Ford Lehman fuel pump

My buddy in an Albin 27 lost power in a bad place when his fuel pump failed. My question is: given the lack of forewarning and the potential for serious situations, does it make sense to routinely replace the lift pump as part of regular maintenance? And if so, what is the frequency of replacement or the expected service life of the pump?
They are relatively inexpensive ($80) and I do carry a spare, but I’d rather replace it at the dock and not in a sloppy seaway.
Any thoughts?

One of the problems with lift pumps is that they are rarely removed and the filters cleaned. Its very rare for them to fail but I too carry a spare. The most common problem with the Ford lift pump is that the rubber diaphragm leaks and that leads to rising oil levels. These are normal service items but most folk simply ignore them. I would recommend changing the lift pump diaphragm every 5 years.

Use a 12v electric pump. Cheaper, makes bleeding & filter changing easier, can be installed anywhere before the injector pump. You can buy 2-3 12v pumps for each overpriced lift pump.

dennisspain said:

My buddy in an Albin 27 lost power in a bad place when his fuel pump failed. My question is: given the lack of forewarning and the potential for serious situations, does it make sense to routinely replace the lift pump as part of regular maintenance? And if so, what is the frequency of replacement or the expected service life of the pump?
They are relatively inexpensive ($80) and I do carry a spare, but I’d rather replace it at the dock and not in a sloppy seaway.
Any thoughts?

Click to expand...

If I had a 10,000+ hour engine I might consider it. It's not a part that commonly fails so a spare is probably good enough.

It's a simple repair. 2 bolts as I recall and a little fiddling to get the arm positioned on the cam. Have a couple of spare gaskets and some permetex. Biggest problem was access. Not a lot of room for a wrench

I carry an elec fuel pump and 3/8 hose for fuel polishing. In a pinch I could use it to bypass the mech pump. With hose it's 2 clamps. If cu you just need two correct fittings. One for the tank or filter, and the other end to the secondaries. That would be my first plan if I lost fuel pump in rough conditions.

Lepke said:

Use a 12v electric pump. Cheaper, makes bleeding & filter changing easier, can be installed anywhere before the injector pump. You can buy 2-3 12v pumps for each overpriced lift pump.

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Plus one! I even removed the lift pump and installed a block off plate on my Lehmans. The plate is a big block chevy block off plate, easily found.

I have a 12v pump added before the lift pump on all my diesels - 2 Detroits, 2 generators. If a lift pump should fail, I just flip a switch mounted near the engine. It makes filling filters or bleeding on the generators fast and easy.

If you care about ABYC for insurance reasons...might want to check regs about adding fuel pumps. USCG says manufacturers have to place them within 12 inches of the engine (Boatbuilders Handbook 33 CFR 183.566)


I don't remember exactly but I believe the ABYC says they have to be powered by an engine electrical system that shuts them down if the engine shuts down (key, pressure switch, etc).


Seems like overkill on a diesel, and I might have it wrong....though worth looking at if trying to comply.



Having them in the system as "priming pumps" and only used in emergencies (can be valved to be out of system) might be acceptable.

psneeld said:

Having them in the system as "priming pumps" and only used in emergencies (can be valved to be out of system) might be acceptable.

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This is how mine are set up - with bypass valves. They're worth their weight in gold when bleeding the fuel system.

OK, I have a question regarding Lehman lift fuel pumps. About 15% of the time I go to start the starboard engine I have to do a quick bleed. I open the fourth (final) bleed nut and pump a few times to get the air out. Usually only takes 4-5 pumps to get solid fuel.

Reading this thread makes me wonder, could the pump be the issue? As was mentioned, I have pretty much ignored them. If the rubber diaphragm is failing, could that cause my "problem"?

I'm thinking it would be wise to replace it nonetheless...

May not be the lift pump.


I have weeps around 2 injector pipes on the injection pump....so fuel drains back towards the tanks sometimes when shutdown due to these leaks.



No problems with the lift pump.

As I said in an earlier post its very rare for the lift pump to fail.
Have you by any chance overtightened the bleed nut and stretched the threads ? its not unknown, I've come across it in the past with an over enthusiastic DIY'er.
Usually it happens after someone has worked on the engine so I would check the simple places first, one piece at a time so you can identify it for your own future knowledge.
I wouldn't replace the lift pump, if you just removed it, clean the interior, check the diaphragm is in good condition and the non return valve is working. When reassembling check the faces of the brass 'O' rings on the fuel lines for a good seal.
Be calm, methodical and you'll succeed.

Diaphragm would be simple to replace of you could find one, but I suspect your micro leak is somewhere in the fuel line. If you still have copper connections it might be time to redo all of them.

