filtration

[shorebird]

Couldn't get my Yanmar GMf to fire up this morning. It actually caught once, then quit. Seems like a fuel problem, so I will replace the filter. I have 2 questions: the fuel line leaves the tank, enters a brass filter-looking device, which looks to have a screw-on top, then enters the more conventional filter, (metal canister, clear bowl bottom with drain-cock.) I bought an in-line filter as well. Question 1, what is the brass thingy? Question 2, where is the in-line filter? I thought it would be at the point where the fuel line entered the injectors, but I can see nowhere to install it. I have a Hunter 31.

[dandrews]

Originally Posted by shorebird

Couldn't get my Yanmar GMf to fire up this morning. It actually caught once, then quit. Seems like a fuel problem, so I will replace the filter. I have 2 questions: the fuel line leaves the tank, enters a brass filter-looking device, which looks to have a screw-on top, then enters the more conventional filter, (metal canister, clear bowl bottom with drain-cock.) I bought an in-line filter as well. Question 1, what is the brass thingy? Question 2, where is the in-line filter? I thought it would be at the point where the fuel line entered the injectors, but I can see nowhere to install it. I have a Hunter 31.

Not sure about your first question about the "brass thingy"' but in regards to the 2nd question, the filter is in between the fuel transfer pump, the one you manually pump to bleed the system and the injector pump. There should be hose or perhaps a copper fuel line running from the injector pump back to the filter. This filter will also have a cross point screw on the top that you loosen to bleed up to that point.

Hope this helps.

Don

[Astrid]

The filter with the clear sediment bowl would be your primary filter (often an add on since it helps keep the factory installed filter from clogging up) though usually it is between the tank and the factory filter.. The other filter-like device is the factory filter which has now become the secondary filter.

[hugosalt]

Problem very likely not enough throttle/fuel for a cold start.
Unless you have been having a fuel problem or filters overdue
for a change.
Yanmar recommends to advance throttle for cold start...I cold start my 3GMC with throtte between 1/2 and 3/4" and then
immediately reduce once she starts. Also for cold starts I sometimes flip decompression levers and hit starter then flip levers back and she starts (again with the throttle advanced).

A typical fuel line install should go something like this...
fuel line from tank enters primary fuel filter (as described by OP
as metal canister with clear bowl and drain-cock) sometimes a
racor filter or similiar. (usually not mounted on motor but on
bulkhead)...then to fuel pump(with the manual lever)...then into
the secondary fuel filter(which is mounted on the motor and has
a metal screw on ring towards the top and bowl which is removed when changing filter on the bottom.

Strongly suggest bleeding system and then trying starting procedure above first....unless of course it is time to change the
filters in any case.
Think service manual has diagrams...may be on line, if not I could send.
Hope this isn't more confusing than helpful.
Hugo

[hugosalt]

As it seems that you already have a primary and a secondary
filter I would not install your in line filter...

[shakey doug]

Gday,
I would suggest your fuel system consists of 1. Brass ''thingy'' is a a water trap come sediment collector. 2. primary filter raycor or cav type. 3.Engine mounted secondary filter mounted Fwd Lhs of motor as viewed from front, element for this filter is about 4''x 1.5'' in size.
It would be good idea to clean all filters and traps for future reference & knowledge.
Your motor symptoms could be dirty filters or air within the system caused by leaking seal joints /pipe fittings/ dodgey lift pump

[DeepFrz]

I think its the widget inside the thingy that is giving you grief. Hit it hard with a bronze shoe and see if that works. If not, find a mechanic that knows what the thingy is, and ask him to fix the problem while you watch and learn...

[GordMay]

Yanmar Fuel Filtre (2), and Fuel Pump /w Priming Lever.

[Badsanta]

Photo of the thingy would be great. I always have trouble starting mine after it's been sitting over the winter. What ever the original problem was, now after changing filters you probably now have to bleed the fuel line. You can do this manually up to the injection pump, from there to the injectors you will have to crank the engine while you bleed each injector as air will not pump thru the injectors. Also make sure the battery is charged so you will get proper speed when cranking if it cranks to slow it may not make proper heat on compression to start.

[GordMay]

BLEEDING THE FUEL SYSTEM
(Purging of air which causes shutdown)

This bulletin contains helpful information for bleeding the fuel system of a Yanmar Diesel and other small diesels as well. Please post where your field service personnel can review.
Since the presence of air in the fuel system anywhere between the fuel tank and the injector will "use a no start or erratic running condition, always bleed the air from the system when the fuel system is disassembled, filter changed or run out of fuel.

1. Make sure fuel tank off is in "on" position.

2. Bleed the air from fuel filter. Loosen the air bleed screw at the top of the fuel filter body and
operate the manual handle the lift pump until the air bubbles completely expel in the fuel flowing
from the filter.

3. Bleed the air from the fuel return pipe. Loosen the connector bolt of the fuel return pipe installed on the fuel injector, and bleed the air by operating the manual handle of the lift pump. (If there is more than one injector, bleed the one at the end of the line).

4. Bleeding the air from the fuel line - (line from the filter to the injector pump). Loosen the air
venting screw at the injection pump and operate the manual handle of the lift pump until an the
air bubbles are out.

5. Bleed the air from the fuel injector. Loosen the nipple on the fuel injector side, set the throttle to half and the decompression lever to the decompression position and crank engine. When no
more bubbles appear in the fuel flowing from the end of the injection pipe, re-tighten the nipple.

Yanmar Service Bulletin ➥ http://ldmarineservice.com/files/yanmar_bulletins.pdf

Yanmar Help ➥ BLEEDING AIR

[shorebird]

Thanks for all the informative replies and pics. My real problem is a dismal lack of diesel knowledge, combined with the absence of any manual of any kind for the engine. We bought the boat last year, I changed the oil, then just cruised, and the engine always ran great. In fact we moved the boat just 2 weeks ago into its new permanent slip, and it started right up and ran great. I will obtain a service manual, and start learning yet another skill associated with boating.
BTW, I wonder if the brass "thingy" is just a fuel version of the raw water strainer.