I have a turbo LQ9 I had a $130.00 dollar Walbro 450 installed in. About a month ago I fried the wires on it. I took the truck to the shop and they think I might have gotten a knock off Walbro 450. So they changed it out for me with another Walbro 450 that they supplied and knew would be legit. So I got the new pump in and now my truck is going lean at WOT in Arizona winter temperatures (mid 40s to mid 70s). The truck was on the dyno back in fall in 90 to 100 degree Arizona weather. The truck made 708rwhp through a 4L80, 2 piece steel drive shaft, 9.5 inch 14 bolt rear end, and on 275/55r20 tires. The truck runs on 91 pump gas with meth.

My questions are. Has anyone heard of cheap knock off Walbro 450's on Ebay. Do you think I could be making more power than a Walbro 450 could handle in the cooler weather. Could there be another reason I fried the orginal pump other than it being a fake. Is there any other reasons why changing the pumps would make it go lean.

I'm going back to the shop this week and we're gonna hook a fuel pressure gauge up to it and do some data logging on it to see what's going on. I'd like some other opinions on what the problem might be when I go down there.

 

What year is your truck? What does your fuel system consist of?

 

Yes knock of walbros do exist although it's usually the 255 variety.
It's hard to say if it's your pump running out without knowing more about the build and having a fuel pressure reading. It may be a different weak point in the fuel system. For example if the fuel filter is a restriction it maybe be the problem. Could be any number of points in the fuel line.

 

The truck is a 2005 VHO. Everything is stock non return style except for the Walbro 450, Edelbrock Pro Flow intake with Pro Flow rails, and 1000cc injectors. There is no external fuel filter on my truck. The truck has started missing and popping out the exhaust under boost as well recently. I'm sure it could be a tune issue also. I had a boost activated cutout added to the exhaust after my DP when they did the fuel pump so maybe the exhaust changes screwed up the tune. Although my tuner seems to think it's more the fuel pump rather than the tune.

I should probably add the truck has a turbo.

 

I dont think there are any knock off 400/450s yet. That being said, I am amazed you made 700 rwhp on a stock non return system. What is your fuel pressure at idle and WOT?

 

Are you running meth?

 

alky control 100% meth

 

Going to find out the fuel pressure this week.

 

I bet your fuel pressure is high 40's.

Just a guess, idle pressure is 63-66psi and WO is 47-49.

What type of FI and how much boost?

 

Trick kit with 4" DP, Billet S476 92mm 1.25ar turbo, AI ported 317 heads, JFR 218 cam, and Pro Flow intake. The truck has three boost setting but it made the 708rwhp at 14psi.

What's the fix if it's the fuel pressure. A change to return style or dual fuel pumps.