Anyone running 2 fuel pumps in series?

[turbobob924]

Great information!

I'm going to 80 and E85 on my GN. Maybe add my spare 044 Bosch pump inline.

I think the 60's will handle E85 on my hybrid as I will be running less boost.

 

[TomShea]

2nd pump inline

We used to do this as standard. Back in the day there weren't good intank or even other aftermarket Hi PSI and High Flow pumps. We used a 2nd pump in line and on constant. The trouble with this is if one or the other pump is, or becomes less capable. You can see where I'm going with this.

 

[TomShea]

2nd fuel pump

I don't know what happened to my last reply, but here goes again. It is possible to run a second fuel pump in line. That's all we had way back in the dark ages before the good aftermarket in tank and external pumps. The in-line 2nd pump was very common. The problem was that either pump could be a restriction to the other depending on several factors. We ran the pumps powered by a hot wire relay that was triggered by the same circuit as the first pump so they were both on at the same time. It is not an on demand 2nd pump like if using pumps in paralel that could be off until triggered by a hobbs switch. In response to the concern about the return line. I run a 1500 HP pump with a stock style regulator. I do use the stock feed line for the return and a -8 for feed. I don't have any problem with achieving low enough fuel pressure at idle. Therefore I can say the 3/8 size return line I am using is adequate for the flow without restriction.

 

[RobS]

In response to the concern about the return line. I run a 1500 HP pump with a stock style regulator. I do use the stock feed line for the return and a -8 for feed. I don't have any problem with achieving low enough fuel pressure at idle. Therefore I can say the 3/8 size return line I am using is adequate for the flow without restriction.

I found an article on the turbo buick website that has a chart showing when the stock return line will be overwhelmed.

Fuel Pressure Regulator Flow

I just have to convert GPM to LPH!!

 

[TomShea]

Gallons to liters

I now see all of the replies that were not available to me yesterday or even earlier this am. Hmmmm. Digression again. Back to the subject. I'm sure you know that 1 gallon = 3.8 liters. I wonder if there is some cute way to commit this to memory. Hmmmm, what can I relate 3.8 to?

 

[turbobob924]

Any more information on this?

 

[turbobob924]

Ultimately I need just 15% more fuel than the 340 walpro intank can support so in my case I see the Bosch 044 inline as the trick.

 

[turbobob924]

I also assume I will need to run separate relay for the Bosch in addition to the hot wire kit. The hot wire feed line S/B OK?

 

[RobS]

Ultimately I need just 15% more fuel than the 340 walpro intank can support so in my case I see the Bosch 044 inline as the trick.

http://www.turbobuick.com/forums/e85-technical-forum/276679-parts-way-2.html Post 39 gives some good info on pumps.

I also assume I will need to run separate relay for the Bosch in addition to the hot wire kit. The hot wire feed line S/B OK?

I was going to purchase a 2nd hotwire kit and connect the 2nd pump to it. I would make a ground wire for the pump and connect the low amp circuit of the hotwire kit to the 1st hotwire kit.

 

[The_Six]

Racetronix sell a universal hot wire kit i was going to use it to power the 2nd pump and jump of the stock wiring for the low amp circuit .

 

[TomShea]

Multiple fuel pumps

You can get a spool of 12 ga stranded copper wire for pretty cheap just about anywhere. 12 ga wire for a power lead is so close to as good as 10 ga that the voltage drop in 100 ft is only a nominal difference. 12 ga will use common spade connectors, and is much easier to work with. Radio Shak has 30 amp automotive relays for cheap. You can make a hot wire kit very inexpensively, compared to what you have to pay from a vendor. The Radio Shak relays are not weather proof, so they have to be placed under the hood instead of how the aftermarket (Weather Proof, Packard style) relays in the commercial kits are located, under the rear of the car. Trigger the pump relay with the grey wire with the (normally not used) black connector just behind the alternator. There are 2 open connectors in this area the other one is a double white wire with a green plastic connector. That is the tach lead. With the low cost in mind, it makes sense to run 2 separate power "Hot Wires" one for each pump. Don't forget to complete the circuit with the heavy ga wire for the neg side, or ground. The car body is the ground, not the frame. The tank body is the ground for the in-tank pump, and can be clamped at the flange but not drilled. The small ga wire running out from the sender will be over whelmed if you dont set up additional grounding for the intank pump, when using a hot wire there. The tank body should be connected to the car body with the same size wire that is used for the power feed. The external pump should be grounded to the car body. The Bosch pump that some of us ran as a second (in Line), worked well and lasted. It is a very cost and labor effective way to increase the fuel delivery at higher PSI. This is the real trick, since fuel flow drops off at higher pressure with all pumps. Some more than others. The dual, in-line (in series) will address this better than the parralel set-up. Keep in mind that running 2 pumps, (either set-up) will have it's own set of concerns, over running a single proper capacity pump. A single pump properly sized to supply enough fuel for good power will likely require some additional modification to the system, and therefore extra cost and work.

 

[Racetronix]

Walbro pumps in series and parallel

Some stuff I thought I would post again...

ME is a modified GSS340M pump which has its bypass valve blocked (i.e. XP)
Please see the attachments below for series and parallel pump data.

 

[TurboBuRick]

Nice!

If I am reading the graphs right, the DUAL IN-TANK IN PARALLEL GSS-340ME's is the way to go when you need big fuel. Or am I reading it wrong?

 

[Slow91z]

Looks to me like 2 340's pump WAY more fuel than the 340 392 system

 

[TurboBuRick]

Looks to me like 2 340's pump WAY more fuel than the 340 392 system

After looking at the charts a little closer, I changed my last post. :redface:

 

[Slow91z]

after looking at the charts a little closer, i changed my last post. :redface:

lol

 

[TomShea]

improved fuel delivery

In addition to my last post about wiring the pumps and tanks. It should go without saying that there should be an adequate fuse placed in line, near the source of power. Most use the alternator stud. I have seen some alternators with many extra loop connectors. If this is the case, consider making a remote junction block to connect extra stuff to. Use very heavy ga cable for the feed to this. Consider the 8 ga size that is the lead from the battery to the alt stud. Secondly, I see that the return line size is a concern, as it should be. The ability to lower the fuel pressure to the desired at idle will be the tell. The restriction in the return line is at the rear, not near the front or regulator. Check the lines that are above the right rear axle. There is a sheet metal heat shield there, covering 3 fuel line connections. These are soft (hose) connectors between the hard lines. The 3 lines from the largest are 3/8 fuel feed from pump, 5/16 fuel vent from tank, and the smallest 1/4 return line. This is probably the restriction, and there will be no way to avoid it except to route around it. I have used the stock feed line for a return. You can simply replace the filter with a short peice of hose or just remove and punch it out & replace it. You will have to modify the lines inside the pump hanger in tank. This set up is for an external pump, since the return line needs to take the route of the previous feed. I modify the hanger by adding an additional (Larger) pick up to feed the external pump. This does work well, contrary to what might be assumed by those that claim to know better. These guys might say that it wont work and you need a sump. Well guess what? They are wrong, and I'm the proof along with some others whose cars I have also set up this way.