Moonfish said:

OK, I have a question regarding Lehman lift fuel pumps. About 15% of the time I go to start the starboard engine I have to do a quick bleed. I open the fourth (final) bleed nut and pump a few times to get the air out. Usually only takes 4-5 pumps to get solid fuel.

Reading this thread makes me wonder, could the pump be the issue? As was mentioned, I have pretty much ignored them. If the rubber diaphragm is failing, could that cause my "problem"?

I'm thinking it would be wise to replace it nonetheless...

Click to expand...

I think its much more likely that you have an air leak in the filter or one of the lines.

Ken

You can rebuild most diaphragm pumps, but the valves should be changed, too. Good luck finding the material. Before fuel injection on current gas engines, autos had diaphragm pumps, too. There were many rebuilders of pumps and some sold kits. But I haven't seen a diaphragm pump rebuild kit in a long time. I'd bet most new pumps are made in the same factory. The diaphragm usually fails on the air vent side and would show fuel out of the weep hole. In my experience, failing on the oil side is rare. But if you check your oil every day, you'll catch it early.

Most mechanics today don't want to rebuild anything but the main components of an engine. If that.

I've noticed that several small diesel generators now come with a 12v fuel pump. When my current generator diaphragm pumps fail, I'll go with electric only and keep a spare.

Moonfish said:

OK, I have a question regarding Lehman lift fuel pumps. About 15% of the time I go to start the starboard engine I have to do a quick bleed. I open the fourth (final) bleed nut and pump a few times to get the air out. Usually only takes 4-5 pumps to get solid fuel.

Reading this thread makes me wonder, could the pump be the issue? As was mentioned, I have pretty much ignored them. If the rubber diaphragm is failing, could that cause my "problem"?

I'm thinking it would be wise to replace it nonetheless...

Click to expand...

Its more likely you have a small air leak in the sims filter or someplace in that general location. Just enough to let the fuel back away from that last bleed screw.. This will usually only happen if your fuel tank level is below your injector pump. If you can next time turn the tank valve off after you shutdown. Then make sure next time to turn it back on before starting. If no bleeding is necessary, then you most likely have the air leak issue.

CEC said:

Its more likely you have a small air leak in the sims filter or someplace in that general location. Just enough to let the fuel back away from that last bleed screw.. This will usually only happen if your fuel tank level is below your injector pump. If you can next time turn the tank valve off after you shutdown. Then make sure next time to turn it back on before starting. If no bleeding is necessary, then you most likely have the air leak issue.

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Thanks! I'll try that!

The lift pumps are $105. CDN and no kits foe them around here. Just changed both of mine. They come brand new from Italy where apparently they are in current use. Some tips on re & re. Have a 1/2”wrench bent 30 deg or more...wish I’d had one 40 years ago. Remove the oil filter mount...one bolt...this allows the oil filter to move a few inches for much better access to the lift pump. CHECK the fittings on the inlet side of the pump to make sure they are the correct fitting. I called American Diesel and spoke to Brian Smith on a related matter and mentioned I had an air leak problem in the forward fuel filter on the block. He immediately jumped to the lift pump inlet fitting and said it was a common issue. I checked and sure enough the fitting was a flare fitting that a previous owner had used and apparently they don’t quite make a seal. Brian said this is the only place air can get into the fuel filter because there is no suction for air past this point...the fuel filter could have a fuel leak but not take in air. I hope I haven’t confused you too much...I have been trying to solve this ar issue foe a long time. I am just waiting for some parts and am hopeful this will solve it.Here is a pic of the WRONG fitting.

You can se this WRONG fitting does not seat as the hex part foe the wrench hits the pump casing and can’t be tightened

Lehman Fuel Lift Pump Service Interval

300 Hours is my service interval for the ford lift pump (2-3 years of usage for myself), while the Sabre Lehman manual has it getting a clean out every 200 hours.


https://www.kp44.org/ftp/FordLehmanOperatorsManual.pdf



https://www.asap-supplies.com/diesel-fuel-lift-pump-ford-2722-2725-thornycroft-251-381

JimD1971 said:

300 Hours is my service interval for the ford lift pump (2-3 years of usage for myself), while the Sabre Lehman manual has it getting a clean out every 200 hours.


https://www.kp44.org/ftp/FordLehmanOperatorsManual.pdf



https://www.asap-supplies.com/diesel-fuel-lift-pump-ford-2722-2725-thornycroft-251-381

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Wow. I think mine are original.

A quick read..... so I could be wrong..... but isn't the 200 hr cleaning for the injection pump vent filter if no overflow?


In the manual linked....

I replaced the fuel pump on the Lehman 19 years ago and have put 2,200 hours on it.

With a Racor 2 micron filter upstream of it, never needs cleaning of the pumps intake screen.

I plan on replacing the pump this winter.

