Hey everyone

Heads and cam lq9. Full bolt ons. Walbro 255, marine injectors. Stock intake and TB 1999 truck - return style fuel

I just installed - 1 month ago. Runs 55psi no vaccumm at Idle. Sees 42-44psi at WOT. Wideband is reading lean condition. FP reading off shrader valve on Passenger side fuel rail.

What could cause this? Possible bad pump?

thanks for the help

 

Is the pump getting enough power? My set up runs closer to 60 at idle and I dont even drop below 50 with 83# injectors. Granted on the top end I am now running meth... but still. At 10 PSI with no meth it was the same story.

 

All I did was a Racetronix upgrade kit. Did not hotwire the pump. I figured for my set-up, it wouldn't be needed. My blown CC at 10psi has zero issue with the magnacharger pump...which to my knowledge is the same as a gss340 255gph

 

Split fuel hose between pump & module.

 

I was thinking that. I used submersible line, and was EXTREMELY cautious when installing it. I've ordered a new pump, and a rewire kit to cover all my basis. All I cna think that could cause the issue. Pump and rewire is cheap..so i'll give that a try

 

Has your electrical bulkhead been upgraded to the new style? The older ones that would have come with your 99 are only good to flow around 14 amps. Also, I would definitely upgrading the wiring harness to the hotwire kit from Racetronix. Finally, your low FP could be caused by multiple things, including a clogged fuel filter or leaking fuel hose. I'd recommend using Nylon tubing inside the tank. It's superior to rubber hose and cheaper too.

 

Thanks for the input gmctrk.

I have an email into racetronix to get the link for the hotwire kit i need. Gonna order that. Gonna slap another gss340 in while i have the tank down(only 75$ my cost).
Ordered another Hose for new pump
Got a new fuel filter to go on too. Last time fuel filter was replaced was 2 years ago, truck has seen maybe 1000 miles since then.

Just gonna swap it all out, for piece of mind, and test it all after. If i new there was such issues with the wiring on stock fuel pumps I would have upgraded before.

O well live and learn

 

Just thought id wrap this up. Hot wire kit fixed the problem