Changing Delphi CAV Fuel Filters Yanmar 2GM20

[erasmos]

Changing the filters I have a question. I've got real problems bringing in back the fuel through the primary filter by feeding it with the lift pump and holding all screws tight. now on my 2cnd day and out of ideas.

From what I read on various forums and Yanmar bulletins the problem in not having a fuel feed with the lift pump comes from air slipping out of the system where there are, f.ex. small spaces at seal rings and nuts (on the secondary filter f.ex where I had to replace one of the screws to a bigger and carve a new thread). Because air gets out there's no suck through the filter.

However when loosenin the airbleeds on the 2cndary filter or the screw on the primary there's a whoosh, so there should be some suck in there.

"Way to fix", f.e.x is to put external psi pressure on the system and see where the diesel (/air) escapes I read.

I didn't soak the filter beforehand and am using new rubberring seal. Gear is in neutral and half way and I tried in forward gear half way too. I've been checking hoses leading into the filter for clogging, flow is all the way to the filter.

Somewhat a newbie question but I hope someone can help. How do I can flow through the primary filter?

Greetings,
Erasmus

[Ramona]

Yes this can be a real pain in the butt. Its preferable to have the tanks full so that the fuel in the tank is above the filter in question. If that's the case its not hard to get the fuel through. Don't open the bleed screw on top of the filter, there should be a needle valve up on the fuel pump to allow the air to escape as you pump the fuel through. I have had to remove the valve on the fuel pump on a Kubota and attach a length of plastic tube and suck the fuel up through the filter where the fuel tank was below the engine.

[shakey doug]

G'day erasmus,
I assume your fuel level is below the primary filter and base my answer accordingly.If you are positive all hoses banjo joints etc are in first class order including in tank pipes. Do this: 1.open supply valve.2.dismantle filter, check bottom drain plug seal, check main body seals are in correct positions as sizes are different, if fitted with a glass bowl check for any chips around edge renew holding bolt o ring & bleed screw joint,when reassemblying hold bottom section of filter rotating back &forth this should feel smooth & soft if grinding is felt filter or base are not centralized and bearing on one side.3.undo bleed screw on 2nd fiter &injector leads at injector end.4. bleed screw on primary filter Must not be open.5.hand operate lift pump thru full travel if no resistance is felt or no fuel can be seen at filter after a couple of minutes, turn engine grank 360degs & try again, once fuel clear of air is seen at 2nd filter close bleed 6.put stop lever to run position then throttle to full grank engine over until fuel comes out of injector leads going back a step fuel pump will also need bleeding. Once there reduce throttle 50% tighten leads and and start. Possible causes of fuel not getting thru to 2nd filter.1.blocked suction pipe.2. air leaks at filter or fittings .3. gung under lift pump valve or diaphram has hole or leak around sealing edge.

Good luck.

[erasmos]

Originally Posted by shakey doug

G'day erasmus,
I assume your fuel level is below the primary filter and base my answer accordingly.If you are positive all hoses banjo joints etc are in first class order including in tank pipes. Do this: 1.open supply valve.2.dismantle filter, check bottom drain plug seal, check main body seals are in correct positions as sizes are different, if fitted with a glass bowl check for any chips around edge renew holding bolt o ring & bleed screw joint,when reassemblying hold bottom section of filter rotating back &forth this should feel smooth & soft if grinding is felt filter or base are not centralized and bearing on one side.3.undo bleed screw on 2nd fiter &injector leads at injector end.4. bleed screw on primary filter Must not be open.5.hand operate lift pump thru full travel if no resistance is felt or no fuel can be seen at filter after a couple of minutes, turn engine grank 360degs & try again, once fuel clear of air is seen at 2nd filter close bleed 6.put stop lever to run position then throttle to full grank engine over until fuel comes out of injector leads going back a step fuel pump will also need bleeding. Once there reduce throttle 50% tighten leads and and start. Possible causes of fuel not getting thru to 2nd filter.1.blocked suction pipe.2. air leaks at filter or fittings .3. gung under lift pump valve or diaphram has hole or leak around sealing edge.

Good luck.

Thanks a lot for both suggetions. Shakey Doug, will give the procedure a try.

My main tank is under the engine. My secondary is at barely at filter level with all my reserves in. More like just below the filter and there is no diesel service where Im located current. I tried dismounting and holding the filter below the tank without getting gravity to help fill the filter. Instead I could fill up filter and suck through with a reversed airpump all the way to the lift pump inlet hose - but in my greenesh Im not sure what that indicates? Lift pump will still not operate.

I swapped new o-ring on the glass on primary and will change the rings on the bleed screw as this is what I have in store only.

Will I still be able to do the above procedure w the tank level just below the primary filter? (or do I need to find a petrolstation here in the middle of nowhere w my cans to get that level above).

[erasmos]

Oh Doug one more thing, you said
"6.put stop lever to run position then throttle to full grank engine over until fuel comes out of injector leads going back a step fuel pump will also need bleeding"

what do you mean there?

Most profoundly,
Erasmos

[shakey doug]

Erasmos,
If the lift pump is good condition it should be able to fuel aprox 30'' as long as no air is entering on suction side of pump.Check lift pump for possible valve problems also diaphram condition.Meaning= once fuel reaches 2nd filter h.p fuel pump will require bleeding prior to tightening injector lines.You may have to rig a fuel tank obove h.p. fuel pump to get to service, to help with future bleeding fit a out board priming bulb between tank and primary filter. I am not a fan of electric pumps seen to many give problems better off carrying lift pump spares.

[erasmos]

Following the steps it worked like a charm. Bleed screw on primary shut. There was indeed a small leak in the back of the liftpump. As for diaphram, how is it possible to bleed the lift pump?

Thanks a million I am one happy man. Will install that manual pump too in front of the primary! Off to the ocean!

[shakey doug]

If you have to renew the diaphram, remove pump from engine then undo and remove top section push centre of diaphram hard down and turn 90degs it will then come away, valves can be seen in the top piece held in place by two screws.
When bleeding system including lift pump, open bleeds on 2nd filter & injector hp pump this will allow air to escape, close hp bleed last once air free fuel comes out of 2nd filter bleed screw.

Good Luck!