Yanmar 1GM10 Starting Problems

[Marek11]

Hi,

I have a Yanmar 1GM10 which has got one problem in that it is very difficult to start when it has been left for a few days. If it has been left for a few days then I need to press the start button for about 15 seconds, at least 5 times and then if I'm lucky it will start. After it has started once I can turn it off and easily (first time) restart it a few hours later. When it is running it runs fine without any problems. Bleeding it always helps but I just wondered where the air could possibly be getting in?

Just for an experiment I replaced the fuel line from the tank fuel filter/water separator to the lift pump by a transparent tube so that I could see what was happening. The fuel tank is higher than the lift pump and I discovered that it is quite difficult to get all the air out of this hose. When I tried to bleed it I noticed that the diesel runs down the tube but does not displace the air, but instead the air migrates to the top of the tube. Thus you can think its been bled when in fact the line to the lift pump is still half full of air.

I wondered if anyone has any advice on how to bleed this properly?

Is there any advice on what could be causing this bad first time starting?

Thanks,

Marek.

[delmarrey]

This is one good reason to have an electric pump T'ed and valved into diesel motors, bleeding the system.

You do need to get the air out first and go from there. This may be your starting problem. And if it doesn't start, make sure to drain the wetlift. It may be full.

Check to make sure all your connections are air tight. Do not reuse an old hose connection. Cut the end off and start w/fresh rubber. If an old hose (15 years +) replace the hose.

After the air problem is resolved and still doesn't start right off, check the compression.

[Marek11]

Thanks for the reply. I have been thinking about fitting an electric pump but wanted to keep the system as simple as possible - another component to fail.

I agree I need to make sure that I get all the air out, the problem is I can't be sure I have got all the air out. Even when there is all diesel coming out the bleed point, the tube between the fuel tank and the lift pump can still be half full of air - which really surprised me!

Sorry I don't understand the terminology. What is a wetlift? Something to do with the exhaust pipe?

Marek.

[delmarrey]

Originally Posted by Marek11

Thanks for the reply. I have been thinking about fitting an electric pump but wanted to keep the system as simple as possible - another component to fail.

I agree I need to make sure that I get all the air out, the problem is I can't be sure I have got all the air out. Even when there is all diesel coming out the bleed point, the tube between the fuel tank and the lift pump can still be half full of air - which really surprised me!

Sorry I don't understand the terminology. What is a wetlift? Something to do with the exhaust pipe?

Marek.

I've had an electric pump in place for 10 years, since I bought the boat, and have only used it for less then an hour, so far, for bleeding fuel lines and filling the filter after changes.

A wetlift is an exhaust muffler and trap to stop back flow.


.

[Marek11]

Originally Posted by delmarrey

I've had an electric pump in place for 10 years, since I bought the boat, and have only used it for less then an hour, so far, for bleeding fuel lines and filling the filter after changes.
.

Sorry, I misunderstood what you meant. This is an electric pump that you only use for bleeding? I thought you meant replacing the mechanical lift pump by an electric recirculating pump. A friend has a recirculating pump which constantly pumps fuel around the circuit and back to the tank. This means that the injectors are always primed.

Where do you actually "T" your pump in? This might be a good thing for me to do, like you say.

I will check the wetlift, but its probably ok since the engine starts fine after the first start and there is a non return loop to stop sea water getting back in.

[delmarrey]

Originally Posted by Marek11

Sorry, I misunderstood what you meant. This is an electric pump that you only use for bleeding? I thought you meant replacing the mechanical lift pump by an electric recirculating pump. A friend has a recirculating pump which constantly pumps fuel around the circuit and back to the tank. This means that the injectors are always primed.

Where do you actually "T" your pump in? This might be a good thing for me to do, like you say.

I will check the wetlift, but its probably ok since the engine starts fine after the first start and there is a non return loop to stop sea water getting back in.

What you have to remember is the wetlift is filling up while trying to start the motor. The running of the motor only, has enough pressure to actually blow out the excess water with it's gases.

The system you describe above is probably a scrubber which is a continuos version of what I have.

