1998 Ford F-150. Has been a great truck never any problems in it’s 100,000 miles, until now. A few months ago occasionally it wouldn’t start when warm after turning off the engine for a short stop (5-10 mins). After a half hour or so presumably when it is cold again it starts right up and runs fine. Now it is getting more frequent and needs to be addressed. I am not sure where to start is this fuel system, electrical or computer. Will an AutoZone (where I usually go) diagnostic test detect the problem? I replaced the fuel filter at about 70,000 miles.
If your check engine light has been on or is on then you can get the codes read at a place like Autozone and that might give a place to start. If that works out, write down the exact codes (e.g. P0123) and post those.
Also clarify “won’t start” - I’ll assume that you have plenty of crank, but that the engine won’t actually fire & go.
Problems like this are often fuel related and relate to the engine getting too much fuel. The next time it won’t start hold the gas pedal to the floor as you crank and let up slowly as it fires. If that starts it then it is a sign that then engine is flooded - probably from a leaky fuel pressure regulator. Pull the vacuum hose for the regulator and check for liquid gas - if you find any, replace the regulator.
Also buy a spark tester (any auto parts store) to have on hand. You can hook that up the next time it won’t start to check for spark.
Great suggestions. No check engine light when running. When I say it won’t start I mean that it does crank but no firing. I will check the vacuum hose for fuel.
A while back I had the same problem with a friends 87 Mercury 5.0. After you shut the engine down for a few minutes it would it not start unless you held it at WOT. It then would start on 3 or 4 cylinders and run rough until the other cylinders cleared with black smoke out the exhaust.
During this episode had good spark and you couild smell the fuel.
Checked the fuel pressure regulator and was good. He ended taking the car over to my mechanic and what he found was the engine coolant temp sensor was flaky.
He said at times the coolant temp sensor was showing the coolant temperature at 40 degrees below zero and flooding out the engine. It was an intermittant problem and got worse with time.
First check the fuel pressure regulator as stated above.
It has been suggested to me that I check the coil. These apparently can cause intermittent hot starting problems before they go out. I’ll post results.
Hey, obviously new to the group , but I’ve had the same problem with my f150.Its a 5.0 EFI 200000 miles on it, but I’m trying to restore it a little at a time. Today I went out to crank it and it wouldn’t start. After priming the fuel pump 5-9 times, it finally starts.Switching between tanks, because I know there’s gas in one of them … but after it started it run like a champ. Being on the safe side, I left it home today so not to have to fork out for tow bill. Thanks for the advice in previous statement. I will try replacing regulator and temp sensor.