Hello group,

I have a 2qm20 Yanmar. I have had it for 6 years but it was built in
1978. I don't know if the injectors have ever been serviced. I have 2
new injectors. How much work and how difficult is it to remove the 2 old
ones, put the new ones in and making it work again?. I know the lines
will have to be bled. Is there anything tricky about putting the new
ones in?. I was thinking about changing one, getting it to work, then
changing the other. I have a service manual on the boat but it's in
Mexico at the moment.

The motor has been running a little rougher than usual lately and the
revs have been 'pumping' by about 100rpm at around 1000rpm. Would new
injectors have an effect on this?

Thanks,

Jeannette

On Wed, 09 Apr 2008 22:30:41 GMT, Jeannette
wrote:

Hello group,

I have a 2qm20 Yanmar. I have had it for 6 years but it was built in
1978. I don't know if the injectors have ever been serviced. I have 2
new injectors. How much work and how difficult is it to remove the 2 old
ones, put the new ones in and making it work again?. I know the lines
will have to be bled. Is there anything tricky about putting the new
ones in?. I was thinking about changing one, getting it to work, then
changing the other. I have a service manual on the boat but it's in
Mexico at the moment.

The motor has been running a little rougher than usual lately and the
revs have been 'pumping' by about 100rpm at around 1000rpm. Would new
injectors have an effect on this?

Thanks,

Jeannette

The injectors use a copper seal ring. make sure that you have new ones
before you start. The biggest problem is prying the old ones out, you
will need a fairly stout pry bar for that.

After you get the old injectors out clean the hole where the injectors
mount and reinstall and torque the new injectors. Connect the
injection lines but do not tighten the connection nuts at the
injectors- leave them a couple of turns loose.

Flip the compression levers so that you have relieved the compression,
place the throttle fully open and spin the engine with the started
motor until you see fuel squirting out of the loose injector pipe
connections. Once you see that stop and tighten the injector lines.
Wipe up any spilled fuel.

Place the compression releases in the run position, throttle wide open
and start the engine. As soon as the engine fires pull the throttle
back to idle.

Run the engine for five or ten minutes, checking for leaks, squirt a
little oil around where the injectors fit into the engine - if you see
bubbles stop and re tighten the injectors.

That is about it. Enjoy.

By the way. Injectors are re-buildable so after you change the
injectors have the old one rebuilt and store them, well soaked with
diesel fuel in sealed plastic wrapping for the next time you want to
change them.



Bruce-in-Bangkok
(correct email address for reply)

"Bruce in Bangkok" wrote:


The injectors use a copper seal ring. make sure that you have new
ones
before you start. The biggest problem is prying the old ones out,
you
will need a fairly stout pry bar for that.

Make friends with your dentist.

An old dental pick brings out those copper rings with ease.

BTW, replace the copper washers on any fuel banjo fittings you break
open.

Make life a lot easier when dealling with a Yanni.

Lew

On Apr 9, 5:19 pm, "Lew Hodgett" wrote:
BTW, replace the copper washers on any fuel banjo fittings you break
open.

They're cheap enough to replace. That's what I've done. But, you can
also re-anneal them in hot water. On my 2GM20s the injectors are very
easy to remove. I presume the QMs are similar. I'd be more worried
about breaking the old fuel pipes than getting the injectors out of
the block.

-- Tom.

Injectors in 2QM and 3QM engines are easy to remove ... just two bolts
on the injector hold down (just be sure to 'vacuum' the injector bore
with a strong vacuum to prevent 'crap' from falling into the
combustion chamber before you pull the injector out).

The injectors are also easy to send to an injector shop to be checked
or rebuilt.
"Injector shops" are common in metro areas .... as virtually all
automobiles and trucks nowadays have injectors.

The 2QM and 3QM engines are not all that sensitive to air in their
fuel lines, especially air in the lines downstream of the injector
pump; just bleed out as best you can ... and the engine will usually
start right up.

On Apr 10, 10:34 pm, RichH wrote:
Injectors in 2QM and 3QM engines are easy to remove ... just two bolts
on the injector hold down (just be sure to 'vacuum' the injector bore
with a strong vacuum to prevent 'crap' from falling into the
combustion chamber before you pull the injector out).

The injectors are also easy to send to an injector shop to be checked
or rebuilt.
"Injector shops" are common in metro areas .... as virtually all
automobiles and trucks nowadays have injectors.

The 2QM and 3QM engines are not all that sensitive to air in their
fuel lines, especially air in the lines downstream of the injector
pump; just bleed out as best you can ... and the engine will usually
start right up.

I've done it and it is absolutely trivial. I didnt even replace the
copper seals but simply re-used them. In fact, I removed the
injectors several times (on the mistaken notion they had a problem)
and always re-used the copper seals, no problems at all. My copper
seals always came out with no problems. The banjo unions have never
been a problem even whn I lost the copper seal and cut one from an
aluminum beer can; it worked well for months till I properly replaced
it. Bleeding is also trivial. I am not a mechanic but I am not
afraid to try anything.