Electric AND Mecahnical fuel pumps

Finally got my electric fuel pump installed.
I ran a Carter fuel pump parallel to the stock lift pump. I put ball valves before each of the pumps and check valves right after giving me the ability to run off of either pump by itself, or use both of them. A few people didn't like the idea due to the additional possibility of fuel leaks, but I'm pretty happy with the fact that it will take some seriously bad luck for me to ever be stuck on the side of the road with a bunk fuel pump. And my truck is starting better because I can purge the air out of the system before cold starts, which masks the leak I have somewhere (I am aware that I band-aided it instead of finding and fixing the actual problem).
First pic is before installation (and before I added the second ball valve), second pic is the whole setup bolted to the frame rail just behind the transfer case, third pic is a couple of fittings I added to the fuel filter head to add the second fuel line.

Nice setup! I really like that idea of having a backup electric pump if the mechanical one goes bad. Also nice to have for purging the system after swapping fuel filters too. Speaking of which, ditch that Fram!!!

I knew somebody was going to give me flack for the Fram filter. Only one I could find at 8:30 on Sunday night......

I have been running parallel electric and mechanical pumps for several years.

To better help understand the principle, here is a description :

Think of the original fuel-line in front of the mechanical lift-pump as if it were a model rail-road track; this line between the fuel-tank selector and lift-pump is the main-line RR-track.

Now,we are gonna install a "passing siding", such that our trains can go around the lift-pump.

To accomplish this passing siding, we install two track-switch-turnouts (TEEs), one ahead of and and one beyond the lift-pump, plus track (fuel-line) that connects these turn-outs.

Of course we install our electric-pump within this passing siding.

Now, our trains (fuel) can take either track (fuel-line), the main-line track through the mechanical lift-pump, or the passing siding through the electric pump.


Now, since we only want our trains (fuel) to take the selected route, and we want to be able to accomplish this from our centralized dispatching center miles away (in the cab), we need to install some block signals (check-valves).

Since it is possible for a diaphragm lift-pump to rupture and pour fuel into the oil, we are gonna need a check-valve on both sides of the mechanical lift-pump; thus, fuel-pressure from the electric-pump cannot be forced backwards through the lift-pump and into the crank-case, nor can the engine oil get sucked through the ruptured diaphragm and burned with the fuel.

To prevent the ruptured lift-pump from pumping fuel into the oil while the electric-pump is running the engine, ONE cut-off valve is gonna be needed immediately ahead of the lift-pump.

The only occasion that would require this cut-off valve be closed is should the diaphragm rupture; all other use of the electric pump can be accomplished from within the cab merely by turning ON or OFF the electric -pump; the check-valves take care of the rest.



Now that we have an electric-pump, we can get fancy and install another TEE fitting, then a cut-off valve, then a female quik-couple.

Make a fuel-hose as long as possibly necessary with the matching male coupling on one end.

I use plain old brass air-line quik-couples and thus far have not had any issues with incompatibility with fuel.

Now, we can connect our hose to the quik-couple, open the valve, turn ON the pump, and pump fuel from the truck and into a sippie-cup, BALL fruit-jar, or D-8 CAT dozer.

This little convenience often becomes handy, besides the factor when you show it off to envious onlookers.

I've been contemplating this as well lately. I have the electric setup but if I do decide to run moderate WMO the lift pump would be worlds better

MIDNIGHT RIDER said:

I have been running parallel electric and mechanical pumps for several years.

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Where do ya think I got the idea from? Thanks, by the way.
I liked the idea of running an electric pump, but wouldn't trust one pumping WMO all the time.

After reading your railroad analogy, I realize that if my lift pump was to rupture and puke fuel into the engine, the electric pump would back feed the lift pump through the junction in my filter head. To fully cure this, I should probably add 2 check valves or ball valves on the other side of each of the pumps to fully isolate them from each other

>>> LET'S PUMP SOME FUEL <<<

bike-maker said:

Where do ya think I got the idea from? Thanks, by the way.
I liked the idea of running an electric pump, but wouldn't trust one pumping WMO all the time.

