My cousin called me today with a problem. I'll give as such vehicle info as possible.
2001 F250, 7.3L, Auto, 2WD, Ext. cab, Lariat, approx. 115k. To my knowledge (and his) there is no tuner/chip on the truck, although I have seen a very small puff of black smoke when it downshifts.

He went out to start it to go to work and it wouldn't start. The starter turns he engine over fine, the tach is moving, but he said he couldn't see white smoke. While cracking, it sounds as if a relay is clicking furiously under the dash. After trying to start it several times, the clicking stopped and the truck started fine. It may not do it for several days, but seems to happen every couple of days. Any ideas?

 

Sounds like what mine sounded like when my batteries went south. What was the tach reading when this happens? Have him clean his batt terminals and check connections.

 

He said the tach was moving. To what rpm I don't know. He said it was cranking strongly, though he did say his batteries were super corroded. I tried to get him to take 5 minutes to clean them and put some no-a-lox (sp?) on them.

 

Sounds to me like it starts after the GPR releases. That is probably when the required 10.5 volts to start is available.
It is most likely dropping below that voltage while GPR is operated.

 

Ooh, good point. I hadn't thought about that. That is a VERY good possibility.

 

I was on the phone with a member who had a no start problem. Under 10 volts while cranking.
Had him lift one of the control leads off the GPR so it wouldn't operate. Truck started right up.

 

Battery terminals are clean now. I guess we'll see how it goes.

 

Have him check for 10.5 volts when he first starts cranking.