ineedavtec

A couple of days ago I posted this question here: https://honda-tech.com/forums/forced-induction-16/fuel-pressure-issues-3049092/

Copied original post:
My fuel setup,
Walbro 255 in tank, 044 in line, 8 feed, 6 return, Weldon fpr, fuel pressure gauge on the line before the 044 (readout in car) and fuel pressure gauge on the rail.
Here's what happened, I was idling the car and noticed it sounded like the 044 was working its *** off. Looked at gauge in car and it is reading 0 pressure. This gauge if I remember right usually read around 2 bar. Shut the car down, pulled pump, cause on the dyno the sock came off and was creating issues, plumbing, wiring sock all good. I was beside the road so I had limited tools so I got a ride home and trailered the car back to the garage. I felt it might be the in tank pump (which was an aeromotive 340) and I had an extra Walbro at the house. So I changed the pump, and I'm still having the same issues. I've checked voltage at both pumps and I'm getting 13.6 at the tank and 13.4 at the 044. Car idles fine and the 044 doesn't sound like its working as hard now, but here is my issues. I'm still not showing pressure before the 044 and the pressure on the rail is 100+ psi. The base pressure for the car is supposed to be 60 psi. Other things i've tried is remove the power wire for the 044 from the battery, turn key and in tank kicks on and it shows pressure on the gauge before the 044. Put the power supply line back on the battery for the 044 and turn the key and you will have zero pressure in line before 044. The relay for the 044 is getting its signal from the oem wires that are powering the in tank, and as far as I know I've got no issues from the 044 pumping other than why do I have so much pressure now at the rail and why do I have none before the 044?


I have still no idea what's going on so I thought it might help those looking at it if they had a drawing to see how I had my setup laid out so they could better see the problem. Here's the drawing.



Here are the questions
-Why is this doing this?
-What can I do to fix it to where it won't happen again?

Thanks, I hate to repost, but I'm guilty myself of not going back into threads I've been in before if I know I don't understand what they are asking.

ineedavtec

Could this be the regulator?....I haven't changed the fuel pressure other than to try to lower it after I had this issue. So why is it now 100+ psi in the rail all the sudden without me raising it? When I tried to lower the pressure the car started to stumble when it got ~80psi so I left it just above so I can idle and test it.

tepid1

Would you expect there to be pressure into the 044?

I don't know if I would.... the 044 suction may be more than the discharge pressure of the in tank pump. You may actually have negative pressure before the 044.

You may not have a regulator that can keep up with bleeding off the excessive pressure/flow that the two inline pumps are providing. Rail pressure is a product of the regulator, not what's happening at the inlet of the 044.

ineedavtec

^is negative pressure in that area normal for the walbro/044 setups? It was just wierd to me cause there always was pressure there before I had issues(only put 150 miles on the car so I don't have a lot of time to go by) I haven't tried running the car for fear of running it lean, but it has no issues idling, I'm just afraid to run it cause of the unexplained change in the rail pressure and not knowing the problem is.

boosted_D

iTrader: (1)

I tried to tell you this in your last thread.....

The positive and negative that go from the oem pump wiring to the relay for the 044, try disconnecting those from the relay, and provide a new ground ( anywhere on the chasis) and a new SWITCHED power source ( like to an acc. ignition wire) and see what happens then.

The wiring being jumped from the intank to the 044 may be robbing amperage from the intake, not allowing it to work properly...

If this does nothing, then I too would say it's a press. regulator problem...

ineedavtec

boosted D, I listened to you and tried that, sorry I didn't mention it, but thanks for the idea. I'm going to see if I can still find that adaptor for my fuel rail for the oem FPR and just run the return to a bucket for testing purposes and see if it will hold original fuel pressure, then it's has to be the FPR. Then next step try to find the H-T member that sold me this "new" Weldon FPR, man people these days lol.

ineedavtec

I'm bringing this one back from the dead, cause I still haven't fixed this issue, to update I sent the FPR to kinsler and it checked out fine. I am not concerned with the no pressure before the 044 any longer and also found out that the gauge that was on the fuel rail that was reading 100+psi had malfunctioned and there really wasn't that much pressure there. The car runs as should as long as there is at least 5/8 of a tank or more in it. I am about 80% sure that the only thing that is causing me problems is fuel pick up. I rarely drive this car on the street and this past year all of my track outings have been on pump gas, so having the tank full wasn't that big of a deal. This year I plan to use Q16 all the time at the track and I don't want to have to fill the tank completely with the race gas. I have the material to sump the tank and I am going to try that route and ditch the in tank pump all together. The choice that leaves me is do I buy another 044 and a bracket and use 044 X2 as my fuel pumps or just go with one large pump like a magnafuel 4303 or weldon 2015 or 2035. This car only made 660 at the wheels so I don't feel that it needs a huge pump on it, just looking for ideas or suggestions on how to fix this issue and see if I am going in the right direction to correct the problem. What would you do? ..Thanks