Jason_K

Got a questions guys. Recently I been having an issue with my truck. Under light throttle (and around 1800rpms and again around 2500rpms) my fuel pressure will fluctuate erradically back and forth between the 20psi mark and the 30psi mark. During these jumps my rail pressure will sometimes (but not always) fluctuate from 18,000 up to as high as 22,000psi. It's not the guages because during these occurances the engine sounds like it is missing. Does this sound like a possible fca problem or injector problem or lift pump problem or.....I don't know. Where should I start????

Thanks
Jason

JJPage

My truck behaved similar... without the engine sounding like it was missing.

When I use the Smarty for pressure increase, under light throttle, my rail pressure would fluctuate like crazy. I leave the Smarty pressure on 1, and use my EZ for pressure, the irratic rail pressure ceased. I see you are running TNT-R, if you are raising your pressure with Smarty, you could try turning it back to stock pressure.

You might also be draining your rail, and it's trying to recover, causing both of your symtoms. Try a lower sw#, or less tq management.

It may be your fca, but I would try tuning before spending money on a new FCA.

I guess I should have asked, was it ok, no changes in tuning, and all of a sudden it's acting strange? If so, then I would lean more towards a mechanical snafu.(rpm related, tps?)

madhat

First, I would take the truck back as stock as I could get it... (take off the smarty).

This sounds like a bad fuel flow to me... have you replaced your filter on the Fass?

Do you have an isolator on your FP gauge? That could also be a culprit for the FP, not the RP, tho.

Jason_K

I forgot to mention that if I go WOT the miss is gone and my fp drops to about 23psi and holds strong. My rp will also hit 24.5k with no problem and hold it there.

This is a problem that seems to have started out of the blue. I've been running tnt/r for quite awhile and never noticed a problem til now.



I have FASS pump w/ no filters however I have the little prefilter before the pump itself that has never been changed. I think I'll try that tomorrow. I recently changed my stock fuel filter and removed my 2mic filter in hopes that that would fix it, however that made no change.

I took the isolator out because it was giving me problems

I'll try taking the truck back to stock tomorrow also and see how she runs

Thanks Guys

madhat

Keep on it, dude, and keep us posted.

Jason_K

I'll definitely keep you updated

JJPage

Is the truck throwing any codes?

Jason_K

nope checked it with the smarty and it showed nothing

Bswope

Any luck Jason?

Jason_K

Yep got her fix up! Replaced the little filter before the FASS pump and everything is back to normal. It was such an easy fix I feel stupid for even asking for help

Thanks Guys
Jason

madhat

Live and learn, man. Live and learn. Glad it was an easy fix.

Jason_K

Me too Mad!! And thanks for offering to send me your stock FCA.....You're definitely living up to your title

JJPage

Glad you got it fixed, alot of times they are easy, but it's hard not to imagine all the possibilties.

Was it a little inline fuel strainer, like a Fleetguard FF5079?

Jason_K

Yes that's exactly what it was. I sure am happy it was a simple $5 fix

madhat

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