Is anyone running 2 fuel pumps in series (one after the other). It seems like one would want both pumps running all the time. My concern is if both pumps ran all the time in series, the fuel pressure at idle would be too high. If the 2nd pump was setup to run at a certain psi, it would seem like the 2nd pump would be a massave restriction causing the 1st pump to overheat.
Anyone running 2 fuel pumps in series?
- Thread starter RobS
- Start date
turbo nasty
Turbo Dojo / MNTR
- Joined
- Jul 19, 2001
Parallel
I do not because I have a stock return line, the pressure will rise uncontrollably. My 2nd pump comes on at 10 psi if I remember correctly.
With larger lines it's not an issue to run both all the time.
If you have two of the same pumps, runs them in parallel.
If you have two different pumps, run them in series.
The usual setup is a low-pressure (but high-volume) "lift" or "feed" pump ahead of a much higher pressure "main" pump. Both in series will deliver more than each one individually can. This setup is better suited when higher pressures are needed (say injectors may be a tad small and you want to run higher base rail pressure to compensate). Low pressure flow is usually not so much that is overwhelms regulators with both pumps running.
Two in parallel are better suited at lower operating pressures - but should be staged as needed since low-pressure flow will be great.
If you have two different pumps, run them in series.
The usual setup is a low-pressure (but high-volume) "lift" or "feed" pump ahead of a much higher pressure "main" pump. Both in series will deliver more than each one individually can. This setup is better suited when higher pressures are needed (say injectors may be a tad small and you want to run higher base rail pressure to compensate). Low pressure flow is usually not so much that is overwhelms regulators with both pumps running.
Two in parallel are better suited at lower operating pressures - but should be staged as needed since low-pressure flow will be great.
My guess is that two pumps in series will flow a little more fuel than one pump (maybe 5-10% more) BUT the pressure will be way more than one pump. You need to look at the pump curves to be sure!
I would probably make the stronger pump the first pump and the weaker pump the second pump. Having higher inlet pressure on the weak pump will help it flow more fuel if you keep the outlet pressure fairly low for the 2nd pump. Just be sure you have a capable fuel pressure regulator and an accurate fuel pressure gauge...ie a Procomp Autometer or equal.
You have calculated your fuel flow and pressure requirements haven't you? If not, talk to a professional. There are several I would trust...Jack (Cotton), Cal (Hartline), etc. You will need to tell them everything about your engine HP goals, engine specs, fuel, fuel system, boost goals, etc. Oh yes, be sure to buy whatever you need from the pro that helps you!
Hot Air
I would probably make the stronger pump the first pump and the weaker pump the second pump. Having higher inlet pressure on the weak pump will help it flow more fuel if you keep the outlet pressure fairly low for the 2nd pump. Just be sure you have a capable fuel pressure regulator and an accurate fuel pressure gauge...ie a Procomp Autometer or equal.
You have calculated your fuel flow and pressure requirements haven't you? If not, talk to a professional. There are several I would trust...Jack (Cotton), Cal (Hartline), etc. You will need to tell them everything about your engine HP goals, engine specs, fuel, fuel system, boost goals, etc. Oh yes, be sure to buy whatever you need from the pro that helps you!
Hot Air
There was a board member that did this with an aeromotive pump as the first and a bosch 044 2nd.
http://www.turbobuick.com/forums/e85-technical-forum/308547-i-only-want-buy-injectors-once.html
Thread #34 was where he posted his results. There is a website that recommends running the weaker 1st and the stronger 2nd.
Bosch Motorsports Fuel Pump # 0 580 254 044 [BFP-044] - $189.00 : Jay Racing
I just wanted to hear if anyone had any success running 2 pumps in series and what was needed to make them work right.
Yes and no. I did speak with Mike at full throttle. He said if I did not push my turbo too hard , I could run 60's and e85. We all know a single walbro can feed 60's. I am thinking I would max out 60's somewhere between 21 and26 psi of boost. I have a scan tool but it does not tell me injector duty cycle. So I am not sure exactly when I will need 80's. If I would need 80's ,then I would need a larger fuel pump.
- Joined
- Feb 18, 2006
You can be successful running two pumps in series. I did this back when my intank could no longer keep up. As a quick fix I added a aeromotive a1000 inline. It works fine. The only problem you may have is fuel return line at idle and cruising. It may not be enough to return the extra fuel. You will know if you can't get fuel pressure low enough.
Thanks for your help Rick. Did you run a larger retun line to correct the high pressure issue?
- Joined
- Feb 18, 2006
I'm still using the stock return line. I removed the rubber hose from the line where it goes through the frame and drilled out the hard line a little. I got lucky. It worked.
HTH
HTH
The_Six
Active Member
- Joined
- Feb 28, 2009
So if I run the pumps in series both pumps need to be on all the time? And I shouldn’t have the 2nd one come on at a given boost pressure like the parallel pumps? And the restriction for the regulator return is not in the fuel rail but in the line after the regulator? Is the line from the regulator to the line in the frame the trouble or is the hole line from regulator to tank a trouble? I drive my car a lot I would use it as a daily driver if it didnt rain or snow so I dont want to be wareing things out from running the pumps all the time.
- Joined
- Feb 18, 2006
Both pumps have to run all the time if in series.
The restriction is the return line in the frame rail. Drilling out the frame line where the rubber line connects can result in some extra flow.
My testing has shown no problems with overheating the pumps. After a 100 mile trip the pump was cold to the touch. I concluded that the pump does not have to work very hard to maintain fuel pressure for normal driving.
The_Six
Active Member
- Joined
- Feb 28, 2009
Do you think it would help if you used one of these fittings and ran braided house to the regulator
Summit Racing SUM-2200077 - Summit Racing® AN to Tube Adapter Fittings - Overview - SummitRacing.com
Summit Racing SUM-2200077 - Summit Racing® AN to Tube Adapter Fittings - Overview - SummitRacing.com
- Joined
- Feb 18, 2006
Something like that would prolly help but I'm pretty sure the return line is not 3/8. You would need the same fitting on the line off the regulator.
- Joined
- Feb 18, 2006
If your going to run a new line, run a new feed and use the stock feed for your return. 
681tonburb, you may not have to modify your return line if you go with the bosch 044 fuel pump. The aeromotive pump at idle pressure appears to flow almost 100 lph more than the bosch. Turbo BuRick is useing an aeromotive pump as his second pump, thus he had to modify his return line.
