Problem

[Mike M]

Today I took car out for several hours with wifey doing a bunch of driving highway and in town.
This has happened 2 times last month and again today (scary). I pull off the highway to an exit and I am waiting at the light, I watch my scan gauge all the time, Engine temp was 204 but IAT was 139 and fuel pressure was about 59, while sitting at the light I felt it starting to run rough and within 5 seconds engine shut off. After about 30 seconds I was able to restart it and get it home (1/4 mile away). I pulled it into garage and it was idling fine but I let it sit and get hot again idling in garage for about 2 minutes and I watched the IAT climb to about 140 and sure enough I watched the fuel pump pressure drop from 59-30-25-20 (engine idling rough and stalled)
What is the correlation between high IAT and fuel pump shutting down? Every time it has happened I have been stuck at a long light with very high ambient temps and high IAT temps.

Something in the tune?

[1 Bad Merc]

Do you have a bap or hotwire kit hooked up to your fuel pump? Wondering if you have some kind of resistance in the fuel pump wire that when it gets hot it starts to lower the current.

I know when I switched fuel pumps I had a 15 amp fuse and kept popping it when the motor would get hot. Changed to a 20 amp fuse and so far it's been fine. Check your fuse under the hood as the bigger pumps require more current draw and this might be the fuse on it's way out.

It could also be your fuel pump going out. When it heats up it starts to shut down. I definitely would not get on the car at all until you get this problem fixed-dont want to buy a new motor.

[Marauderman]

Somewhat similar problems lately--may be the fuel rail sensor--mine thru those codes after a bit of stuff like u described---still in mist of determining and and fixing...

[Mike M]

I have not installed my BAP yet, but it is a big ass fuel pump in the tank. Zack thinks it may be the FPDM getting too hot and failing.

I need to monitor its voltage when it happens.

[Vortech347]

Fuel rail sensor or like Zack said you're overheating the FPDM if you are running a bigger 340 turbine style pump.

IAT's in the 140's? Pft. My Fox gets up to 210* open tracking. :)

[RacerX]

You could look at it in the reverse too. FPDM starts overheating, fuel pressure starts lowering, mixture gets leaner, making heads and such much hotter giving higher IAT temps.