Fuel pump volume

[Cathead]

Still a problem.... the “140” is the flow rating in gallons per hour. That equals 530 liters per hour (LPH). Almost the same as the A1000. It also seems to have very small inlet and outlet connections (3/8” NPT). I found a review on Summit where they indicated the pump had an inlet flow problem when starting, and that the solution they used was to mount the pump very low under the tank. Not low enough and the fuel will flash to vapor at the pump inlet. Doesn't seem practical.

https://www.summitracing.com/parts/maa-4140/reviews/

My setup has two Bosch 205 LPH high pressure pumps, running at 58 PSI. The one in the stock tank location always runs, and supports 500+ flywheel HP on straight motor. The one connected to the bottom of the tank only runs when the nitrous system is armed, more than adequate for a 300-shot (dry).

Are you looking for a fuel system that will also supply the fuel for the nitrous, or would you use a small stand-alone fuel cell, with its own pump?

How much fuel you need can be estimated from the flywheel HP on motor, plus the max nitrous shot. The problem with getting the numbers exactly right depends on the geometry of the combustion chamber and the quality of the tune. Bottom line.... you want to err on the fat side.... go a bit oversize on the pump “just in case”. It's possible the stock pump could support 500 HP (low pressure) carb on the perfect setup. But then there's the issue of how old the pump is, what the supplied voltage is at the pump, how efficiently the lines are routed, etc.

You might want to check what voltage you are getting at the pump connector. 13.5 volts will flow more fuel than 12.0 volts or less. Upping the wire size to the pump can sometimes solve problems. There are voltage boosters available, but I don't know how long the stock pump would last at 16 volts. Could even be a dirty sock on the stock pump bucket.

I have a new Aeromotive pump #11203. Would that be any better or more of the same problem with delivery, etc.?

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[Injuneer]

The Aero 11203 pump appears to have some sort of internal flow control adjustment. The fact that they show a wide range of HP applications would seem to confirm that. On the other hand, even though almost as large a capacity as the A1000, the recommended max carb HP is only 1/2 of the A1000.

The install instructions mention using a -6AN or -8AN inlet line. -6AN is equivalent to 3/8 NPT. But the instructions also caution “These sections of fuel line should be as large a diameter and as short as possible to reduce the tendencies for vapor lock, cavitation, and premature wear....”.

It is possible for them to design the pump's internal feed to minimize the “net positive suction head required” (NPSHr) to avoid cavitation. NPSH is calculated based on the sum of the pressure in the tank, the pressure exerted by the height of liquid above the pump inlet, less the vapor pressure of the fuel. I would trust Aeromotive's design capabilities (except for their problem LT1 AFPR).

The review of the Mallory pump caught my eye because the reviewer indicated it was sometimes necessary to pressure the tank to insure flow. That may mean the Mallory pump requires more NPSH at the pump inlet than the Aero 11203.

I would use a -10 AN line on the inlet side, at least from the tank to the filter, then an -8AN with a smooth conversion adapter to 3/8”NPT at the pump. Keep the pump as low below the tank as possible. Minimize sharp 90-deg elbow in the inlet line routing, using a long sweep elbow if possible. Make sure the fuel is not heating up due to the pumping energy (excess flow, requiring large return), or exhaust components near the return line. In the NPSH calculation, you want low vapor pressure, and heat increases the vapor pressure. Note Moe's description of fuel heat up problems with the A1000. I've seen large fuel systems on high HP applications that require a cooler on the return line.

I have a design handbook that I got from Kinsler Fuel Injection many years ago, and I have always followed their recommendations with no problems.

[Cathead]

The Aero 11203 pump appears to have some sort of internal flow control adjustment. The fact that they show a wide range of HP applications would seem to confirm that. On the other hand, even though almost as large a capacity as the A1000, the recommended max carb HP is only 1/2 of the A1000.

