Ms6 fuel rail pressure loss past 5000rpm

[Enki]

Corksport, local hardware store.

 

[Rogi]

another update, i did swap the x-ring with an old one. here are the datalogs, it is definitely hpfp related, not sure if i maybe installed the parts wrong when rebuilding the pump or what. am going to take it all apart tomorrow and re do it. @Enki do you have a good write up on the rebuild procedure by chance? i followed corksport how to video for reference last time

 

[Rogi]

Corksport, local hardware store.

i will check at local hardware store, the reys kit i purchased through graveyard, am going to contact them on monday aswell, hopefully they can work with me on a new one.

 

[Enki]

Corksport has you do too much. Focus on the internals and spill valve, clean them with napththa, lubricate and prime with redline injector cleaner. I think theres another thread around here somewheres that covers most of this.

 

[Rogi]

Corksport has you do too much. Focus on the internals and spill valve, clean them with napththa, lubricate and prime with redline injector cleaner. I think theres another thread around here somewheres that covers most of this.

noted, i will take the hpfp apart tomorrow and double check my work. i saw the thread about the rebuild but noticed that the orientation of the pieces for the damper is different than what corksport mentioned on their video. from the forum it shows :
Washer with Lip "lip goes away from pump'
Washer
Pancake
Spring


but on the corksport video it is
Washer with Lip "lip goes away from pump'
Pancake
washer
Spring

any insight on which is the correct order?

 

[Enki]

Doesn't matter, that's not a moving part and doesn't need to be removed, pretty much ever.

 

[Rogi]

Doesn't matter, that's not a moving part and doesn't need to be removed, pretty much ever.

okay yea i did too much then when rebuilding the pump the first time. i took everything apart like the corksport video showed. i know you said earlier on this thread that you had an issue before with the internals not retracting via spring force fast enough for a full stroke. what was the cause in your instance?

 

[Enki]

Piston was sticking forward. I can't remember if it was an issue with the internals themselves or something else, but I've probably seen most of the issues that you can have with the HPFP.

Also, don't forget to put that spring puck back in if you take it out; pretty sure if you leave it out your fuel system will get damaged.

 

[Rogi]

update - i took the hpfp apart again, followed the rebuild procedure from a thread on here. everything seemed fine. i did read on the thread that the seal screw should be tightened down to 30ish ft lb rather than 40ft lb which is what the corksport instructions say. i tightened it down to 30ft lb and put it back in the car. here are some data logs afterwards. datalog 1 showed great fuel pressure with no loss, got up to 6400rpm. second log shows fuel pressure still good but toward the end of the pull, it looks like the fuel pressure was starting to go down, still above 1600psi though. 3rd log shows that the fuel pressure begins to drop again from 5800rpm to 6500rpm and it gets down to 1100ish psi. i am now debating if i should just pull the trigger on another hpfp, only thing that makes sense to me is that the redline fuel injector i used to prime the pump with got fully diluted by the 3rd log and something internally is getting stuck up again.

 

[Enki]

If by seal screw you mean the retaining nut for the internals, I always go hand tight then give it a slap with my hand to seat it. It can't really go anywhere and it's never backed off on me, so I don't sweat it too much.

Honestly if you did everything by the book, it shouldn't be the internals; might be the fuel filter or ITFP or hell, even the reg. With the engine super hot, can you do another KOEO PRV test?

 

[Rogi]

If by seal screw you mean the retaining nut for the internals, I always go hand tight then give it a slap with my hand to seat it. It can't really go anywhere and it's never backed off on me, so I don't sweat it too much.

Honestly if you did everything by the book, it shouldn't be the internals; might be the fuel filter or ITFP or hell, even the reg. With the engine super hot, can you do another KOEO PRV test?

this is what im referring to as to the seal screw, corksport says 40 ft lb, i did 30 ft lb on it this time. and will do the KOEO PRV test and report back

 

[Enki]

Arguing semantics here but its less of a screw/fastener and more of a retention nut. I probably put 10-15 ft-lbs on by hand, so don't sweat that too much.

 

[Rogi]

here are some logs of KOEO fprv test. Pressure climbs up slowly but then kind of stalls at around 1760psi, sat there for a good bit and it wouldn't really climb up or go down. i did rev the engine and shut it off so it builds up higher pressure from the get go. did get a check engine light p0335 for crankshaft position circuit A sensor and U2023 for my keyless entry. i think that is more to do with the fact of shutting the car off immediately after revving the engine, i cleared the codes and repeated the same procedure of shutting off the car right after revving the engine, those codes came right back up. I know that the fprv should crack open at 1850ish psi but am curious if my return style fuel setup would affect the fprv build up pressure?

 

[Enki]

Return shouldn't matter unless it's causing the pressure/flow to the HPFP to drop off.

 

[Rogi]

Return shouldn't matter unless it's causing the pressure/flow to the HPFP to drop off.

is it normal for the pressure to build up very slowly? Am trying to figure out if I need to further look into my fprv. Am going to swap it out with my old one tomorrow just to see if there is any difference

 

[Enki]

If the engine (and in this case the fuel rail/injectors) isn't/aren't hot enough, yes.

 

[Rogi]

update- installed my old prv and did the KOEO test, here is the data log. opened up at 1800ish psi. I have a new ITFP arriving tomorrow. Am going to hook up a mechanical gauge to my fuel pressure regulator and get a good reading while driving before swapping the ITFP. Am also going to pressurize the whole fuel system KOEO, turn the fuel pressure to 80psi and see if there are any leaks. only things that have not been swapped out at this point are the ITFP and fuel pressure regulator.

 

[Enki]

Did you swap out the fuel filter sock?

 

[Easter Bunny]

If your pulling the itfp you should change the filter sock too

 

[Rogi]

Did you swap out the fuel filter sock?

Yes I replaced the filter sock with a 3x15” hydramat