Fuel pump issue, is it going out..????
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From: Houston (The Champions)
Fuel pump issue, is it going out..???? Working on a 2002 WS6. Its got 20K miles on it. Its a built 6 liter with an STS turbo and meth. I noticed the other day while driving that when I get on it the fuel pressure guage drops to about 10 lbs. Then yesterday while driving normaly the guage started dropping off again, then while at idle it started dropping off and the car died. What the hell. Is my pump taking a crap or what.
I have had the same problems with 3 walbro fuel pumps. I found that I had two problems, fuel pump was not venting enough(causing cavitation in the tank) and not enough voltage to pump in WOT conditions. I had removed my evap canister and plugged the the vent hose from the gas tank. Stupid of me.
I removed the plug to fix my cavitation problem. Since Im NA engine I found Kenne Bell makes a boost of pump for negative pressures to activate (bump voltage up in wot) to help ease the work of the fuel pump. Less voltage = more amps and more voltage = less amps. To much Amperage over time can kill our fuel pumps.
I removed the plug to fix my cavitation problem. Since Im NA engine I found Kenne Bell makes a boost of pump for negative pressures to activate (bump voltage up in wot) to help ease the work of the fuel pump. Less voltage = more amps and more voltage = less amps. To much Amperage over time can kill our fuel pumps.
Staging Lane
Joined: Oct 2008
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From: DALLAS TX
wow that all seemed to make sense exept the less voltage=more amps and vice versa. check out ohms law. volts and amps are direcly porportional. irrelevent, i know...
Yep! 
Seems as tho the Walbo failures are being reported more frequently....
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From: Houston (The Champions)
Just pulled my 255 out. Looks like I need a second. Im looking at the high side of 680 RWHP, and I know that one pump isnt enough. But how do I know if the one I already have is ok, or going out.
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I think the start to get dark around the top of the pump due to heat. Atleast when I pulled one out a TA long time ago that what the walbro look like. On a Side note if your going to run twins have them on a seprate feed line out the bucket to a Y. That will help the pumps fuel pressure better.
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Sorry if I sounded harsh, as I'm not trying to be argumentive here, but do not wish to mislead anyone either. I continuously have to answer this question for my customers every week since they heard somewhere it was too small. You are correct that a bigger line will flow more & can be better under certain circumstances, but for most people (99+%) it is not necessary.
The stock outlet will support 1000+rwhp. No need to reinvent the wheel here. Unless you are finding this as a limitation, it will be of little use to change it. Without the actual need, it is just extra cost/work. That stock connector has already exceeded your rwhp on E85, so it is proven sufficient for some serious flow.
The stock outlet will support 1000+rwhp. No need to reinvent the wheel here. Unless you are finding this as a limitation, it will be of little use to change it. Without the actual need, it is just extra cost/work. That stock connector has already exceeded your rwhp on E85, so it is proven sufficient for some serious flow.
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From: Houston (The Champions)
Well, I dropped in the new 255 Walbro. The fuel pressure came up to bout 55. It was at 48 before. And now when I get on it (boost turned all the way down) the pressure only drops a few lbs. When before it would drop to about 10 lbs. Now, I guess I need a second 255 Walbro to maitain the 55 lbs fuel pressure, so I can turn the boost back up.
If you are referring to your F-body listed in your sig., you could experience a pressure drop even if he pump is up to capacity due to the rear mount regulator. If you are pushing over 550rwhp, then you may need more pump as well.
Thread Starter
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From: Houston (The Champions)
Ok guys. I installed the new Walbro 255 and the idle fuel pressure is sitting at 55lbs. Which is better then the 45lbs it was before the pump change. Anyways I just took the car and made a pass. The boost never got above 8psi. But the fuel pressure dropped to 35lbs. And according to HP Tuners that was datalogging the pass, my injector duty cycle sky rocketed to 112%. What now, I need a second fuel pump...???? Bigger injectors...????