I have a T at the tank. One side goes to the pump, the other to the filter.

There is a three way valve between the filter and the tank. One side goes to the outlet of the pump, and the other to the T at the tank, the third side to the filter.
With the valve in #1 position the fuel flows from the tank and into the filter.
With the valve in the #2 position the fuel flows from the tank, thru the pump and into the filter. IAW's the valve has two inlets and one outlets.

[WorldWind]

Nice'n'tidy Delmarrey..
Clean is where it's at

[bill good]

This might seem silly ...but I had trouble starting my 1GMS then one day rediscovered they need the power lever to be fully open for start as per owners handbook!! Also the diaphragm in the mech fuel pump seem to grow with time resulting in lost stroke. Pump has to be chanced as a complete unit as no parts available. A point where air can get in is the bleeds on the fuel filter being stripped.

Regards Bill

[Marek11]

Thanks very much for the info. I will look into implementing the same configuration.

Great picture of the engine. Looks very neat and clean!

Bill - "the power lever to be fully open for start as per owners handbook!!"

Yes, good point I only recently realized the same thing

Marek.

[Watercolor]

Except for the suggestions already raised I'd check on two things, the performance of the engine fuel pump and a dip in the fuel line between the filter and the tank.

I mention these two items especially because you have a gravity feed fuel tank.

I wonder if the gravity feed pressure is masking a weak pump once the system gets running and is why it takes so long to start the engine after a 2 day wait. Does it start right up after 12 hours off? Also if the tank is low on fuel (low fuel level is relative and depends on the flatness of the bottom, the motion of the boat and the list of the boat) you may be getting air in that way. If you don't use the engine a lot (like only in and out of the harbor) a 1/4 to 1/3 tank of fuel may create the introduction of air. The other thought I had is to look for a sag or dip in the fuel line between the tank and the filters. The line should drop steadily to the filters.

Good luck

[gjordan]

Starting hard after several days but easy if it has been run in a day or two is a sure sign of air getting into the system. Look for all the potential leak points but realize it can be in the injection pump itself. I had a Pathfinder(VW) diesel that started fine if it was run every day but needed 2 minutes of grinding if it sat for a few days.(it was a self bleeding system which I still dont understand). I finally talked to an injection shop and they said bring in the pump and we will fix it. A new front seal and I never had anymore problem with starting.___Just a possibility ____Grant.

[Marek11]

Originally Posted by Jedg

Except for the suggestions already raised I'd check on two things, the performance of the engine fuel pump and a dip in the fuel line between the filter and the tank.

I mention these two items especially because you have a gravity feed fuel tank.

I wonder if the gravity feed pressure is masking a weak pump once the system gets running and is why it takes so long to start the engine after a 2 day wait. Does it start right up after 12 hours off? Also if the tank is low on fuel (low fuel level is relative and depends on the flatness of the bottom, the motion of the boat and the list of the boat) you may be getting air in that way. If you don't use the engine a lot (like only in and out of the harbor) a 1/4 to 1/3 tank of fuel may create the introduction of air. The other thought I had is to look for a sag or dip in the fuel line between the tank and the filters. The line should drop steadily to the filters.

Good luck

Hi,

the fuel pump (lift pump) is new, but I guess it could be letting air in at the seal. I will check this weekend. The fuel line is pretty much vertical between the filter an the lift pump. So its probably ok.

Originally Posted by gjordan

Starting hard after several days but easy if it has been run in a day or two is a sure sign of air getting into the system. Look for all the potential leak points but realize it can be in the injection pump itself. I had a Pathfinder(VW) diesel that started fine if it was run every day but needed 2 minutes of grinding if it sat for a few days.(it was a self bleeding system which I still dont understand). I finally talked to an injection shop and they said bring in the pump and we will fix it. A new front seal and I never had anymore problem with starting.___Just a possibility ____Grant.

The injection pump is something I haven't considered and its one thing I haven't replaced. So I will definitely look at replacing this or at least checking it for being air tight.


Thanks to everyone for all the suggestions. I will report back when I find the solution!

Marek