Manual Selector Valves / Electric AND Mechanical fuel pumps

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bike-maker

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I've had people ask me about my fuel system, and have never started a post on it, just commented on others.
So here we go; I have been running this setup for about 4 years now, and it still works perfect.
I'm running a Carter P4070 electric fuel pump parallel to the stock mechanical fuel pump.
Props to MidnightRider for giving me this idea in the first place.
When I first set this system up, I wanted manual valves, the redundancy of two fuel pumps, was running a lot of WMO (which electric pumps don't like), but the ability to prime the system with the electric. So I kept the stock mechanical and added an electric along side it.

On the way to a family Thanksgiving dinner years ago, my stock fuel selector valve stuck in between the 2 tanks. It was pulling from the front, and returning into the rear, which overflowed the rear tank and dumped about 5 gallons of diesel along the interstate. After some redneck engineering to get me home, and a wonderful dinner at the kids table (some of the adults couldn't handle my stink from pouring a gallon of diesel down my shirt), I took out the FSV, "adjusted" it with a sledgehammer, and threw it in the garbage.

First off, the manual valves.
Ordered some from McMaster-Carr; Diverting 3-Port Bronze Ball Valves Part #4373K52; they were about $26 each.
Mounted them just to the left of the driver's seat so I could finagle the valves while driving.
Supply in front, return in the rear shown here with both switched to the front tank:

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And here with both switched to the rear tank:

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Another pick from underneath the truck:

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Also note I am running rubber lines everywhere - truck was converted from gas to diesel, so this was the easiest way for me. Both valves are identical, with the supply lines being 3/8", and the return lines are necked down to 5/16". Lines were extended from where the FSV used to be, over to the valves, and then back to the fuel lines running along the frame rail.
As far as making the stock fuel gauge work.....I'm running 2 aftermarket gauges, with aftermarket senders in the tanks.
The stock gauge could be switched between tanks by the stock tank selector switch in the dash after some wiring; but I went in a different direction, so I can't help anyone there.

Here's the electric fuel pump assembled and ready to go in:

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Notice the ball valve on the side going to the mechanical pump - so I can shut off fuel supply to the manual pump if it happens to rupture and start pouring diesel into the crankcase.

Just after the ball valve is a diesel rated check valve; there's another located just after the electric pump. The check valves isolate the two sides from each other. I got the check valves through my work, but they could also come from McMaster for a little less than $20 each.

Here it is installed on the frame rail, just behind the transfer case.

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The pump gets it's power from a relay in the engine bay that is triggered by a switch in the dash.
The line off of the pump goes up to the fuel filter, the other goes to the mechanical fuel pump, then up to the filter where they T together; just added a couple fittings to the inlet of the fuel pump here:

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So basically, I turn on the electric pump with the glow plugs, then turn the pump off as soon as the engine fires, and let the mechanical pump supply the fuel. In instances where I've lost prime in the fuel system, from things like changing the injection pump to just running out of fuel, having the electric is REALLY handy.

Also, by running 2 separate valves for the tank selectors, I can run the supply from one, and return it into the other using the electric pump. I can transfer fuel from one tank to the other, with the engine running or not. Has come in handy quite a few times.

The only issue I've had with the setup; you can't just leave the electric running along with the manual pump full time (not that you need to anyway). After it's left idling for about a minute with both pumps running, the fuel pressure to the IP starts to creep up enough that it starts advancing the timing. I'm not sure how much, but you can hear the engine start to clatter a little louder.
One of my current projects involves adding some fuel pressure gauges - one pre-filter and one post-filter - at which point I can keep track of whats really happening to the fuel pressure with both pumps running.

Otherwise, it's all ran perfect for a number of years now.

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lotzagoodstuff

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Very well thought out fuel system ;Sweet I gotta say that I would have never thought of running two fuel pumps in parallel, but it's really a great idea in regards to priming, redundancy, and running WMO. Being able to push fuel from one tank to another is pretty awesome too. When I ran WMO a few summers back, I was always guessing what my mixture was, and it would be pretty cool to be able to pump some diesel into your WMO tank to "thin it out" on the fly. Now if you put a polishing filter in the circuit, you could seriously use this feature to clean fuels by transferring them from one tank to the other. Might get a little tight for space depending on what filters you ran, but it would be pretty nice to know you could clean your WMO on board your truck.

I really like all the Parker stuff too ;Sweet particularly the aluminum swing check valves. The big over the road truck OEMs buy lots of them and they are really simple/nice/cheap.
 

franklin2

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Can you elaborate on how you used the aftermarket fuel gauges and sending units? We just had a question about using them, and I was wondering how you mounted them in your tanks and or what type of sending unit you used.
 

jaed_43725

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I will be doing something quite similar soon. Mine is stuck on the front tank. Although I may just convert to 1 tank and that being the rear. Eventually I will have enough cash to make that a 30 gallon rear and not care about it capacity. As it is the truck barely travels 50 miles when it does drive.
 

79jasper

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Looking good.
Only suggestion I have is maybe check or ball valves on both lines going into the filter.
Even if you close that valve at the pump, wouldn't it still back feed the steel line going to the mechanical lift pump, in turn still filling the crankcase with diesel?

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snicklas

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Good article, off to tech and stick. Will be locked to help integrity of info.

Thank you!!!
 
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