Help with P0193 after fuel pump install

[LEATHAL VENOM]

2003 Cobra - car shut off while driving the other day and after inspection found power at the pumps but no fuel pressure - order new Deatschwerks 340 lph pumps and a PPRV delete kit, after the pumps came in and the tank was dropped I found the fuel line was corroded and that was the problem but I had the new pumps so I put those in anyways. The car started and idled fine but would not go into boost at all, just cut out at 4,000rpms and I got a P0191 DTC for fuel rail pressure sensor range performance - I removed those pumps thinking they were too much flow for my setup and installed the factory flow rated fuel pumps which actually came with PPRV delete built in (Carter complete fuel pump hanger Part# P76130S) - I also changed out the fuel filter (motorcraft). Now I am getting a P0193 fault for fuel rail pressure sensor "a" circuit high. I replaced the fuel rail pressure sensor thinking it may have been damaged from the higher flow pumps but the code is still present, the code is actually there even with key on engine off. The sensor is getting 5v power, 5v signal, 0v ground. Frps shows 2.8v while engine idling. I am getting 39 psi on scanner and 29psi with mechanical gauge on fuel rail at idle as I should when its not acting up. Fuel pressure shoots to 60 and the voltage spikes to 5.1 after idling for a while and engine starts to run rough. I have driven it to monitor fuel pressure and performance and after driving around for 5-10mins the scanner shows a dip to as low as 18 and as high as 60 but it does seem to recover to 38-39 quickly and hasn't stalled but it won't always go into boost, I can get 14-15psi when leaning into it for a gear or two but then I will try to make another quick pull and boost gauge only pulls up to about 3psi. I don't want to keep driving it as it is clearly not good and don't want to hurt anything. I have checked for a vacuum leak but can't detect anything, I have wiggled the wires for the frps and other engine sensors with engine running but nothing changes, there is 5volts at the pin in the pcm for the frps. Hoping someone has heard of this problem before or can point me in the right direction.

Below are the mods on the car:

2003 Cobra
Stieg Stage 6 Ported Eaton
KB Boost a Pump wired pre-fpdm
MAF Extender
2.93 upper / 4# Lower
3.2" Alt Pulley
NGK TR6 gapped at 0.032
JLT RAI
MRT High Flow Cats

 

[Roush6018]

fuel pressure circuit A too high is your code. the pcm needs to see that sensor to determine the fuel pressure. you should be able to test the output voltage of the sensor at the connector on the fuel rail, compare that reading to the same wire at the connector for the pcm, for the fuel pressure circuit A. if there is a voltage reading at the sensor and you can not get the same reading at the PCM, there is a problem with the wire making the trip through the wiring harness.

i did have a problem with my stock (cheap) alternator causing my fuel pressure to drop on a dyno pull with no check engine lights . now i run a J2 alternator from lethal perf.

i think your fuel pressure should be 50-55 psi at idle warm engine. and during a pull it will drop but not much maybe 5-10 psi loss.

 

[01yellercobra]

Stock pressure is 39psi. 29psi at idle on a mechanical gauge is good. Have you logged FPDC? I'm curious what the ECU is making the pumps do when it starts acting up.

 

[LEATHAL VENOM]

No I havn’t, I will look for that on the scanner and see if I can monitor it. I ordered a new FPDM yesterday thinking it may be damaged from age or just from the boost a pump over working it for the last 12 years, I am skeptical that it is the problem as I am getting 17.35 at the pumps but maybe under load the FPDM is screwing up. Thanks for the suggestion.

 

[01yellercobra]

I would bypass the BAP before switching out the FPDM. Those are known to randomly start acting weird.

 

[LEATHAL VENOM]

The FPDM is just plug and play so I will try that first, if the light is still on I will bypass the BAP to rule it out.

 

[LEATHAL VENOM]

Still struggling with code P0193 - I've replaced the Fuel Pump Driver Module and the same code comes up P0193 - when I turn the key on with engine off I get 5.1v at frps and I'm getting 17.35v at the fuel pump which seems wrong to me, I think the Boost-A-Pump is designed to ramp up voltage not supply max voltage right away. If I start the car the voltage at the frps remains at 5.1v until I crack the throttle and then it settles down to 2.8ish, the fuel pressure seems good on the scanner at 39psi but the service engine light remains on.

