I see that Neil is running a A1000-6 FPR with his Walbro. I just bought a Walbro and am wondering what others have found with their tune once they have installed the higher pressure pump. Can the stock FPR handle the extra fuel at idle without a re-tune.

Jim -

I was told (can't remember by whom) that the stock fpr wouldn't be able to divert enough fuel back to the tank at idle and under low load conditions. When this happens, it causes the car to run rich. It was for this reason I went with the Aeromotive adjustable fpr. BTW, just left you a voicemail message about this.

Neil

When you have a high flowing pump you need to have a regulator that can bypass a large abount of fuel. If the regulator(and/or the return line) can't bypass the fuel, it becomes a bottleneck that raises the base fuel pressure to a higher amount. If the car was tuned with a 40psi base fuel pressure, and your new pump sits at 65psi, your tune will be off.

That is what I was seeing in the archives. It makes sense unless the tune is scaled back but that approach seems more like cause and effect type tuning. Long term the better fuel pressure regulator seems like it might make more sense.

You can do a fairly simple test to see if the fpr can keep up with the new pump. Take a base fuel pressure reading with the stock pump and fpr. Swap pump with new one. take fp reading again. If the value is the same, the fpr can handle the higher flow.

My question to you: Why are you upgrading your pump? If your car is tuned correctly with the current fuel system, don't change it. If you are looking for more performance and are going to retune for more power, go right ahead.

I am upgrading the fuel pump because we are adding more power and the car is tracked almost exclusively. Worrying that the car getting enough fuel is something I don't want to have to worry about. Especially if the stock pump is running at capacity. We are also getting a new tune for this set up in the near future. I like over engineering vs under engineering.

Yeah, running out of fuel would be bad!

Makes perfect sense. The only time you run into problems wit over-engineering a monster fuel system is when you go with a monster fuel pump, a small tank, and a low hp motor. You bypass a ridiculous amount of fuel, heat it up unnecessarily(it gets heated up by continually pressurizing it, and by passing it through the now warm pump and components), and wear out the pump faster. You can also experience vapor lock in bad cases. A walbro is not a huge pump. I'm talking about Aeromotive A1000 and bigger.

Also, if you are worrying about pickup issues, you can go with a low pressure pump in-tank that feeds a reservoir that feeds a high pressure pump. The reservoir makes sure the high pressure pump has a good constant supply of fuel through a section of hard corners, and it gets replenished in the straights.

That is exactly what I am looking for. I have fuel pick up problems in sweeping corners like the carousel at RA which is off camber and tilts the car to the left. Although my new suspension may solve that issue. Do you have a recommendation on a secondary fuel pump.

You really don't need anything crazy for the in tank pump. Basically it is just a "lift" pump to keep the reservoir filled. It can be a low pressure pump for a carbureated application, from summit or a production car. One with a decent flow rating would be good. It just has to be able to flow more than the walbro is going to suck up.

The reservoir can be mounted anywhere, and then just gravity feed an inline pump like the bosch 044 or something else. It can just be a little square box with an inlet and outlet.

jim im running the stock FPR with the Walbro and have not seen any difference in richness at idle or anywhere except where i was running out of fuel up top. I dont think you need an adjustable FPR. Im running basically the same tune as you.

Karl e-mailed me last night and said I shouldn't have any issues as well. Good to know though from someone who has is already.

makes me want to upgrade my fuel pump...as an insurance measure.

Makes perfect sense. The only time you run into problems wit over-engineering a monster fuel system is when you go with a monster fuel pump, a small tank, and a low hp motor. You bypass a ridiculous amount of fuel, heat it up unnecessarily(it gets heated up by continually pressurizing it, and by passing it through the now warm pump and components), and wear out the pump faster. You can also experience vapor lock in bad cases. A walbro is not a huge pump. I'm talking about Aeromotive A1000 and bigger.

Never even thought about this sort of issue using a too big fuel pump!! great heads up...thanks

Last time i checked my LIFTs they were both at -0.04 & -0.03. Keep in mind i never reset tye adaptions and have riven the car around for ~125miles or so since the Walbro upgrade. My idle actually smoothened out even better and Jim that cold start issue has settled up since.

Not to distract from the thread too much, but is the OEM FPR a 3.0 bar or a 3.5 bar or a 4.0 bar?

I have run into the FPR issue hotrodding Volvo turbos. With a Walbro 255 high pressure tank pump, the standard Bosch 3.0 bar FPR on a Volvo B230FT 4 cylinder turbo is overwhelmed and cannot recycle the extra fuel during idle and low fuel need conditions, causing the pressure to rise by about 1/2 bar.

Philip Bradley

ours is rated at 3.5bar.