Check my (newbie) thinking on fuel

[captstu]

The problem may be simpler than you think.

If the last thing you did was change the Racor filters, you can assume the problem is related to that change.

Did you pre-fill the filter bowls when you put in the new filters? If you did not pre-fill the Racor bowls than the air in the boels is your problem. The engine pump will not routinely fill the bowls with diesel fuel when the filters are changed, you must do it by hand.

[Tanqueray]

The first time I changed the filters on my O’Day 322 with a Yanmar 2GM20F, I was a bit unsure how to do it. It has an old Groco fuel filter.

But it was pretty easy to change both filters, fill both filter bowls fuel of new fuel and crank the engine…I didn’t need to bleed anything (I thought a Yanmar would self-bleed to some extent).

I hope the OP can get her old girl running.


Greg

[Compass790]

Originally Posted by Tanqueray

The first time I changed the filters on my O’Day 322 with a Yanmar 2GM20F, I was a bit unsure how to do it. It has an old Groco fuel filter.

But it was pretty easy to change both filters, fill both filter bowls fuel of new fuel and crank the engine…I didn’t need to bleed anything (I thought a Yanmar would self-bleed to some extent).

I hope the OP can get her old girl running.


Greg

You didnt get any air in the injection pump & she has I suspect. Sadly they don't self bleed in that era with Bosch pumps anyway. IME there is no escaping going thru bleeding at the injector pump & at the injectors once the air is in there.
It's hard trying to coach a newbie through the procedure ( for me anyway) without being there.
I was at my 1/2wits end & had to call on Wotnames help.
She better get it running after that. lol.

[captchetco]

A common point for an air leak into the fuel line, is a shut off valve usually just ahead of the Racor. (Sometimes called a runaway valve) The reason these can be such a problem, is that most of these fuel valves are designed to work under low positive pressure, but when installed on the fuel line between the tank and the lift pump they are working under a low negative pressure, a vacuum. They will work this way frequently for awhile, but are prone to failure under a vacuum. They work long enough, you probably won't go back to the auto parts store and complain. You can get vacuum rated shut off valves, but you have to look hard. In a pinch, you might just be able to remove the valve and connect the fuel line from the tank directly to the Racor. eliminating the valve all together.

[djousset]

Update:

I was able to bleed whatever air was locked in the system and the engine is up and running. Yay.

With one cranking intermittently and one on the squeeze bulb it only took a few tries before it caught and held. I did notice that with the throttle at rest/idle the engine surged on and off for a bit, I assumed it was working the remaining air through the system or my bulb squeezing had delivered too much fuel? Eventually it stopped and idled normally. I’d love know what caused that so I can be aware if it ever happens again.

Thanks for all the advice and encouragement, it made a big difference in my confidence and how I approached things.

[Wotname]

Originally Posted by djousset

Update:

I was able to bleed whatever air was locked in the system and the engine is up and running. Yay.

With one cranking intermittently and one on the squeeze bulb it only took a few tries before it caught and held. I did notice that with the throttle at rest/idle the engine surged on and off for a bit, I assumed it was working the remaining air through the system or my bulb squeezing had delivered too much fuel? Eventually it stopped and idled normally. I’d love know what caused that so I can be aware if it ever happens again.

Thanks for all the advice and encouragement, it made a big difference in my confidence and how I approached things.

EXCELLENT NEWS - WELL DONE!

OK, I don't normally shout but this is well worth shouting about.

The initial surging was due to the residual air getting pushed through the injector by the injector pump. Rest assured it had nothing to do with squeezing the bulb.

Remember there are two 'sides' of fuel delivery. The low pressure side and the high pressure side. The thing that delineates these two sides is the injector pump. Everything from the diesel tank up to the input side of the injector pump is the low pressure side. Everything after the output side of the injector pump is the high pressure side.

The low pressure side contains pressures ranging from a slight vacuum to a couple of psi, say 5 psi max. This pressure is created by the lift pump and if used, the squeeze bulb.

The injector pump takes fuel in at around 5 psi and pumps it up to around 2,500 psi hence why it is called the high pressure side.

Any small change in the low pressure side makes zero difference to the pressure in the high side.

BTW, diesel at 2,500 psi is dangerous (ie fatal) so be cautious when working on the high side.

[Wotname]

Further to my above post.

Normally you don't have to touch the high pressure side (ie anything between the output of the injector pump and the injectors).

Almost all (>95%) of the time, you only have to bleed the low pressure side and while there are some exceptions, the general principle remains the same.

Always work from the tank towards the input side of the injector pump. Once you get all the air out of the lines and components and have an "air free" supply to the input side of the injector pump, you are good to go!.

Typically there are a couple of points in the low side of the fuel supply that have bleed points (bleed screws etc). Typically theses points are on top of the fuel filter(s) and on the 2GM20 also at the input side of the injector pump.

