Walbro 255 Problem

[TimG]

I've been having a hard time trying to start my car since the fuel system upgrade and I suspected the old walbro is hurt. I've been getting a lot of leaking past my sending unit to tank seal, even with a 1/4 tank of gas. I found this weird so I did some investigating. I lifted my sending unit off the tank with the car running and found a high pressure stream of fuel jetting out of the circled port on the top of the pump.

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The stream had so much pressure that it hit the glass of my open hatch 5 feet above it. Does anyone know if this is normal? The general thought is that it's failed from some local guys but I'm looking for someone who had the exact same problem happen to them.

 

[donniekak]

I believe that is the high pressure release valve. It should not be bypassing fuel until 80 ish psi.

 

[TimG]

My fuel pressure gauge reads 37psi like normal. I wonder if adding the Bosch 044 inline pump when I did my fuel system upgrade is causing such a restriction, that it's seeing that high of pressure (80+psi) in the lines pre-inline pump but good fuel pressure (40psi @ idle) after the pump. My idea was to run the in-tank pump for daily driving and turn on the extra pump via a switch for the track and or spirited driving. I suppose I'll see if it's spraying out the relief valve with the Bosch working as well.

 

[NOSLO2PT0]

The Walbro is operating under 0 pressure if it's feeding the 044. The relief valve won't come into play. Borrow another pump and toss it in and see if the problem goes away.

 

[TimG]

I suppose I should have mentioned that the 044 pump isn't electrically hooked up. Basically speaking, the only pump working is the in-tank 255. I just need to put the led on for the negative terminal on the 044 when I get home from work to see if it fixes the relief valve issue.

 

[airmail96]

I think that will fix your issue. Sounds like the bosche is just acting like a restriction.

 

[TimG]

I think that will fix your issue. Sounds like the bosche is just acting like a restriction.

My thoughts exactly.

 

[jrohner]

I don't think you can just pump fuel through a non-working pump. Your pressure between the two fuel pumps is exceeding the pressure of the 255's relief valve.

 

[TimG]

Definitely the case. I got the second pump going and sure enough, the relief valve issue stopped.