The install instructions mention using a -6AN or -8AN inlet line. -6AN is equivalent to 3/8 NPT. But the instructions also caution “These sections of fuel line should be as large a diameter and as short as possible to reduce the tendencies for vapor lock, cavitation, and premature wear....”.

It is possible for them to design the pump's internal feed to minimize the “net positive suction head required” (NPSHr) to avoid cavitation. NPSH is calculated based on the sum of the pressure in the tank, the pressure exerted by the height of liquid above the pump inlet, less the vapor pressure of the fuel. I would trust Aeromotive's design capabilities (except for their problem LT1 AFPR).

The review of the Mallory pump caught my eye because the reviewer indicated it was sometimes necessary to pressure the tank to insure flow. That may mean the Mallory pump requires more NPSH at the pump inlet than the Aero 11203.

I would use a -10 AN line on the inlet side, at least from the tank to the filter, then an -8AN with a smooth conversion adapter to 3/8”NPT at the pump. Keep the pump as low below the tank as possible. Minimize sharp 90-deg elbow in the inlet line routing, using a long sweep elbow if possible. Make sure the fuel is not heating up due to the pumping energy (excess flow, requiring large return), or exhaust components near the return line. In the NPSH calculation, you want low vapor pressure, and heat increases the vapor pressure. Note Moe's description of fuel heat up problems with the A1000. I've seen large fuel systems on high HP applications that require a cooler on the return line.

I have a design handbook that I got from Kinsler Fuel Injection many years ago, and I have always followed their recommendations with no problems.

Thanks for the info. I bought the pump years ago for my 70 Camaro build but never used it. I brought it up more for zooguy's issue. I personally think his problem is more associated with the regulator but...
If you think this will work zooguy and you're interested, just PM me and we can work something out.

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[zooguy]

Are you looking for a fuel system that will also supply the fuel for the nitrous, or would you use a small stand-alone fuel cell, with its own pump?

No i have a stand alone system
For the wet side.

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[zooguy]

I brought it up more for zooguy's issue. I personally think his problem is more associated with the regulator but...
If you think this will work zooguy and you're interested, just PM me and we can work something out.

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I appreciate the offer and I might be contacting you about it ... I'm going to try something silly and change my fuel filter and see if that helps.... this is a metal gas tank and it did sit for about 3 years with gas in it and I can't remember if I change the filter when I got the car back up and going. It could potentially be that simple or it could be just needing some adjustments with the tuning. But it does feel like it's running out of fuel.

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[zooguy]

Maybe not the complete problem but it wasn't helping ... i got underneath the car and changed the fuel filter. From the looks of the filter it's been underneath there for a while. I don't recall changing it so I'm sure it's not the original 1994 fuel filter but I'm sure it wasn't flowing as freely as it could.... I had my fuel pressure set at 7 PSI and after changing the filter when I turned on the fuel to get the system primed I looked at my fuel pressure gauge on the regulator and it was showing 12 PSI. So I reset the fuel regulator down to 7 PSI and I'm going to go take a test drive we'll see how it goes.

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[popo8]

And????

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[zooguy]

Haven't really had the opportunity to test it yet.

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[Cathead]

Maybe not the complete problem but it wasn't helping ... i got underneath the car and changed the fuel filter. From the looks of the filter it's been underneath there for a while. I don't recall changing it so I'm sure it's not the original 1994 fuel filter but I'm sure it wasn't flowing as freely as it could.... I had my fuel pressure set at 7 PSI and after changing the filter when I turned on the fuel to get the system primed I looked at my fuel pressure gauge on the regulator and it was showing 12 PSI. So I reset the fuel regulator down to 7 PSI and I'm going to go take a test drive we'll see how it goes.

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If the filter change made that big of a difference, you might want to check out the fuel pump sock as Fred suggests in post #10. Also, Fred mentioned the proper wiring to the pump. I ran a separate relay for my fuel pump, as advised by Tyree, when I was having an issue with mine wanting to lean out at around 6K rpm. Adding the relay and 10AWG wires fixed it. I think you're on the right path.

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