After reading your railroad analogy, I realize that if my lift pump was to rupture and puke fuel into the engine, the electric pump would back feed the lift pump through the junction in my filter head. To fully cure this, I should probably add 2 check valves or ball valves on the other side of each of the pumps to fully isolate them from each other

Click to expand...

You are gonna really enjoy that electric-pump set-up.



I really like all of the useful advantages of my by-pass electric-pump and it will perform many tasks that the mechanical-pump cannot; however, I have never really trusted electric-pumps to be the main delivery-pump.


I also prefer the CARTER; I have dozens of Holley REDs, BLUEs, and BLACKs, that I use on all sorts of fluid-transfer projects, and for back-up pumps on less important trucks; but, I just do not trust the Holleys nearly so much as the Carters.




As for mechanical lift-pumps, I still believe that if research and trial-and-error were performed, we could come up with a piston lift-pump such as that used on the Cummins, that will work on these IDI I-H engines in place of the diaphragm-pump.


Besides delivering tons of fuel volume with authority, and throwing a heavy pulse of fuel with each stroke of the inclusive manual primer-pump, by design --- there is no way for fuel to leave the piston-pump and enter the crank-case --- they have no diaphragm to rupture.


As far as I can tell, the mounting bolt-pattern of mechanical lift-pumps is pretty much standard on all commonly used engines, both gas-burners and diesels.

The piston-pumps do not have a weird shaped operating lever; they have, instead, a straight in-and-out plunger-rod that rides the cam-lobe.

The piston-pumps stroke to cam-lift ratio is adjusted by the use of mounting-flange spacers; for use on the B-series Cummins, a 3/16" thick spacer is used.


I see no reason why, armed with the cam-lobe lift dimension and it's distance from the pump's mounting surface, that a piston-pump could not be used on the I-H engine.

Here is a picture of a piston-lift-pump :

http://www.oreillyauto.com/site/c/s...ake=Dodge&model=Ram+2500&year=1995&vi=1095814


That one is pictured upside-down to the way it sits when mounted.

The red cap shown at bottom is the fuel outlet.

The center red cap is the fuel inlet.

The black button above the inlet is the manual fuel primer-button.

The mushroom-tipped rod on the left side is the plunger that rides on the cam-lobe.

The pump pictured is manufactured by Delphi; whereas, all of the ones that I have are manufactured by Carter.


Also, the part-number of the pictured pump is for the 30-PSI 2nd Gen. Dodge/Cummins; the Cummins part-number for the low-pressure piston-lift-pump that would maybe work on an IDI is Cummins 3936320.


That pump looks a bit more that a wimpy diaphragm-pump, does it not ??

Here is another view of a different brand of piston-pump :

http://shop.advanceautoparts.com/we...tex_18770616-P_52_R|GRPFUE2AMS_1539455271____


That pump has a more impressive looking primer-button (the black accordian gizmo) than the Delphi pump.

It also is not shown oriented as it would be mounted.



Another feature that I find curiously lacking on the I-H IDI diaphragm-pump that is commonly included on just about every other diesel engine made is a hand-operated manual priming-lever; everything else diesel has them.


Here is a picture of a standard diaphragm-pump that DOES HAVE the manual priming-lever:

http://shop.advanceautoparts.com/we...x_3141632-P_52_R|GRPFUE2AMS_1539438762____BBV


I believe that pump is also pictured upside down.

The priming-lever is that little handle-thingie that is on the side of the pump housing and in line with the cam-lever; it works the pump the same as if the cam were working it.

