Oh No! New Owner with another Diesel Bleeding/Fuel Question

[arf145]

Sorry Folks. But I've looked through past posts and I still have a question. Just got a Pearson 28-2 with a 2GM20F Yanmar. Boat had been neglected last few years, so today I replaced engine fuel filter assembly (owner had stripped out the bleed screw). Filled the bowl with diesel while putting it on. Replaced all the crush washers on the engine filter. Bled the line at the filter, using the built in lever, then ran the engine for a bit to see that all was well.

Then I put a new cartridge in the Racor 210 (I think thats the model). Put the new gaskets on the bottom and top of the Racor cartridge. Filled the Racor with diesel as best I could, and tried to keep the fuel in there as I screwed that blasted big center screw into it while laying across the drive shaft area. Bled at the engine filter bleeder until solid fuel came out. Ran the engine for 5 minutes so I could change the oil.

After the oil change, I started the engine again, but it ran for 20 or 30 seconds and then started stuttering badly, so I killed it. Figured I had more air in there. At the engine filter bleed screw, I pumped (again using the little lift pump lever) for an hour and saw plenty of air jiggling the bleed screw but little fuel.

Where is all this air coming from? Do you think I've got a leak back at the Racor? Maybe the two O-rings on the center screw need to be replaced? Is the plastic screw on the side of the Racor a bleed screw? Do I need to bleed there?

Going back for round 2 tomorrow, so hoping to hear from someone telling me what idiotic thing I've done or forgotten to do.

Thanks.

Tom

[rewell6]

I just took an old Racor off an old diesel suburban I have. After I replaced the filter it started leaking air. Every night it would drain back to the tank. I replaced the Racor with something newer (can't remember) and haven't had another problem. It took me 2 months to find the problem and that was every day.

The problem is probably in the racor or you don't have any fuel in the tank.

The plastic screw on the side? What model racor is it?

You could bypass the racor to see if that solves the problem.

[arf145]

Tank is 3/4 full, so no prob there. It's a 210 or 225 I believe. Takes an R12S cartridge (sorry, forgot to write down details).

But I am considering just replacing it.

Tom

[Rockter]

Arf...

The old diesel weaknes... drawing air and you can't see where.

Firstly, you might try the old "handful of soapsuds" trick. MIx up some washing up liquid and froth it up. Grab a wee bit of the froth... say a cubic inch.... then place it over your suspected leak and watch to see if the air in the bubbles gets drawn in somewhere.

I had these problemes on the olde Volvo, until I fitted a fuel pump between tank and filters. Then leaks are seen by diesel weeping out, and not unseen air leaking in. You see the leaks very easily, and crucially, unless its peeing out, the motor still runs!!!!

A suitable fuel pump will be the Stewart Warner 235A-D.... and it's about $70.
It is very good at charging the system (to 5 psi) and testing for leaks. Once you have found your leaks, you can fix them and switch off the pump. I leave the pump running all the time, and I acccept the fire risk of a pressurised system. I reason that it's better that than the motor stopping.

I would not replace the hardware just yet. It is probably only an O-ring weeping or something.

One other way to pressure test without the pump is to rig another fuel line and connect it to the input side of the Racor. Take the other end of the fuel line up to the deck and pour some fuel into the end of it via a wee funnel. If you managed a head of say 4 ft, then you would have a pressure test pressure of about 1.5 psi (or so) and leaks will be apparent. Then you don't have to buy the pump, well, not yet anyway.

[teshannon]

Did you also bleed the fuel system up at the injector manifold? I may have that terminology wrong but on my Yanmar besides bleeding the filter you need to bleed the rest of the system up to the injectors. Try searching for a thread that may explain the complete bleeding process.

[Rockter]

The problem with bleeding is that you need something to pressurise the fuel to get the air out. The air gets in on the vacuum part of the system. It is very difficult to test that without pressurising it with something. With a fuel charge pump, everything downstream of the pump shows a leak by weeping out, but the motor will not stop.

[Gary M]

I have the same Yanmar just an older model, and to bleed it I just loosened the bleed screw on top of the engine mounted filter. I tried the little lever thingy and it did not do mush so I turned the engine over and it pumped diesel up to there and it sprayed out. I would try that but put some paper towels or a rag over the screw to keep the mess down.

After changing both filters this was all that I had to do, did not have to bleed at the injectors.

If that does not work a suggstion I got from here is to install an outboard motor priming bulb in the fuel line near the tank.
Then if you want to bleed your lines or test for leaks it is easy to pressure it up. I am going to install one some day but so far have had no issues bleeding.

Do you have the Yanmar manual ? it explains how to bleed the injectors if necessary.

Good Luck
Gary

[RichH]

The GM and QM Yanmars are quite easy to bleed and usually its not necessary to bleed all the way to the injectors. You have to be careful when bleeding many of the old racors as they can trap an 'air bubble' in the top of the filter housing 'head'. The best way Ive found is to permanently apply an electric fuel pump that is compatible with diesel oil, place it 'in-line' between the tank and the racors. With a momentary switch/button simply open the 'guard filter' housing on the engine, energize the fuel pump and that that will allow you QUICKLY purge all the racors, and fuel line between the tank and the engine mounted 'guard filter'. Be careful when reinstalling the filter cartridges/canisters especially those with the older style 'flat gaskets' as these are prone to 'suck air' if not exactly reinstalled. Be sure to install the gaskets 'wet' .... wipe fuel all over gasket surfaces when reinstalling. Most of these older model Yanmars will start and soon 'self-purge' with a wee bit of air in the fuel delivery lines.

[Idiens]

Be careful about turning the engine over to pump fuel if you have a water lift. Without the engine firing, there will be a build up of water in the exhaust, which might back-up into the cylinders = end of engine.

[teshannon]

Mt Yanmar needs to be bled at the injectors or it won't start. I learned that from first hand experience after I managed to run out of fuel!