Hey guys, I need some serious help with my carb in my 86 f150, it keeps acting up on me and not wanting to run. So what happens is I think the choke has either went out or is about to because it is not fuctioning properly at all. So the other day I went out to mess with it and I cranked the truck and let it run for a good 10 to 15 minutes and then used a little string to tie the choke flap almost all of the way open, assuming it would run being that it was a hot day. So while doing this the truck idled great with no problems. I decide to take it up the road to try it out. I get going and its running good through first and good through second, and then I shift to third at about 35 to 40mph and it putters a little bit and dies and then will not crank so I had to go get my other truck and pull it home since it died about 1/4 of a mile up the road. It had been running fine untill a few days before this it starting wanting to cut off on me while driving home one night. I really need to get this fixed, so do you guys think it could still just be the choke or maybe the carb all together. Oh and it is a 4.9L with the electric choke.

Any help is appreciated, Thanks Guys!

 

When you say it will not crank do you mean is won't start or it won't actually turn over?

 

If you have the engine warmed up, and the choke tied open, then it's not the problem at the moment.

When it quits, you need to jump up and take the aircleaner off, and look down the carb throat and push the throttle back. You should see fuel squirt down in the engine. If you don't you have a fuel delivery problem like a filter, pump, or a clogged line.

If you did see fuel, then you need to take a screwdriver and pull one of the sparkplugs and see if you have spark. If you don't then the ignition module could be bad. They are known to fail when they get hot.

 

It will turn over and eventually fire, but this time the battery actually died on me, But there again, after it finally cranks it will only run for so long and then will quit and it seems like it only tries to cut off under a light load at low rpm's. What i mean is like I said it did above, it will run alright through first and second and then when i hit third and the rpm go down then it wants to sputter and died on me. I'm not sure whats going on, does this sound like a clogged fuel line possibly?

 

I had an 80 model F350 4x4 with 400M that did exactly the same thing. My problem was solved with a new module box. I replaced the module box and it fired right up never to stumble again, at least as long as I had it.
You must be careful when buying the module. There were three different color codes on the wires coming out of the module box. I can't remember all three of them but two of them were brown and blue. The colors must match the color code on your distributor wire that plugs into the box.
Hope this helps. Bob

 

I pretty much know its getting fire becuase I replaced the motor no long ago and put a whole new ignition system in it plus I had checked the fire the day before and it was fine, But I will check again just to be on the safe side. Do you guys have any more suggestions, I would really like to get her running good.

Thanks!

 

It sounds like the ignition module to me as well.

Be the first thing I'd check.

 

Ok, Ill try it, but when you say module do you mean the ignition control module?

Thanks!

 

The Ignition Control Module. That's correct. It's most likely the TFI-IV on this truck.

 

Alright Thanks, are there any other idea though before I spend the money for a new module, because I dont think you can return electrical parts if that doesnt work.

Thanks Again!

 

it sounds to me that your problem is fuel related, especially considering the fact that you could get it started again after it failed. check your fuel flow first and foremost, and look at your fuel filter.

 

Most auto parts stores can test the ignition control module to see if it is bad.

 

Did you change the ignition coil when you put the new ignition system on? Check the ground. The paint on that new engine might be the culprit.

Unplug the EGR valve for a bit as well. It could be opening early and leaning the mix out too much. Also check and make sure the PCV valve rattles. It's supposed to open under low vacuum to draw more air. It could cause a stall if it stays open.

 

Guessing, guessing, guessing. Is there a problem with actually seeing if you have fuel or spark when it quits? You need to check it right then and there on the side of the road when it quits and won't run.