Fuel pumps

[Exekiel69]

I need help to understand how pumps work. I have a fuel volume problem I believe with My actual pump and I do not want to spend money on another pump so I thought about installing two pumps (both rated 10psi) on the same fuel line. Is there a problem with this? What happen if one pump eventually dies, will the other one still be able to pump through the dead one until I get somewhere I can replace the dead one? Or should I put a separate line for each pump so both pump fuel into the same fuel line?

Right now My fuel pressure is good but as soon as I put My foot in it the pressure goes down fast and the pump I have right now can take 15psi all day so I'd like to supply more fuel to it.

Any help is appreciated.

 

[NCheek]

What kind of pump are you running at present?

 

[Exekiel69]

The one used by carrier, it is a facet pump. I have a fuel pressure gauge at the IP and when the key is ON the gauge will read about 8-9 psi but once the engine is running it goes down to 4-6 psi and when I step in it hard it will go almost to 0psi so unless there is some restriction the volume isn't enough and I thought instead of buying another pump I would first use the several I have (two at the time) in stock.

So does installing a couple on the same fuel line (in series?) will affect anything if for some reason one quits working some day or can I just use it like that until I get to install another one in its place?


Thank You.

 

[NCheek]

I suppose you could run two pumps in series and not have to worry about potential crankcase flooding like a manual pump, but the pump closest to the IP is going to restrict the extra pump.

Do you happen to know the flow specs on the stock Cummins lift pump? The Carrier is rated for 30 GPH but it seems that the 5.9 is thirstier than that... Comparing numbers will be a good direction to get started.

It also seems like I read something about GenLightning drilling out part of his pump to improve flow. Have you done this? I'm going to review the thread where he talked about it and post back.

 

[NCheek]

I wonder if maybe the Facet would do better pushing? I may rethink my set up and move it down lower. Mine runs 6-8psi right off the bat ( we're in the 30*s here). May have something to do with differences in the Ford and Chevy plumbing?

As for enlarging the ports, I was only able to do the input side as the output fitting in the pump can't easily be opened up. There's been 2 failures with these pumps, both, I believe, were running WMO and the pumps were up higher. I wonder if running it down lower might be the key?

I did check with my supplier, and he really doesn't want to get involved with warranty issues But you should be able to take it to a Carrier dealer. Wish I could offer more help.

This I what I found...

Maybe finding a more Cummins-friendly pump is the answer.

 

[Exekiel69]

I don't know the volume required by the cummins IP but I read somewhere that it should have 3psi of pressure minimum at all times.

Now even if the pump closest to the IP restricts the one closest to the pump how would that matter if the pump is supposed to push fuel even if it is not needed and therefor create pressure.

You are right about buying a pump better suited for the cummins but to tell You the truth I'm tired of buying new pumps just to find out they don't pump as much as they should, so I thought I might as well use two at the time so if they die some day down the road I can use one that is really good. In all this years I have this pumps and they never died, they just don't pump as much. I'm not saying there is no restriction on the line from the tank but I just put a new one just in case so that is unlikely to be what happens here.

What if I install both pump in parallel would that be a problem if one of them die down the road. I want to use two pumps bc one of this is not enough but I want to do it in a way that will only help keep the pump with enough fuel all the time and if one of the pumps is dead have enough time to go to the next exit and replace the failing pump with a good one and carry on.

Thank You.

 

[NCheek]

Parallel looks like a more sound than series. While not as good as an appropriately sized sized pump, I would try it. If nothing else, you will have the same results as you did with the original pump.

 

[Exekiel69]

That is what I'll try first, two pumps should make the same fuel pressure but twice the volume in theory and I already have several of them enough to not want to buy a new one even if it is just as good all by itself.

Thank You.

 

[subway]

if its a fuel supply problem you might want to think about running larger fuel line. the 5/16 line is not all that large. you could move allot more volume more easily

 

[Dsl_Dog_Treat]

if its a fuel supply problem you might want to think about running larger fuel line. the 5/16 line is not all that large. you could move allot more volume more easily

Ez, I agree with Jared on larger diameter fuel lines as well. If changing the pumps has had no ill effect on supply, then I would tend to lean towards a larger delivery line.

 

[Exekiel69]

I agree, is it possible to drill the input on the fuel tank selector, bigger? That is about the only restriction I can think of on My setup.

Thank You.

 

[lotzagoodstuff]

FYI, the Carrier pump has 1/8" npt ports, which are probably a restriction. If you are running 5/16" hose barbs, your flow path is probably about .250". If you jump up to 3/8 hose barbs, you will most likely get another .030" of flow diameter. You could ream one out a little larger, but keep in mind that you would be thinning the wall and making the part weaker.

Although I think the Carrier pumps are high quality, I do believe the porting is too small. Generally speaking, you can't put "too large" a port on a pump, especially on the suction side. They probably didn't need it for their fuel sipper ****** applications, so they ported it 1/8" npt.

Two pumps in parallel would fix your supply issues, so long as you take all the restrictions out prior to the pumps and plumb larger lines when you tee the two pumps together.

Good luck

 

[Exekiel69]

Well I plumbed the two pumps in parallel today and man what a difference. It was easy since I keep one pump mounted on the frame in case the main pump dies and now I can see a steady 7-8+ psi idling and no less than 4-5 psi at full throttle.

I have a couple of filters before the pump so that will slow the flow a bit but it is much better than one pup alone.

I guess now I'll start the search for a pump that is set to 10psi but can bring twice the flow. Anyone know of a good one?

Thank You.

 

[lotzagoodstuff]

Holley Blue pump: 110 gallons per hour unregulated, should be around 14 psi. Regulated to 9 psi should be around 90 gph. Should be more than enough, I have one on my racecar which certainly thirsty.

 

[subway]

Barney stepped up to the holley blue from the red when he had fueling issues like you. if you have a red the only differance between that and the blue is the regulator spring.