86 Bronco Starting problem

[dcbasic]

I own a 1986 302 EFI Bronco. IT runs good if driving it for 1 minute or an hour. But once its shut off even if its a minute it will not start again. I spray starter fluid in the throttle bodies and it wont start and there is spark to the plugs. I have replaced the distributor cap, rotor, plugs, distributor modulator, coil and fuel relay with no luck at all. The motor turns over but will not start but if I wait about 20 minutes it will start again. Any help is greatly appreciated.

 

[Broncobill78]

Air, spark & fuel. That's what the engine needs in order to run, one of them is missing if it won't fire. Do you have spark at the plugs or did you maybe ck it at the coil ? Any chance the starter is dying and needs to cool off before it will turn it over fast enuf to catch ?

 

[BroncoJoe19]

All this electronically controlled stuff is out of my reach, but I am quickly learning, (I think). I recently learned that there is a coolant temperature sensor that has something to do with either fuel delivery, or spark timing.

Definition: A variable resistance thermistor that changes resistance as the engine's coolant temperature changes. The sensor's output is monitored by the engine computer to regulate various ignition, fuel and emission control functions, and to turn the radiator-cooling fan on and off as needed.

From what you stated above, it sounds like your truck will start cold, but not hot.

I don't have a clue if one goes bad, if it would cause your problem, but this is a great forum, and I am sure one of the more knowledgeable people will jump in.

Good luck

joe

 

[Seabronc]

I own a 1986 302 EFI Bronco. IT runs good if driving it for 1 minute or an hour. But once its shut off even if its a minute it will not start again. I spray starter fluid in the throttle bodies and it wont start and there is spark to the plugs. I have replaced the distributor cap, rotor, plugs, distributor modulator, coil and fuel relay with no luck at all. The motor turns over but will not start but if I wait about 20 minutes it will start again. Any help is greatly appreciated.

Try removing the SPOUT connector, that makes the distributor run on the basic mechanical setting. Without it in the computer can not adjust the timing. I wouldn't suggest running too long that way but it would get you off a main highway. Running an EFI without it will not allow the computer to adjust for knock, emissions, etc. If you want to read a great writeup on EEC operation, take a look at this link http://fordfuelinjection.com/?p=3 . Ryan really knows his stuff, stinks as a business man but he is a technical wizz.

By distributor modulator, do you mean the TFI module sticking out the side? A flaky distributor pickup will give this type of symptom.

Good luck,

>-

 

[BroncoJoe19]

SeaBronc said... Try removing the SPOUT connector, that makes the distributor run on the basic mechanical setting. Without it in, the computer can not adjust the timing. >-

BroncoBill78 said...

Air, spark & fuel. That's what the engine needs in order to run, one of them is missing if it won't fire.

I looked up in my Haynes manual cold vs hot starting problems. Other than fuel and ignition problems, it mentions a dirty or clogged air filter may cause HOT starting problems. I guess it will start very rich when it is cold, but not so easily when it is hot. Not enough AIR as noted above.

I was thinking that ignition timing and compression are also needed, but didn't know SeaBronc's little trick. That one is a keeper.

joe