Please help before I scrap this truck !!!!!

[jaxom6996]

I am about at my wits end with this truck. I have an 84 F-250 4.9 I6. Sometimes she runs fine for a while, ( 35 - 45 mins ) other times just dies out after 5 mins. I have replaced the distributor cap, rotor, plugs, wires, ignition coil, ignition module, fuel filter. Ripped the entire dash and steering column apart looking for dead grounds. The only other thing I can think of is rebuilding the carb. I would buy a new carb but who has an extra $320 at x-mas.... Any help would greatly be appreciated!!!!!!

Oh, almost forgot....strong smell of gas, fuel mist or something comes out of carb, pops and hesitates. Then she starts and runs ....maybe

[big white bufflo]

have you had the coil pickup in the distributor tested or replaced auto zone can test themor the crank sensor

[jaxom6996]

Thank you for responding BWB. Not sure what the coil pickup is, but I did replace the dist. cap, rotor and module. I'm not sure where the crank sensor is, need to get a haynes or chiltons. it does look like the crank wobbles a bit.... not sure if its the crank itself, the pulley or the the bearing thats worn. Had it out 2 days ago, ran ok for about 15 mins, then started with the sputtering, backfiring and not wanting to start again. after about 10 starts, it idled fine for 20 mins ( while the cops were running my paperwork ) then ran another 10 mins till I got home then it died again right in the driveway.....

[MagicRat]

The coil pick-up is a magnetic trigger within the distributor itself. It's located just below the dist rotor.

I don't think your truck has a crankshaft position sensor. That's only necessary for EFI systems.

You have already addressed all the obvious sources of trouble. So here's a couple of suggestions. Does this truck start easily when cold? I wonder if the fuel tank is improperly vented, so the truck builds vacuum in the fuel tank after running for a while. Try driving with a loose gas cap and see if the situation improves.

Also, have you checked the ignition timing?

Finally, it may be possible the carb is dirty inside, some dirt is rolling around in the float bowl and occasionally blocks up the jets. A rebuild kit is a good idea. Since you are pretty handy, rebuilding these is not a big deal and is a lot cheaper than a new carb.
They are pretty straightforward to rebuild. A couple of spray cans of carb cleaner and a source of compressed air and blow-gun is handy when rebuilding the carb.

[timd]

This is an old thread but I had a car that would idle fine but had no power; would only go about 20-25 MPH. I had mist coming out of the carb also. Turns out it was a collapsed muffler causing all the trouble. Punched a big hole in it and it drove fine (loudly). Replaced same and all was well.

[Mrbizness1]

Originally Posted by timd

This is an old thread but I had a car that would idle fine but had no power; would only go about 20-25 MPH. I had mist coming out of the carb also. Turns out it was a collapsed muffler causing all the trouble. Punched a big hole in it and it drove fine (loudly). Replaced same and all was well.

I had a loose baffle in the Cat convertor did the same thing