kennetch1

I hope I am doing this right since I am new to the forum, any way here goes. I have a 08 f150 XLT 4.6L. A few days back I drove to work and when I came out not more than half an hour my truck would not start. It would not turn over. All the lights on the console and dash seemed to work but it would not turn over. I had a meeting and could not deal with it. Later that day after work I tried it again and it started. Drove it home, shut it off and again tried to start it, same thing, nothing. Checked the battery, reading 12.19 v. Couldn't use the scanner need a new one. Left it till the weekend. Again it started, took it for a run, no problems, brought it home shut it off, again it would not start. Left it for about 5 hours, again it started. Can some one please tell me what might be causing the non start when the engine is warm?

MJ14

Check your fuel pressure. I've seen them get warm and then drop pressure before causing it to not start until it cools off. You'll have to get it warm and then check though.

kennetch1

I think I am also going to check the fuel pump driver module. could be the reason it is losing pressure. will check back when I have done that. Thanks again.

connorfx4

Yup, I'd also imagine it could be the FPDM.

Rick's 06

When you say it won't turn over, are you saying the starter isn't even cranking? If so, you've got an electrical problem with that, not your FPDM. It's always a good idea to check that too to make sure it hasn't rotted out on you, but I don't think that's your problem. May want to double check your terminals are clean and tight along with your grounds. If you're able to, next time it has this problem, I'm thinking a voltage check at the starter or even a simple continuity check of the starter cable might identify some problem.

connorfx4

Ah good catch. Agreed

kennetch1

Yes, the starter isn't even cranking. Well checked the starter and solenoid. Before that had a problem with my scanner connecting with PCM, had a blown fuse, connected and no codes. Back to the solenoid, it had corrosion on the positive post. I heard clicking coming from the relay switch as I turned it over and held it for a few seconds. Gonna follow the wires and check for continuity, voltage after I clean the posts. It still doesn't explain why it would not turn over after it warmed up. Could the relay be taking too much voltage because of the corroded posts causing the switch to heat up and breaking contact? The relay in fuse box is R01. Have to limit my time with the truck because of work and cold. working outside in -15 C weather with lots of snow. One step at a time. Need to find problem as the parts store is 129 kms away. Want to make just one trip. Thank you for your guidance and will keep you posted.

kennetch1

Forgot, checked the FPDM it looked okay for a truck that has 261,000 kms. Very slight corrosion but seemed okay.

Rick's 06

Your relay might be going bad. Sometimes they still click, but don't make good contact on the inside anymore. You should have 6 similar relays in your fuse panel. One of them is for your starter. Try switching it with another one and see if it works. That would tell you if you have a bad relay. Look at your owners manual and it will tell you which relay is for your starter.

DrGriffin

I had a similar issue on a different vehicle. It ended up being the starter. Not sure exactly what was going on but when it was heated up it would not work. You might get by with cleaning the terminals but I bet you will need to replace it.