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Fuel Pumps And Headaches

digginfool

digginfool

Well-known member
Ever since I went to the LSA in 2015, I've been running an Aeromotive A1000 Marine fuel pump with a Racor Water separator on the inlet side as well as the Aeromotive 100 micron inlet filter. I got a little over 400 hours out of the first pump before it failed. I sent it in to be rebuilt and purchased a replacement pump, that way I would have a spare. The new pump didn't even make it 100 hours before it failed (metal particles clogging up the 10 micron output filter causing low fuel pressure, forcing the engine into limp mode). I replaced that pump with the rebuilt original pump, sending it in for its own rebuild. The rebuilt pump didn't last 10 hours before failing in the same manner. I spoke to a tech at Aeromotive and while discussing the problem, he asked about my setup. He then advised me to move the water separator to the output side of the pump. This seemed very odd to me, especially thinking about what 65 psi might do to the seals on the filter housing and how fast the pump could empty my tank or cause a fire should fuel start leaking out. I'd never know until I felt the heat or ran out of gas as the fuel pump and water separator is mounted low under the seat rigging. Out of an abundance of caution, I went to the Racor site and found the maximum operating pressure for my water separator is 7 psi. Damn good thing I didn't do it. Now, that all being said, I still have this problem. TBH, my fuel tank is not sumped and I'm pulling from the top through a 3/8" pickup tube. I know this is not exactly an ideal setup, especially with the added vacuum head of the water separator and inlet fuel filter. I'd be happy with the 400 hours I got the first time around but can't live with sub-100 hour lifespans. I've thought about adding a low pressure lift pump for some time but one that matches the flow of an A1000 is pushing $400.00 on its own. It would be a huge job to replace the fuel tank for one that is sumped but if that's the path I have to take, I guess it is what it is. Any thoughts on using a lift pump as opposed to a sumped tank? Any alternative ideas out there?
 
Diggin,

This is an item on my list with my new build. If you follow CG requirements, you end up basically where you are (fuel pump above tank) or you have to have a fuel pump in the tank. Anti-siphon (where required) valves only make the pressures in the fuel lines similar to mounting above the tank. It does not take much to clog the filter on the suction side of a HP fuel pump.

Fuel pumps mostly fail due to issues on the pickup (suction) side, the in tank fuel pump is the best way to resolve.

On my new build I intend to install a primary fuel pump in the tank (Like k2p suggested) with a backup plumbed in outside and accessible. Fuel filter will be in the high pressure line and needs to be rated for same (I haven't got there yet, let me know what you come up with).
 
Ok, went through this with Butch Avon's and Frank Chirino's build, same pump, the pump is cavitating due to too small of a pickup, you need at least 1/2" ID " dash 8 or even better dash 10" line to feed a 10 micron pre filter, through pump to post filter of 100 micron, to a regulator that will supply the pressure needed plus return to tank which keeps the pump cool due to the recirculation back to tank, and at tank level, let it force it up to the fuel inlet of engine, if engine has a return from fuel regulator, run that through the racor "if you wish" back to tank.
 
Found a picture of Frank's setup, this is running a 6.2 supercharged LT-4 flawlessly.
 

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John Fenner said:
Ok, went through this with Butch Avon's and Frank Chirino's build, same pump, the pump is cavitating due to too small of a pickup, you need at least 1/2" ID " dash 8 or even better dash 10" line to feed a 10 micron pre filter, through pump to post filter of 100 micron, to a regulator that will supply the pressure needed plus return to tank which keeps the pump cool due to the recirculation back to tank, and at tank level, let it force it up to the fuel inlet of engine, if engine has a return from fuel regulator, run that through the racor "if you wish" back to tank.
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It's funny you say that, John. I actually thought about putting the separator on the return feed sometime around 3 this morning while I laid in bed awake trying to solve the world's problems. LOL It was either that or removing the 100 micron inlet filter and let the Racor do the primary filtering. It's kind of silly having a 100 micron filter/separator feeding a 100 micron inline filter. Either way, I need to reduce the vacuum head on the inlet side the way I'm currently running it. I'm running -10 lines already. I know the pickup tube is too small but replacing it requires surgery as well (the 3/8" line is as big as it can be; nothing larger would fit through the current bung). The fuel pump is on the bottom of the boat, as low as it can go so kind of stuck with either a sump or an in-the-tank pump as K2P and Slidin Gator suggested. It seems that no matter which path I take, it's time to crack the piggybank open. That and find a fabricator that won't mind working on a fuel tank, although installing an in-the-tank pump is something I might be able to handle on my own since it shouldn't require anything more than cutting a proper sized hole in the top of the tank and drilling some holes for the mounting. Thanks guys. I appreciate the comments.
 
