i have an 87 f-150 300 I-6, 2 wheel drive, with the four speed manual. It runs great, but once it gets hot, if you turn it off it wont start till it cools off. I have replaced and troubleshooted relays, thought it may have been a map sensor but it still has the problem. Yesterday I used a can of electronic freeze spray and cooled the coil off. It started right up...tried that about 3 or 4 times. Would a coil cause this??? I picked one up this morning, it was less than $20 so no big deal. The symptom itself is really not a problem unless you are running errands or run out of gas (since the sending unit is bad too).

Thanks,

Justin

 

Those older fords had the Duraspark ignition, with the tfi module on the distributor. Excess heat, in particular will cause the symptoms you have. Next time it craps, have an ice pack on hand and chill the tfi. If it starts right up, go buy another module. ( don't buy the cheap one ). Fuel pumps are the next worst offender.

 

I forgot to mention that I replaced the ignition module. Yea I used to have a ranger that was notorious for the ignition module crapping out all the time. The fuel pressure seems fine, I dont have a gauge that will go high enough to measure the actual pressure...but it sprays every where when you open the schrader valve!

Thanks for the thought

 

Yes, coils can get sensitive to heat, too. Has the symptom reoccurred since swapping the coil? Buy a Haynes manual & a cheap digital multimeter, and follow the ignition diagnostic procedure.

Another thing is the fuel rail cooling blower. Does yours still work? It's thin black squirrel-cage blower near the battery with a hose that runs into the intake cage. The relays sometimes die. They were used on 4.9s in '87-89 until the engineers realized that raising the fuel pressure would accomplish the same thing.

Get a fuel pressure gauge & see what you've got. Check the chart at the bottom of this diagram. (The top of the diagram doesn't apply to your truck.)

****KRAP****
SuperMotors is down at the moment, but by the time you read this, it should be back up. Click my signature link, go to the EFI Fuel Pump album, & find the diagram with the pressure chart at the bottom.

 

Thanks steve,
I havent been able to swap the coil out yet, going to try and do it tommorrow evening so keep your fingers crossed. Yea the fuel rail blower seems to work, if the coil doesnt fix my problem I will have to check out the relays. I have to admit that it is an odd symptom!

Thanks again

 

well I changed to coil and it had the same problem. I decided the last thing that could possibly be the cause would be something in the distributor itself. Pulled it and inspected everything, didnt change the reluctor, thought about it but didnt. Reinstalled the distributor...timed it by ear and havent had the symptoms since. So who knows, it runs great and starts every time! Unless there was a loose conection on the plug to the ignition module, I cant figure it out.

By the way I am getting close to 18mpg highway (at 70 with the cruise set) is that pretty good?

 

With no overdrive that's damn good mileage.

Adrianspeeder

 

18 is almost too high to be correct.

If the problem comes back, read this thread & look at the photos linked in it.

 

Yea I thought it was pretty good mileage! I topped the tank off, drove it a good piece, then topped it off and checked the mileage...I did it twice! I am happy!

 

Well guys the problem is back...it runs great but wont start when its hot. Just a quick question, the cage fan that is connected to the fuel rail...is it supposed to run after the truck has been parked and turned off for a while? I noticed yesterday that after it has set for about 5-10 minutes the fan kicked on. It ran for a good bit, really didnt time it though. I just thought it was odd that it came on after the truck was turned off. I have also noticed that when it is running the truck wont start. I still have some troubeshooting to look into but any ideas are appreciated.

Thanks

 

Did you read that thread I linked above?

Yes, it's normal for the injector fan to run whenever it detects that the fuel rail is too hot (even if the truck is OFF). But it shouldn't interfere with starting.

 

Yea steve I looked at that post...I am not too sure what to do with it though...maybe I am dense or something I dont know. Are you suggesting that I switch to the BOSCH relays?

A new development...if I pull the timing sprot off the distributor it will start when its hot. I am starting to think the computer has a problem.

Sorry Steve I guess I just need things spelled out for me! Thanks for all the help I really appreciate it!

 

Yes, as the photos in that thread show.

The SPOUT connector?



Follow the ignition diagnostic procedure in Haynes.