Possible Fuel pump or relay problem?

[Germ]

So i took my mothers car which is a 1998 ford explorer sport. 4.0 SOHC...Drove her to work then went to visit a friend in the hospital. Well i accidently parked in the wrong building so i went to go back to the car and it would not start at all...i tried to start it 7 times or so. so before calling a tow truck i figured i'd let the car cool down to see if anything changes...came back an hour later and voila! started and drove the rest of the day like nothing ever happened.

My mom took it the next day on the highway and she said it surged a bit but did not die on her...pulled it into a parking lot turned it off and tried to start it again right after...did not start until she got out of work...now the kicker is this...It ONLY happens when it is hot outside (Miami,FL) but even when its hot out it will start the first time just not after the motor gets to temp and its hot outside...It has no problems starting in the morning or at night...

Could this be a faulty relay? or the FP itself...When you try to start it,it turns over and starts but only makes it to 300 rpm then immidieatly sputters and dies. i have a 1999 explorer sport and i have been through 4 fuel pumps so i know the symptoms...but my mothers car is not being as obvious as mine...HELP!

 

[greasemanicure]

FP relays are notorious for this. When it acts up, swap it with an identical relay that is next to it. If it fixes it, get a new relay. Mine came and went like that, not with heat but more random. No trouble since changing the relay. When it does not start, can you hear the fuel pump kick in with key on engine off?

 

[JEastonjr]

maybe check the FP. its easy enough. it cant hurt,

 

[imp]

Check for fuel pressure while cranking. If pressure normal, pump & relay OK, regardless of engine temperature at the time. Hard to imagine relay becoming heat sensitive to work/no work. Fuel pump internal temperature follows fuel in the tank temperature (plus some operating increase internally) as the fuel flows through the pump motor windings, to cool it. imp

 

[Germ]

I changed the relay and so far the problem hasnt shown but its hasnt been as hot...so i guess i will give it a couple of days to see if it persists. thanks for the info gentlemen.