I have a few boats running with the FST RPM350 fuel filter on the high pressure side (~70 psi) with e85, it has a burst rating of 250 PSI. http://www.fstperformance.com/#!rpm350/c1wg7 It also gives me a convenient location to put my fuel pressure sensor. Note: Once you remove filter, the o-ring swells and you can't get it back on so, don't do it in the woods without a replacement.

Like stated before, pump needs to be as low as possible, preferably below the fuel level or you should run a lift pump or in tank setup.

My preferred setup is in-tank pump to RPM350 to ethanol sensor to fuel rail. No regulator because I am using the Fuel Pump Control Module. I have had customers play with the fuel pressure after I tune which changes AFR. Only fitting below deck is on the fuel pump hat.
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digginfool said:
Nice and clean. Looks to be about the same height as my fuel tank. Did you have to use the extension risers with that?
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I did, I just broke a longer piece of aluminum, replaced the one it came with and extended the wires, it's a 60 gallon tank.
 
Greg this is my set up and have never had a pump failure after doing it this way. I have 10An feeding both pumps. The front pump is just a back up pump but I haven't needed it. I do run it ever so often just to make sure it's working if I ever do need it. With that said you know how many hours I use to put on my boat each year. The pump will never survive pulling from the top of tank and with a 3/8 fuel line. I like the in tank pump that FOzzy2 did but I want everything out front and easy to get to with how much I was on the water running the boat.
 

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Coast Guard requirements for all enclosed fuel plumbing (as in a deck over) call for means to prevent fuel leakage from tank through fuel system when engine is off. On a fully primed system, any point below the tank fuel level presents opportunity for siphon leakage from the tank and into the hull. They give 3 options:

1: Run all lines, pumps etc. above the top of the tank
2: Install an anti-siphon valve at tank connection to feed runs below the top of the fuel tank
3: Install an ignition switch activated shut off valve at tank outlet to feed runs below the top of the fuel tank

Option #1 is the optimum, using an in-tank fuel pump.
Option #2 is sure to cavitate an HP pump and requires a lift pump prior to feed. This is not a good option.
Option #3 works great to feed pumps down low, but the valves are expensive and more complication.

My thinking is to go option #1 with in-take pump. My experience is that any back up pump I install will be rotted out by the time I need it. So I will add a 3/4" bung to the bottom of the tank with metal tubing to an access point, screw in a ball valve and plug the outlet. I will carry an external back up pump and plumbing I can field repair quickly.
 
You are 100 correct Sliden Gator. On the plus side thankfully we are exempt from Coast Guard regulations. I set mine up with shutoff valves. I personally only added the second pump for back up because I was putting well over 500 hours a year on my boat. From my experience customers are not usually too happy having to wait and watch me working on the boat when they are on vacation and paying.
 
Slidin Gator said:
My thinking is to go option #1 with in-take pump. My experience is that any back up pump I install will be rotted out by the time I need it. So I will add a 3/4" bung to the bottom of the tank with metal tubing to an access point, screw in a ball valve and plug the outlet. I will carry an external back up pump and plumbing I can field repair quickly.
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Or even easier, do like I do, and carry a spare for the in-tank. It's like 8 nuts to pull the in-tank system out and a couple worm clamps to change the pump.
 
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