On Fuel Pumps and Gas Filters

Dear Dr. Motorhead,

Last summer I had some problems with my boat, it was with my carburetor, actually. It went something like this. I was driving along and the engine was running real rough, and then it finally conked out. I tried and tried to get it going. Out of desperation, I pulled the choke and it started. When I pushed in the choke, it died. Being the semi-intelligent person that I am, I made a re-attempt to the starting process with the choke again closed. Again, she started up and was running. The engine continued to run only as long as I had the choke pulled. Mind you, not very smoothly, however, smooth enough to get me home. I placed a call to my favorite boat mechanic. Yes, some of us do allow others to work on our beloved craft. He identified the problem as a dirty carburetor, cleaned it and sent me a hefty bill. Not that he takes advantage of my goodwill, he is fair and honest. I know when I get charged a dollar, I get a dollars worth of work. Unfortunately, it is never just a dollar. I must mention, he also replaced the little fuel filter stating, “that’s what caused the dirt to get into the carburetor in the first place”.

Back in action, I enjoyed boating for the next few weeks when history began to repeat itself. Exactly what happened before, happened again. By now, it was the end of the boating season. Not only was I frustrated, so was my mechanic. He accused me of all sorts of wrong doing, including buying dirty gas. I was humiliated beyond belief. How could anyone accuse me of something so awful as buying dirty gas? I decided to have the boat stored and not deal with any of this until spring.

Here it is only December and I can’t get this whole issue off my mind. What is the deal? How could this problem manifest itself as it has? Please help me redeem myself and clear my good name. Oh the shame of it all, being accused of purchasing dirty gas.


Mortified “Mort” Anderson

Dear Mort,

I can help with your good name. Don’t worry you will remain in good standing within the antique boating community. To totally redeem yourself, you may need to hire a new mechanic — one who doesn’t make crazy accusations without first identifying what is really wrong with your boat. Here is the deal, banana peel.

The first assessment is correct – your carburetor was dirty. This was identified by your need to close the choke to keep the engine running. You see, the jets within the carb. get clogged and can’t get enough fuel into the important fuel air mixture for proper combustion. Therefore you need to block out some or most of the air going into the carb, keeping the fuel air mixture somewhat correct. As you said, this works “kind of” good. You really need everything clean to do the job best.

So, let’s get to the problem and clear that good name of yours. Do yourself a favor, replace the little fuel filter. They work OK. The best thing is have a cartridge-type fuel filter and water separator type installed. This filter is very similar to the oil filter on your car. The one I use is made by OMC. Doesn’t cost much and works great. Every spring, spin off the old filter cartridge and replace it with a new one. Like I said, just like an oil filter. They can be purchased just about anywhere. Dirt and debris can come from within your gas tank, especially if your tank is older and has not been reconditioned. Water can come from condensation, so you need a good fuel filter even though you buy only the cleanest gas.

Here is the rest of the story. And with this, you can give some testimony to your attorney for your suit against the mechanic for his slanderous remarks made to you in public. Even those little fuel filters will work longer than just a few hours of operating time. And besides, when filters get clogged with junk, the engine stops and starts, or stops completely. The gas just doesn’t get to the carburetor. The problem you have is the fuel pump. Yes, the fuel pump. The diaphragm inside the pump is beginning to deteriorate. This sends little pieces of black rubber into the carburetor. Fuel filters, even the ones installed in the sediment bowl on the fuel pump, are always upstream from the diaphragm. Therefore there is nothing to catch the diaphragm debris, it goes right into the old carb.

Replace the filter with the canister type if you desire. Replace the fuel pump, FOR SURE, clean your carburetor, and go boating. And fear not, your reputation is still UN-besmirched within the ACBS community.

Hope to see you all at the Minneapolis Boat Show in January.

Dr. Motorhead