65psi running fuel pressure after intank walbro install
11-13-2010, 04:12 PM
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65psi running fuel pressure after intank walbro install hey guys, wondering if anybody else has run into this issue. I installed a walbro 255 intank pump with hotwire kit and now my car pegs my wideband full rich (10.0:1) only when I spray it on a wet kit, on motor it runs about 11.5afr-WOT. I think it has to do with the fuel pressure. I never measured it before the pump, I always had good afr, on and off the kit. But now I have 55psi at key on-engine off. when I start the car, it bumps to 65psi (im thinking because the hotwire kit is putting alternator voltage straight to the pump??) but the factory regulator should be taking care of this. My theory is this: runs fine on motor because the fuel trims have adapted for it. Runs rich on the bottle because I have 65psi flowing through my jet measured for factory 55psi fuel pressure (which obviously will never be used long enough for the long term fuel trims to adapt too). So, has anybody else had a similar issue after a walbro install? I was thinking of just adding an aftermarket inline regulator near the rail and set it at 55psi. Any suggestions/opinons welcome.
car has a TSP MS3 cam, 42lb injectors, walbro 255 in tank, Frost mail tune, HSW wet plate kit.
car has a TSP MS3 cam, 42lb injectors, walbro 255 in tank, Frost mail tune, HSW wet plate kit.
11-13-2010, 08:17 PM
#2
Actually your kit stould have been tuned for 58psi,
did you verify pressure while at full throttle.... it should not be 55 then. It is normal for you to see 62-65 at idle w/ a bigger pump. This normally goes back to 58 after you get under a slight load.
Keep in mind thre is 8% difference in flow between 55 & 65psi... meaning the difference between 10:1 & 10.8:1 air fuel.
Verify full throttle pressure first. You may have been compensating for too low of pressure before the pump change.
did you verify pressure while at full throttle.... it should not be 55 then. It is normal for you to see 62-65 at idle w/ a bigger pump. This normally goes back to 58 after you get under a slight load.
Keep in mind thre is 8% difference in flow between 55 & 65psi... meaning the difference between 10:1 & 10.8:1 air fuel.
Verify full throttle pressure first. You may have been compensating for too low of pressure before the pump change.
11-14-2010, 09:55 AM
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ok thanks, ill have to get a pressure gauge with a longer hose and run it to the windshield. And yeah the kit is jetted for 58psi. its just wierd to me that it started doing this after the pump. I ran the kit once or twice before the fuelpump swap and it was fine in the high 11.8 to 12.0 range. And it always ran perfect before the cam swap on the bottle.
