School me on FL120 fuel pumps...

[socalrider]

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!

 

[DavidM]

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

 

[STB]

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!

-Greg

 

[STB]

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...



-Greg

 

[PM]

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.

pete

 

[socalrider]

Thanks all. This is great.

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.

 

[SoWhat]

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

 

[socalrider]

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 )

 

[STB]

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.

 

[Doug]

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.

 

[socalrider]

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.

 

[psneeld]

where does one hear Lehman fuel pumps are an issue and need to be replaced regularly?

 

[socalrider]

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.

 

[psneeld]

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.

 

[fgarriso]

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!

 

[rgano]

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.

 

[Alisske]

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.

 

[rgano]

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.

 

[Eagle Pursuit]

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.

 

[Ski in NC]

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.

 

[Marinex]

Our boat is a 1967 and has had nothing but a racor and the engine filters feeding the mechanical pump for more than 50 years, simple but effective. The mechanical pump has been replaced once.



On diesel generators I used to service for work , many times it wasn't so much a blockage as air being introduced and then starting up only to die again several minutes later. The little burst of diesel on restart will run that engine for a looooong time before the process repeats.


I once forgot to turn on the valves on the fuel tank and I had enough fuel to startup and travel out of the harbour before the engine stopped and I said WTF!


Very efficient our old Lehman!

 

[socalrider]

You guys are just fantastic - thanks so much for these responses.

I'm trending toward one of two different paths (removing the BS Algae-x is a given for both):

1. Eliminate the electric pumps and maybe replace with a simple bulb pump like this and rely on the lift pumps (maybe swap out for good measure), or

2. Remove the lift pumps (I imagine I'd need to fab a blanking plate) and rely on the electric pumps, re-wired to turn on with the ignition key.

 

[socalrider]

I had fuel problems 3 years ago. Installed Holly electric pumps and removed the lift pumps. PROBLEMS solved.
The Algae X is pure BS!

Thanks - great feedback. Any tips on the lift pump removal? Did you need to fab up blanking plates?

 

[psneeld]

Someplace there is a thread where pre-made blanks are available. Its a standard pump for I believe the aftermarket blanks are for a big block Chevy.

Someone may have that info at their fingertips and post it here.

This may help....

https://www.trawlerforum.com/forums/s6/lehman-lift-pump-electric-fyi-27981.html

 

[jleonard]

Thanks all. This is great.

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.
.

This sounds similar to what happened to my single FL 120 on my maiden delivery voyage. After struggling I finally got back to my home port and was able to properly check things out.
Bottom line, I replaced the lift pump and that comes with a new flexible (rubber) section to transition the copper lines to the pump.
After talking with Brian ant ADC I learned the it is common for the original flex hose to delaminate internally and shut off the fuel.
I'm convinced that was the problem.
I changed a few things around, added a course filter and plumbed an electric to use as a back up and for riming, but never had another hiccup for the 15 years I owned the boat.

 

[catalinajack]

I would make a different choice, that is, get rid of the mechanical pump. I use Walbro pumps that are rated for 18,000 hours.

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

 

[STB]

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.

Maybe that depends upon the pump? The ones I've seen one can blow right through like they aren't there. This one, in particular, has plenty of reviews on the Web and Amazon from people using it in exactly this application.

I'm normally concerned when people use transfer pumps with an intermittent rating for a continuous duty application, for obvious reasons, not one of these.

Maybe solenoid or membrane pumps present more of a restriction than rotary vane pumps like this?

 

[catalinajack]

You do not have to fabricate a block-off plate. Simply purchase a block-off plate for a Chevy big-block gas engine. The ports are exactly the same. Less than $10 on Amazon. Comes with a gasket. Got this tip here a long while back.

You guys are just fantastic - thanks so much for these responses.

I'm trending toward one of two different paths (removing the BS Algae-x is a given for both):

1. Eliminate the electric pumps and maybe replace with a simple bulb pump like this and rely on the lift pumps (maybe swap out for good measure), or

2. Remove the lift pumps (I imagine I'd need to fab a blanking plate) and rely on the electric pumps, re-wired to turn on with the ignition key.

 

[PM]

"Hunting" or "searching" on a F.L. is most often injectors or injector pump.

pete

 

[psneeld]

"Hunting" or "searching" on a F.L. is most often injectors or injector pump.

pete

If searching includes losing rpm then returning to normal, I would disagree.

I had quite a few episodes with air leaks till I reworked my fuel system.