Fuel Pressure Relief Valve Question

[twintzs]

How do you determine if the Fuel Pressure Relief Valve is bad? I'm having fuel pressure drop in the 2500 to 4200 rpm range but then will hit targeted hpfp.

I've searched and it seems the only way to test is to read the ap fuel pressure after car is off. I get 500 psi and it increases slightly. Then another time I have the fuel pressure drop below 60 with car off.

Is there a How to on replacing this part?

Thanks in advance.

[mrmonk7663]

HOW-TO: Replace Relief Valve (RV)

The test you performed is the reccomended test. I am diagnosing this issue with a buddy's car now. Sometimes fuel pressure shits the bed, sometimes it holds strong. My car with key on engine off drops pressure real low...it does not build...but my fuel pressure with car on is spot on. Weird.

[twintzs]

Well I got the 2150 upgrade garage fuel relief and no change. Pressure still drops between 3k and 4k rpm. Now what. I can't just keep throwing money at everything. Please help.

[EdgeAutosport.com]

Is the fuel pressure failing at peak load?


my guess is internals

[G26]

If its dropping at peak load, around 2.0 +, then your internals are bad.

[mrmonk7663]

If not at peak load, then possible it is your in tank filter clogged up?

[EdgeAutosport.com]

Or spill valve, post logs op!

This thread is useless without a log

[twintzs]

I apologize. Here is a log from a day ago.

[G26]

Originally Posted by twintzs I apologize. Here is a log from a day ago.

What internals do you have? That looks like the kmd drop fuel psi at max load syndrome lol.

[twintzs]

Yes I have the KMD internals. This log was taken in 4th gear at 2500 RPM to 6500 rpm.

[leon78]

Your "Actual" is great. (HPFP Act. Press. (PSI) vs HPFP Des. Press. (PSI))...but the desired is dropping off? You can leave it so your commanding 1749 across the RPM range.... the Fuel Pressure Relief Valve is still giving you over 2000 psi NP. And peak load is happening 3000 rpm prior to the strange drop off? I'm curious as to whats going on...subbed.

[twintzs]

I have a dyno session set for tomorrow morning should I cancel it based on the log?

[G26]

Originally Posted by leon78 Your "Actual" is great. (HPFP Act. Press. (PSI) vs HPFP Des. Press. (PSI))...but the desired is dropping off? You can leave it so your commanding 1749 across the RPM range.... the Fuel Pressure Relief Valve is still giving you over 2000 psi NP. And peak load is happening 3000 rpm prior to the strange drop off? I'm curious as to whats going on...subbed.

His desired is staying at 1749, its his actual that is dropping around 2.15 load.

[leon78]

Originally Posted by G26 His desired is staying at 1749, its his actual that is dropping around 2.15 load.

Ahh, thanks....I looked over that dip where it goes down to 1350ish cuz it jumps right back up just fine. Why does the Calculated Load effect the mechanics of the HPFP (KMD wise) ?, electric signal says time for fuel cut?

[G26]

Originally Posted by leon78 Ahh, thanks....I looked over that dip where it goes down to 1350ish cuz it jumps right back up just fine. Why does the Calculated Load effect the mechanics of the HPFP (KMD wise) ?, electric signal says time for fuel cut?

Because load is effectively torque. At max torque fueling demands are the greatest.

[twintzs]

I removed the internals last week and inspected them. I wasnt sure what I was looking for but I did take some pictures.

[twintzs]

I'm concerned about the dyno session should I not go? I dont know how bad this is.

[GLORIFIEDBOZO]

Pretty sure this isn't bad internals, it looks more like some sort of fuel cut to me. Are you running the HPRV in this log? Who is tuning you? @phate may have a little more insight on this.

[twintzs]

here is the log with the upgraded hpfp relief valve. Boost_Creep has been tuning me great guy he thinks it maybe internals but can find anyone local to switch out with to test.

[GLORIFIEDBOZO]

Originally Posted by twintzs here is the log with the upgraded hpfp relief valve. Boost_Creep has been tuning me great guy he thinks it maybe internals but can find anyone local to switch out with to test.

This opened to jiberish for me, and I am not excel smart enough to unjiberish it

[mrmonk7663]

Same..the log is in the wrong format in excel...can't read it.

[phate]

Originally Posted by twintzs here is the log with the upgraded hpfp relief valve. Boost_Creep has been tuning me great guy he thinks it maybe internals but can find anyone local to switch out with to test.

I've pulled some failing KMD's to find they looked perfect. That pressure drop looks like internals, rather than a relief valve issue.

@Boost_creep

PS - The data log he posted just needs to be parsed by using the "Text To" function in Excel.

[twintzs]

well, I just took off the spill valve and it looked perfect. No gunk or anything not that I was running E85. I only us 93.

Originally Posted by phate I've pulled some failing KMD's to find they looked perfect. That pressure drop looks like internals, rather than a relief valve issue. @Boost_creep PS - The data log he posted just needs to be parsed by using the "Text To" function in Excel.

