Fuel System upgrade ??

[halflife]

I just bought a cobra and it has a fuel issue. It has stock pumps with a BAP so the pprv valve is still in there. From searches it seems that is the issue based on what is going on. Fuel pressure drops during shift under mid-hard acceleration. So if I have to drop the tank I might as well upgrade. I was thinking Ford GT pumps. I talked with the shop that is going to tune the car and they said they just do Gt pumps and rewire the fpmd with a thicker gauge wire and it is fine. I see you can do a upgraded fpmd on lethals site and then they also have the dual fpmd similar to the gt 500.
My car has a whipple, running 17lbs on pump gas. I dont forsee really uping that much as it is allot more then i am used to and the car is very streetable which is what i need. I would like to keep stock lines/rails for now and maybe upgrade in the future. also any benefit to the Fore hat if I am not going to upgrade the lines now?
Thanks

 

[evil 03]

Yes u need Gt pumps your in luck I got a set right here for $150 shipped to your door I had them in my cobra but went to a stand alone set up

 

[halflife]

yeah I know i need the GT pumps, more concerned about what to do with the FPMd
1. upgrade wiring and leave stock fpmd
2. get upgraded fpmd from lethal
Zone 5 Performance 99-04 GT/Mach-1/Cobra STAGE 2 Modified FPDM [LP-STG2MODIFIEDFPDM] : Lethal Performance, Performance parts for Ford Mustangs

3. get twin fpmd kit from lethal(or is this an overkill for my set up)
Lethal Performance Dual FPDM Wire Harness Kit [LP-DUALFPDMKIT] : Lethal Performance, Performance parts for Ford Mustangs

thanks for the offer but i am going to buy new. glws

 

[evil 03]

I never change my fpdm I know a lot of people still running stock fpdm

 

[halflife]

so you are running GT pumps with no other changes? I have 60lb injectors too, not sure if that effects it....thanks

 

[broke7]

If you run GT pumps and a BAP, you will need an upgraded fpdm, as the GT pumps draw considerably more amp's, and will soak the fpdm, and overload it, and eventually burn it up. It would be safe bet if your running just the GT pumps and no BAP to get a modded fpdm also.

Whipple @ 17psi DOES NOT and SHOULD NOT require GT pumps. You are not making the power to require the pumps. BAP, 60, stock line, and stock pumps with PPRV delete will support 600-640whp depending on the vehicle.

In your case I would delete the PPRV, get the lethal BAP rewire kit, keep the stock pumps and if you still dont have the fuel (which you should have plenty) rewire the pumps with a large wire off the fpdm.

For reference. I ran stock pumps, with a BAP, stock hat assy, with PPRV delete, homeade -8 line kit,stage 2 fpdm, lethal BAP wiring kit, and 60's. This combo support 676 SAE on a 2.8H @ 24psi. It maxed the pumps at 6100rpm. I just swapped to GT pumps and now im at 81% duty cycle. Im actually gonna yank the -8 line off the car and go back to stock line.

I see way to many people dropping money on fuel systems, or have done incorrect research and going overkill when the stock stuff does a good job, save yourself some time and money and work with what you have.

 

[halflife]

thanks for the advice. i was just thinking of upgrading the pumps since i have to drop the tank anyway for the pprv delete. pain in the ass job so might as well knock it out in one shot.

 

[JB]

I see way to many people dropping money on fuel systems, or have done incorrect research and going overkill when the stock stuff does a good job, save yourself some time and money and work with what you have.

+1

Take it from the man, as he knows these cars better than most :rockon:

And if you're going with GT pumps, do it right and do FPDM upgrade

 

[broke7]

thanks for the advice. i was just thinking of upgrading the pumps since i have to drop the tank anyway for the pprv delete. pain in the ass job so might as well knock it out in one shot.

unless your car is bucking like a bronco inbetween shifts, dont bother yanking the pprv.


I would datalog rail pressure, it should maintain 38psi +/- 2psi all the way thru the rpm, unless its dropping pressure in the upper rpm's your pumps are fine. You will also be able to correspond this with fuel pump duty cycle as well...when pumps max, your rail pressure will start to fall from the 38psi mentioned above.

Your pressure is supposed to fluctuate between shifts, its the natural state of behavior of the returnless fuel system, it will spike then drop once you let off the throttle.


Again, 17psi whipple will not max the fuel system with a BAP and 60's.

 

[halflife]

thanks for the input. Yeah it scared the crap out of me because when i shifted my fuel pressure guage dropped to zero for a second. The guage reads about 24 at idle and about 40 plus under accelration. guess it is time to learn how to datalog on my tune. the car does buck for a second when i shift under medium-hard acceleration. it only does it though when i take my time switching gears. if the foot is the floor and I bang through the gear it is ok and does not drop.

 

[FlaSeaDude]

When I installed my GT pumps, I also installed a dual FPDM setup with heavier wiring. I love the setup and I have no fears of overloading the stock FPDM...:beer:

 

[blackvenom77]

.Im actually gonna yank the -8 line off the car and go back to stock line.

Could you please explain why you are doing this? You already have the 8 line installed, why go back?

 

[halflife]

well i ordered the pprv delete and bap rewire kit. thanks everyone for the advice, hopefully this will fix it!