A lot of air in Racor filter. Engine stopped running

[phantomracer]

The yanamar (3gm30) engine stopped running due to air in the system. I noticed a huge amount of air in the filter. After searching the boats fuel line, I didn't notice any leaks. Then again, if it were a small leak on the vacuum side, it wouldn't show up anyway (unless it were huge)

The boat yard said that some racors are supposed to have air in them (larger ones) but was unsure about the smaller one.

Whenever I have changed the filter, the fuel has always been at the very top of the filter. Never a drop of air.

I assume (pic attached) that this is not normal for a Racor 200fg filter.

Would the air be coming from the inlet side (it is partially pressurized with an in-line electric lift pump after the tank and before the filter), or the output side.

the system is: tank/lift pipe - hose - electric pump - hose - racor - hose then engine.

[bmm32005]

Check the easy things first, like fuel in tank, lines leading into Racor. I found a brazed fitting on my pick up tube in the tank had a very small hole in the brazed area. Re brazed the fitting and solved the problem. This was on Ericson I used to own. Your Racor may also be due for a re-build of all the rubber seals.

[Capt.Alex]

Does the fuel drain back to the tank after you shut down the engine, preventing restart? or does the engine stall while running? If it's draining back to the tank, it is probably an air leak between the racor and the engine, or in the racor itself. If it sucks air while running, check the pickup in the tank for pinholes, or the lines from the tank to the racor. If you have not ever rebuilt the racor, it wouldnt hurt to do so. You can get a rebuild kit with all of the gaskets and o-rings. You would be surprised how much gunk can come out of one when disassembled. Sometimes a good cleaning and replacement of all the seals can solve an issue such as yours.

[phantomracer]

sounds good. I do replace the orings every year that come with the filter. Are there other seals that need replacing?

As time is of the essance, I am having the boat yard play with it. We discussed everything mentioned above to locate where it is.

the engine is dying while driving.

If I bleed the filter so it is full, it stays full. It does not drain. If I run the engine, more and more air fills the filter.

I assume the filter should stay full (it always has)

There is an electric lift pump in the mix as well, which, I guess could be sucking air there too.

This is something in my wheelhouse to fix, but strapped for time, and an upcoming rendezvous, so, reluctantly, having them fix it. at least I will have someone to blame if they don't get it right

I didn't know there were other gaskets/seals on the 200fg filter to replace. I will look into that as well. There is no fuel leaking out of the filter though, but good to know it can be serviced. The boat yard said this was a very good filter for the boat.

But, will rebuilt it this winter, if they don't, just to be on the safe side.

[barnakiel]

lock off the fuel at the tank

open your filter

fill it from the top with clean fuel

Does the level remain fixed? It should.

Now close the filter. Open the valve on the tank. Start the engine. Some bubbles may come but then they should stop soon. If they keep on coming, you have an air leak between the filter and the tank.

b.

[phantomracer]

Originally Posted by barnakiel

lock off the fuel at the tank

open your filter

fill it from the top with clean fuel

Does the level remain fixed? It should.

Now close the filter. Open the valve on the tank. Start the engine. Some bubbles may come but then they should stop soon. If they keep on coming, you have an air leak between the filter and the tank.

b.

I think that is what is happening. THe level will stay high for a long time, but starting the motor will make the level go down. So, it is most likely between the tank and the filter?

[Safari38LH]

I have had what sounds like the same problem for two years. When the engine was running you could see air bubbles plopping up from the bottom of the Racor every 30 seconds or so. No one (5 different mecanics) could figure it. One mechanic bypassed the Racor and the engine ran fine so we ended up putting in a new Racor and its been running like a champ. Could have been a fitting but no one could pinpoint it

[Stu Jackson]

You also have the pump in the wrong place. Should be tank - hose - filter - hose - pump - hose - engine secondary filter - engine.

You could have a leak at the pump. Also check the filter usually at the bottom of the pump.

[phantomracer]

Originally Posted by Stu Jackson

You also have the pump in the wrong place. Should be tank - hose - filter - hose - pump - hose - engine secondary filter - engine.

You could have a leak at the pump. Also check the filter usually at the bottom of the pump.

agree. was like this when I got it. The engine mounted pump is still there. The electric one just helps in bleeding.. but does run when running i might change the order at some point.

The boat yard will test each segment til they locate the leak. I would do it (not that hard) but I just don't have the time to do it.

[keepondancin]

I had a similiar problem years ago. Every 5 hours of engine time and I would have to top off the Racor and bleed the fuel system. Turns out that the inlet fitting was an elbow, and the previous owner had paid to have the tank cleaned. The service person used the high heat colored silicon to reseal the access port, which broke down from the fuel, and small balls of silicon was blocking the elbow. There was enough vacuum to allow air into the filter. Cleaning the elbow and replacing every seal I could find, along with removing the silicon on the access port resolved the problem. I did the same as Safari, and that's how I determined that it was the Racor, and disection was how I found the problem.

[Stu Jackson]

Originally Posted by phantomracer

agree. was like this when I got it. The engine mounted pump is still there. The electric one just helps in bleeding.. but does run when running i might change the order at some point.

WADR, I'd do it NOW. Why? 'Cuz if the small filter in the bottom of the pump clogs up, your engine will stop. At the very least, take it off and inspect it. A ten minute job...OK, it's a boat, 20 minutes!

[phantomracer]

Originally Posted by Stu Jackson

WADR, I'd do it NOW. Why? 'Cuz if the small filter in the bottom of the pump clogs up, your engine will stop. At the very least, take it off and inspect it. A ten minute job...OK, it's a boat, 20 minutes!

They are going to inspect/clean the filter on the pump and/or bypass it. Might reroute it as well. but got to find the source of the leak first..

[barnakiel]

I do not know the fg200 personally (I wrongly posted as if you had fg500). If it is top loaded then inspect also the top cap - it has a seal and if this seal is gone or twisted, your filter might be sucking air from there.

When filter cap is suspect, it may be difficult to judge this. But you can sometimes wrap the whole filter top with a plastic food wrap - if the air leak stops - the cap may be leaking air.

Normally, with top loaded filters the open filter fill test checks for leaks between the mechanical lift pump (this one btw the filter and the engine) and the shut-off valve (at the tank).

In your case there is a pump in line to the tank so this test will check the line to there.

BTW is there enough fuel in the tank and is you pick-up pipe sound? Maybe you get air into the system before the electric pump?

Have a look at the top cap of the filter. And make sure it closes tight!

Let us know how it goes.

b.

[Snore]

Before you go too crazy, try this. Remove the fuel filling cap.

I chased an apparent fuel starvation problem for 2 weeks (p/t around work) until I sprung for a mechanic. He found that there was a problem with the vent hose(long story there). That two feet of vent hose cost $700.

The easiest way to check if the tank is getting air back, is to remove the filling cap. If the problem repeats, it is not the vent line.

[phantomracer]

Just an update. Got the boat back. The fitting on the hose to the dip tube was sucking air. They did test everything else. Filter was fine, would hold vacuum, the rest of the hoses and fittings were fine.

They removed all traces of the Teflon tape used an and used thread sealer.

Motored for a few hours yesterday without problem, and no air in the filter. I think we are good!