I do have an electric pump upstream of the engine mounted pump for priming and back up. As long as the diagphram in the pump is not the failure, the electric pump will fuel the engine. Most of the pump failures are check valves coming loose or getting stuck.

In 29 years running a pair of Lehman 120s, I changed the lift pumps (very cheap, by the way, so skip the replacing valves and diaphragm ideas) once somewhere in the middle of that time. Kept a spare aboard. NOT a fanboy of replacing something that needs no electricity or failure prone connections to keep those babies running! That said, I did have a Facet electric pump (more expensive than my lift pumps) plumbed into the system in such a way that I could pressurize either or both engines and all associated filters.

Tangler said:

You can se this WRONG fitting does not seat as the hex part foe the wrench hits the pump casing and can’t be tightened

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I just discovered the same issue on my installation. New remanufactured Lehman with 10 hours on it, have been chasing an air leak in the fuel system. Engine runs great for a couple of hours then with no warning just stops dead. Fires right back up and we carry on, until the next time it happens.

My mechanic used the wrong type of fitting. Only caught it because an old timer on the dock clued me into this as a potential issue.

Block off the hole in the block, toss the two filters from hell, install an electric pump with modern, good quality fuel hose with nice quick disconnects. An hydraulic shop can make the hoses, the filters can be replaced with a single remote-mounted easy-change filter (I used a Racor 500 with 2 microns but there are others) and you can mount the pump anywhere, might be best to remote mount it because of the vibration of the old clam crusher. No way for an owner to measure the vibes and most pumps don’t publish vibration-toleration specs.

Racors are designed to have the fuel sucked through them but they can tolerate a small amount of pressure so you could mount the pump upstream to prime the filter. If pressure upsets you use a pressure-rated filter. No reason to be a hostage to old engineering. Don’t forget to change the Simms pump oil as per the manual!

Moonfish said:

OK, I have a question regarding Lehman lift fuel pumps. About 15% of the time I go to start the starboard engine I have to do a quick bleed. I open the fourth (final) bleed nut and pump a few times to get the air out. Usually only takes 4-5 pumps to get solid fuel.
...

Click to expand...

Hi, I installed a fuel polisher in the Celestial. I bought the first batch of ball valves at Home Depot. I found that they all had air leaks under vacuum. In a previous lifetime, I worked with folks who used only Conbraco's Apollo valves, so I did an online search of their website, but found no data re vacuum. I called the company and asked - they (she) assured me that the Apollo valves worked well under the vacuum that my fuel pump could generate. I installed all Apollo valves and had no further problems with valves. I then found that the large Racor filter's O-ring on the top screw could leak air, unless new O-rings were used.

Lift pump issues

I purchased a new lift pump for 1980 ford Lehman and installed it with some of the same issues mentioned above. It seemed it came out very easy with no pressure on the lever arm. The new one slipped in easily also. The manual did not indicate any potential way to screw it up. Have I missed anything?

That said it seems to work fine in bleeding the secondary filters but when I try to bleed the two bleed bolts on the high pressure pump no fuel comes out. Any suggestions?

Loon said:

I purchased a new lift pump for 1980 ford Lehman and installed it with some of the same issues mentioned above. It seemed it came out very easy with no pressure on the lever arm. The new one slipped in easily also. The manual did not indicate any potential way to screw it up. Have I missed anything?

That said it seems to work fine in bleeding the secondary filters but when I try to bleed the two bleed bolts on the high pressure pump no fuel comes out. Any suggestions?

Click to expand...

I inserted a small Facet electrical fuel pump in my system to avoid the finger and thumb-killing routine of working the lift pump flipper. Then I opened the single bleed valve on the Simms pump of my FL120s to watch the bubbles pass out of the system. Barring that, open the Simms pump bleed valve (assuming you have the Simms) and hit the starter for short periods to bleed the air.

Wayne said:

Hi, I installed a fuel polisher in the Celestial. I bought the first batch of ball valves at Home Depot. I found that they all had air leaks under vacuum. In a previous lifetime, I worked with folks who used only Conbraco's Apollo valves, so I did an online search of their website, but found no data re vacuum. I called the company and asked - they (she) assured me that the Apollo valves worked well under the vacuum that my fuel pump could generate. I installed all Apollo valves and had no further problems with valves. I then found that the large Racor filter's O-ring on the top screw could leak air, unless new O-rings were used.

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Yes, always use a new O ring.

Found problem with fuel bleeding secondary filters in the 120 ford Lehman. When I replaced the gasket ring(upper) I put it on the top of the filter instead of in the groove in the upper casting. It blocked the fuel circulation slots and kept it from circulating. Interesting that it seals the filters in that(wrong) configuration with no leaks. Once changed, no problem with bleeding. Thanks for all the input.