I have a 1983 bronco w/ a H.O. 302 out of a mustang. I am having problems with it. I can be driving down the road 55 mph @ 2000 rpm and my tach just drops to 0. No bogging down no slow dying or cutting out it just shuts off. I can put it in neutral and start it with the key while it is coasting or it will start back up like a standard but mine is an automatic. Also I have 3 cyl that are not firing. I replaced distributor, plugs, wires, cap, rotor, and checked compression, push rods, rocker arms , springs, plugs, wires, firing order everything I can think of. Could it be my ignition control module? Like it is not telling the distributor when to fire on those cylinders. Or is it electrical like it is losing power. On the way to work today stopping at stop lights when it turned green and I gave it gas it would cut out and go and cut out and go until it built up enough rpms to keep it going.
I haven't had it very long and the previous owner has never had the problem.

Bronco I just want it running again

 

had kinda the same problem mine ended up being a bad fuel pump ran for about 15 minutes, then started running rough---put a pressure guage on it, and showed pressure dropping off replaced that and the filter--ran good then also check the small wire on the positive side of the solenoid (has a fusable link) mine got hot from repeated and long cranking intervals, and finally burned in half

 

now if i remember correctly that engine has an ignition module that was fastened to the firewall. this happened to me years ago and if i got out and tapped on the ignition box the car would start and run fine untill it happened again. sometimes quite often and other times it rarely happened. when i replaced the box the problem went away for good.

 

Are you really running it firing on ONLY 5 cylinders? Must be a heck of a lumpy idle

I am assuming the 302 HO you are referring to is the carburetor motor, with the mechanical fuel pump.

Did you verify no spark at those 3 cylinders?

What ignition system do you have... DuraSparkII? A DuraSparkII distributor has a vac advance, and if you pop the cap off, it has a "paddle wheel" with 8 paddles on it. And a coil pickup piece that senses when each paddle (tooth, really) is lined up with it. The pickup coil has 3 wires (2 wires to the pickup coil itself, and the third wire is a ground wire). There is an outside connector hanging out of the distributor for harness connection to the pickup. And the DuraSparkII control box will be mounted somewhere, fender or firewall.

If you are actually missing spark at 3 cylinders, and spark plug wires are good, check and see if 3 of those teeth in the distributor are broken off. Also check if the distributor shaft can be wobbled side-to-side like bad bearing or worn shaft.

 

I had a loose wire at the coil do similar things to me.

I'd check the whole ignition system over, starting with the coil, wire, cap, rotor, plug wires, and plugs (in that order). Something is not getting through somewhere.

Dan Q

 

Are you really running it firing on ONLY 5 cylinders? Must be a heck of a lumpy idle

No lumpy idle. While it is running i can pull off cyl 3, 4, and 7 wires from the distributor and the motor idle doesn't change. I replaced the ignition module and I believe it fixed the dying problem.(at least on the way home it didn't die) It has a new distributor, rotor, cap, wires, plugs, and now ignition module. It is firing through the wires and plugs we checked it on the scope. It is not firing in the cylinder. Compression? We have compression 125 (psi?)<-- I guess. Don't really know how it is measured. The guy I go to is stumped I think he is leaning to pulling th cam an checking to see if it is wore down and maybe it is not hitting the lifters right or enough to open the valves for it to fire?

Thanks for the replys. People in the fourm are always nice and helpful to people like me who can't just seem to get things going. Once again thanks for the help and maybe we will come up with something to get it going.

 

well now I think I have a stuck solenoid---battery was dead in it this afternoon charged it and when I hooked up the positive cable, the small fusable link wire on the positive side of the solenoid started smoking---it was burned off the other day, so I spliced new wire in---

 

A couple more ideas on the 3 dead cylinders:

Be absolutely sure that the plug wires are arranged to get the correct firing order for the cam that's actually in there:

302HO/351 is 1-3-7-2-6-5-4-8.
302 regular is 1-5-4-2-6-3-7-8.

Sounds dumb, I know, but sometimes people think they have an HO, but it really had the regular firing order cam, or vice versa. It is interesting that you have dead 3 of the 4 cylinders that would be affected with that kind of firing order mistake, those are cylinders 3, 4, 7, and the fourth one would have been 5.

If the firing order IS correct, I would pull off valve cover, and do a good visual on the problem cylinders. Then turn the crank with a breaker bar and socket on the crank nut. Verify that the valves open and close OK? no bent pushrods, etc.?

One of these ideas should nail the problem. Since reasonable compression readings (yes, it is in PSI) have been taken on the dead cylinders, that seems to say no holes blown in pistons, etc.

 

Dude.... print that reply. That's one of the proverbial answers to your questions, and Torky2 nailed it. With the interchangability in the SB Ford motor, you have to watch your firing order. I never nailed it like Torky2 did, but the firing order can be suspect. If you were having other mechanical disorder, the engine would generally complain like hell (backfiring through carb, damn nearly stalling out, etc).

Good post Torky2. Big plus on ya.

Dan Q

 

Alright may be this is it. I will double check my firing order tonite and see if it is right. We have pulled the valve covers and on the dead cylinders are not loose, no broke springs, push rods are not bent and with the valves closed you can spin the push rods.<---Good sign? And every appears to be working correctly. I mainly go by what I am told to repair it. My brother-in-law's dad has a shop and that is where I go to "turn a wrench" (I am no mechanic I jut try and if i get stuck I ask what to do) he tells me which part to pull off an I do it. I have access to tools, car lift, scanners and scopes to check things out with with no labor charges and all it costs is parts and help with other vehicles. He has been in the repair biz his whole life and I have never heard him say the he don't know about something. Except for my bronco. He says we need a exploration day. Just start taking it appart until we find something. He thinks it is the cam is wore down and the lifters are wore and it is not opening the valves enough to fire. It would be nice to buy something that runs good but for $2000 I can't beat it. I printed the post and will check the firing order tonight.
Thanks for the help again

 

Engines don't wear out suddenly, and your problem appeared immediately while driving normally.

Suspect a simpler, more common problem, fuel or fire. However you have replaced most ignition parts. Make sure your timing is set correctly, and then check fuel pressure at throttle body manifold.

good luck

 

YOUR RIGHT THE ENGINE DOESN'T WEAR OUT QUICKLY. I JUST BOUGHT IT A FEW MONTHS AGO.

 

pull the connector plugs on the alternator and make sure they aren't burned---mine burned out on the big connector and caused it to cut out