If I bypass the Boost-A Pump so its running on the factory setup I am getting 4.8v at the frps with the key on engine off and 60psi on the scanner, when I start the engine the frps voltage drops to around 2.7v and fuel pressure sits around 39psi on the scanner. I know I can't run the car on this setup as the car needs more fuel than the factory pumps can provide under heavy acceleration which is why I have the boost-a-pump in the first place.

I am thinking the boost a pump is the problem however I was hoping for someone to chime in just incase I am missing something. I don't think the PCM or wiring could be the issue if the light goes out with the factory setup and the voltages go back into line. I'm not sure if it is possible that the tune somehow has been compromised and causing this issue but it would mean the tune is only bad when the boost-a-pump is hooked up which doesn't make sense to me either.

I'm out of idea's, any thoughts before I pull the trigger on a new Boost-A-Pump?

 

[01yellercobra]

It depends on how the BAP is set up. If it's wired pre FPDM without a Hobbs switch it's going to give the full 100% all the time.

You can drive the car part throttle without the BAP installed. If it comes down to it, I would get upgraded pumps over another BAP.

 

[MG0h3]

If I’m reading this right, you got max fuel pressure at idle with the BAP hooked up.

If it doesn’t happen with the BAP bypassed, I think you’ve found the problem.


Sent from my iPhone using svtperformance.com

 

[LEATHAL VENOM]

BAP was installed 12 years ago and it was wired pre-FPDM without the hobbs switch and no dial is in the car to adjust. Is it suppose to have 17.35v going to the pumps at idle or is the BAP suppose to ramp up voltage as the car goes into boost?

 

[01yellercobra]

It depends on how the BAP is set up. If it's wired pre FPDM without a Hobbs switch it's going to give the full 100% all the time.

BAP was installed 12 years ago and it was wired pre-FPDM without the hobbs switch and no dial is in the car to adjust. Is it suppose to have 17.35v going to the pumps at idle or is the BAP suppose to ramp up voltage as the car goes into boost?

Pretty sure I already answered that question.

 

[LEATHAL VENOM]

01yellercobra - If the voltage is right at the pumps with the way the BAP is wired and the only thing I’m doing different is removing the BAP from the system and the check engine light goes out and the voltage readings go to normal ranges for the fuel rail pressure sensor what else should I be checking if it isn’t the boost a pump. The only thing that is different between before this problem happened and now is that the PPRV was deleted, not sure that would cause this condition.

 

[03' White Snake]

You tried running the new 340 pumps with the BAP?? Probably damaged the FRPS. I had an issue with a BAP and stock pumps popping the FRPS just turning the key on. Was sending too much pressure to the rail. Removed BAP and replaced sensor, all better. I then upgraded to GT pumps, no BAP.

Remove the BAP, replace pumps with GT pumps and dual FPDM’s or Black306 modified FPDM. A single stock FPDM cannot drive both GT pumps.

 

[01yellercobra]

01yellercobra - If the voltage is right at the pumps with the way the BAP is wired and the only thing I’m doing different is removing the BAP from the system and the check engine light goes out and the voltage readings go to normal ranges for the fuel rail pressure sensor what else should I be checking if it isn’t the boost a pump. The only thing that is different between before this problem happened and now is that the PPRV was deleted, not sure that would cause this condition.

If everything works fine when you take off the BAP I think you found your issue. The whole point of the BAP is it raised the available voltage to the pumps. People wired them pre FPDM to the voltage is always there and the FPDM can regulate it.

If it was working fine before the PPRV delete then either something happened to the wiring or it's a coincidence. Which has been known to happen when working on cars.

FWIW, I ran the old style GT pumps on a stock FPDM for years with no problem. I did have a wire upgrade at the time though. But as mentioned, if you have the 340 pumps installed then remove the BAP. You don't need both.