Ford lehman 12v Fuel pump
- Thread starter Bigfish
- Start date
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Airstream345
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Are you planning to replace the mechanical lift pump or use it as a supplemental/priming pump?
jleonard
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catalinajack
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I do. And, I removed the mechanical pump from the engine. Works fine for me and I do not see any downside to doing so. If one fails, I will install the spare but the fact is they almost never do so. Plus, replacing the electric pump is far easier than replacing the on-engine mechanical pump and no worries about a failed pump diaphram pump diesel fuel into the crankcase and risking an engine failure. Plus, it's thhen much easier to prime filters. What's not to like?
catalinajack
Guru
If you remove the mechanical pump, a big block chevy block-off plate is a perfect fit. Be sure to use a gasket sealant such as Permatex #2. Thesexare available on many automotive websites, less than $10.
Pete Meisinger
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I once had an electric pump to supplement the mechanical pump on a large gasser. It would fuel starve at high RPMs. I just added it in line before the mechanical. Worked fine.
Only problem was that the constant "TICK" drove me nuts at trolling speed. I put it on a switch so I could shut it down at low speeds.
pete
Only problem was that the constant "TICK" drove me nuts at trolling speed. I put it on a switch so I could shut it down at low speeds.
pete
Lepke
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Any 12v fuel pump that's rated for diesel and has a flow rate of double your max usage will work fine. I have a 12v pump on all my diesels for filter changes and bleeding. Each will run an engine on its own. I buy the pumps on eBay, usually for less than $20 and haven't had one fail yet. They're cheap enough, buy two. Then you have a spare.
RT Firefly
Enigma
Greetings,
Mr. B. Our 2715 uses about 2 GPH. Lehman's return very little to the tank(s).
Mr. B. Our 2715 uses about 2 GPH. Lehman's return very little to the tank(s).
C lectric
Guru
At 135HP and ~ 18hp per gallon for engine of that design the engine COULD theoretically use 7.5 GPH or 8 GPH for simple figuring. Maybe about another 10 or 15% for fuel return since the return on these engines is not a lot compared to many other engines..
So maybe just over 9 gph the pump would have to move. Allow for 10gph.
You want to size the pump to supply the engines capacity, not just what you think you may use or you could strangle the engine if more power were ever needed , even if for some strange reason.
Just my thoughts???
So maybe just over 9 gph the pump would have to move. Allow for 10gph.
You want to size the pump to supply the engines capacity, not just what you think you may use or you could strangle the engine if more power were ever needed , even if for some strange reason.
Just my thoughts???
catalinajack
Guru
Bob Smith used to run his demo Lehman with no receptacle for the return line. Lehmans return very little fuel per hour likely no more than a few ounces.
C lectric
Guru
WOW what??
That the return fuel quantity is so low OR that you need to allow for so much fuel use.
If the latter there is a big difference between what most of us actually use and what the engine is capable of using. The capable would only come up if you ran the engine full tilt where it is trying to produce full HP. But you do need to allow for it.
Most of the vessels these Lehmans are installed in and the **way they are run** usually means they only burn 2 or 3 GPHr.
That the return fuel quantity is so low OR that you need to allow for so much fuel use.
If the latter there is a big difference between what most of us actually use and what the engine is capable of using. The capable would only come up if you ran the engine full tilt where it is trying to produce full HP. But you do need to allow for it.
Most of the vessels these Lehmans are installed in and the **way they are run** usually means they only burn 2 or 3 GPHr.
OP
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Bigfish
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I was surprised how little returned to the tank... The fuel polishing guy said the engines used one third of what was pumped to it... Somebody's wrong...guessing its the polishing guy
OP
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Bigfish
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Since I said wow, read my thread from this morning... "Fuel tank disaster..." Trying to get 20 gallons of fuel out of my bilge so I can reconnect the wires to my bilge pumps... Notice from the Coasties that if they have to clean up what I spilled it's a minimum $47,000 per day!! I'll have to owe it to them...
Comodave
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I took the last seminar that Bob Smith gave. He said that they would return between a pint and a quart in a days running.
