Rail pressure surge.

Jonnydime · Dec 21, 2019

I have been having a rail pressure surge problem pretty much the entire time I have owned my Harley truck. It was most prevalent when the truck had a cp3 dual fueler and got substantially better with a duel k16 kit. It was still there but I just attributed it to the fact that I had ported fuel rails as well. Well over the past few weeks while the trans was out for converter work I swapped in some stock rails hoping that would solve the problem completely. I guessed wrong. So I’m down to the hpfp’s or the injectors. What is a solid way of isolating the hpfp’s so I can check if one of them is causing this issue and the other pump is masking the problem? I can’t easily remove the front pump since my atmospheric turbo is mounted to it. Will removing the belt let me run the truck long enough to check things out?

co04cobra · Dec 21, 2019

What tunes? I have dual K16s with ported rails and didn’t have rail surge for several years. I recently switched to sotf tunes and bad surge from the start. Once I got a tuning revision from a different tuner it seems to be back to no surge.

Jonnydime · Dec 21, 2019

I haven’t played with the tune yet so that could be the problem since I’m still running the last tune I wrote to try and solve the surge. I’ll try more tomorrow. It’s weird it was completely gone on my drive home but when I went out for another drive it was right back where it was.

White_monster · Dec 21, 2019

Reset the adaptive fuel tables

Jonnydime · Dec 22, 2019

White_monster said:
Reset the adaptive fuel tables

This is another thing I have thought about and haven’t done yet that I’m also going to try today.

Jonnydime · Dec 22, 2019

White_monster said:
Reset the adaptive fuel tables

I'm going to assume this is still an ids only thing since I can't find it anywhere on forscan?

co04cobra · Dec 22, 2019

Some of the latest updates on snap on scanners will do it also.

Jonnydime · Jan 2, 2020

If it matters it only does it above 188-190° oil temp and it’s like a switch.

White_monster · Jan 4, 2020

Hot fuel then. Put a cooler in up front

DEEZUZ · Jan 4, 2020

Yea but what's the fuel temp. Still have fuel cooler? Pump working?

Jonnydime · Jan 4, 2020

I don’t think it’s fuel temp since I never had these problems on the red truck which had no cooler and I do have a cooler on this truck. I think the temp problem just coincides with whatever map it switch’s to. I haven’t gotten a chance to take it to the shop to have the fuel tables reset yet either.

Jonnydime · Jan 4, 2020

But I will monitor fuel temp just to be sure.

PrecisionEngine · Jan 4, 2020

I could be wrong, but I thought when you load different tunes it automatically resets fuel tables.

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Jonnydime · Jan 4, 2020

It’s happening with sub 100°f fuel temps.

Jonnydime · Feb 15, 2020

So after resetting the adaptive fuel tables a total of eight times the issue seems to have corrected itself.

Jonnydime · Jul 6, 2020

Surge is back but it was never really gone. After resetting the adaptive fuel tables it will subside for a while but then it comes back. When I get time i am going to pull the front mounted pump and run it with a single pump to try and narrow it down.

Sixfoh · Jul 6, 2020

Mine seems to have a quick surge issue when fuel temp reaches 118. Kinda annoying. It will only happen once or twice right at that temp. Then will run normal. If it never hits 118 it also works fine.

Jonnydime · Nov 23, 2020

So I pulled the front pump and the surge is gone. So this is either a fuel temp issue or a PCV/HPFP issue. Is anyone testing these pumps so I can verify? Can I ohm the PCV and VCV?