OK... here's my story: '94 XLT 4x4 Bronco

Engine dies suddenly without warning... crazy thing is that it usually happened during low RPMs but this time it happened on the freeway!

Usually what happens is the engine just stops... tacometer drops suddenly to 0 and all I can do is pray that I can steer my car to the shoulder and that it starts again.

I have recently changed the plugs, wires, dist cap. So I am pretty sure its not one of those.

I have a feeling its the alternator, but don't have a clue how to test if its dying or not.


Anyway... once I am on the shoulder I try to crank the motor, and I usually get it by the 3rd try.

Anyone have any idea what my problem is or experience something like this before?

Thx in advance....

Jaja

 

I would say you have a loose conection, if your alt. were dead, the engine would run off the battery, and if the battery got too low to kill the engine due to the ignition not getting enought power, you would not be able to crank the engine over after it dies. The ignition system draws close to nothing. I would check under the hood while the engine is sitting idling and shake any wires that have anything to do with the ignition or fuel pump, relay, or reg. You should be able to find your problem due to elimination.
Good luck bro.

 

Yea sounds electrical, did you check battery posts and cable ends?
in particular the small ground plug into your ignition harness, if corrosion or a loose connection cuts off or reduces voltage (9 volts mininum) your truck will shut off.

 

Excuse the ignorance, but what is the "small ground plug into your ignition harness"?

Thx

 

Another thing... I noticed when I am driving my truck and stopped at a light, the voltmeter goes down a tad bit, esp when I have my lights on. - thats why I thought it was my alternator.

Do alternators gradually die out, or do they just stop functioning period?

Thx

 

Alternators usually just flat out quit. I would definitely do as the others have suggested. Clean battery terminals, check connections. There is an outside chance you have a TFI module beginning to die. A heat related failure could possibly cause it to suddenly quit like that. The only reason I am thinking this might be a possibility is that if you were dealing with a bad connection or corrosion, restarting shouldn't take 3 tries, it should require finding the loose connection or cleaning the corrosion right there on the roadside. Heat can cause micro electronics (like the TFI module) to malfunction then, when they have cooled enough, they will work again. If there doesn't appear to be anything wrong anywhere else and the problem persists, its a last resort.

 

yup do as previously stated, clean and check you battery cables, while you have it idleing move,bend and flex the all the wires from the dist. to the coil and the wires from both of them to the ECM and also check the relay for the ecm. make shure all the conection are pluged in good. good luck DW

 

you can turn on your high beams with truck running and pointing towards some reflective glass like a storefront at night, then turn on all electrical devices (a 12volt heater would help load your system really well) If your high beams go dim momentarilly then go back to normal the alternator is fine. If the lights stay dim your alternator isnt making enough power for your current needs.

The TFI module is a definate suspect, however my experience is that it causes rough running intermittent episodes wich can go away if you shut down and restart (quite often 3 cranks though)

 

Hey thank you all for your help....

I know this happens to everyone, but as soon as I posted this problem my truck started to run without any problems.

(I even drove 600 miles from LA to Sequoia Nat'l Park and back...)

The only problem I have now is that my A/C isn't functioning after that time my truck froze....

I tried the "remove the negative terminal to reset the ECU" trick... and out of ideas... does anyone think it could be some relay of some sort?

Thx

Jaja

 

A/C quit working? Out of curiosity, was it running the day you had the latest difficulties? Could be the clutch relay/solenoid was dying and shorting things out. Now that its completely "dead" there is nothing to create the short any more. Electricity is a strange fickle beast and it can "talk" to its components in odd ways. I'd have the compressor and drive clutch electronics checked out.

 

Greystreak,

How does one check the "compressor and drive clutch electronics" - sorry for the ignorance..

J

 

Jaja,

Sorry, I could have been a bit more enlightening. When you turn the A/C on, does the clutch on the compressor engage and actually make the compressor spin? With the engine running, you can have someone turn the A/C on and watch the front of the compressor pulley. If it begins to spin, then the clutch is working properly. If not, something has gone wrong with the solenoid that activates the clutch. There is a small two wire connector at the top of the compressor right behind the pulley that controls the solenoid. You can check this connector for damage and voltage. Obviously, with the A/C ON you should get battery voltage across the two contacts. OFF should yield nothing. Checking the voltage only verifies whether power is getting to the solenoid. (Rules out a blown fuse basically). My thinking is that perhaps the solenoid was weak and shorting somewhere and the short was causing the ignition problems. And now, if the clutch does not engage, the solenoid may have completely failed. Since it has failed, there is nothing to cause the short anymore.

Contrived, I know, but I have seen stranger things. If thesolenoid is the problem, some shops will repair the clutch/solenoid assembly. But most often they simply want to replace the whole compressor. Its sometimes cheaper than fixing it. (Like replacing the VCR because repairing it would cost more than buying a new one).

Note: The procedures mentioned above assume that you are dealing with an air conditioning system that has no leaks and a good refrigerant charge to it. If not, this check of the system may not work.

 

Thx for the info... I'll check it out today.

J