# Question about running two fuel pumps in series



## Chozen (Aug 22, 2007)

I am running an Aeromotive inline fuel pump that is installed underneath my car and I want to change the stock in tank one to a WalbroWalbro will flow 520 lbs/hr @ 13.5 volts and 45 psi, the Aeromotive I have will flow 325 lbs/hr @ the same 13.5 volts and 45 psi. So, the Walbro in the tank flows more fuel, while the Aeromotive downstream of that flows less. Does this mean that my fuel can only flow as much as the Aeromotive, or does this mean I will get more flow than the Walbro by itself?


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## trmn8r (Apr 16, 2005)

Chozen said:


> I am running an Aeromotive inline fuel pump that is installed underneath my car and I want to change the stock in tank one to a WalbroWalbro will flow 520 lbs/hr @ 13.5 volts and 45 psi, the Aeromotive I have will flow 325 lbs/hr @ the same 13.5 volts and 45 psi. So, the Walbro in the tank flows more fuel, while the Aeromotive downstream of that flows less. Does this mean that my fuel can only flow as much as the Aeromotive, or does this mean I will get more flow than the Walbro by itself?


good question. i would probably look at it like a pressure washer you have faucet water. then the pressure washer has like 3 seperate water compressors. i goes to one, then the second give that pressure more boost, then the third gives it max pressure. now im not sure if that principal works with the fuel pumps. i would have to search some more. if i find something ill post it


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## rogoman (Dec 16, 2004)

Chozen said:


> I am running an Aeromotive inline fuel pump that is installed underneath my car and I want to change the stock in tank one to a WalbroWalbro will flow 520 lbs/hr @ 13.5 volts and 45 psi, the Aeromotive I have will flow 325 lbs/hr @ the same 13.5 volts and 45 psi. So, the Walbro in the tank flows more fuel, while the Aeromotive downstream of that flows less. Does this mean that my fuel can only flow as much as the Aeromotive, or does this mean I will get more flow than the Walbro by itself?


If you install the pumps in series, the fuel pressure will rise well beyond 45 psi which is something that you don't want. 

Install the pumps in parallel; this will maintain the pressure at 45 psi and will combine the volume output of each pump. However the size of the lines should be increased to take advantage of the increased volume.


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## Chozen (Aug 22, 2007)

Thanks. I'll probably just delete the Aeromotive and install the Walbro in the tank then.


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## Kyu-ju-kue (Mar 9, 2007)

rogoman said:


> If you install the pumps in series, the fuel pressure will rise well beyond 45 psi which is something that you don't want.
> 
> Install the pumps in parallel; this will maintain the pressure at 45 psi and will combine the volume output of each pump. However the size of the lines should be increased to take advantage of the increased volume.


I'm low on sleep and might be thinking about this wrong, but if 2 suppliers are connected to a receiver, won't the receiver catch the total applied amount from both suppliers making the end result 90psi, and if you have 1 supplier supplying another supplier which then supplies the receiver, the psi will be a better regulated 45psi?


Basically what I’m saying is if you were trying to fill a bath tub, if you used the sink faucet(45psi) along with the bath tub faucet(45psi) wouldn’t the tub fill faster due to the increased volume(90psi)?

If he installed a regulator that’s adjustable from 0-90psi, he won’t have to worry about over pressurization …at least to the engine anyway.


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## Asleep (Jan 19, 2003)

Kyu-ju-kue said:


> I'm low on sleep and might be thinking about this wrong, but if 2 suppliers are connected to a receiver, won't the receiver catch the total applied amount from both suppliers making the end result 90psi, and if you have 1 supplier supplying another supplier which then supplies the receiver, the psi will be a better regulated 45psi?
> 
> 
> Basically what I’m saying is if you were trying to fill a bath tub, if you used the sink faucet(45psi) along with the bath tub faucet(45psi) wouldn’t the tub fill faster due to the increased volume(90psi)?
> ...


not in a series though. in my head, unless im not visualizing this right because im on tramadol for back pain right now, lol, im picturing it as if its like running a smaller hose into a bigger hose. one of them is going to be a restriction, right?


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## Kyu-ju-kue (Mar 9, 2007)

AsleepAltima said:


> not in a series though. in my head, unless im not visualizing this right because im on tramadol for back pain right now, lol, im picturing it as if its like running a smaller hose into a bigger hose. one of them is going to be a restriction, right?


The big hose will have more fluid at a lower psi, if it supplies the smaller tube the volume will go down, but the psi will increase. A smaller hose to a bigger hose will be the opposite.

Can someone clearify this a little more?


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