@phate

Any way to test the internals? I just bought the upgraded relief valve and dont have the money to drop another $300+.

[G26]

Originally Posted by twintzs well, I just took off the spill valve and it looked perfect. No gunk or anything not that I was running E85. I only us 93. @phate Any way to test the internals? I just bought the upgraded relief valve and dont have the money to drop another $300+.

Put your stock ones back in.

[Boost_creep]

Originally Posted by twintzs well, I just took off the spill valve and it looked perfect. No gunk or anything not that I was running E85. I only us 93. @phate Any way to test the internals? I just bought the upgraded relief valve and dont have the money to drop another $300+.

Brian,

If you still have your warranty card, kmd should replace them for you. I personally have not had to go down that road, but it appears others have.

Did you call kmd yet?

[twintzs]

Originally Posted by Boost_creep Brian, If you still have your warranty card, kmd should replace them for you. I personally have not had to go down that road, but it appears others have. Did you call kmd yet?

I talked to some guy who sounded like a prick. Kept calling me bro and just told me that it could be a number of things and he couldnt diagnosis over the phone. Based on searching it appears i need to talk to a Mara at KMD.

[G26]

Originally Posted by twintzs I talked to some guy who sounded like a prick. Kept calling me bro and just told me that it could be a number of things and he couldnt diagnosis over the phone. Based on searching it appears i need to talk to a Mara at KMD.

Tell them you know and they know this is a common problem caused by their bull shit.

[Boost_creep]

Originally Posted by twintzs I talked to some guy who sounded like a prick. Kept calling me bro and just told me that it could be a number of things and he couldnt diagnosis over the phone. Based on searching it appears i need to talk to a Mara at KMD.

Yes, Mara is very pleasant to deal with. I can look back and see if she has a direct email, but I think if you just send them a general email, she would be the one who replies. I'll take a look though.

Edit- ok, I just found it. mara@kmdtuning.com
Pretty self explanatory. Lol.

[EdgeAutosport.com]

Same thing happened to me, pulled my kmds and they looked fine. swapped spill valves with the kmds still in the pump and the problem went away for a couple pulls and came back.

I ended up putting in a new pump with AT internals and no problems since then but I still think my in tank is going out because even at wot my pressure dips to 1650.

[twintzs]

Originally Posted by eric@edgeautosport Same thing happened to me, pulled my kmds and they looked fine. swapped spill valves with the kmds still in the pump and the problem went away for a couple pulls and came back. I ended up putting in a new pump with AT internals and no problems since then but I still think my in tank is going out because even at wot my pressure dips to 1650.

Where is your pressure dropping to 1650 above the 4k range or below even with the AT internals?

[EdgeAutosport.com]

let me see if I can find some recent logs


Seems like pressure isnt dipping anymore so it looks like it was the pump/spill valve

[G26]

Autotechs ftw. 11k miles and counting.

[G26]

Btw, just had a local nator guy install his ptp fp internals, and his fp is dipping bad.

[mrmonk7663]

We have a local 3071 car that had PTP internals and had to ditch them for another option...They just wouldn't put the pressure out that was needed. DJ was tuning the car actually. The internals were an older batch though, so maybe they have changed.

Originally Posted by G26 Btw, just had a local nator guy install his ptp fp internals, and his fp is dipping bad.

[phate]

Internals are hit and miss, no matter which way you go. I've worked with several cars with PTP pumps that work great, as well as KMD, CPE, and AT.

[mrmonk7663]

Honestly, this is a rather unfortunate thing ...but yes it is true.

Originally Posted by phate Internals are hit and miss, no matter which way you go. I've worked with several cars with PTP pumps that work great, as well as KMD, CPE, and AT.

[twintzs]

Just a random thought could the low pressure be how I'm taking my logs. I get into 4th gear cruise until I get to 2500 RPMs then I hit the log button on the AP then I stomp on the gas to 6500/7000 rpm.

[mrmonk7663]

No.

Originally Posted by twintzs Just a random thought could the low pressure be how I'm taking my logs. I get into 4th gear cruise until I get to 2500 RPMs then I hit the log button on the AP then I stomp on the gas to 6500/7000 rpm.

[Ms3_Miami]

Originally Posted by G26 Btw, just had a local nator guy install his ptp fp internals, and his fp is dipping bad.

yup thats me..asked John at PTP for a refund and ordered AT fp internals from Edgeautosport . I know two guys on here that have the PTP fp internals for 30k miles on E85 without an issue

[mattydame]

Hi everyone. I have a 2011 Mazdaspeed 3. Until about 2 weeks ago everything was great. I was on my way home from work when all of a sudden I lost all power and my car started jerking violently and the throttle did nothing. The idle would almost stall but would keep running. I was able to make it home going on 10 mph. I checked my fuel pressure and it seems to be lower than normal. Does anyone know if the fuel pressure relief valve would cause this problem? Thanks