ok i have replace my fuel filter, my wires and plugs, my cap and rotor, and a new inline fuel pump. OK after i got all that done i thought my truck was fixed. i wouldnt go for 4 miles and die. well when we drive it at night time it drives perfect. but when the suns comes out it still does the same crap after 4 miles it just dies. im out of solutions and i need help.

 

Normally I'd suggest float adjustment, float valve, another missed filter in the carb inlet or internal. But this Dracula Only Drives At Night thing is wierd! Just for fun, try driving with lights on during the day. This may be the clue. Overvoltage that stresses something that disappears with the added load of headlights?

-Ed

 

What is the temperature at night vs the day. I am thinking maybe hot coil dying vs coil staying cooler at night possibly? Cols often die when hot only at first until they die the rest of the way but difference shouldn't be that great.

Rather than shotgunning parts though, try to do some troubleshooting when it dies. Do you have spark? Fuel? If no spark, where is it missing? Are you getting pulses at coil, out of coil and to plugs?

Is this EFI or carb? If EFI, run codes and see what it says.

Good Luck,

Lee

 

im thinkin maybe ignition module. sometimes u can pour water on em and cool em down and then theyle work till they get hot again.

 

well my truck is and efi

 

Since it is EFI, I would get a code scanner for about $30 from any parts store or Wal-Mart and run a scan. The failure should be in memory. If you can run it and make it fail, it would be even better.

I just tried to troubleshoot a friends ford a few weeks back that was strange. The memeory code said it was a bad TFI but then when we got it to quit running we had codes for TFI and fuel pump. Turned out the ignition switch was bad and killing power intermittently. We would have changed the TFI if we hadn't seen that hard real time failure for the fuel pump. That was the clue that the problem was power and not the actual units since there wasn't anyting in common with the two. Sure enough, a little wiggle on the ignition and we could hear the fuel pump cycling on and off along with the various relays.

I agree with oldfordtrucksrule that it could be an TFI also. They fail often but are kind of expensive so if you could get a good idea for sure before buying one, it would be nice. Both the TFI and coil are heat sensitive. If you are ever feeling rich though, it is often nice to have a spare TFI handy.

Good Luck,

Lee

 

I'd be willing to bet on the ignition module(silver or black box mounted to your inner fender, under the hood)

They can get hot, and fail, and are more common that coil failure.

 

TFI is mounted on the side of the distributor in an 86 F150 5.0 EFI setup.
You will have to either pull the distributor or loosen it and rotate it to get to both screws. The screws will require a special tool. It's only about 7 bucks.

To avoid pulling the distributor completely, mark the position of the distibutor, loosen it and rotate it only as far as necessary to get to the second screw. When finished, realign the marks you made. Most times that is close enough to get the truck running until you can fine tune the timing.

Could also be the pick-up coil inside the distributor. They fail much the same as a TFI when they get hot. After they cool they will usually work again for a while longer. You will have to pull the distributor and disassemble to change the pickup or you can get a new distributor for pretty cheap.

I had this situation happen about 2 years ago. Mechanic (Trained by Ford) indicated that it is usually a good plan to change both the TFI and the pickup at the same time.

 

well we took my truck to a mechanic and they found out it was the two fuel pump were bad so they replaced those. the truck would run fine if the tank was full and that must of been when it was at night and if just broke down in the day.

 

That's one for the books! Glad you got it running, keep those mechanics!

-Ed