Fuel flow problem

[Tmacmi]

I have a Yanmar 2qm15 it has worked flawlessly for as long as I have owned it (1 year). It has two fuel filters in line. The primary (closest to fuel tank) and a secondary filter in bowl housing on the engine itself.

I had to change the primary fuel filter which was originally a Racor 200 fgm with a 30 micron filter to a modern screw on Racor 230rmam also with a 30 micron filter.

I replaced the secondary fuel filter in the bowl with a 10 micron filter (that is what was there)

I also replaced the hoses.

Now the engine is sputtering out and dying after 45 minutes. Its happened 3 times straight at about the same time frame.

After it happens the secondary fuel bowl on engine appears to be empty. I have to reprime it. However there is fuel in the primary filter.

Its almost as if the fuel pump runs out of upmf to draw the fuel.

I replaced the fuel lines with 5/16", which was what was there. Do you think increasing the size would help?

Thank you

[HeinSdL]

Have you tried bypassing the primary filter? Straight from diesel tank to fuel pump?

[Cheechako]

When you change filters fill both devices full of fuel before you close them up. In the case of your new spin on filter, fill it up and carefully spin it on.
Do that now.
Then Bleed the engine at the aft injector with the engine running until no air bubbles appear.
Also, be careful you didn't leave an "up" loop in your new line that may house an air bubble.

[Tmacmi]

Originally Posted by Cheechako

When you change filters fill both devices full of fuel before you close them up. In the case of your new spin on filter, fill it up and carefully spin it on.
Do that now.
Then Bleed the engine at the aft injector with the engine running until no air bubbles appear.
Also, be careful you didn't leave an "up" loop in your new line that may house an air bubble.

I realized that the new filter was in essence an "up" loop. So I shortened all the lines to make them as straight as possible.

Now the engine won't even turn over. I've checked the battery. The voltage is good.

A couple of times I would hand crank and the engine would turn over from the start button after that. Now there is nothing.

I don't see how the two can be related.

Stumped and frustrated on a holiday weekend at the shore.

[Cheechako]

Originally Posted by Tmacmi

I realized that the new filter was in essence an "up" loop. So I shortened all the lines to make them as straight as possible.

Now the engine won't even turn over. I've checked the battery. The voltage is good.

A couple of times I would hand crank and the engine would turn over from the start button after that. Now there is nothing.

I don't see how the two can be related.

Stumped and frustrated on a holiday weekend at the shore.

you mean it wont crank with the key? Totally unrelated issue if so. I had a little Kubota engine once that had a fuel hose barb elbow on the engine. If you turned it one way it created an air bubble, the other way it was fine. It was only like a 45 degree rotation!

[a64pilot]

How much cranking did you do before it wouldn’t turn over anymore?
It’s not hard to hydrolock a motor from cranking excessively, your still pumping water, but with no exhaust it’s not being blown out, pretty soon the muffler fills up, and water gets into a cylinder and you can’t compress water.

Pull injectors and after turning off the seacock spin the motor over, see if any water comes out. If not then you dodged a bullet. But leave the seacock closed until the motor starts.

If water blows out the injector holes, drain the muffler, put oil down the cylinders and with a rag over the holes spin it until you get all the water / oil out and do your best to get it running ASAP, do not open the seacock until the motor is running.

My guess is you have an air leak, in the fuel system

[Chayal]

Originally Posted by a64pilot

How much cranking did you do before it wouldn’t turn over anymore?
It’s not hard to hydrolock a motor from cranking excessively, your still pumping water, but with no exhaust it’s not being blown out, pretty soon the muffler fills up, and water gets into a cylinder and you can’t compress water.

Pull injectors and after turning off the seacock spin the motor over, see if any water comes out. If not then you dodged a bullet. But leave the seacock closed until the motor starts.

If water blows out the injector holes, drain the muffler, put oil down the cylinders and with a rag over the holes spin it until you get all the water / oil out and do your best to get it running ASAP, do not open the seacock until the motor is running.

My guess is you have an air leak, in the fuel system

THIS^

It sounds like it’s hydrolocked OP. Doesn’t take much cranking.

The no crank issue and stalling are definitely 2 separate issues.

There’s air coming in from somewhere from what it sounds like ^

[Chayal]

I would not increase the size of the hose ^

Since it suddenly started coming to a sputter and dying after filter change... look over your work. Ensure all connections are leak free and sealed. I always use a thread locker for the barb fittings on those.

Could also be a bleeding issue..

First you gotta get that water out of there ASAP if it is hydrolocked... I’m hoping it’s just a poor battery or starter connection, but if you cranked long enough with the raw water intake open and no engine start... more then likely hydrolocked.

[Tmacmi]

Originally Posted by a64pilot

How much cranking did you do before it wouldn’t turn over anymore?
It’s not hard to hydrolock a motor from cranking excessively, your still pumping water, but with no exhaust it’s not being blown out, pretty soon the muffler fills up, and water gets into a cylinder and you can’t compress water.

Pull injectors and after turning off the seacock spin the motor over, see if any water comes out. If not then you dodged a bullet. But leave the seacock closed until the motor starts.

If water blows out the injector holes, drain the muffler, put oil down the cylinders and with a rag over the holes spin it until you get all the water / oil out and do your best to get it running ASAP, do not open the seacock until the motor is running.

My guess is you have an air leak, in the fuel system

I don't have the injector puller to remove the injector. Is there another way to resolve this, presuming it is the issue.

I tried pushing the pushing the starter button with the pressure relief lever engaged at it didn't crank.

[Chayal]

Do you have a hand crank for your engine?

If you remove the air filter housing and attempt to hand crank you may be able to push the water out directly through intake. Again, assuming it is hydrolocked...

This happened to me before, and many others I’m sure.

[Tmacmi]

Good news is that I found that not cranking was a bad push switch. I passed and it’s cranking.

Bad news is that it won’t start.

I have bled the lines all the way to the rear injector.

Still scratching my head.

[Chayal]

Very good news!

What’s your bleeding method?

[Tmacmi]

Originally Posted by Chayal

Very good news!

What’s your bleeding method?

The new primary Racor has a priming piston. I pump fuel with that to the secondary, close that, then to the first injector, then close, then to the second injector, close.

Its strange that before this most recent round of work, the engine would start after priming just to the secondary filter.

[HeinSdL]

Originally Posted by Tmacmi

Good news is that I found that not cranking was a bad push switch. I passed and it’s cranking.

Bad news is that it won’t start.

I have bled the lines all the way to the rear injector.

Still scratching my head.

But do close the raw water inlet! Until the engine starts

[Chayal]

Ok.

Everything passed the injection pump is the high pressure side, and typically does not require to be bled.

Bleed your primary first until no bubbles appear,

Then jump to the secondary filter( the engine mounted one) and bleed that until no air bubbles appear using the engine mounted lift pump lever. Should be a little 10mm bolt on the top, really easy to strip so be careful when tightening.

Then jump down to your injection pump and bleed that. There’s another 10mm bolt with a Phillips slot.

I find cracking the injection pump bleeder half to 3/4 turn and pumping the fuel pump lever at least 50 times does the trick. You’ll see the little air bubbles come out of the injection pump

Injection pump needs to bled mate.

Happy to hear your qm didn’t take in water. Sure sounded like it!