Two Stock Lift Pumps

[Turbine Doc]

Woody I guess the answer you are looking for is yes, 2 might do a better job than 1. I'm not convinced you need 2, but the redundancy is certainly worth the 45 bucks even if you don't see a difference from the fuel flow. I don't think you answered earlier, do you have a fuel pressure gauge?

99% of time 1 lift is plecould get to a nty, I normally run my Heath h/o (OEM style) and secure the Walbro, if towing moderate I run the Walbro. What prompted FTB and dual lifts was watching lift pressure fall off, EGT & rpm not climbing a hill when loaded and I was a max throttle sustained the set speed but as I climbed the grade I started falling off 70 mph to 55 all green parameters I , had the engine but not the fuel.

FTB 1st, opening to full flow out the FM to the & @ the IP was an improvement, but I still could use more fuel to keep from dropping fuel to 0 psi to IP,bigger lift (walbro) then parallel was ticket for me, but I can tow to 18K when I am hooked up to my backhoe on my g/n trailer.

When hauling a camper I could see similar load/loss of power not from weight, but "sail area" wind drag of high frontal & sides of a camper of any size with exception of a "pop up" that would be lower than the truck pulling it.

A necessity for most, no; if you want maximum performance from your 6.5 yes.

 

[Turbine Doc]

sorry i didnt answer i do not. but when i floor the truck at a complete stop there is a slight delay like the turbo stopped spooling for a milisecond then all hell breaks loose and i think that is from not having enough fuel pressure to support the ip's demands. nothing like that when i roll into it

Woody for about $20 of tubing and using same test gage as you use to trouble shoot a weak lift as in the reference area, you can temporary run a gage in the cab and know if low lift pressure/feed is an issue for you. Turbo lag could be weak vac system, that same gage can be used to verify that as well, I had a pinhole in the diaphragm of wg actuator on side of my GM-8 back in the day that would cause lag you describe also.

IMO every 6.5er needs a vac/press test gage, a volt meter for checking gnds/volts, and a load cell for testing batts as part of their routine tool/survival kit

 

[Woody35]

got the volt meter and load tester but i need the pressure gauge. vac system is 6 months old so i kinda doubt that is the problem but you never know. thanks for the info again

 

[Turbine Doc]

Tee into the line for WG actuator supply after solenoid look for vac there, if all good there, then put a mitey vac or similar on the WG can to see if it holds vacuum

 

[NVW]

I would personally put them parallel if they are running at the same time. That way when one fails it won't lose some flow due to pushing or pulling fuel through the other pump.

 

[buddy]

Well, turbos dont really spool at idle from a stop, thats called turbo lag, so it takes a moment to get your power. While moving the turbo may at least be spooling more at some higher RPM.

The one thing you need to know is it doesnt matter what a pump is rated at if its not pushing that much volume anyway. The ratings are a capacity, not a fixed value, this is not understood by everyone. So there is no flow difference with these in parallel or series at the same pressure with the same diameter hose and same IP demand/restriction, if both exceed the demand. Whether its 10psi and 50GPH or 10psi and 100GPH, if the demand is only 20GPH they both push the same flow. You may actually get more flow from a lower rated GPH with higher pressure as long as it exceeds the demand, because the IP bypasses some fuel and at a higher input pressure it might put more back to the fuel tank quicker.

Since they are flow on fail pumps and the IP can pull fuel through them I think even in case there is a failure it will be fine.

 

[Dave01]

I've wondered about the quantity that gets bypassed and returned to the tank. I've never thought it was much, but also have never pulled the return line to look.

I had a stock LP, then a Walbro, now a Raptor. With the Raptor my fuel pressure stays much steadier, still drops but only to maybe 5 psi under load. I assume I bypass more fuel with this pump, but it's just a guess, I don't know for sure. This pump should be delivering more, and steadier, fuel flow to the IP, but since what I see is only pressure, not volume, hard to be sure.

 

[WarWagon]

What are your thought about adding a second stock lift pump inline with the other one already there. My uncle works at the parts store so i can get them pretty cheap. I already got the FTB

Inline is like 2 12v batteries making 24v aka PSI. (600 amps at 24v) Parallel is like 2 12v batteries making 12v and 1200 Amps aka GPH.

One pump has the valves fail in parallel and you loose all pressure. Likely with bio diesel.

 

[Dave01]

Inline is like 2 12v batteries making 24v aka PSI. (600 amps at 24v) Parallel is like 2 12v batteries making 12v and 1200 Amps aka GPH.

One pump has the valves fail in parallel and you loose all pressure. Likely with bio diesel.

I don't agree - two batteries in series makes 24 volts as you say, but two 7 psi pumps in series makes 7 psi, not 14. The hope is that they will maintain that 7 psi under load better than 1 pump, meaning they are feeding more volume.

 

[buddy]

But if your 24V with 2 12V batteries in series at 600amps are only feeding something that needs 100Watts, that means its only drawing 4.2 amps so it doesnt matter that another battery is rated at twice that capacity in amperage, it wont feed that draw any better. And with electrical current a lower voltage will need more amperage capacity because Power (Watts) = Voltage x Current. So you need double current to get the same power if the voltage is half which applies to electical current and not so much fluid flow. With lower current you get less voltage drop across long distance which is why commercial power comes across power lines at like 10,000VAV, and the transformer steps it down to 120VAC. It is the demand that needs to be considered.

If a pumps pressure rating is determined by a pressure differential then putting them in series could bump the pressure to double. because the first one will go from suction to 7psi and the other may see ambiant/atmostpheric as being 7psi and the dead head push to 14psi, a 7psi differential across it. Not all may work that way though.

 

[Matt Bachand]

Series will build higher pressure, but it will drop faster due to flow demand.

Parallel should build less pressure, but it should not fluctuate as much.

Probably same flow, just in different PSI when not in true demand?

 

[Turbine Doc]

I've wondered about the quantity that gets bypassed and returned to the tank. I've never thought it was much, but also have never pulled the return line to look.

.

Should not be that much extra remember the Walbro & GM pumps are self regulating if there is no place for fuel to go the pump stops pumping which is part of the pulse you see on a gauge