87 TBI - Sporadic Starting

[routha]

All,

I've been surfing here for sometime and am thankful for the wealth of knowledge you all have shared.

I bought my 1987 Chevrolet Scottsdale (4x4, 350, TBI, auto, fleetside) back in October. I had been searching for one off and on for the past few years. I found this one on Craigslist and after checking it out in person I had to have it. I get loads of compliments and love tinkering on it in my free time. However, it's been a pain. in. my. arse. lately!

It won't start! The GD thing turns over fine but won't fire!

Prior to this it has happened about 3-4 times.

The most recent time it happened I pulled the fuel line from between the filter and injectors. Fuel came out from the filter so I ruled out the fuel pump?

I watched while someone else turned it over briefly and I wasn't getting any fuel from the injectors. I unplugged the injectors and tested the amps but didn't get a reading. I pulled the loom off the wires to look for corrosion, etc. I didn't see any that should keep it from getting a good connection. However, there was some slight discoloration where the 2-3 factory splices were.

I checked the connections to and from the distributor and all of the fuses under the dash. Nothing looked bad or like it needed to be replaced. I checked the spark at the plug by grounding it with a wire to the battery and didn't see any spark

After about two hours trying to diagnose the issue, I had my friend try to start while I was under the hood and IT FIRED.

GD thing!

However, this morning (after a month and about 1,000 miles of driving) it would start. Same thing; it turns over but won't fire as if it isn't getting fuel.

Does anyone have any suggestions? I am really tempted to swallow my pride and take it into a mechanic. Before that I am going to pick up one of the diode test lights to plug into the injectors and start pulling back the loom again.

I've searched through a few forums and couldn't find anyone with a similar issue. So, if this has previously been posted I apologize.


Thanks you all! I will upload a photo of the truck after this.

 

[routha]

Here it is. More pics to follow in a later thread as I continue to dial it in for car show season

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[Charlie]

 

[routha]

Thanks, fella! I look forward to searching and sharing on here.

 

[SDJunkMan]

Welcome. Nice looking truck!

 

[routha]

Welcome. Nice looking truck!

Gracias! Ya can't beat the look of these trucks.

 

[1987 GMC Jimmy]

Intermittent spark and injector pulse loss tells me there’s an issue with the ignition control module. It’s weird for them to not fail so clearly, but the TBI ones are more complex so it happens. Take it to Autozone, have them test it multiple times. Welcome!

 

[routha]

Intermittent spark and injector pulse loss tells me there’s an issue with the ignition control module. It’s weird for them to not fail so clearly, but the TBI ones are more complex so it happens. Take it to Autozone, have them test it multiple times. Welcome!

I'm in with the guys at O'Reilly's pretty well. I'm going to call around and see if I can have someone from there or AutoZone come out and test it.

Right now I can't get it to fire so it's stuck in the driveway.

Does anyone have a link for a wiring schematic of the TBI/fuel system? My Haynes maunual doesn't and I haven't found a good one online yet.

 

[1987 GMC Jimmy]

You have to pull the module, and they have to test it on the bench at the store. It only takes a second to take the distributor cap off and get it.

 

[routha]

You have to pull the module, and they have to test it on the bench at the store. It only takes a second to take the distributor cap off and get it.

Good to know. Thanks!

 

[routha]

I just went into the TBI/EFI conversion part of the forum and saw all the threads about TBI issues. Rookie!

 

[routha]

UPDATE

I got home after picking up parts, licking my wounds, and a beer run, and lo-and-behold the GD thing started right up.

I'd already picked up a new ignition module so I replaced the old one. I'm going to take the old one in to get tested within the next couple of days.

In case anyway googles TBI issues in the future, I'll post a couple pics of the instructions from my manual, what the module looks like, where it is, and how I replaced it. These forums with pictures have paid dividends for me on all sorts of projects (the squarebody, my atc 250r, CT70, supermoto)

Thanks to those who responded. Hopefully this was the cure, as it's been one of those issues that's resolved itself on its own before.

Cheers!

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[1987 GMC Jimmy]

Ooh, that was quick. I should have mentioned this. Do not trust anything other than a Delco or maybe a Delphi module. Maybe a BWD brand, but nothing else unless it’s a spare. Those house brand ignition parts are complete junk. The Delco modules are made here with some care (I’ve had one burn right out of the box), but I can’t say the same for the other two quality brands, and I can’t say anything good about Duralast or MasterPro unless it’s to save you from being squished by a semi on the side of the road

 

[routha]

Ooh, that was quick. I should have mentioned this. Do not trust anything other than a Delco or maybe a Delphi module. Maybe a BWD brand, but nothing else unless it’s a spare. Those house brand ignition parts are complete junk. The Delco modules are made here with some care (I’ve had one burn right out of the box), but I can’t say the same for the other two quality brands, and I can’t say anything good about Duralast or MasterPro unless it’s to save you from being squished by a semi on the side of the road

Thanks for the advice. . . I've been fussy about the parts I've put into it so far. The alternator and water pump were AC Delco. The radiator I skimped on because I was hasty and I ended up paying for it. I won't go back to Carquest after that ordeal; when I brought back the brand new, leaky radiator, the guy behind the counter said, "not much we can do, did you try crimping the ends?"

The second radiator has held up so far and that came from Auto Value. They've been AWESOME to work with. They took money off of parts without me asking because it was a day late and gave me a dealership rate on parts. They also stock Delco parts which O Reilly's, CarQuest, etc don't.

The ignition module I got is Standard brand. At first I was apprehensive but the guy at Auto Value advised me they've been in busy 80 years and made in the US. I'll give it a shot and see what happens.

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[1987 GMC Jimmy]

I’ve never heard of the store or the brand, but if it’s made here, I’d give it a shot if I were in the same position. What brand was the old one, or did it say? Sometimes you actually do have to stick your head up the bull’s ass to get a good look at the t-bone instead of taking the butcher’s word for it, but that comes with the territory of working on a vehicle, trying to save a few bucks, and testing the waters with different brands that are somewhere between trash and solidly reputable.