In-Boat Fuel Tank Cleaning

[IDoSeaDoo]

I just purchased a '97 Challenger with the famous 787, and had a great two days on it. Toward the end of the second day, however, I began experiencing fuel-starvation symptoms. The boat would not reach peak RPMs, but would idle and rev up to maybe 3k. If I went from idle to full throttle, it would rev the engines for a second or two, then cut back down to slow rpms. It was dark, so I idled her back to the docks. Today, I checked my fuel filter and found that it was almost completely covered with gunk. The boat did sit with half a tank of fuel for two years prior to my purchase. The question is: Has anyone out there developed a way to clean the tank without actually removing it? I'm not too excited to pull the motor again... I have an old fuel injection pump from my old eclipse that I'm thinking of building some sort of fuel recirculating device to circulate a fluid and use a filter to catch the particulates. Anyone have any experience in such things?

 

[Dr Honda]

Personally... I'd put a large, in-line fuel filter in it... and call it a day. That way... you can change it once in a while.

BUT... there can be other issues. You could have a leak in the fuel select valve... or the carbs need a good cleaning. Regardless... DO NOT run the engine if it's bogging like that. A lean run can cook it.

 

[kicker]

What he said, I would also add check and clean the Rave valves if needed. If the valves are gummed up they that will give you similar symptoms as well.

 

[IDoSeaDoo]

Checked the raves prior to reassembly/break-in (20 gallons of premixed fuel ago). Popped the caps off and they move up/down fine (though one is worn and needs a new housing judging from the black goo spilling form it). I ran it only at low speeds once I realized it wasn't running right at higher RPMs. Luckily, I still have perfect compression in both holes, so I think my break-in was successful.
I think I'm going to use the spare SeaDoo filter assemblies I have and some sort of settling basin to make a fuel recirculation device. Recirc low volatility mineral spirits for a few hours and clean out the filters periodically. It would be nice to have a little spray-ball, like the pharm industry uses to knock the crap off the walls... I'll see what I can conjure up with my assorment of odds and ends Will keep a couple fire extinguishers nearby!

 

[IDoSeaDoo]

Good point doc, I do plan on checking the fuel select valve as well. Looks like it'll be pain in the ass based on where it's mounted :/

 

[Spimothy Leary]

if gas sat that long, i'd drain that tank completely... and start freshy fresh.

 

[IDoSeaDoo]

I drained about 95% of what was in there before, couldn't get the bottom of the last couple quarts as I kept losing syphon, and there are three baffles where crap can settle to.

 

[IDoSeaDoo]

Well, my tank-cleaning idea worked I used an old automotive fuel pump from a fuel injected car, some 1/4" hose, a generic inline fuel filter and two seadoo fuel filters (the plastic ones with the cage screens that allow settling action) to make a circulating system. I put the filters before the pump and one more generic inline filter after (just in case). Circulated fuel for about 2 hours through it and pumped a WHOLE BUNCH of junk out of there. On the return, I put on a little brass air hose fitting that restricted flow and made it spray harder and with a flat, blade pattern to knock more crap off the bottom/sides. It worked rather well: that weekend, I ran the boat for about 15 gallons and the filter barely had anything on it. If you attempt to do this with fuel as I did, know that this is a very dangerous procedure and youshould have AT LEAST a good fire extinguisher nearby.

 

[RodInEscondido]

I do not know if you found it out just by chance, but I found (after removing the fuel tank from 89 SP) that regular solvent would not touch that heavy honeylike crap on the bottom of the tank and needed to use gasoline to clean it out. Much easier with the tank out than to be picking up the boat and shaking it around.

I have been toying with the same idea for circulating/filtering the fuel in my boat that tends to have about 100 gallons sitting in it for periods of time ... concern is the duty cycle of the fuel pump running full-flow.

Rod

 

[IDoSeaDoo]

Don't know much about duty cycles, all I know was mine was a centrifugal pump, which means it needed to be primed. I did include a primer bulb in my setup so as to be able to easily prime the system when I turned it off.