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Old 04-09-2021, 09:52 AM   #1
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School me on FL120 fuel pumps...

On our CHB41, I have two tanks feeding a valved manifold, which then feeds the two engines through parallel systems, each comprising:

1. Algae-x "bug killer". I strongly suspect these are BS & am thinking of removing
2. Carter electric fuel pump
3. Racor duplex filters
4. Engine lift pump
5. Engine series fuel filters
6. Injector pump

I've tried running with the Carter fuel pumps on and off. On our trip to Catalina, I had a couple of instances where the port engine bogged down unexpectedly while the Carters were off under steady conditions, then came right back up. On the return trip I left them on & didn't experience the issue. I actually made it down to the engine room while this happened once, and didn't see any movement on the pressure gages at the Racors. Previous owner had recommended running with the Carter pumps on, but that seems redundant to the engine lift pump.

I'm trying to figure out what could have caused the bogging, and whether my current installation should be modified. I'm going to run through the whole system for spring PM in the next month or two & can modify at that time if necessary.

Thanks!
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Old 04-09-2021, 10:30 AM   #2
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First get rid of the Algae X system. You are right, it is BS. Then you may get by without the electric pumps.

Your engine stalling problem could be related to a restriction in the Algae X system.

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Old 04-09-2021, 10:45 AM   #3
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What do you mean by bogging? Low RPMs for throttle setting? Unstable RPM/fluctuation? Change in smoke color or volume? Change in sound or vibration? Etc?

How did it transition into this state? Sharply or gradually? What about recover?

My 1st thought in these situations is always filters, even if changed recently. This especially includes water in the bowl, a sticking ball valve, or debris in the separator.

My 2nd thought is the lifter is marginal and needs rebuilt.

My 3rd thought is fittings, especially 90s, where I've found clogs with teflon tape (never....).

My 4th thought is rubber lines which can start to peel from the inside.

My 5th thought is a suction leak somewhere between the lifter and assist pump.

Happy hunting!

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Old 04-09-2021, 10:47 AM   #4
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As for the Algae-X....we have a saying in software...

Novice programmers add corrective code...
Experienced programmers remove defective code.

I've never seen an engine experience problems for lack of an AlgaeX...

:-)

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Old 04-09-2021, 10:48 AM   #5
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There is at least a million F.L.s out there which run with twin (or single) Racors, lift pump, secondaries and injector pump (in that order). I just don't see any need for the electrics unles it is related to your "Algae X installation.

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Old 04-09-2021, 11:03 AM   #6
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Thanks all. This is great.

Quote:
Originally Posted by gkesden View Post
What do you mean by bogging? Low RPMs for throttle setting? Unstable RPM/fluctuation? Change in smoke color or volume? Change in sound or vibration? Etc?
It happened a couple of times: cruising along at 7.5-8kts, engine revs matched by ear. Port engine just starts to lose RPMs as if I'm cutting the throttle. Once it slowed down and died. Luckily it started right back up and was fine after that for the rest of the passage.

I'll certainly remove the Algae-x, go through the filters, lines, etc. & check the Racor ball valves, etc. I do wonder if the Carter electric pumps were put in as a band-aid to something else (maybe back pressure from the algae-x?).

I've heard that the FL120 lift pumps can be an issue & should be replaced regularly; I'll do that as well. Has anyone blanked them off & relied on electrics instead? I've heard some like the electric lift pumps for priming, so not sure if I want to pull them out.
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Old 04-09-2021, 11:05 AM   #7
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A magnetic fuel conditioner???

"Operating on the principle of induction on the process of combining kinetic and magnetic energy to influence the behavior of electrons, the LG-X Series Fuel Conditioner provides a powerful magnetic field and the flow of fuel provides the kinetic energy."

I think I'll stick with my annual bottle of biobor
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Old 04-09-2021, 11:08 AM   #8
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A magnetic fuel conditioner???

"Operating on the principle of induction on the process of combining kinetic and magnetic energy to influence the behavior of electrons, the LG-X Series Fuel Conditioner provides a powerful magnetic field and the flow of fuel provides the kinetic energy."

I think I'll stick with my annual bottle of biobor
Yeah no kidding. It's a flux capacitor. I'll have fun pulling them apart to see if there's really anything at all inside (other than maybe a ball of teflon tape )
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Old 04-09-2021, 11:17 AM   #9
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The curious thing to me is that the engine restarted right away. Does that mean without the electric pump and with relatively few turns?

If that is the case, I suspect an obstruction before the lifter pump after which a vacuum is able to develop and overcome the lifter...but not the lifter with the assist pump.
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Old 04-09-2021, 11:23 AM   #10
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Our single Ford Lehman has an algae-x installed by a previous owner. Sceptical about it’s usefulness but left it in the system. Never thought it might be creating an obstruction. We do not have an electric fuel pump, just the lift pump. Suspect your problem may be a failing lift pump or clogged filters, etc.
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Old 04-09-2021, 11:26 AM   #11
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Quote:
Originally Posted by gkesden View Post
The curious thing to me is that the engine restarted right away. Does that mean without the electric pump and with relatively few turns?

