RedRocketZ28

iTrader: (19)

I will definitely check that out. I still have a stock style filter in the stock feed (now return) line. Maybe it is plugged. Fuel pressure does rise a bit, then hold steady for a few seconds, then start to drop as RPM's increase more. I was under the impression that a blockage in the return would make pressure go even higher than what it is supposed to be. Thus the reason I didn't think to check that out.

Sarg

iTrader: (6)

From my experience, blockage in the return will only make it higher when the car is not using fuel like at idle or cruise. At this point it is trying to return a bunch of fuel and if it is blocked or too small it is unable and so pressure backs up. As you get on it and it has to return less fuel, psi will drop to where you have the spring set on the return. Just throwing it out there. Seems you have gone through a ton of other options. I know it was definitely a puzzle for me when I ran into this.

RedRocketZ28

iTrader: (19)

I appreciate the suggestion. I will definitely take a look at that. My patience is running thin with this issue.

Camaro9969

iTrader: (12)

I am dealing with almost the same issues as you are right now. Last year 20psi afrs were perfect only thing i changed was i did one of those fuel lab filters which i'm taking off. But this year 17-18psi my afrs were 12.5's to even some 13s. Last year 10.9-11.1's throughout the pass.
Have you checked your voltage??? I noticed with mine once i made a few passes and under hood temps were through the roof it dropped from 13 to in the mid to lower 12's so i decided to go with a truck alternator and adding a 3rd pump to see what that does. I am in the same boat as you so i'm trying to figure this out. Hope yours gets fixed soon

RedRocketZ28

iTrader: (19)

I have a fuel lab filter too, but it was on the car last year after I upgraded the fuel system. The filter still looks brand new too. Are you checking pump voltage or just voltage via the scanner? Mine via scanner shows 13.1-13.2 at all times. I need to check voltage at pumps though. I had to relocate the battery this year but everything was ok on the dyno it seemed. I am still wondering if I didn't have an issue with my wideband on the dyno and fuel pressure was dropping then too. If that is really the case, then I am surprised this motor is still living after getting 19-20 psi shoved down it.

I think I may add a 3rd pump as well, or upgrade the hat on the fuel bucket and put in another 340 in place of the walbro 255. Eventually, I will need it anyway. I just hate taking the "throw money" at it approach, ha. Thankfully, I have a great friend who is allowing me to try parts from his car while it is down.

I will keep updating here with things I try. Keep me posted on your issue as well.

Camaro9969

iTrader: (12)

I have been checking it in the scanner but i had my buddies help me out and we relocated all the pump wiring and relays to the back of the car right off the battery instead of the hotwire kit being off the alternator i am going to hop on the dyno to test it out because anything over 17psi is dangerous on the roads near me. I'll let you know later on in the week after I get it back running again. Just irritates me that only thing different from this year and last is the filter. I also added meth and when i made a pass with it on my IAT's went down i saw no change in my afr's which was odd. But i'm going to throw as much fuel at this pig as i can.

RedRocketZ28

iTrader: (19)

Sounds good, thanks. I am certainly frustrated with this issue.

stevieturbo

I dont see how a blockage in the return could be causing the problem.

get a mityvac or other manual pressure source.

Run the pumps, engine off or on, doesnt really matter. Then apply pressure to the FPR and see if you have any ability to create a rise in FP with air pressure.

Sarg

iTrader: (6)

If the fpr can't return enough fuel the pressure will back up causing it to rise. An easy way to test this is to have the engine running and try adjusting the fuel pressure up. If you crank on it several times and nothing happens this is most likely your problem. Keep trying to add pressure through the fpr until you see it barely rise, back it down a hair and go for a spin. Monitor fuel pressure and see if it solved the issue. But if you are able to crank down on it several times and it does not immediately rise you more than likely are backed up.

stevieturbo

His problem is...it doesnt rise though ?

STEEPSS

iTrader: (30)

1. Test the vac reference line for leaks from the block
2. Switch out the FPR
3. Add another / or bigger pump

It has to be something simple. I highly doubt that its a blockage issue because you cant get enough fuel pressure. Since it worked before, my money is on the regulator.

Sarg

iTrader: (6)

And he said it dropped....

stevieturbo

Not rising is more or less same thing, except dropping is worse. Blocked return wouldnt cause that

Sarg

iTrader: (6)

I guess you didn't read what I wrote. I have seen this first hand while trying to tune a car. If the return is too small, at idle it may read 58 psi because at idle or cruise when it is trying to bypass a ton of fuel it will be incapable. As you get into boost and start to use fuel, it will start to drop to what you have it ACTUALLY set for (hence trying to turn it up to see if it moves up or not) and fuel pressure will drop. I have witnessed this personally while trying to diagnose and tune a car with these symptoms. I don't know if this is what he is experiencing, but it is really easy to test out as I outlined above. Maybe hard to explain, but this absolutely can happen and it will in fact drop.

Camaro9969

iTrader: (12)

So I figured out my issue and I say try the same just for the hell of it.......I had that same fuel lab fuel filter. I swapped it to a mangafuel stainless fuel filter 25 micron took it for a ride and instantly noticed the afrs went to 9.8!! Hope yours is the same issue.

RedRocketZ28

iTrader: (19)

This was with your 3rd pump installed though correct?

RonSSNova

iTrader: (3)

Agree. This is a simple and important test. Also easy to do. You can even rig up a bike pump to apply the pressure.

I'm running the Holley FPR. In early tuning, I decided to check that the FPR would reduce pressure with vacuum applied. So turned the pump on and connected the mighty vac. It wouldn't hold vacuum. And it bled off rather quickly. No doubt it would do the same with pressure applied!

Vacuum/pressure is applied in the "hat" of the FPR. Where the adjuster screw is. And guess where the leak was?

Applied Teflon sealer to the adjuster screw, problem fixed.

On the return line. It really needs to be as big as the feed line. Just makes sense. Yes you can get away with smaller. But at idle/cruise, you are returning nearly all of the fuel to the tank. You don't want the return to act as a restriction.

Ron

Camaro9969

iTrader: (12)

I added the third pump took it for a ride and it was the same wot was 12.6-13.1. Changed filter first pull 9.8 it was a good feeling to see that.

RedRocketZ28

iTrader: (19)

Good deal. I will give that a shot. How did the fuelab filter look? Mine looks brand new. I am running the 10 micron cellulose element. Which one did you have? Lastly, is this the filter you bought?

http://www.jegs.com/i/Magnafuel/665/...06180000277169

I had the big fuelab. Thanks man.

Camaro9969

iTrader: (12)

Yup same 10 micron one and looked brand new. And yup exact one I bought just order the fittings it doesn't come with them