1999 Ford F150 6 cyl Four Wheel Drive Manual 78000 miles
My truck does not start when it is hot outside - especially if parked in the sun.
If it is cool out (60's) it start fine and runs great. If it's in the 80's and parked in the shade it will start fine - if moved into the sun it will not start. If its 100 out it won't start no matter what.
I found that when the ignition is turned to on (engine is not running) and its hot out there is no buzz from the fuel pump. If its cool there is a buzz.
So I check the voltage at the plug on the frame rail by the fuel tank. When it will start it shots up to 12 or 13 volts. When it won't it only goes up to 7 or 8 volts.
Next I thought maybe it was the fuel pump relay. In the fuse box under the hood there were several relays that looked the same. I took the one for air suspension, which I don't have, and switched it with the fuel pump relay. This did not change anything.
I have tried starter fluid when it will not start and it runs briefly and dies.
One other thing I have done is sprayed the truck with water when it won't start. If its parked in the sun and in the seventies this will cool it down enough to start. If its any warmer this will not work. As you can probably tell I have been trying to figure this out for a long time. What should I try next?
Thank You in advance!
Thursday, May 7th, 2009 AT 4:43 PM