Racor Draining Back

[JLR]

I have an issue with the racor on my forward Genset draining back. Replaced all I could in the racor already and may need to replace it with a new one but I thought I would ask whether I may need a check valve to prevent the draining back instead. I do not want to throw a valve every time I use it so a gate valve is not my answer. The genset is not sucking air and runs great once it gets going. I have checked with Bruce M. and he suggests it is likely some sort of a tiny air leak, not large enough to leak diesel but large enough to let air in the system. He suggests that a check valve is probably the easiest way to resolve the problem. Assuming I wanted to knock myself out, where would I check for air leaks I guess between the part of the racor above the turbine and the genset? Once again, I have already replaced the ball and gasket and the other gaskets look perfect. Also, when I remove the lid, there is still a vacuum even though the fuel had drained back. One last question--could this be a simple cold temperature issue? I never noticed it in season up in the North here. Also, there is a small white bleed valve in the fuel line on the 20KW Onan itself. Never saw this before but when that valve is closed, no fuel goes to the genset. Has anyone ever seen a bleed valve on the genset itself like I describe?

 

[saltshaker]

There's a ball that acts as a check valve inside the Racor. Either it is gunked up or it was removed and put back incorrectly.

 

[seasalt]

Maybe the little gasket on the ball is upside down?

 

[JLR]

Been there, done that, replaced both and gasket is installed properly, per t/c with Racor and contrary to the Racor pictures that went with the ball and seal kit. That's the first thing I thought of as it had been an issue on another boat. I only wish it were that easy.

 

[Finalee]

I went through this. There was gunk in the tank ,along with a clogged primary filter. The fuel would siphon back and empty the racor. Only after both ends where cleared did all work correctly. This has happened 2x in 1000 hours.
the

 

[JLR]

Check with Racor. They said if the racor is above the tank, some seem to drain back. They do not make a check valve to prevent this but say installing one will solve the problem. Duplicate racors for duplicate gensets mounted at the same height--one drains back and one does not. Now to find a suitable one way valve for diesel fuel to install.

 

[saltshaker]

Check with Racor. They said if the racor is above the tank, some seem to drain back. They do not make a check valve to prevent this but say installing one will solve the problem. Duplicate racors for duplicate gensets mounted at the same height--one drains back and one does not. Now to find a suitable one way valve for diesel fuel to install.

While a check valve may solve the problem, I don't think that's the right approach. This is a new problem and the current setup has worked for almost 20 years. Find out what is wrong and fix it. I'm still betting on the check valve in the Racor. Try swapping the Racors for the generators and see if the problem persist or moves with the filter.

 

[JLR]

Lot's of ways to attack this. However, when the fellow who built the boat (or the functional equivalent of same) says a one way valve is the best solution, that's fine for me. Alternatively, I could just buy an entirely new Racor and see if that solves the problem. If it does not, it has been a waste of time and money. Swapping racors is a good idea. However, I am reluctant to "involve" another genset in this issue and prehaps compound my problems when all things are put back together with some remote change of damaging fitting on a perfectly good setup. Frankly, I am still convinced it is a cold weather phenomenon because for the boat was south for its entire life until I brought it north. This issue only emerged after the boat was decomissioned over the winter.

 

[JLR]

Added the one way valve yesterday and also replaced the lid and T handle gaskets. No luck. The Racor still appears to drain down about 2-3 inches from the top after it has run and sits a bit, but that may just have been absorbed in the new filter I put in. I have now bought an entire gasket replacement kit for the Racor. However, having already replaced the ball and seal as well as the lid gasket and the T Handle gasket, I only have a few left to replace. I am not optimistic. However, I am still convinced that somehow, this is a cold weather phenomenon only and of no concern in season. Hopefully, the rebuild kit will fix/eliminate the Racor as the problem. Mystified as to where the fuel (1-2 inches) is going with the one way valve installed.

 

[Glory]

Something you might want to check is the return line for air, remove the return line and submerge it in a container of fuel to see
It there us any air in the fuel. If yes, I would replace the fuel line, regardless is construction material, one section at a time. If no air I would pull the bowl off the Racor and spin the turbine out and have a look at the ball and seat location and the fitting headed into the Racor, especially if it's a 90 degree elbow, for debris.

Ir removing and replacing fuel lines are a bare, you can always block off one end and pressurize the line and see if it holds pressure.

JM

 

[JLR]

Fully rebuilt the Racor yesterday. Looks like it might have been the problem. I will check in a few days on the drain back. If that did not do it, I will wait for the warmer weather and see if the problem still exists then.

 

[jim rosenthal]

If that doesn't solve the problem, and you think the problem is due to the Racor, you might think about another form of fuel filtration- try one of those Fleetguard systems from Seaboard Marine in CA.

 

[BOATER BOB]

Just a thought but I'm thinking it could be on the generator side of the set up after you put in the check valve and still had the leak down .Maybe a leak in the gen fuel system or a leak in the the injection shut off valve letting it return through the return line.
Bob

 

[JLR]

All good suggestions and much appreciated. Hopefully, in a few days I will know for sure.

 

[doc g]

I admit I'm too lazy to have read all the previous posts in their entirety but I had an issue with one of my gens and to track it down I used a piece of clear tubing and a 12 volt fuel pump . I found leaks at the fuel pump. If you pressurize areas that were under vacuum you may find leaks, which would be air leaks on the vacuum side.....Pat

 

[JLR]

Although the situation is much improved after the Racor rebuild and the installation of the one way valve, I am still convinced that I am getting a drain back situation through the return line. I will wait for warmer weather to see if this remains an issue but during the course of doing other service on the genset, my mechanic reported that the jumper fuel lines on the genset itself (to and from the fuel pump) were devoid of fuel after having the genest sit for about an hour or so. While I have no real problem starting the genset, or having it run properly, I am of the belief that I should not have to "start" it more than once.