42 diagnostic from the 1987 GMC Light Duty Truck Fuel and Emissions Including Driveability manual:

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[Jppr26]

Should I skip step one since I have no spark and the truck wont start

 

[chengny]

Should I skip step one since I have no spark and the truck wont start

Yeah, since you already know that code 42 is being thrown (and the engine won't start anyway), I would move on to step 2.

 

[Jppr26]

Ok so I did step 1 and i got a ohm reading of 637, so I have a open circuit or a bad module, the module is a brand new BWD, mabey it's bad I'll take it back and trade it in. Is there a bench test I can do on the next one before I put it in?

 

[Jppr26]

I think I miss read that, I have a open circuit or a bad connection or a bad modular

 

[Rusty Nail]

The ignition module is the ONLY part in that truck what will kill BOTH spark AND fuel.

Hope this helps!

 

[Jppr26]

The ignition module is the ONLY part in that truck what will kill BOTH spark AND fuel.

Hope this helps!

Copy that, it dose help I just though it weird that replacing it got my fuel back but not spark, and the one I replaced was new as well

 

[Chevyguy]

Copy that, it dose help I just though it weird that replacing it got my fuel back but not spark, and the one I replaced was new as well

All the new parts are made in China these days. I've had good luck with Well's ignition electrical parts. I replace my module on my 87 V-20 at every tune up. I got mine at Car Quest and it has a lifetime warranty.

Clayton

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[Jppr26]

Ok I learned something today, first was whole testing a old coil vs new one to see if it really was bad dont use small wires for jumpers as they will get hot and melt off insulation to your fingers and burn you.

second the non coil top mounted distributors ESC type, when pulled, if they are working you should feel as the pickup magnet hits the contacts, you should feel it.

My original distributor spun freely with no resistance. It was a night and day difference for me. Any way truck is running fired right up after stabbing the new one in,

 

[1987 GMC Jimmy]

Wish I would have gotten to you sooner. On a TBI, I like to check spark at the coil first. You can rule the one part out, and if spark’s not leaving the distributor cap, it’s bon voyage old distributor (or at least the replaceable components. Here’s another little nugget of info in case you run into this again.

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