Yanmar 2GM20 (lift pump?) problem

Georgio

Georgio

Well-Known Member
Joined
23 Jan 2003
Messages
1,797
Location
Solent/south coast
georgeisted.blogspot.com
Hi Folks,
Can you just sanity check what I have done/diagnosed.

Whet to run the engine today and after a short while 20 secs it dies, felt/sounded like fuel starvation from a blocked coarse filter (as I experienced before having my tank cleaned).

Checked the coarse filter, not dirty apart from the odd spec so I put a new one in and removed the air. Started the engine but it died again same symptom.

I then checked for air in the fine filter but after lots of pumping on the lift/low pressure pump could not get diesel out of the bleed screw.

Removed fuel line from lift pump inlet - no problems with fuel flow (tank is above it) and refitted, tried pumping aging and no joy.

Removed fuel line from lift pump to fine filter - no blockage and clean but before refitting I pumped again and nothing coming out.

Diagnosis - knackered fuel pump?

Before I order a new one can someone confirm I haven’t missed anything obvious

I have removed and opened up the fuel pump and the diaphragm looks ok but I'm guessing there are some one-way valves in the top than may be the problem.

Thanks in advance.
 
Before you condemn the pump, you should have tried it again after rotating the engine crankshaft 1/2 to 1 turn. Your problem might have been the operating cam on full lift, preventing diaphragm movement.
 
Do you mean the wee hand lift pump?

I thought mine was buggered but it is just such a low capacity pump it took for ever to get fuel through... I was going to but another one but local supplier told me they sell so few they would be surprised if it was... A bit more perseverance got me going...
 
Georgio said:
Good tip, thanks.

I think I did turn the engine over by hand so I dont think this would be the problem with the pump.
Click to expand...

If you did that, and the diaphragm is also OK, then a valve might be playing up. The inlet and outlet valves are held into the upper part of the pump body by a keep-plate. They can be removed to check their operation.
 
onesea said:
Do you mean the wee hand lift pump?

I thought mine was buggered but it is just such a low capacity pump it took for ever to get fuel through
Click to expand...

I persevered for a very long time with mine and still never got fuel through to the engine filter. Yes, I know about the cam position thing.

Dirty great outboard motor priming bulb just after the tank solved it all. I could get fuel squirting across the cabin from the engine filter bleed screw if I wasn't careful :)

Never had any trouble with it when the engine was actually running though.

Pete
 
I wonder what the relative levels of your fuel might mean if the pump isn't effective. I worked out that on mine, if the tank is more than half full I don't need a pump as gravity does the job. Around the half tank scenario, I think a syphon establishes itself so it should keep going - but below quarter tank I suspect that she wouldn't start without a lift pump...

Rob.
 
Thanks for the suggestions, I have a new pump on it's way.

The tank is full and with the pipe taken off the liftpump inlet there is a good supply/stream of diesel just using gravity. I'm sure it's the pump, will hopfully fit the new one on Tuesday night. Replacing the fine filter housing while I'm at it because the thread on the large bleed screw is going (I gather this is not uncommon, is it actually made from cheese?).
 
Georgio:

Did the new lift pump fix things? I have the exact same problem on one of my 2GM20's and I'm very close to replacing the lift pump. We were underway when the engine just died. The fuel flow to the inlet side of the lift pump was fine but no amount of hand pumping would get fuel to the line filter. I was able to get back to port by constantly squeezing the squeezy bulb for nearly two days straight. What a pain! My left wrist is now twice as large as the right one. I'm told that the diaphragms on these pumps don't last forever and that they are virtually unfixable. Thanks in advance.

Phil
 
Gents
I know I'm a bit late on this one but had the same issue last week, I found that by stripping the pump and blowing sharply through the pump non return valves cleared the problem.
A small piece of grit or ? Must have lodged in there.
Llew
 
rob2 said:
Impressive performance, Phil - but surely you know to count to 100 then change hands...? ;-)

Sorry, couldn't resist.

Rob.
Click to expand...

Ha! Good one! Perhaps I should have mentioned that, while I was squeezing the bulb, I sitting on the cockpit sole with my back against the back of the cockpit and my left hand in the battery box where the Racors are located. In order to squeeze right handed, I would have had to be kneeling and facing aft while the boat was being tossed around -- not good. Maybe you needed to be there.

Phil
 
i know this is an old thread but I wanted to chime in with what i think is the actual issue (for people like me searching for an answer). Look to see where your tank is in relation to your primary and secondary filters, if the lift pump cannot get fuel to bleed and the tank is the lowest part of the system it could be that you have no check valve at the tank. The fuel drains back to the tank faster then the poor little pump can pump it.

https://www.parker.com/literature/Racor/Tech_Install/15335_500MA&MAM_Marine_Turbines.pdf
 
Matwill said:
i know this is an old thread but I wanted to chime in with what i think is the actual issue (for people like me searching for an answer). Look to see where your tank is in relation to your primary and secondary filters, if the lift pump cannot get fuel to bleed and the tank is the lowest part of the system it could be that you have no check valve at the tank. The fuel drains back to the tank faster then the poor little pump can pump it.

https://www.parker.com/literature/Racor/Tech_Install/15335_500MA&MAM_Marine_Turbines.pdf
Click to expand...
Old thread, but I dont follow what you are saying. The lift pump has two valves in it and will pump air as well as fuel. The fuel will not drain down to a tank at a lower level because there is no way to allow air into the system to replace it, unless there is a leak before the pump.
As for the OPs problem, had the same and it was the pump. Yet to see a 'check valve' at the tank.
 
You must log in or register to reply here.

Share this page

Top