Is my HPFP dying?

[Onaginata]

So recently my ST started to bog down like it had ran out of fuel and then died. I started the car back up and it ran fine. After driving it for a couple of days to and from work, i've noticed this starts to happen after driving for about 20 minutes and eventually will happen continually. When it gets bad, I can restart the car and drive for 30 seconds to a minute before it happens again.

I set up my accessport with FRP actual and lowside FP to monitor what's going on. When the car starts to die, the FRP actual drops to around 60-70psi. The lowside FP has held a constant 108.9 or 109 psi. Additionally, the ECU has thrown these two fault codes, P0087 (FRP too low) and P008B(low side FP too high). Considering this, I did a bit of research and figured that the lowside fuel pressure sensor was bad and I'd need to replace it, so I ordered another one. While waiting for the lowside pressure sensor to arrive, the lowside pressure started changing it's reading. It will now read between 90-105psi and will occasionally ago back to 108.9/109psi. This makes me think that something else is going on too.

What do you guys think, is my HPFP going bad? It seems like both my HPFP and the lowside pressure sensor need to be replaced. I've been looking for an excuse to buy the XDI HPFP and the uprated injectors, but I want another opinion before I move forward.

Funny how it works out sometimes, but the fuel issue started right after I ordered my S280 kit which is set to arrive today lmao....

Mods:
Full Cobb Stage 3 package
Cobb OTS 93 octane Stage 3 tune

thanks,

 

[JDG]

What is the Lowside Fuel Pressure Voltage being sent to the LPFP when it is reading ~108psig? Sounds like you are on the right track with the sensor upstream of the HPFP.

What mileage is on your car?

 

[Onaginata]

What is the Lowside Fuel Pressure Voltage being sent to the LPFP when it is reading ~108psig? Sounds like you are on the right track with the sensor upstream of the HPFP.

What mileage is on your car?

I will check the voltage this evening when I get back home. My car is at ~70,000 miles. Not sure if I made it clear, but the lowside pressure never read below 90PSI even when the FRP had dropped.

 

[Onaginata]

What is the Lowside Fuel Pressure Voltage being sent to the LPFP when it is reading ~108psig? Sounds like you are on the right track with the sensor upstream of the HPFP.

What mileage is on your car?

Okay, so thank you for the suggestion. I ended up not needing to test the voltage as the sensor arrived yesterday afternoon. After installing and clearing the fault codes, the engine ran great. The lowside FP was back down to the 60-90psi range and appeared to be reading correctly again. The fault codes did not come back and after driving around for about a half hour, the HPFP hadn't lost pressure again.

It's strange that the lowside FP sensor would cause the HPFP to lose pressure, but i guess the ECU might not know what to do with the lowside pump if it doesn't get an accurate pressure signal. My guess is that the lowside pump was being shut off due to the pressure too high fault and that was starving the HPFP. That or the HPFP was being shut down by the ECU if that's possible.

Thanks for the help!

 

[M-Sport fan]

How much was that sensor, and how much of a pain was it to swap out the bad one, and install the good one?

(I am thinking about getting one even before I need it, and keeping it in the car along with a fuel pump relay, to try and prevent getting stuck anywhere because of either of those going bad on me.)

 

[Onaginata]

How much was that sensor, and how much of a pain was it to swap out the bad one, and install the good one?

(I am thinking about getting one even before I need it, and keeping it in the car along with a fuel pump relay, to try and prevent getting stuck anywhere because of either of those going bad on me.)

The sensor was $63.99 from Summit Racing. You could probably find it a bit cheaper elsewhere, but you can't beat the reliability of a vendor like Summit.

Replacing it was super easy. It screws into a block on the fuel supply line that leads to the HPFP and is under and behind your intake crossover pipe. It can be removed and replaced without taking anything off, but since I was about to install my S280, I went ahead and removed the headlights, wipers and cowling at the base of the windshield. Even removing all of that stuff, it would be a 20 min job tops.

Here's a link to the sensor.
https://www.summitracing.com/parts/mof-cm5250

 

[M-Sport fan]

^^^THANKS!!

Yes, Summit is where I bought my Method MR501VT wheels, as they had the very last set in existence for our rides (or even that would ever be made for them), and they even worked with me on the price, matching vendors who did not even have any left!

 

[felopr]

So recently my ST started to bog down like it had ran out of fuel and then died. I started the car back up and it ran fine. After driving it for a couple of days to and from work, i've noticed this starts to happen after driving for about 20 minutes and eventually will happen continually. When it gets bad, I can restart the car and drive for 30 seconds to a minute before it happens again.

I set up my accessport with FRP actual and lowside FP to monitor what's going on. When the car starts to die, the FRP actual drops to around 60-70psi. The lowside FP has held a constant 108.9 or 109 psi. Additionally, the ECU has thrown these two fault codes, P0087 (FRP too low) and P008B(low side FP too high). Considering this, I did a bit of research and figured that the lowside fuel pressure sensor was bad and I'd need to replace it, so I ordered another one. While waiting for the lowside pressure sensor to arrive, the lowside pressure started changing it's reading. It will now read between 90-105psi and will occasionally ago back to 108.9/109psi. This makes me think that something else is going on too.

What do you guys think, is my HPFP going bad? It seems like both my HPFP and the lowside pressure sensor need to be replaced. I've been looking for an excuse to buy the XDI HPFP and the uprated injectors, but I want another opinion before I move forward.

Funny how it works out sometimes, but the fuel issue started right after I ordered my S280 kit which is set to arrive today lmao....

Mods:
Full Cobb Stage 3 package
Cobb OTS 93 octane Stage 3 tune

thanks,

Sounds like a bad lowside fuel pressure sensor
just monitor low side fuel pressure and high side fuel pressure for a couple of days and see if anything is out of the ordinary
hpfp pressure at idle is around 600-700psi
low side is around 60-70ish psi
When you give it the beams, hpfp can go up to 2900ish psi and low side can go up to 100ish
both readings shall go up and down in a predictable manner, If you see any spikes or numbers being still, is a sign that that sensor is going bad

https://www.rockauto.com/en/catalog...uel+&+air,fuel+injection+pressure+sensor,6376
CM5250 = low side sensor
CM5225 = high pressure sensor

high side sensor location:


low side sensor location

 

[Onaginata]

Sounds like a bad lowside fuel pressure sensor
just monitor low side fuel pressure and high side fuel pressure for a couple of days and see if anything is out of the ordinary
hpfp pressure at idle is around 600-700psi
low side is around 60-70ish psi
When you give it the beams, hpfp can go up to 2900ish psi and low side can go up to 100ish
both readings shall go up and down in a predictable manner, If you see any spikes or numbers being still, is a sign that that sensor is going bad

https://www.rockauto.com/en/catalog...uel+&+air,fuel+injection+pressure+sensor,6376
CM5250 = low side sensor
CM5225 = high pressure sensor

high side sensor location:
View attachment 39042

low side sensor location
View attachment 39043

Thank you for the detailed response. The lowside FP sensor ended up fixing it!