Yanmar 2GM20F Fuel Lift Pump Leak

[Nom De Guerre]

I have diesel leaking from my 2GM lift pump. I replaced the crush washers on the banjo fittings and they appear to be staying dry (don't appear to be the source of the leak). The leak appears to be between the upper and lower half of the casing, where the gasket is (seam is wet and drips from there into the bilge pan).

What is the current thinking? Can I replace a gasket or some other part(s)? Do I need to replace the whole unit? Should I leave it and plumb in an electric instead, and, if so which one?

I'd appreciate a recommended southern Ontario source for any parts suggestions as well, if you please.

 

[Benny17441]

A Yanmar replacement lift pump for the 2GM is listed at Torrensen Marine for $81.96.

 

[Deadline]

Not so fast

Or it could be the fuel line/banjo fitting. That's less expensive to replace unless you're sure it's the pump, which rarely fails.

 

[kloudie1]

I had a leak between the diaphragm and body of the pump on my 3 GMF. I think it is the same pump as on the 2 GM.. I was able to tighten each screw around the top cover and the leak stopped. I used a 90 degree screwdriver to get at all of the screws.. not easy but can be done.
Make sure the oil level in the crankcase is not rising.. A hole in the pump diaphragm would let diesel into the crankcase, thinning out the engine lube oil .. Not good.

 

[Joe23455]

fuel lift pump

had the same problem with my pump, same engine, thought the pump was obsolete, so I took it apart, carefully traced the old gasket, put in a new one.
four seasons ago and still fine, the pumps are built nice so they should last.

Joe
s/v trinity

 

[steveebryant]

I too have the 2GM20F engine. I have solved a similar "leak" on my engine by tightening the little screws which hold the two halves together.

I still may want to replace the manual lift pump as I don't believe that it works. I have removed the fuel line and proceeded to operate the lift pump manually and saw no fuel pumped out the end of the disconnected fuel line.

I might add that the engine is a little difficult to start if it has been setting a day. By difficult I mean that, on a warm to hot summer's day, I must press the starter 5-6 times before the engine picks up and starts running. It make me think that, after the engine sets for a period of time, fuel backs out of the line; or, there is a small amount to air in the line or perhaps in the injectors somewhere; or, a small air leak which would allow the fuel to fall back in the line.

My friend has an engine like mine and his starts immediately.

How difficult is it to replace the lift pump altogether?

Are there any little tricks one should be aware of when attaching the new pump?

And finally, have you any idea what could be causing the slow engine starts?

PS, the fuel filters (and separator) have all been replaced and the fuel and the fuel tank are absolutely clean.

 

[steveebryant]

A Yanmar replacement lift pump for the 2GM is listed at Torrensen Marine for $81.96.

I too have the 2GM20F engine. I have solved a similar "leak" on my engine by tightening the little screws which hold the two halves together.

I still may want to replace the manual lift pump as I don't believe that it works. I have removed the fuel line and proceeded to operate the lift pump manually and saw no fuel pumped out the end of the disconnected fuel line.

I might add that the engine is a little difficult to start if it has been setting a day. By difficult I mean that, on a warm to hot summer's day, I must press the starter 5-6 times before the engine picks up and starts running. It make me think that, after the engine sets for a period of time, fuel backs out of the line; or, there is a small amount to air in the line or perhaps in the injectors somewhere; or, a small air leak which would allow the fuel to fall back in the line.

My friend has an engine like mine and his starts immediately.

How difficult is it to replace the lift pump altogether?

Are there any little tricks one should be aware of when attaching the new pump?

And finally, have you any idea what could be causing the slow engine starts?

PS, the fuel filters (and separator) have all been replaced and the fuel and the fuel tank are absolutely clean.

 

[Joe23455]

not to change the thread and this does go with taking the pump apart to repair, but Steveebryant, it does sound to me that air is in your fuel line. Did you or have you bled the fuel system after working on it ? This must be done to any diesel when the
system is opened for changing out filters, pump work etc. otherwise it is a struggle to
kick or even start at all. Also, check all points of fuel system for tightness. Hope this helps.
Joe s/v trinity

 

[steveebryant]

not to change the thread and this does go with taking the pump apart to repair, but Steveebryant, it does sound to me that air is in your fuel line. Did you or have you bled the fuel system after working on it ? This must be done to any diesel when the
system is opened for changing out filters, pump work etc. otherwise it is a struggle to
kick or even start at all. Also, check all points of fuel system for tightness. Hope this helps.
Joe s/v trinity

Thanks for the reply Joe23455!

I did open the system and have not gone through a bleeding at the cylinders. I don't know how to do that. I have some idea but have never done it and am a bit afraid that I will make things worse. I don't really know which of the nuts on the line(s) I should be loosening and how careful I should be when tightening them back up.

If I do attempt it myself, (with someone's detailed instruction to follow for the 2GM20F Yanmar-pictures would be ever so useful), I wounder if I should be prepared to replace any of the fittings. I don't know if this is the proper term but I hear about "crush" fittings and "banjo" fittings. (?) Would it be a good idea if I replaced any of those fittings while I am doing the bleeding?

Thank you all for any contributions you can make to this conversation.
Steve

 

[arf145]

The fuel pump on my 25-year-old 2GM20F started leaking like that a year ago and I just went ahead and replaced it. That pump diaphragm doesn't last forever and the new pump isn't all that expensive, as others have pointed out. In a case like that, I'd rather have a new part and one less piece on my worry list.

