1987 350 tbi no start

[Squarescare]

Hey all my truck was working fine went to use it today noticed negative battery terminal cable popped off while driving last time must have been from a bump now I put it back on truck won't start thinking I fried something electrical turns over fine has an occasional little fire on a cylinder or two but really doesn't even come close to starting can somebody point me in the right direction and what I might have fried or is it just coincidence?

 

[Squarescare]

Just verified its getting fuel, can see with air cleaner off gonna try a spare coil pack i have out of junkyard truck dunno if that ones anygood

 

[Goldie Driver]

Worth a try, but we just had a '92 S-10 ( spider injection ) that took an ignition coil so my guess would be that. Your guess is cheaper, though.

 

[Squarescare]

Not the coil pack (ignition coil) god damn it gonna jum in distributor cap

 

[Rusty Nail]

how does the negative cable coming off while driving hurt the distributor cap?

-asking for a friend

 

[Squarescare]

how does the negative cable coming off while driving hurt the distributor cap?

-asking for a friend

I dunno how it hurts anything but the truck doesnt run anymore and it used to. Thought i found the problem with my corroded cap I had a brand new one laying around I changed it didn't make a difference same rotar though

 

[YakkoWarner]

I had mine do that and it turned out to be a bad pickup in the distributor, but your situation is different because you are getting fuel pulses which means the pickup is signaling the ECU. Ignition module inside the distributor might have been damaged electrically (with the neg. terminal falling off the battery who knows what voltage fluctuations occured or where).

 

[Squarescare]

I had mine do that and it turned out to be a bad pickup in the distributor, but your situation is different because you are getting fuel pulses which means the pickup is signaling the ECU. Ignition module inside the distributor might have been damaged electrically (with the neg. terminal falling off the battery who knows what voltage fluctuations occured or where).

I just tried the ignition module (out of junk yard truck) cause i was thinking the same thing no dice. I dont get it, maybe its not getting enough fuel? That really doesnt seem to be the case from watching the injectors. These trucks arent that complex but seriously im stumped and i froze my ass off working on it all day for no results so far


I still feel in my bones this is electrical maybe im wrong, but im gonna go over the grounds tomorrow. Can anyone tell me how important the rear ground is (the braided one from engine block to firewall) that is the only visibly ugly one

 

[YakkoWarner]

If you can see the fuel pulsing out of the injectors it shoule be enough to at least idle. This might be a time to hook up one of those remote start triggers to the starter and with the key on, crank it and check for spark from the coil secondary (but not the throttle body in case it does spark).

It couldn't have gone out of time unless the distributor was physically moved (or something just happened to break mechanically inside the engine at the exact same moment as you turned it off which seems unlikely).
Are you sure the coil and module you grabbed from the parts truck are any good?

 

[Squarescare]

If you can see the fuel pulsing out of the injectors it shoule be enough to at least idle. This might be a time to hook up one of those remote start triggers to the starter and with the key on, crank it and check for spark from the coil secondary (but not the throttle body in case it does spark).

It couldn't have gone out of time unless the distributor was physically moved (or something just happened to break mechanically inside the engine at the exact same moment as you turned it off which seems unlikely).
Are you sure the coil and module you grabbed from the parts truck are any good?

No im not positive any of the parts I took are good it came from an old parts truck that did run 10 years ago when I parked it in the woods so no no guarantee and yeah I can see the injectors pulsing and fuel coming out The parts truck distributor cap was in much better shape than mine though. I was playing an odds game thinking the odds of having two trucks with the same broken part was super unlikely. I'm done for tonight I'll let you guys know what I find tomorrow if anything

Oh one last thing I saw a video on YouTube moments ago about a guy with an '88 van TBI sat for a year couldn't get it running crank but no fire turned out to be his negative battery terminal where it mounts to the engine was dirty so for ***** and giggles I'm going to try that. And thanks for the input so far i appreciate it i need this truck running

 

[gmbellew]

I’d follow the “cranks but won’t start” diagnostics in the emissions and drivability manual from the Reference Library and see where it leads you.

 

[Squarescare]

I’d follow the “cranks but won’t start” diagnostics in the emissions and drivability manual from the Reference Library and see where it leads you.

Ill check it didnt know there was a such a thing

 

[Squarescare]

Definitely a no spark issue getting fuel from injectors and even starting fluid made no difference. Cleaned up all grounds no dice. Used the paper clip odb1 jumper trick got a code 12 no reference pulse from distributor code. Not sure what the most likely part is to be bad only thing i didnt swap was the rotor

Edit i can physically see the injectors pulsing so i guess its between the ecm and distributor

 

[YakkoWarner]

Your distributor is at least sending the pulse to the ECM - if you don't get a reference pulse from the distributor the injectors won't trigger at all. I'd test for spark on the coil-to-distributor high voltage lead - disconnect it from the cap and lay it near something grounded like a valve cover, then crank with key on. You should get all kinds of spark between the lead and metal object (don't hold it it your hand or with a metal tool, you'll become the ground and that is painful). If you get nothing there, then ignition module or coil are likely to be the issues (module is more electrically delicate than the coil so I'd start there).

 

[Squarescare]

Your distributor is at least sending the pulse to the ECM - if you don't get a reference pulse from the distributor the injectors won't trigger at all. I'd test for spark on the coil-to-distributor high voltage lead - disconnect it from the cap and lay it near something grounded like a valve cover, then crank with key on. You should get all kinds of spark between the lead and metal object (don't hold it it your hand or with a metal tool, you'll become the ground and that is painful). If you get nothing there, then ignition module or coil are likely to be the issues (module is more electrically delicate than the coil so I'd start there).

Im headed to pick em up now thanks