Yanmar Lift Pump

[casual]

I,have a Yanmar 4JH3E,I,am concerned after reading threads about lift pump's failing.Should they be changed after so many hour's is there a normal life ecpectancy.
Thanks for your input

[Ex-Calif]

I wouldn't preemptively change one. If you cruise far from home you may want to carry an overhaul kit or a spare.

The difference in a new pump vs. overhaul kit for mine was $40 - I bit the bullet and bought new - I suspect mine is failed.

[casual]

Originally Posted by Ex-Calif

I wouldn't preemptively change one. If you cruise far from home you may want to carry an overhaul kit or a spare.

The difference in a new pump vs. overhaul kit for mine was $40 - I bit the bullet and bought new - I suspect mine is failed.

Other than no fuel supply,are the sympton's?
Thanks

[centaur]

My experience of fuel lift pumps. not my Yanmar 3 GM 30 thankfully, is that they fail intermittently. A good test is to check the flow from the positive side. This should be a good steady stream when the engine is cranked. Just make sure not to overdo it with a water lock exhaust system.
Spares are always a good idea, just make sure they are the right ones.
I generally fit new spares, covers warrentry issues, and keep the originals for emergencies.
Centaur

[Charlie]

I have a 4JH4E and have had problems with the lift pumps. I replaced the lift pump and still had problems. I installed an electric pump after the Racors and have had no problems with that. The problem is that now I need electricity for the engine to run.

IMHO it is better to install an electric pump and know how to replumb the fuel lines to avoid the lift pump then to have a spare lift pump.

[casual]

Originally Posted by Charlie

I have a 4JH4E and have had problems with the lift pumps. I replaced the lift pump and still had problems. I installed an electric pump after the Racors and have had no problems with that. The problem is that now I need electricity for the engine to run.

IMHO it is better to install an electric pump and know how to replumb the fuel lines to avoid the lift pump then to have a spare lift pump.

That is my idea,What do you do with the lines and lift pump?
Thanks casual

[Agape39]

Originally Posted by Charlie

I have a 4JH4E and have had problems with the lift pumps. I replaced the lift pump and still had problems. I installed an electric pump after the Racors and have had no problems with that. The problem is that now I need electricity for the engine to run.

IMHO it is better to install an electric pump and know how to replumb the fuel lines to avoid the lift pump then to have a spare lift pump.

I have done the same with my 4JH4TE, installed it as a backup pump but did not reroute lines, am I missing something?

[casual]

My other concern is the diaphram going bad and diesel fuel entering the enging oil.Have seen this happen while ump was still pumping fuel to the engin.When taking lift pump out of line is there a plate that can be inserted and lift pump removed?This leaves only the electric pump for fuel sorce.

[Agape39]

Originally Posted by casual

My other concern is the diaphram going bad and diesel fuel entering the enging oil.Have seen this happen while ump was still pumping fuel to the engin.When taking lift pump out of line is there a plate that can be inserted and lift pump removed?This leaves only the electric pump for fuel sorce.

Good point

[Safari38LH]

I have a 4JH2E and just had to replace my lift pump. The engine has 1200 hours on it.

[Agape39]

Sooooo, I have this to look forward to, mine has 450 hours. I have been warned on diaphram pumps. I have always had electric lift pumps, I.e. my westerbeke, and always carry an extra. What the issue is is fuel in the crankcase, very dangerous!

[Charlie]

Originally Posted by casual

That is my idea,What do you do with the lines and lift pump?
Thanks casual

Sorry it has taken me so long to get back to you. All I did was 1) disconnect the input line from the fuel tank to the lift pump. 2) Ran the disconnected line to the on engine fuel filter input, and 3) Then I took the output line from the lift pump (that connected to the on engine fuel filter) and circled it back to the input line. I had to get a longer piece of fuel line in order to do it.

Originally Posted by casual

My other concern is the diaphram going bad and diesel fuel entering the enging oil.Have seen this happen while ump was still pumping fuel to the engin.When taking lift pump out of line is there a plate that can be inserted and lift pump removed?This leaves only the electric pump for fuel sorce.

I am not positive about this but I think that if the plumbing is rerouted that there is no fuel oil in the diaphram. It is possible that the fuel oil would leak from the seals of the pump though.

Originally Posted by Agape39

I have done the same with my 4JH4TE, installed it as a backup pump but did not reroute lines, am I missing something?

No if my engine were not creating oil I would not have rerouted the lines. It is a good idea to be able to reroute them easily IMHO (meaning getting an extra long bit of fuel line to connect the lift pump to the on engine fuel filter) because if the diaphram starts leaking you can then reroute the fuel lines quickly and stop or decrease the amount of fuel oil contamination into the lubricating oil.

I am still working on why my lubricating oil is being contaminated. I have two theories 1) Injectors are leaking raw fuel past the rings or 2) the seals on the fuel injection pump are letting oil or 3) There is a way for fuel oil to enter the lubricating oil system thru the diaphram pump even if there is no fuel going thr the lift pump. So now I try to sail and change the oil more often.

[Agape39]

Great info Charlie, thank you. I am going to look into it so I am prepared.......as they say, if it's gunna break you know where and when it's going to happen!

[SailorHarry]

If you want to rebuild your lift pump, Google Ocean Navigator magazine July 2011 and look for the article that I wrote on rebuilding my 4JH2E lift pump. I routinely rebuild mine at around 2200 hour intervals (so far, twice in the 15 years that we have lived aboard). Good luck, SailorHarry