Now that you have been successful once, you will be able to do again and with a bit of practice, you will be able to do it minutes. Might I suggest you go back and again identify the bleed screws (in order) from the tank through to the injector pump and although your engine might be old and dirty, pour some warm/hot water over the bleed points, clean them and paint them yellow or red. You will glad you did one day!

[Compass790]

Mightily relieved to hear that you got it going. Knew you could but didnt know if you would give up before you did.
Out of curiosity did you ever bleed the injector pipes at the injector end?
Realised too late I should have sent you a link from youtube to identify bleed points

https://www.youtube.com/watch?v=4hWhas3RzA

He has got the last one wrong though. You dont bleed air from the injector from the bolt on the top of the injector. Thats the return line for excess fuel leaving the injector. You bleed air at the nut that holds the pipe on that goes into the injector on the side of the injector.
You want to rid air from the incoming fuel to the injector.
The knowledge you have gained is essential.

[djousset]

@wotname: Thx for the detailed explanation. I plan to do as you suggested with cleaning and paint. The one at the input to the injector wouldn't budge so I'll be looking further into that.

@compass790: Originally I did loosen the excess fuel return line screw, my logic was that it was the last downstream point so if I could bleed that I'd have it all out. I also loosened the nuts at the fuel pipes where they enter the injectors but lost my nerve when there was no air or fuel coming out and retightened quickly.

[Compass790]

Originally Posted by djousset

@wotname: Thx for the detailed explanation. I plan to do as you suggested with cleaning and paint. The one at the input to the injector wouldn't budge so I'll be looking further into that.

@compass790: Originally I did loosen the excess fuel return line screw, my logic was that it was the last downstream point so if I could bleed that I'd have it all out. I also loosened the nuts at the fuel pipes where they enter the injectors but lost my nerve when there was no air or fuel coming out and retightened quickly.

Thanks for answering the question. Ah, you have to have fuel spurting out of the end of the fuel pipes entering the injectors before it will run. Anyway it will be now if you loosen them but dont. It must have bled itself.

If the injector return line goes back to the tank rather than the final fuel filter it's a waste of time to bleed the bolt on top of the injector. I can see the point of bleeding there if it goes back to the fuel filter.
Good onya for seeing it thru.
Bet the wine tasted good
I needed one too.

[Wotname]

Originally Posted by djousset

@wotname: Thx for the detailed explanation. I plan to do as you suggested with cleaning and paint. The one at the input to the injector wouldn't budge so I'll be looking further into that.

@compass790: Originally I did loosen the excess fuel return line screw, my logic was that it was the last downstream point so if I could bleed that I'd have it all out. I also loosened the nuts at the fuel pipes where they enter the injectors but lost my nerve when there was no air or fuel coming out and retightened quickly.

OK, I am sitting here mulling over a mulled wine (it's winter here and at 8pm, its -2C) .

A couple of comments...

1. Although I didn't mention it before (sorta assumed you knew - sorry), the return line is part of the low pressure side of the fuel system. So loosening or tightening it has no effect on the high pressure side.

2. Don't be like me when it comes to a difficult bolt or screw. I used to leave them alone thinking to let sleeping dogs lie...Every time they woke up later and bit me when I was looking the other way. Now days I sort it out before I get caught out later.

Put another way - one day you will really need to be able to open the injector bleed screw and if you can't, something bad will happen.

So my suggestion is to find a suitable time (soonish) and a suitable place and tackle the job. If you break something and it isn't urgent, you will save yourself a big headache compared to breaking something when it is desperately urgent.

The injector bleed screw is probably the most important one as it is the last point on the low pressure side of the fuel flow. The others (upstream) are nice to have but the last one is the most important for fast bleeding.

3. Now you know more about the fuel system and have your first bleeding notch on your belt, re-read the whole thread as many of the previous posts will now make more sense to you.

3. Wottie pours another glass and toasts your success!

[Uncle Bob]

Originally Posted by Wotname

OK, I am sitting here mulling over a mulled wine (it's winter here and at 8pm, its -2C) .



3. Wottie pours another glass and toasts your success!

Mmm, mulled wine, wottie, now I am going to have to follow suit.

[Wotname]

Originally Posted by Uncle Bob

Mmm, mulled wine, wottie, now I am going to have to follow suit.

[djousset]

Duly noted wotname and compass790, all good suggestions and much appreciated. What is mulled wine anyways?? Tonight it's rum and a Bada Bing cherry for me.

This forum has been invaluable to this newish (yet old), stubborn (yet cautious), adventurous (yet fearful) sorta-sailor. Thank you.

[Wotname]

Originally Posted by djousset

Duly noted wotname and compass790, all good suggestions and much appreciated. What is mulled wine anyways?? Tonight it's rum and a Bada Bing cherry for me.

This forum has been invaluable to this newish (yet old), stubborn (yet cautious), adventurous (yet fearful) sorta-sailor. Thank you.

Winter time beverage - https://www.google.com/search?q=mull...4dUDCAw&uact=5

More suited to cold weather gentleman sailor - although that is not I