FUEL PRESSURE HELP

[riflex]

So after searching and reading some threads on here, im still confused on what could be causing my fuel pressure to drop. I am 90% sure it is the relief valve that is the culprit but my symptoms are to inconsistent to be sure.

Im pretty much fully bolted, one step colder plugs gapped to .28, with 2 gallons of E per full tank (E15 mix?). Been running autotech internals for over a year now with no problems until now.

Sometimes (not all the time) during cold start, it will idle at 500 rpm with low fuel pressure around 250 psi. After a quick tap of the throttle, everything goes back to normal. Also, ive noticed a couple times during WOT, the car will hesitate at high rpms and studder/pop.

Today, when starting the car, i noticed a bad clicking/clanking from the HPFP. I performed the relief valve test after a cruise to my parents house. I turned the engine off and pressure slowly started to drop to 40-50psi. I WAS SURE it was the relief valve after seeing this. I went back inside my parents house and a couple hours later left to go home. When I arrived home, i decided to perform the same test. However, this time, the pressure held and continued to climb as people stated it normally should.

Does this mean it is starting to fail? OR is it something different like the ITFP or internals?

[alden]

Originally Posted by riflex So after searching and reading some threads on here, im still confused on what could be causing my fuel pressure to drop. I am 90% sure it is the relief valve that is the culprit but my symptoms are to inconsistent to be sure. Im pretty much fully bolted, one step colder plugs gapped to .28, with 2 gallons of E per full tank (E15 mix?). Been running autotech internals for over a year now with no problems until now. Sometimes (not all the time) during cold start, it will idle at 500 rpm with low fuel pressure around 250 psi. After a quick tap of the throttle, everything goes back to normal. Also, ive noticed a couple times during WOT, the car will hesitate at high rpms and studder/pop. Today, when starting the car, i noticed a bad clicking/clanking from the HPFP. I performed the relief valve test after a cruise to my parents house. I turned the engine off and pressure slowly started to drop to 40-50psi. I WAS SURE it was the relief valve after seeing this. I went back inside my parents house and a couple hours later left to go home. When I arrived home, i decided to perform the same test. However, this time, the pressure held and continued to climb as people stated it normally should. Does this mean it is starting to fail? OR is it something different like the ITFP or internals?

Odd that it's intermittent. When I do the test, mine always drops to 40-50 psi, however I have no weird symptoms other than that to speak of. Car runs totally fine otherwise.

[riflex]

Those are the only symptoms I have noticed. During cruise, car seems to hold pressure fine though i do not know what normal cruising psi should be at. ill try to grab some data logs today

[riflex]

so after grabbing my logs. my fuel pressure seems pretty constant. however im still getting some studder/ predetonation at WOT. could this be injector seals? or hpfp internals seizing? not getting any cel's

[Thor Hammer]

Pull the pump apart and inspect the O-rings. 2 years of E85 and perhaps there is a tiny bit of black death going on. Are you using the right oil for running E85?

I'm no expert but could also be sticky spill valve. Here is a thread for reference:

Resolving HPFP corn woes (black death/sticking spill valve)

Also, check your ground on your pump along with the connector.

[flapjack]

Originally Posted by riflex Im pretty much fully bolted, one step colder plugs gapped to .28, with 2 gallons of E per full tank (E15 mix?).

2 Gallons of E85 per tank with the rest being 93 oct is more than E15 unless you are mixing it with gas that is ethanol free. More like E21.

Are you even tuned for an E85 mix? Just looking at your logs I'm highly betting you aren't. Your timing is very low at the top end and your AFRs are so lean at WOT it makes my ass pucker up. If you aren't tuned for E85, stop putting it in your tank.

In your second log I can see where it hesitated at full throttle, that looks like an overboost induced fuel cut to me. Your boost spikes all the way up to 22.37 psi which is about the highest value the stock MAP sensor can read. When boost spikes higher than ~22.5 psi, the ECU cuts fuel to save the motor from a catastrophic overboost condition.

Boost spikes are common on the factory 2-port boost controller. At your modification level, you need to ease into the throttle more or upgrade to a 3-port set to run in interrupt.