2003 Cobra stutter/fuel psi issue..

Hi guys, I have a 2003 Cobra that I have just purchased 2 weeks ago! Drove car home 2k miles with 0 issues. Well last week I found out the intercooler pump was not working, it would run and pull fine wot through gears but it sprayed coolant on windshield which lead me to stop driving car this last week until I got the pump! Well I got pump installed today and all went well with it circulating great, I ended up taking the car for a drive today and it would fall on its face and stutter after letting off throttle between shifts etc..while it does this I can actually watch fuel pressure drop to 0 then right back up to around 40. Any clue what could be the culprit of this? The battery light came on within 2 miles of home Aswell! Any possible way it’s related to a dying alternator? Or possibly a FRPS? Thanks a ton in advance guys!

A dying alternator could cause all kinds of issues. If you're getting the light I would have the alternator and battery tested. And plan on swapping the alternator soon.

Try replacing your fuel filter. Had a similar issue in an old mustang of mine

Thanks for the replies guys! I’m hoping it’s in correlation with the battery light coming on that it was wanting to cut out and such.. I ended ordering a alternator this morning and will put it in this week! I’m also going to replace the FRPS just to be on the safe side Aswell, I love the car so far just hoping it will get cleared up with a new alternator!

Hey guys! Got an update, I installed the alternator today and now battery light is off(alt was bad). Well the fuel issue/cutting out is still there! Then decide to go ahead and spend the money to buy a new frps and that didn’t seem to help either! I can sit with car out of gear and rev it and when I let out of throttle the fuel pressure will drop to 0 then come back up! Unplugged the vac line on frps and the psi drops to about 10, did this with both old and new frps. My question is where do I go from here? Is there a fuse or something that could affect one of/both the pumps? Possibly just a bad pump? Any help will be greatly appreciated! Thank you

Do some research on the "PPRV delete" and see if that might be causing your issue. Is the hesitation only happening after you let off while you're shifting in high RPMs or does it happen even if you shift while driving "normally?" It sounds like a similar issue but don't go dropping your fuel tank just yet.

EDIT: also, how many miles on the car? Fuel filter might be worth replacing if it's easy for you to get the car in air. Cheap assurance.

Thank you for the reply! The car currently has 95k miles, I will definitely check the fuel filter, it does it when letting off, between shifts, it will even do it when sitting in neutral and I give it a good revv, the fuel psi will drop to 0 then come back to roughly 20 at idle.

Peters211 said:

Thank you for the reply! The car currently has 95k miles, I will definitely check the fuel filter, it does it when letting off, between shifts, it will even do it when sitting in neutral and I give it a good revv, the fuel psi will drop to 0 then come back to roughly 20 at idle.

Click to expand...

It could be a "sticky" PPRV valve, a bad pump, the filter, tune related..... I'd start with the filter if I were you because it's cheap and relatively easy. At 95k miles it'd be recommended anyway most likely. Do you have a handheld (SCT or similar) or a way to check Fuel Pump Duty Cycle?

Do you know anything about the tune that is on the car?

https://www.svtperformance.com/threads/cobra-is-bogging-down-after-wot-pulls.1106518/

From a different thread:

"I had been having an issue with the fuel system that several guys in the area had been having. After WOT the fuel pressure would drop to about 10psi for a couple of seconds....

...Answers to some of the questions:

The fuel pressure problem turned out to be the 'Fuel Pressure Relief Valve’ (or whatever it is called) A device in the fuel line that bleeds pressure of the fuel line by dumping fuel back into the tank. The valve opens at 55pdi give or take… In a high boost setup, the fuel line can hit that pressure on a WOT pull. The valve dumps the gas, and pressure drops.

The Octane Booster was not Torco but was specifically made for performance cars in low octane states. Not the best, but probably not my biggest issue.

The ’48 valves’ were either me doing math while sleepy…. Or I have opted for the super secret 6 valve mod ;-)

And about 98% sure it was the fuel pressure issue above that did the damage…. "

https://www.svtperformance.com/threads/well…-i-blew-it-up….482473/page-2