03 pumps going bad?

[wjfawb0]

Last night my car began to stumble and died. It restarted and I got where I was going. Later, when I started the car again, the fuel pressure was running at 39-40psi under 18 vacuum all the way to 0 vacuum. It was running rich and got horrible gas mileage down the interstate for about 55 miles and then the pressure started working normally again. Pressure started running 30psi at idle to 39psi at 0 vacuum and then increased with boost after that. This morning car runs fine all the way to work (16miles of interstate). This afternoon the fuel pressure is running full time around 39-40psi again. Car starts stumbling after running for a while so I go to the ford dealership and get a new fuel rail pressure sensor (FRPS). I did this because the same symptoms happened last year and replacing the FRPS took care of it. Well, after the install the car still runs at 39-40psi fuel pressure and starts stumbling after warming up. I can't get my Xcal2 datalogger to work, so I can't get more info on what is going on.

Tonigt I start the car and drive it to the gas station. It is working normally. I get into boost and the pressure is working fine car is running great. Sure enough though, after about 10 minutes of constant running a random studder starts up. It appears the fuel pressure is dropping when the studder occurs. I can't be sure because it is an electric gauge with a full sweep needle. Hopefully I can get the datalogger to work tomorrow and find out more info.

Anyody seen this before or want to take a guess at the problem? At first I thought for sure it was the FRPS, but after replacing it the car ran the same as before. The FRPS that failed last year didn't rupture and let gas into the vacuum line. That was at 45,000 miles on the odometer. the car now has 58,000+ miles on it.

 

[Oh Three Cobra]

Thats weird. Sounds like the FRPS but you say it didn't fix the problem? Your fuel pressure also seams way high at idle.

 

[wjfawb0]

Thats weird. Sounds like the FRPS but you say it didn't fix the problem? Your fuel pressure also seams way high at idle.

That's the problem. Half the time when I start the car it runs at 40psi idle. The other half it runs normally around 30psi at idle, 40psi at 0 vacuum and up further when boosting. Either way, though, the car starts to stumble/studder violently after 10-15 minutes of driving. If I can get the Xcal2 datalogger to work, hopefully I can figure it out.

 

[postban]

I've gat a set of used pumps for sale in the market if you end up needing them. Hope you get it unfuxored

 

[wjfawb0]

Update:

I got a used FPDM from a return system converted Cobra, and now my car is running fine again (for the last two days at least). I am going to be upgrading the wiring and fuel lines in the near future to prepare for a new power adder (hopefully next year). I have to get a house and garage for the car first, though.
Thanks for the pumps, postban. I'll put them to good use eventually, I'm sure. :thumbsup:

 

[03SoCalCobra]

One of my FP's went bad a few months ago. Big time studdering/missing about 100 at WOT.

 

[wjfawb0]

UPDATE:

I believe I finally found out what was going on with the car actually. At the time I swapped FPDMs, I also removed my MAFXtender which was set to 0 anyway. I recently installed a new aluminum motor and also reinstalled the MAFXtender set to 1 (don't worry I changed the tune and dynoed for th eMAFX change). While swapping out the jumper for the actual MAFXtender I noticed that the red power wire was frayed and broken off from the MAFXtender where the hermetic sealing material is inside the plastic body. This intermittent power connection is likely what cause my problems. I resoldered the connection and installed it and the car runs fine. Previously the MAFX was hangin out from the carpet and a passenger probably stomped on the MAFX or played kick the vital electronics. My bad for leaving it out in the open. :bash:

The fuel pressure fluctuation seems to have been from my IAT1 sensor or air temperature sensor right after the MAF. When I finally got my XCAL2 datalogger I found that the temperature at startup was often a random number that never changed while running the car. If the temp at startup read 188*F the car would run 50psi delta drop across the injectors thinking it was hot as heck outside. If the car started and the sensor read 72* it ran the normal 39psi delta. I replaced the IAT1 sensor and now when datalogging the air temp from intake reads about ambient and fluctuates when I get goin down the highway or rev the engine. Good times. Boost/vacuum, fuel pressure gauges, dataloggers and dynos make diagnosis a lot easier than replacing sensors until it works right. :thumbsup:

 

[supercobra506]

i got some bad gas and mine was doing that till i filled up again.