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TBI won't fire up

Mastiff

Mastiff

1/2 ton status
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Fired up fine two weeks ago, now it just cranks with no hint of firing up. I can hear the fuel pump running before I start cranking and it turns over nice and fast. I just found out about this, so will have to put off serious troubleshooting until next weekend, but I was wondering what common problems you guys would look for first. I cranked it and checked in the throttle body and there was fuel wetness in there, so there's at least some fuel getting in. I think I would get a hint of a fire even with low pressure, so I'm thinking spark. Dead distributor module?

I posted a similar thread to this a year ago or something, but it turned to just be a vacuum leak from a cracked rubber cap. In that case it seemed like it was trying. Not this time.
 
Id try a plug against the block for spark, and work your way back. Could be a coil
 
Bent77 said:
Id try a plug against the block for spark, and work your way back. Could be a coil
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Just one coil in the old TBI. Do coils just randomly die sometimes? The one in here dates to 1990 or so I think.
 
My 6 month old coil quit last week randomly on my camping trip. 25 bucks later i was back on the road
 
Mastiff said:
How did you determine that it was the coil?
Click to expand...
Process of elimination. No spark at plugs. Checked voltage going into coil which was good. Checked spark at output of coil and got nothing so i replaced it and it fired right up
 
That's where a separate coil beats coil in cap. It's possible but challenging to gain access to the coil leads.
 
A bad pick up coil in the dist. will kill fuel and spark. I usually spray starting fluid in, and see if it will run. If it does, then you have spark, but no fuel. If you are getting fuel, then the pick up coil is working, but no spark, then look for the module in the dist., the coil, rotor, etc.
 
If you suspect the distributor (after checking for spark of course!) I would highly recommend just buying one of the aftermarket complete distributors.

Yes, the quality probably isn't that great, but if it fixes the problem, then you can "rebuild" the other one with (hopefully) good components. And if you fix the one, you end up with a spare.

It's cheaper to buy complete than it is to replace each component in the distributor unfortunately. But again, full transparency, that's the cheap distributors. With "quality" components (whoever makes those anymore) I'm sure a complete distributor would be far more.
 
dyeager535 said:
If you suspect the distributor (after checking for spark of course!) I would highly recommend just buying one of the aftermarket complete distributors.

Yes, the quality probably isn't that great, but if it fixes the problem, then you can "rebuild" the other one with (hopefully) good components. And if you fix the one, you end up with a spare.

It's cheaper to buy complete than it is to replace each component in the distributor unfortunately. But again, full transparency, that's the cheap distributors. With "quality" components (whoever makes those anymore) I'm sure a complete distributor would be far more.
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It is amazing how many people claim to know how to install a distributor correctly but actually do not. Back in the day before distributorless engines I worked with all kinds of mechanics with big ego's that claimed they knew how to correctly in stall a distributor. After they screwed up the install I would have to go in behind them and install it correctly. The big ego mechanics always hated me even more than than they did before when this happened.
 
Exactly one time have I stabbed a distributor and been dead on lol. If you mess with the distributor and it won't start afterwards, 99 times out of 98 you put it in wrong. :rotfl:
 
Ok guys. I went out there after the truck sat for a week and it fired right up. It wouldn't start for anything last time, so how can I trust it to drive out to the boonies?

But here's the weird X-files thing: The same day the truck wouldn't start, my garage door opener was on the fritz. The inside controller that is hard wired to the motor assembly (and right next to the truck, with the wire going over top the Blazer) would not work and the LCD screen was sort of flickery. The door still worked though, because I could use the outside keypad to make it go up and down. Today the truck starts, and the garage door is miraculously fixed too. I took it for a coincidence, but now I'm thinking WTF. Still could be, but could it be some sort of EMF thing or something? :eek1:
 
Mastiff said:
Ok guys. I went out there after the truck sat for a week and it fired right up. It wouldn't start for anything last time, so how can I trust it to drive out to the boonies?

But here's the weird X-files thing: The same day the truck wouldn't start, my garage door opener was on the fritz. The inside controller that is hard wired to the motor assembly (and right next to the truck, with the wire going over top the Blazer) would not work and the LCD screen was sort of flickery. The door still worked though, because I could use the outside keypad to make it go up and down. Today the truck starts, and the garage door is miraculously fixed too. I took it for a coincidence, but now I'm thinking WTF. Still could be, but could it be some sort of EMF thing or something? :eek1:
Click to expand...
This is why I like having (and carrying to the woods) things like spare fuel pump, swappable relays, and a spare, known good distributor.

I had a fuel pump that would randomly decide to stop working, but never when I had the time or place to properly diagnose what was causing the vehicle to die. That too had me worry about where and when it might fail next, or for good. Luckily(?) when it did it was near my house. Not in an area I could work on it (had never been in that area at night, what an eye opener!) but at least the tow wasn't too bad and I knew exactly what the problem was, finally.
 
Mastiff said:
Fired up fine two weeks ago, now it just cranks with no hint of firing up. I can hear the fuel pump running before I start cranking and it turns over nice and fast. I just found out about this, so will have to put off serious troubleshooting until next weekend, but I was wondering what common problems you guys would look for first. I cranked it and checked in the throttle body and there was fuel wetness in there, so there's at least some fuel getting in. I think I would get a hint of a fire even with low pressure, so I'm thinking spark. Dead distributor module?

I posted a similar thread to this a year ago or something, but it turned to just be a vacuum leak from a cracked rubber cap. In that case it seemed like it was trying. Not this time.
Click to expand...
Check the fuel injector fuel pods see if anything is coming out. Then check fuel pump pressure. Could be something easy like a bad fuel filter.
 
Well, the x-files part is over. The garage door is on the fritz again and the truck still starts. I guess I just drive around in towing range until it breaks again.
 
Just FYI. I had a weird issue once. TBI wouldn't start, everything checked good. I got pissed one day and just layed on the starter and kept cranking it then she fired up and ran fine. Didnt have too much problems starting it until the next morning then same thing.
Turns out it was a bad Oil Pressure switch. It would not allow the vehicle to start until the oil pressure built up to close the switch.
 
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