[RyanGT]

When the fpdm goes into "thermal shutdown" What does it feel like? Im curious if mine is or not. My car gets choppy and if stays that way unless i let off (no throttle for 4-5 seconds) and then all of a sudden everything goes back to normal.

Gas tank is full and it still happens, No leaks in tank or out, wiring is all good (actually now have wiring upgrade). Im running a BAP with the gt supercar pump. 42lb injectors. pprv valve is also removed.

Might be something completely different, but just wondering how you really diagnose thermal shutdown.

[ModMustang97GT]

Why do you suspect thermal shut down? Is that the code you are getting? Also, what exactly happens when it freaks out. Does it feel like some cylinders aren't firing, does it turn off, does it bog?

[RyanGT]

Heard GT pumps use a lot of voltage. So maybe im boarder line.

It jerks and stumbles, with a/f going up and down 3 or so points. I let off it goes to 20 a/f for 4-5 seconds then is totally fine after. I go in neutral (push clutch in) and it wants to stall out goes to un normally low idle but jumps back up to normal. Its such a weird problem.

[ModMustang97GT]

Sounds like your electric system install got botched. Take it in ASAP. Running that lean can cause some serious issues. 15:1 is considered pretty lean on our cars. 20:1 is nuts, you could fry your piston rings.

[RyanGT]

Was happening before the wiring. its in neutral with no load that it goes to 20. Not the actual driving in gear.

But what would this thermal shutdown feel like?

[ModMustang97GT]

I'm not sure about the thermal shut down. The thermal shutdow would be likely due to the car going sooo horribly lean at idle. Lean makes it heat up. I would expect it to try to richen the shit out of the mixture, kick your fan on full blast and watch your heat guage climb. I don't know that the car will actually shut it down. It would feel like pre-detonation, the car would pop and run like total shit and it probably start revving all fucked up. I don't know this for a fact, but that would be my guess of what would happen. Call your mechanic, and if you don't have a good one. Call my mechanic, he knows his shit.

[RyanGT]

Doesn't happen a lot, happened twice in 40 miles i just drove. And that was only on a weird load (going up a hill) or just reaching the top of the hill is usually when it happens. And it doesnt kick it into making it rich, goes exactly where it was supposed to be, like a switch was off and it got turned on. Only does it on decel and idle. It would just be surging or bucking a little bit till i let it fix itself by going to idle.

Shop knows their shit, they are a mustang specialty and been helping out a lot. I have been having problems since i went up with boost on the kb. They figured it out that it was a bypass issue with the kb's that kb was denying to the bitter last... until they said what was happening and kb was like "oh yeah that... "

Car is so close to better! This is the last major issue thats bothering me. Its been out of good working order for the past year. Been undrivabile until the past month lol.

[Randy Stinchcomb]

is this on a stock oem FPDM or one thats been "tweeked" by Mark @ Zone 5?


also there is an updated FRPS, do you know if yours starts wth "F8CF" or "3R3E"

[jivepepper]

I have never experienced it, but going by your description I would suspect the voltage to the pump or a problem with the pump. You could also have an internal gas tank leak.

I bought an used modified FPDM.

[RyanGT]

I had the tank dropped to double checked, then the shop pressure tested it. No leaks! Its a stock fpdm. I have no idea about the numbers. Let me pull it out and check. year 2000 if that matters.

[Randy Stinchcomb]

Originally Posted by RyanGT I had the tank dropped to double checked, then the shop pressure tested it. No leaks! Its a stock fpdm. I have no idea about the numbers. Let me pull it out and check. year 2000 if that matters.

ok but the FRPS is the little black sensor on the fuel rail and the older ones (F8CF) have had issues, 3R3Z-9F972-AA (3r3e 9f972 aa) is the latest/greatest version and also, since the GT(40) pump requires more voltage, (like you stated) you might want to look into one of those "tweaked" FPDM from Mark @ Zone 5 Performance

[RyanGT]

ohhh didnt see you said frps instead of fpdm haha. Sneaky!

You know you might be right about the frps, since i upgraded to a little bigger vacuum line it has run significantly better. And that issue happened less. let me go look for numbers real quick.

[RyanGT]

F8cf

[RyanGT]

Hot damn you got me all excited, this could be one of the problems. My tuner said he could not get the voltages ironed out. The fuel pressure was all over the place no matter how much he nit picked.

Swapping the gt pump back in helped. And larger vacuum line made a big difference in drivability. He said that its probably something electrical (then said to try upgrading vacuum lines). Or i had a vacuum leak which i searched for a few times (with carb cleaner trick).

[Randy Stinchcomb]

Originally Posted by RyanGT F8cf

ok, well thats the FRPS that we've had issues wth and iirc the cars acted like they were suffering from Vapor Lock.....

[RyanGT]

Bought it and so far hasn't got rid of that weird issue. It feels a little more stable so far though so i wont return it. And gives me one less thing that it could be...

[jivepepper]

Have your alternators out put checked it could be a low amp problem, and most parts places check for free.

[RyanGT]

Never had a problem with the alt though. Charges and keeps voltage high. Ill have to check it this week though! In car test or take the unit to a shucks?

[RyanGT]

Well it made a difference i jumped the gun. Im going to reset the computer and see if that helps. Driving it a little further it did it 10 times less! and when it did it recovered faster. Im detecting a slight misfire at times though... so im thinking of swapping plugs again.


Running the tr6's atm. What is a better plug? Some say autolite 103's? but they are comparable? im also running a BAS. Turned it up and it feels better. WOT it doesnt do it though so maybe its just the tune needing to be dialed in a bit further now with the right parts... Just thinking out loud. What do you guys think?

[jivepepper]

Originally Posted by RyanGT Well it made a difference i jumped the gun. Im going to reset the computer and see if that helps. Driving it a little further it did it 10 times less! and when it did it recovered faster. Im detecting a slight misfire at times though... so im thinking of swapping plugs again. Running the tr6's atm. What is a better plug? Some say autolite 103's? but they are comparable? im also running a BAS. Turned it up and it feels better. WOT it doesnt do it though so maybe its just the tune needing to be dialed in a bit further now with the right parts... Just thinking out loud. What do you guys think?

The more you explain it, the more I think your have a voltage/amp prob. I would at least go, and get it checked. If I'm wrong your not out of anything.

It sounds like your not making enough amps/volts and that's why the bas and the modified fpdm helped.

What I was getting was occasional slight miss while cruising and it would really act up sometimes and felt like it wouldn't take the gas. Then finally when the alternator went it would miss bad at wot and 4k+, But before that it only did the little miss at cruise and not wot.