Hi Harold;

It certainly looks like both fuel lines are connected to "out" ports. I bet the filter has been clean since day one as nothing has been through it! The fuel line from your tank should go to the "in" port and the "out" port should go to the inlet of your electric lift pump so the pump draws fuel through the filter. The outlet from the lift pump should go to the engine.

Remove the nylon plug from the "in" port on the filter and remove the fitting from the "out" port that comes from the tank and interchange them. Remove the small screen from the lift pump and clean it out. It is likely almost plugged with black goo. You may actually have to get your tank cleaned and filled with fresh fuel. At the same time check to see if there is a small screen on the fuel pick up tube inside the tank. If there is, remove it as you don't want it to clog up at the wrong time!

You should also change the fuel filter on the engine. Good luck and hope this helps.

Wow! That is amazing. Certainly doesn't give one much confidence in the people who screwed these things together.

Crazy. I am going below this evening to check mine as well!

I change my filters regularly but a couple of years ago I had a problem where the line going into the filter heard from the tank (which makes a 90 degree turn into the filter head) clogged up before the fuel even got to the filter.

With the problem you had, I'd strongly suggest taking the whole unit out and cleaning it thoroughly.

On the 375 the fuel is filtered and then what is not used is returned to the tank. So I assume this means the fuel is constantly being cleaned. Is this the same as fuel polishing?

I used to think it was constantly recirculating the fuel but this year on our M35A I got a little surprise. When I installed the parallel filter system and a new fuel pump and bled the engine, I found that the fuel was only by-passing the pump and recirculating to the tank when the bleeder wheel on the fuel pump was open. When it is closed the fuel does not go back to the tank. You can hear the pump tone change when you open or close that wheel and when open you can hear fuel dripping into the tank, when closed the pump pitch goes up and fuel stops dripping. I confirmed this by pulling the return line off at the engine and testing it.

I am not sure if this is the way it is supposed to be, I always though it constantly recirculated but mine is not doing that. So no free fuel polishing for me, unless I leave that wheel open. Not sure what the effect of that would be haven't tried it with the engine running. Might try that one day and see what happens.

Harold.. FYI

Re cleaning the tank, when I had my problem I took my tank out to clean it, assuming it had junk in it. What I found, at least around my home port, was that there reallly is no one to clean it so you might want to start looking into it.

It was suggested by some to have a radiator shop clean it. That might work a) if you can find a radiator shop these days; they simply replace radiators in cars now, and b) if your tank isn't plastic.

I resorted to getting gunk deck cleaner from Home depot, sloshed that around in the tank after letting it sit for a day or so. Drained that and stuck the head of my power washer in the tank from as many angles as possible. Drained that then sloshed some diesel fuel around in the tank then drained that and let it dry as much as possible.

All said and done it seems to have worked though there was no visible junk in the tank when I started.

Harold...

I don't know if you could see anything with the sensor removed. First, you'd have to get your eye down pretty far into the locker and then you'd have no light. You might want to try removing the wood panel/bulkhead that covers the tank from the aft cabin,shine a strong light on the tank (I assume yours is plastic like mine is...obviously if its aluminum its a different story) and then look from the sensor opening.

If you can see that the tank is clean, then I wouldn't take it out. One thing I did do and forgot to mention was I replaced the fuel line running from the tank to the filter. The tech who first diagnosed the problem blew threw the line into the tank and said it wasn't clogged, but after remioving the tank I felt it was just as easy to go the whole way at that point rather than take a chance.

You say you want to check to see if it's corroding.... do you have a metal tank? If so, my suggestions are canceled. I think I'd just take it out, check it an clean it. With metal I very much doubt you'd be able to see junk in it.

New but related topic... someone in the thread mentioned something about the screen in the tank. Most tech's will tell you to take the screen off as you can't clean that if it gets junked up. Let the filter do its job and change that.

Also, when I took out my pickup when I removed the tank, I found the end piece had been pulled off thru the insert port (the pickup is actually a hard tube with a soft tube stuck on the end with the filter on the end of that... It goes thru a fitting that is screwed into another fitting. Both have to be removed to get the pickup out and someone obviously undid the first, smaller fitting and then pulled until the pickup came out leaving a short piece in the tank) and the pickup actually ended a good 3 inches off the bottom of the tank. If I was down half a tank and hit rough seas I could have gotten air into the line with the sloshing of fuel and you know what that means.

I got a new piece of fuel hose to add to the pickup and made sure it ended about 1/2 inch off the bottom. That was two years ago and no problems so far.