If that is the case, I suspect an obstruction before the lifter pump after which a vacuum is able to develop and overcome the lifter...but not the lifter with the assist pump.
Yes that's right - no electric pump & re-started immediately.
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Old 04-09-2021, 11:35 AM   #12
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where does one hear Lehman fuel pumps are an issue and need to be replaced regularly?
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Old 04-09-2021, 11:46 AM   #13
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Quote:
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where does one hear Lehman fuel pumps are an issue and need to be replaced regularly?
A couple of folks on this forum had advocated the lift pumps be replaced as PM every few years as I recall. Some had raised concerns that the diaphragm could fail, which would fill the engine with diesel.
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Old 04-09-2021, 12:12 PM   #14
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The diaphragm could fail at any given moment after new out of the box.


So get rid of it all together and use electric pumps or think that they are like many diesel parts made to last a decade or more (and often do).


Haven't noticed an abundance of reports of failed lift pumps nor do I recall it being a priority item by American Diesel or BOMAC for regular replacement.


What interval? Unknown to me whether it be time or hours...but I seriously doubt it needs replacement every couple of years. It may be a weak spot so going electric may be a good answer anyhow.
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Old 04-09-2021, 12:47 PM   #15
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Quote:
Originally Posted by DavidM View Post
First get rid of the Algae X system. You are right, it is BS. Then you may get by without the electric pumps.

Your engine stalling problem could be related to a restriction in the Algae X system.

David


I had fuel problems 3 years ago. Installed Holly electric pumps and removed the lift pumps. PROBLEMS solved.
The Algae X is pure BS!
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Old 04-09-2021, 01:29 PM   #16
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Excepting the AlgaeX thing, I ran a similar system with my two FL120s. When my electric "priming pump" was installed between the tanks and the Racors, a valved bypass line was run around it to avoid the pump's screen becoming a restriction. When I started having engine shutdowns due to air ingestion (just about a 100 percent your problem), I would go below and close the pump bypass valve and opening the appropriate vale to pressurize the appropriate Racor before switching the pump on. Then it was a simple matter of bleeding the injector pump which was under pressure. I would leave the pump running until end of voyage. Eventually, that air leak was tracked down to a crimped o-ring under the Racor tee-handle, but you have been given a number of other places to look as well.

BTW, the reason the electric pump was installed was to enable me to fill the Racors (which were mounted high in the engine room) whenever I had occasion to open them with fuel levels at anything less than nearly full. Prior to that, I carried a gallon jug of fuel. It turned out to be invaluable for a number of reasons.
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Old 04-09-2021, 03:08 PM   #17
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I had a situation making a 12 hour run with my Lehman 120. I have a small 26 Groverbuilt so I run at higher RPM than a trawler. (Run 2200 at cruise)

The engine RPM started to “hunt” (vary slightly up and down) then it basically because it starved for fuel and ROM dropped and then conked out in about 3-5 seconds.

I checked my fuel gauges, tanks, for a minute or two, then tried to start her up. Fired right up, ran for 5-10 min, then same thing occurred. Checked all my fuel lines etc..... then did the whole cycle again.

It was a nice calm day, so I started going through the fuel system. The only hint I got was when I opened the racor filter top, I heard a “hissing” sound. That meant that my line blocked was aft of the primary filter.

The only thing saw was an electric auxilliary fuel prime pump that was plumbed into the system to help fill fuel filters after changing. (I never used it, and it was on my “things to do list”)

I just removed it and it fired right up, and problem was gone.
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Old 04-09-2021, 03:12 PM   #18
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Quote:
Originally Posted by Alisske View Post
I had a situation making a 12 hour run with my Lehman 120. I have a small 26 Groverbuilt so I run at higher RPM than a trawler. (Run 2200 at cruise)

The engine RPM started to “hunt” (vary slightly up and down) then it basically because it starved for fuel and ROM dropped and then conked out in about 3-5 seconds.

I checked my fuel gauges, tanks, for a minute or two, then tried to start her up. Fired right up, ran for 5-10 min, then same thing occurred. Checked all my fuel lines etc..... then did the whole cycle again.

It was a nice calm day, so I started going through the fuel system. The only hint I got was when I opened the racor filter top, I heard a “hissing” sound. That meant that my line blocked was aft of the primary filter.

The only thing saw was an electric auxilliary fuel prime pump that was plumbed into the system to help fill fuel filters after changing. (I never used it, and it was on my “things to do list”)

I just removed it and it fired right up, and problem was gone.
Yes, that pump was improperly installed. A bypass line with a valve would have solved the problem and left you withy an emergency fuel pressure pump, as I described above.
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Old 04-09-2021, 07:35 PM   #19
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Socalrider, I’m including a post I made a while ago, maybe it will provide you a hint.

“ We have a Lehman 90 with Racor 500 filters. The convienient location for the filters is under the pilot house floor within reach of the floor hatch next to the motor. This location was chosen by the PO. The Racor kept filling with air and of course, stalling the engine. A month of diagnosing and replacing hoses, fittings and finally the filters did not solve the problem. We were stumped until I mapped out the fuel path profile. I discovered that all told, we we drawing the fuel up over the top of the system by around 48 inches. This was a combination of all the vertical distances involved. It turns out that for our little pump to suck the fuel through that vertical distance, the system would pull air in through one of the many hosed clamped fittins in line instead of pulling fuel up that far. We ended up putting a lift pump down low near the tank to push the fuel up to the Racor. No more air. Lesson learned: keep track of your vertical draw on the system and don't exceed the vacuum that your fittings will allow. I don't know how to calculate the maximum, but we were somehow over that number.”

Good luck.
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Old 04-09-2021, 08:10 PM   #20
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If you have an elec pump in the system, either run it full time or have a bypass line open when it is off. When off they present a decent restriction to fuel flow.
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