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Fuel starving below 1/2 tank after new fuel pump?

2K views 19 replies 13 participants last post by  Jack B 
#1 ·
I'm running into an issue with my car stalling in turns after I get below a 1/2 tank of gas and below a 1/4 tank it becomes almost undriveable. RSI installed a Walbro 400 back in June during my Engine rebuild and Roe install. Someone just mentioned to me that the fuel basket used was too big? What does that mean?

Other people have this issue?
 
#5 ·
I don't think the new pump fills the canister like the oem pump. That problem is pretty common when you get away from the oem pump set up. Both acceleration and high G turns can keep the fuel away from the pump intake. In the oem system the pump can also pull from the canister. The oem pump supplies the system while it also fills the canister, therefore guaranteeing fuel is always covering the pick up.
 
#8 ·
From Kevin at UR. I was talking to him about my new ride and he said "don't boost when it gets under 1/3 tank. I always start looking for gas when it gets to 1/2 tank if I'm going to be running them hard."

I also had the RSI hanger in my SC car and never had any issues.
 
#9 ·
Just got my car back and was taking it home on a long highway drive. I was between 1/4 tank and empty. When traffic stopped (it was rush hour) it would try to die at idle. Having recently read this post I decided to fill up and see if that fixed the issue. It did. So, I don't know if it's a half tank or 1/4 or 1/8 or what, but there appears to be a problem. I guess as long as I know the sweet spot the fix will be keeping it full. But hopefully I'll get more than 1/2 a tank of use out of it per fillup.
 
#10 ·
I gotta wonder why that is. does the factory setup have problems with this? Will, can you go into some detail as to why this is. it's not a big deal to me anyway, as I worry about running out of gas all the time and typically don't get to a 1/4 of a tank without filling up.
 
#12 ·
The issue was already explained earlier in the thread.

The OEM pump refills the basket while it supplies fuel to your engine. The aftermarket pumps do not refill the basket. The basket refills by self leveling of the fuel in the tank. Therefore, at very low fuel levels (roughly 1/8 to 1/4 tank) the basket can run dry on you.

This is nothing new. This has always been the case on builds with aftermarket fuel systems that utilize the stock fuel basket. Refill your fuel tank between 1/2 and 1/4 tank and you have nothing to worry about.;)
 
#13 ·
Not that I don't understand the explanation above (because I do...), but just to clarify, my problem had nothing to do with acceleration or high g curves. Sitting in traffic on level pavement. Anyway, filling up at 1/4 tank is no big deal if that's the answer.

Back to my regularly scheduled morning tequila shots.
 
#17 ·
I have the same problem with an aftermarket pump, however, the only time I have issue is at the drag strip or autox, in both cases it is always with slicks where the car accelerates in first gear for a long stretch. In my case the acceleration is forcing the fuel to the back of the tank and when the bottle runs out of residual fuel, it nose dives.

I am taking out the after market 255 lph pump this winter and replacing it will a Gen III pump which is supposed to also be a 255 lph pump. I already have the Gen III pump, it merely needs a different connector. In my case when I ran the nitrous (350 shot) the 255 lph pump and BAP were sufficient. A SC is a little different, but, early on there were several Roe cars doing 650 HP with the oem pump (190 lph) and a BAP.
 
#19 ·
This is why I stuck with the stock pump with a KB boost-a-pump, and the 2 Paxton inline pumps with FMU. 909 rwhp and no fuel problems.
 
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