Urgent help needed with FRPS sensor

[dutch]

Ok, so the bullitt left me stranded last week. Started bucking after a long drive to finally die on an intersection. Felt like a fuel problem and pulled codes P0190 and P0193, so I ordered a new fuel pump and rail pressure sensor.



Stupidly, the next day the car starts and runs fine (didnt leave garage). Figured I'd hook the laptop on and see whats happening. Everything looked fine until after 60min of idling and reving, I stabbed the throttle and saw the FRPS peg 90psi in milliseconds. Which scares the PCM, who drops FP duty cycle. At first this happens just with a small WOT jab and it regains itself fast. After a while, it goes bezerk trying to compensate for silly signals from the FRPS (10psi followed by 90psi) and it gets stuck in a loop with the fuelpump.



So at this point I was sure that the sensor was wonky and swapped my new one in.. same problem, engine was still hot enough and it just kept on going nuts. If I pull the FPRS plug it defaults to 40psi in the PCM and it calms down, so the fuelpump is just down as its told by the PCM.



I'm stumped now, I measerud the FPRS plug, perfect 5v on signal and vref KOEO. Wiggled the plug and entire harness with engine running and eye on laptop, nothing. So no obvious wire shorts.



Datalogging today I also gained DTC's for the speedsensor in the trans (sitting in garage, revving) and the odometer went to - - - - - - -.



So I'm guessing something is wrong in PCM wiring, but so far I can't really see anything wrong. What stumpes me is why this gets worse as the car get warmer, but in the first hour or so it generally behaves unless I really provoke it with WOT revs. After the first hour, almost every rev causes the sensor to shoot to 90psi.



Included a photo of the FRPS data and FP duty cycle. As you can see, it works for a little bit and then the signal goes bezerk.

 

[95opal]

All dashs means the PCM isnt communicating with the cluster or any one of the CAN BUS items in the car. I would assume bad PCM or cluster.

 

[07GtS197]

Could also be a failing ccrm as well. I’d be more inclined to say it’s that than a failing ecu.

 

[dutch]

I thought about the CCRM, but fuelpump, AC and fans are all working correctly and Ive never lost comms with the ECU while datalogging for hours the past week.

It seems somehow the wiring in the FRPS is overloaded when I go WOT and it starts to get overloaded more often and heavily the longer the car runs.

 

[cobrajeff96]

I'm more of a 1st gen SN95 guy so I'm not too sure about New Edge things. But have you looked at the MAF yet?

 

[07GtS197]

Still, with the dashes showing up on the dash that’s a classic sign of ccrm issues. The relay for the fuel pump could have a cracked solder joint causing intermittent fueling issues.

 

[cobrajeff96]

Could be that the relay is just so worn that the inner armature is making poor contact and arcing inside. I'm pretty sure the relays inside are not solid state variety. It's easy to swap in a known good CCRM. That's like a 30m job.

 

[07GtS197]

I’m pretty sure all automotive relays are solid state. The ccrm uses a four pin relay but I’m pretty sure it’s pretty much the same thing as a regular automotive relay otherwise. It’s been a while since I fixed a ccrm.

 

[cobrajeff96]

Not very common back then, actually. Certain components were, most not (attached).

 

[07GtS197]

I was under the impression a solid state relay was the regular electro mechanical automotive relay but even google has it wrong. I see it now.

 

[dutch]

I will check the CCRM, but I dont think its at fault. As far as I can see, the fuelpump is doing as told bij de PCM, because the PCM is seeing silly number from the FRPS. I will verify with a mechanical gauge, but I dont think the real fuelpressure is speaking from 10 to 90psi in milliseconds.

 

[96blak54]

Them stock Ford FRPS are failure prone. Do yourself a favor and swap it out with something other than motorcraft

 

[dutch]

First thing I tried was swapping in a new Standard Motor Products FRPS. Acts the same, sadly.

 

[cobrajeff96]

Is there a fuel pulsation damper like in the older SN95s?

 

[cobrajeff96]

I was under the impression a solid state relay was the regular electro mechanical automotive relay but even google has it wrong. I see it now.

SS relays have no moving parts, they're pretty much just transistor logic. They last a really long time.

 

[dutch]

Is there a fuel pulsation damper like in the older SN95s?

Yes, the chrome UFO thing?

 

[cobrajeff96]

Yea