1987 Squarebody Chevy Truck - Problems

[M-61]

Slow sputtering would lead to fuel starvation.
Fuel pump is a likely culprit.
Many cars get their signal from the ignition to start the pump and of course the pump should run continuously. However when you turn the key to “ON” not crank but ON you say you sometimes hear the pump. That’s the pump priming the line to the TBI. If you continue to turn to START it should crank and fire up. Yours does not sometimes except after a cool down period.
I now lean towards a faulty fuel pump. Be nice to change the filter also, but that’s not your problem.
I believe the pump is in the tank.
Now for the disclaimer:
I’m an expert in nothing. I doubt I’ve ever opened the hood on your type of vehicle. Also the fact the key is not needed let’s me wonder about what I mentioned before.
Older the vehicle the easier the troubleshooting.
Alan Shepard went into space with way less computer memory than the drivers side mirror on a Mercedes’.

 

[M-61]

It's kind of a slow sputtering shutdown.

To be honest here, I learned not long after I bought the pickup that you don't even need to put a key in the ignition. I usually run it without one. I'm not sure what that means as far as the ignition switch goes, but it has worked fine for about 30K miles that way. Haha!

Lot’s of things have worked flawlessly for 30,000 miles.
It merely opens another group of possibilities.
Very difficult to get a complete never mind accurate description from the customer due to no fault of theirs.

 

[M-61]

I had the same problem on my '95 chevy. The ignition switch has 3 parts. One is for the fuel pump. Replace the switch.

 

[gunsandgunsmithing]

Ignition control module. Cheap, easy to fix and a common issue.

 

[miningshawn]

Hey guys, my old Chevy finally started giving me problems. It's a 1987 Chevy K10 with TBI. It died on the wife the other night coming home. She'd already driven it 30 miles to the lake, parked for a few hours, then started coming home. Got about 15 miles and the engine died at 65mph. She coasted to a stop on the side of the road. Got it pulled to an approach. It would crank, but not fire. Came back the next day and it fired right up. I drove it another 8 or so miles and it died on me. Pulled it home. It will occasionally start and idle for about 10 minutes, then die. When turning the key to acc, I can hear the fuel pump turn on sometimes, sometimes not. Usually not if it has already idled then died. The tank and pump were new about 8 years ago. New plugs and wires about 4 years ago. It's got a new fuel filter now, but that hasn't made a difference. Should I start troubleshooting the fuel pump relay? What else should I look at?

Distributor igniter. Very common problem with the TBI. All of the classic symptoms are there.
Add: might as well change the cap and rotor while you're in there.

 

[Mike Casselton]

Could be as simple as vapor lock.
A new gas cap is cheap and fast.
Next I'd look for the collapsed line.

 

[gunsandgunsmithing]

Distributor igniter. Very common problem with the TBI. All of the classic symptoms are there.
Add: might as well change the cap and rotor while you're in there.

Never heard it called that but is that the same as the ignition control module? If so, you're right..they were a very common issue and often shoed the symptoms the op described. That's where I'd bet. Seriously, I'd throw a few bucks and a few minutes at replacing it before I did anything else.

 

[lazyMlazyK]

Thanks for the suggestions folks, keep them coming! I'll see if I can check a few things out this weekend and report back if I'm able to determine anything.

Anyone know how to troubleshoot the fuel pump relay?

 

[WillyTP]

Hey guys, my old Chevy finally started giving me problems. It's a 1987 Chevy K10 with TBI. It died on the wife the other night coming home. She'd already driven it 30 miles to the lake, parked for a few hours, then started coming home. Got about 15 miles and the engine died at 65mph. She coasted to a stop on the side of the road. Got it pulled to an approach. It would crank, but not fire. Came back the next day and it fired right up. I drove it another 8 or so miles and it died on me. Pulled it home. It will occasionally start and idle for about 10 minutes, then die. When turning the key to acc, I can hear the fuel pump turn on sometimes, sometimes not. Usually not if it has already idled then died. The tank and pump were new about 8 years ago. New plugs and wires about 4 years ago. It's got a new fuel filter now, but that hasn't made a difference. Should I start troubleshooting the fuel pump relay? What else should I look at?

You should definitely look at a new truck.

