So I've been having this really bad fuel pressure drop when I hit WOT. The pressure goes from ~2100ish psi down to ~1000ish psi. It only happens on WOT. It happened so bad once that it sent my car into Power Reduced Mode. I can drive normal just fine, however.

Since noticing the problem, I replaced my HPFP. After doing so, the problem still exists. I've confirmed with my tuner that the tune is not commanding any lower psi on WOT or any other issues like that. My next thought was that the in tank fuel pump may be the culprit. Possibly gummed up from the infamous E85 goo or just wore out. Problem is, there aren't any OEM replacements available in the country right now.

Has anyone experienced this before? Has anyone put an aftermarket fuel pump into our stock canister before? I'd like to hear input from anyone that has relative info to share.

 

If you've already replaced the HPFP, my vote is the E85 did a little too good of a job cleaning things inside your tank and gunked up your fuel pump/filter/sock based on what you're describing.

I believe there have been a few people that have done pump swaps. They'll need to jump in here and give you the details on that though.

 

What are all your mods and tune and boost? Full e85? If you have no other fuel mods than you are prolly just running out of fuel period due to the high amount of torque coming on so low in the rpm range and the high pressure pump cant keep up yet. Does it still do it say if your going at 45 in second and hit it so the revs are up?

 

You might want to try attaching a pressure gauge to the schrader valve before the hpfp to see what your "low pressure" side looks like at wot. It's going to really be your only way to know for sure without blindly throwing parts at it.

 

Reduce the wgdc table in the midrange 4-5000 rpm it will solve the problems .. Also bringing in boost slower will help... This is the downside of eee hpfp can't keep up

 

lol

 

It says in his sig pic that CCSS3 tuned it. I figured he would've already seen it and fixed it when they were tuning it if tuning was the problem, so I assumed we were down to hardware possibilities. That's a big drop, and going into limp mode would have been pretty obvious. lol

 

well, i am also tuned by him and everything is good except my wgdc table, i was going thru the same drop in fp and it was being blamed on spark blow out when it was in fact just too much boost for e47 in that high torque range... my wgdc was about 10 higher in the midrange on that tune compared to BYT.. i lowered it and all problems and fp drops are gone... and the car goes faster lol

 

Mines doing the same thing. Heres a screen shot.

 

Thanks a lot for the responses.

Mods are BNR2871, full bolt ons, E47.

This didn't start happening until the BNR went on oddly enough. I just ordered a DW300 from Dietch Werks just in case.

I have switched back to 93 and dosed some Seafoam just to see if it was the E85 goo before I tear apart the fuel setup.

 

20psi on BNR2871 != 20psi on K04. Of course you're going to need more fuel

 

Its not going to be the E, its the taxing the fuel stock fuel system part. And I cant say just an intank pump is going to change it. Also would recommend the aeromotive 340 stealth pump over any other for the cobalt.

 

im not claiming to know more than the basics about tuning, because i dont, but i would simply try adjusting the wgdc before i rip my car apart... (if you havent already)

 

Mongo, you need some work on the fuel trims lol.

 

They are not E85 friendly. I think Matt tore one up as well as Buddy of mine using E85.

Forgot, 27psi on the BNR.

 

Soooo no chance on checking that fuel pressure prior to the hpfp still huh?

 

I don't have a fuel pressure gauge nor do I know what schraeder valve you're talking about. Pictures?

 

the black cap under my cp covers the shrader valve. It's right before the hpfp

[IMG][/IMG]

 

Ohhhhhhhhh! I see now. Any idea if I could rig something up from Lowes or Home Depot?

 

ehhh not likely. It's a schrader valve so you need a special fitting. It's sort of like a bigger version of a valve stem on a tire. You can get a fuel pressure tester from just about any autoparts store that should fit. The bigger issue is going to be figuring out a way to watch the fuel pressure while your driving. The lines on the testers generally aren't all that long unfortunately.

maybe find a way to rig it so the gauge is kind of hanging out where the hood and the windshield meet, and have someone with you to watch the fuel pressure when you go wot

 

Okay thanks. These testers do connect to the valve fine tho? I could rig up my go pro under there.

 

Well first thing first... I am tuning op.. Ops issues didn't start happening until just recently. Previous logs fp was fine.. Sooo I had him replace the hpfp. Nothing within the tune is causing it to dip. Other then the fact he is on e 47 and the bnr on 27lbs.

2010ss, lowering boost will create less boost so therefore create more psi in fuel since its not being used. All your doing is shadowing the problem.. Not fixing it..


Mongo is full e85, so his trims are skeet due to the fp loosing pressure so trims have to counteract and add fuel there!

 

Yeah they thread right onto the valve and lock on tight. It aint going anywhere unless something pretty substantial rips it off. They make a couple different sizes, so just make sure it threads on correctly before you leave the parts store.

 

Thanks.

I will try this before ripping out fuel canister.

 

Also for the fp to work he would need to be where the fp drops which is only at 4800-5200ish before is good and after is good. So in order to do it hell need to be driving, so it'll need to be a large line lol