 

[Nom De Guerre]

I had a leak between the diaphragm and body of the pump on my 3 GMF. I think it is the same pump as on the 2 GM.. I was able to tighten each screw around the top cover and the leak stopped. I used a 90 degree screwdriver to get at all of the screws.. not easy but can be done.
Make sure the oil level in the crankcase is not rising.. A hole in the pump diaphragm would let diesel into the crankcase, thinning out the engine lube oil .. Not good.

For the love of monkeys, there always has to be a critical wrinkle, doesn't there? It'd be nicer to think that I can try the tightening body screws route with no downside other than some more fuel to mop up if it doesn't work. I’ll keep a close eye on the oil level (shouldn’t be hard, it’s right at the full mark already – hopefully it doesn’t already include fuel).

had the same problem with my pump, same engine, thought the pump was obsolete, so I took it apart, carefully traced the old gasket, put in a new one.
four seasons ago and still fine, the pumps are built nice so they should last.

Joe
s/v trinity

Joe, I take it the gasket was separate from the diaphragm, is that right? Just a perimeter gasket with screw surrounds and the diaphragm sits inside of that?

The fuel pump on my 25-year-old 2GM20F started leaking like that a year ago and I just went ahead and replaced it. That pump diaphragm doesn't last forever and the new pump isn't all that expensive, as others have pointed out. In a case like that, I'd rather have a new part and one less piece on my worry list.

True enough. This is, I suspect, a 1985 original pump.

Thanks too Benny for the Torrensen source.

 

[rardiH36]

Thanks for the reply Joe23455!

... and have not gone through a bleeding at the cylinders. I don't know how to do that. I have some idea but have never done it and am a bit afraid that I will make things worse. I don't really know which of the nuts on the line(s) I should be loosening and how careful I should be when tightening them back up.

If I do attempt it myself, (with someone's detailed instruction to follow for the 2GM20F Yanmar-pictures would be ever so useful), I wounder if I should be prepared to replace any of the fittings. I don't know if this is the proper term but I hear about "crush" fittings and "banjo" fittings. (?) Would it be a good idea if I replaced any of those fittings while I am doing the bleeding?

Steve

Not a detailed answer, but here is a link to Yanmar's Operations Manual pdf page for the GM series engines. Just in case you don't have it already. Page 19 has information on bleeding the lines right up to the injectors. Also lots of good practical how to and need to know stuff in the manual.

Also I have attached a photo of the bleed page from my GM Series Service Manual. Better pictures I think and also an extra step. I don't have this engine (a 2QM20 instead), but the PO thought the boat had a 2GM20. Hence my possession of the manual.

http://www.yanmarmarine.com/theme/y...ines/Operation-manuals/GM-OP Manual-Multi.pdf

 

[Joe23455]

Yes the gasket was seperate from the diaphragm as i can remenber.
Hope that helps.

Rardi, thank you for attaching the same page i was trying to attach to this
as i got on line.
I kind of look at bleeding the fuel line like bleeding the old house staem/water heat radiators. Start at the bottom of the sysem and work your way to the top till the air leaves the system. In a fuel line is is usally nothing more then a few bubbles per
joint you are working on. Once you start you will see it is not to difficult.
Joe s/v trinity

 

[steveebryant]

Dear Group, Steve here,
Thank you guys for all the helpful comments and pictures and other references. And pardon me from breaking in on your conversation about lift leaking lift pumps; that's what got my attention originally as I too had that problem. Please consider this question:
It has been hot here in Oklahoma with 100 degree weather. It takes 4 or 5 attempts on the starter for a a couple of seconds each before my 2GM20F picks up. Once running, it sounds good with plenty of power. If the weather were cooler, it would be a little more difficult to start. Does that sound like an issue with air in the fuel system?

 

[steveebryant]

I am still not certain how this Sailboatowners chat group works and who all out of the many members will have opportunity to hear my question so I will probably post this question elsewhere in some other forum. In case you should happen to see the posting elsewhere, I am just trying to get a consensus from as many knowledgeable people as I can. This is my first diesel and I have little experience.

 

[anchorclanker]

Go to the local library at look for books on diesels, should be some basic manual. Knowing how an engine works is how you learn to fix any one in particular. While it would be simplistic to say a diesels a diesel, there are more similarities than differences when it comes to troubleshooting and repair.

 

[steveebryant]

Yes, I agree. I have actually bought several (at least three) books specifically on small marine diesel engines. They have been useful to me. Every time I read them, I learn something; often, I realize I just read something I had previously forgotten. I've actually followed instructions and completed maintenance tasks as a result of the insight these books have afforded me. Most, if not all, of my books have a trouble shooting section. Experience is the best teacher. And yes, perhaps one day in the not to distant future, I will attempt to follow the instructions as best I can by reading and looking at the pictures and proceed to properly bleed my engine. But until then, I'd still like to pose my question to an experienced mechanic to see if the specifics of my problem (as best I can describe them) rings a bell with him.

 

[Joe23455]

How is the condition of your batteries ? How old ? Starting with one battery or two ?
Just some thoughts that have nothing to do with fuel delivery.
joe
s/v trinity