Bleeding Yanmar 3gm30

dgadee

dgadee

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This has probably been done to death, but I am moving from a sensible self-bleeding Vetus to a 3gm and can't quite work out what I should be doing.

There is a filter just above the fuel tank. How do you bleed that when there's no way to force fuel into it?

There appears to be an electric fuel pump. When I switch on the engine key (and hear the high pitched tone) there is no vibration from this pump. Does that mean a possible flaw or just that it it doesn't take power from the on key, but when the starter button is pressed? The two are some distance apart and I'm on the boat myself.

I can understand the bleeding of engine mounted fuel filter and the high pressure side of the system, but fuel may not be getting that far.

This a new to me boat which has been out of the water for about a year without - I presume - having had the engine started.
 
There should be a manual lift pump on the starboard side of the engine just behind the secondary filter. Use this to lift the fuel when bleeding. If it is not getting to that point you will probably have a leak in the primary filter setup but that is where to start (assuming the fuel inlet pipe isn't blocked in the tank).
 
ctva said:
There should be a manual lift pump on the starboard side of the engine just behind the secondary filter. Use this to lift the fuel when bleeding. If it is not getting to that point you will probably have a leak in the primary filter setup but that is where to start (assuming the fuel inlet pipe isn't blocked in the tank).
Click to expand...

Yes, have been pumping away at that. What is the relationship between electric pump and manual one?
 
I was going to refer you to a website where you can download the Yanmar manual, but your problem has nothing at all to do with the engine itself. I've often wondered about how people draw fuel up a dip tube to start the siphon effect which feeds the fuel to the lift pump (my own boat takes the fuel from a tap at the bottom of the tank). Even so, I need the fuel level in the tank to be higher than the top of the primary filter to gravity feed for bleeding the filter.

If I understand your description of the installation, you must either pressurise the tank or suck it down to the lift pump. The problem with pressurising the tank is that the breathers must be closed off. Many are connected by hoses, so you can stick a cork in the hose. Sucking fuel down is also not so simple, although most of us did it when we couldn't afford to run the motorbike and had to raid the lawnmower! It helps if there is a tap in the line to allow you some time to reconnect the line to the pump...

Some people advocate fitting an inline manual pump - the type used to prime an outboard from a remote tank. It can be used both to prime the lp side of the system and bleed the hp side and will allow adequate flow of fuel through when not in use, but being rubber, it has a finite life and should be replaced every few years.

Rob.
 
rob2 said:
your problem has nothing at all to do with the engine itself
Click to expand...

+1 - the boat's fuel system is unrelated to the particular engine installed, and may or may not be the same as any other boat of the same type.

I second the suggestion of an outboard-style pump immediately after the tank. Gives a lot of flexibility and options in dealing with the fuel system.

Pete
 
The description of a high speed whining noise from the pump suggests it to be a centrifugal one. Centrifugal pumps do not self prime, whereas the more usual lift pumps and in-line bulb ones do. You may be able to get the pump to prime by back-filling it from the engine end but this can be difficult depending upon the layout of the system.
 
Primary filter above fuel tank.

You say the primary fuel filter is above the fuel tank. The easiest way to fix that is to fit a bolt on manual lift pump to the inlet of the primary fuel filter, similar to this one, available through various suppliers.

http://www.ssldieselparts.co.uk/primer-bolt-type-p-434.html

When ordering make sure you get the right thread (most are size 1/2x20unf) you will also need one of these

http://www.ssldieselparts.co.uk/banjo-bolts-p-371.html
of the same size and complete with copper sealing washers.

Providing the Yanmar mounted lift pump is working properly, then you should not need an electric one as well.

These engines are normally fitted with the excess fuel being returned to the fuel tank. Providing yours is installed this way then after bleeding the primary filter all that is needed to bleed the remainder is to continue pumping. There is a relief valve fitted in the injector pump that will divert excess fuel back to the tank. Mine is installed this way and is very reliable. George
 
Problem solved. The electric pump has nothing to do with the engine at all. It was the fuel pump for a heater which is no longer there.

But thanks for the advice. Engine now running well. I will look into the extra pump - seems useful to have.
 
BTW Once you get fuel to the engine fuel pump via both filters and the pump bl;eed screw, it is often not nec to mess with the injector pipes, I have found ( deliberately shutting off the tank fuel outlet to 'learn'/practise how to bleed it right through and all), just give it full throttle and crank, ( water inlet OFF as we all state on this forum ahem), one, two then the third cylinders kick in ..
I use a outboard priming bulb, v quick and easy to locate..
 
I'm not really an advocate of fitting additional pumps, either electric or rubber bulb. If the system has worked in the past, it will work the same in the future provided all the components are sound. Air leaks are the enemy on fuel systems.
 
dgadee said:
Problem solved. The electric pump has nothing to do with the engine at all. It was the fuel pump for a heater which is no longer there.

But thanks for the advice. Engine now running well. I will look into the extra pump - seems useful to have.
Click to expand...

Just for your information and anybody else having a similar problem. If your primary fuel filter is higher than the fuel tank then the easiest way to get fuel flowing is to fill the fuel tank as much as possible, remove the fuel tank breather pipe, not from the tank but at the end where it discharges from the boat, open the primary fuel filter water runoff tap and then blow hard and consistently into the fuel tank via the breather pipe. You will create pressure and fuel will flow as far as the primary filter, this should then produce the syphon effect. Done this loads of times after removing the filter and bowl for cleaning
 
Blueboatman said:
BTW Once you get fuel to the engine fuel pump via both filters and the pump bl;eed screw, it is often not nec to mess with the injector pipes, I have found ( deliberately shutting off the tank fuel outlet to 'learn'/practise how to bleed it right through and all), just give it full throttle and crank, ( water inlet OFF as we all state on this forum ahem), one, two then the third cylinders kick in ..
I use a outboard priming bulb, v quick and easy to locate..
Click to expand...
Wouldn't that break up the Jabsco impeller, churning the engine over with the seacock shut?
I am not arguing, just wondering if shutting the seacock is more likely to cause damage than the chance of water getting in the exhaust valves?
If I planned to turn the engine much with the cock shut, I would feel uneasy unless the pump cover was removed, and something to lube the impeller was smeared in.
I presume your impeller survived the treatment!
 
Indeed, I would not want to advise misleadingly but after cranking thus, I then stopped the engine and water was evident in both the intake and outlet pipes fromt eh raw water pump itself. Perhaps the airlock and the deflection of the impellor vanes is suffice to prevent melt down for those few seconds until the engine fires and the revs increase?
I believe ( at some expense haha) one can buy rundry impellors these days too, should you wish?

By the way I have a very high rise injection elbow, the cast bronze elbow is sat atop 300mm of threaded ( scaffold pipe spec?) tube rising vertically from the manifold/heat exchanger..but it is surprising how efficient those water pumps are if you suck from a washing up bowl just on the starter motoer and watch..
 
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