Man, lotsa good ideas there. I really like the idea of using one of those pumps, but it's hard to argue with the price of a standard replacement lift pump, especially when trying to ruin it with WMO.
I think the only thing left to do to my fuel system is junk the stock electric tank selector valve in favor for 2 mechanical ones (yet another idea copied from Midnight). I'll try to find 4 way valves for both the supply and return switches, thus enabling me to eventually install a third in-bed tank, or in the mean time use the 4th port for pumping fuel out of the tanks and into a container. The 2 seperate valves would also enable me to transfer fuel between tanks without leaving the driver's seat.

just for what its worth you are going to love that carter pump. I ran a holley black with my setup and have it mounted in the same location as yours. The holleys are all solid mounted and i feel had an influence on the little 7 months mine lasted before it pooped out. I installed the 18psi Carter pump and love how it comes with its own plate and mounts with rubber isolaters. Its even quieter than my Holley was. I deleted my lift pump just because my VE pump loves to eat way more fuel than that little lift pump ever could put out. Good looking setup man.

My electric pump is mounted just behind of and directly under the driver's seat. You can't hear it over the sound of the engine even at idle..............and the clutch disengaged (makes a BIG difference on my truck).

bike-maker said:

I knew somebody was going to give me flack for the Fram filter. Only one I could find at 8:30 on Sunday night......

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Hey its all good man, just was giving ya a hard time about it. Its at least something until you can get something a bit better. Avoid the NAPA store though...$45 for a filter in my area.

http://www.fleetfilter.com/mm5/merc...fleetfilter&Product_Code=33617&Category_Code=

I like that price better.

Btw, I REALLY like the ideas for adapting a different mechanical lift pump to these engines like Midnight was suggesting. Not only would it make the system prime-able, but it would also enable us to eliminate one of the failure points in these engines.

If someone who has a block dis-assembled enough that they could rotate the cam and get measurements of the low and high points on the fuel-pump lobe, then a bit of measuring of the piston-lift-pump stroke and some math should yield all the information necessary to make one of them work.

It is no biggie if the bolt-pattern were to be off as a little slotting of the holes should cure that.


Actually, I am surprised that I-H doesn't use the piston-pump on these engines in other applications, like maybe in the big U-haul trucks or school-buses.

HMMM Verry good idea.... I have a block with a cam in still, I will look into that myself. I like the look of that piston pump. I was thinking of a electric pump to replace the manual on my motorhome aplication, but I am also a little leary of electric only.

racer30 said:

HMMM Verry good idea.... I have a block with a cam in still, I will look into that myself. I like the look of that piston pump. I was thinking of a electric pump to replace the manual on my motorhome aplication, but I am also a little leary of electric only.

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Like I earlier said, spacers are added behind the mounting-plate to adjust the pump's stroke to be compatible with the cam-lobes lift.

On the 6BT Cummins, a simple 3/16"-thick spacer is used.

Using a spacer requires the use of TWO gaskets, one each side of the spacer.

Some engines do not require a spacer; some others require differing thicknesses of spacer.

Thus, by adjusting the pump stroke to work with cam lift, these piston-pumps can be fitted to just about anything.

The operating rod tip actually rides the cam-lobe, so the lobe would need be pretty much straight in through the hole.

They are standard issue on 2nd Gen. Dodge/Cummins, but be aware that that particular part-number puts out a steady 30-PSI --- way too much for our needs.


The Cummins #3936320 is about ideal at around 15-PSI.(or is it 3639320 )

They make them as low pressure as 7-PSI, maybe even lower.


A good way to see if they are even feasible would be to just pick up one for a 1994-1997 Dodge/Cummins; keep it clean and hang on to the receipt; try it for fit and feasibility; then, return it and get your money back.

Or, if you are in really good with someone at the parts-store, just tell him what you are doing and he will probably just loan you the pump.


The outward dimensions and mounting pattern are the same for all of the piston-pumps; any changes in output PSI are accomplished internally.


Actually, I am surprised that this modification hasn't been in common use around here from way back.

racer30 said:

I was thinking of a electric pump to replace the manual on my motorhome aplication, but I am also a little leary of electric only.

Click to expand...

If I were using an electric-pump as my sole means of propulsion, I would use TWO installed it tandem; such that, should one fail, all I need do is flip the switch that turns the other one on.