I hate to say it but it’s terminal. Just put that old rig out to pasture and I’ll be there in a few days to put her down and properly remove it for you. No charge on my part and I will not accept tips for my services. I don’t normally say this in public but the old “Hawaiian tropic blue” square body is one of my favorites!

 

[Retired shooter]

Had several of those golden oldies, still have a 454 big block one ton in the shop.
What I learned, as several have stated is the electronic module will go bad. Sometimes just overnight.
Also learned to replace with AC Delco parts, as the others would not last at all. Got to the point I bought the modules two at a time, kept a spare in the glove box. Usually after that , they would last forever and never give any problems,
Good luck

Retired shooter

 

[Retired shooter]

Make sure if and when the module gets replaced, put dielectric grease between the module and the mounting surface.

Retired shooter

 

[lazyMlazyK]

Never heard it called that but is that the same as the ignition control module? If so, you're right..they were a very common issue and often shoed the symptoms the op described. That's where I'd bet. Seriously, I'd throw a few bucks and a few minutes at replacing it before I did anything else.

Are you guys taking about the distributor pick-up coil? Would that affect the fuel pump?

 

[lazyMlazyK]

I just put a little gas down the hole through the air cleaner, it was able to start up and run on that for just a bit before dying out again. The fuel pump wasn't kicking on.

 

[lazyMlazyK]

You should definitely look at a new truck.

I hate to say it but it’s terminal. Just put that old rig out to pasture and I’ll be there in a few days to put her down and properly remove it for you. No charge on my part and I will not accept tips for my services. I don’t normally say this in public but the old “Hawaiian tropic blue” square body is one of my favorites!

Haha, I appreciate the offer but I'll probably hold onto it for awhile. I'm the third owner, a d I bought it with about 80k miles on it. I wish the paint was in better shape, I really don't mind the blue. The hood and roof are the worst, but the drivers side door panel is starting to rot out now. Might try to get the whole thing sprayed with Rhinoline next year, we'll see.

 

[lazyMlazyK]

Or maybe this?

Make sure if and when the module gets replaced, put dielectric grease between the module and the mounting surface.

Retired shooter

Are you talking about this part?

 

[Coyotefurharvester]

Yes ECM, it also controls the tbi and the fuel pump on/off. Ecm will turn off the fuel pump if the is a 20 sec no start sequence(like vapor lock, empty tank, etc). Ecm, tbi are also linked to distributor. Ecm can be intermittently failing prior to complete no start situation. I think you could have spark, but no fuel pump signal from ecm. Your ignition switch is in the ecm system indirectly.

 

[gunsandgunsmithing]

If pouring fuel down the throttle body got it running, it's probably not the module, but fuel related, as you suspected but can still be the module. They have a history of going bad instantly, like cutting off the key, but starting back after a cool down. Just check fuel pressure and fire. The module is inside the distributor, but it's an easy fix. They typically don't have anything to do with fuel but this one might...it's possible.
You can typically cycle the key on/off 3 times to dead head the puimp. It might hit if it's pressure related rather than ignition. Where's Butch?

Here's a pic of yours.

 

[miningshawn]

If pouring fuel down the throttle body got it running, it's probably not the module, but fuel related, as you suspected but can still be the module. They have a history of going bad instantly, like cutting off the key, but starting back after a cool down. Just check fuel pressure and fire. The module is inside the distributor, but it's an easy fix. They typically don't have anything to do with fuel but this one might...it's possible.
You can typically cycle the key on/off 3 times to dead head the puimp. It might hit if it's pressure related rather than ignition. Where's Butch?

Here's a pic of yours.
View attachment 1366712

The fuel pump will not activate without a signal from the "ignition control module", commonly called the dizzy igniter by us wrecking yard rats that have seen this problem dozens if not hundreds of times.
This problem will drive a person nuts. Just replace it, it's $30.

 

[ebb]

If you replaced all the parts that have been suggested here you would have more money in it than buying another truck. Get someone to diagnose the problem and replace the one right part to get it running again. My 1982 square body had a mechanical pump but the 1989 and 1996 I had stopped dead when the fuel pump went , I know for a fact the 96 when the computer sensed no fuel it shut off the ignition.