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Thoughts on draining fuel tank with repower?

L

lennyd

Contributing Member
I am expecting that my new rebuild of my previously rebuilt engine (long story but had to rebuild an engine that was done wrong by the orig company etc) should be getting installed next week, and am seriously considering getting out as much of the old fuel and all the crap that has accumulated over 20 years and everything that the new fuels have cleaned from the tank before sucking it into the new engine.

The tank is aluminum, the boat is an 90 sea ray, and the last time it ran was in 07, and the last time it ran right or for any real time was early 05. Also when it was "Trying" to run in 07 I was finding all kinds of sludge like crap in the intake manifold during the many times the carb was replaced for inspection and rebuilding etc.

My question is would you recommend to do this, and how should it be done??

My mechanic (whom I trust mostly) is saying to just pump it out through the normal fuel outlet that would feed the filter and carb, but I was thinking that there may be some kind of screen or pre filter like used in many auto and motorcycle tanks and that any crap would just collect or clog up at that point./

What do you think?
 
Bruce, it is a little tight for space, but I hope there is at least room to partially remove it. Have to replace one of the wire leads that to it that is no longer connected so better be able to access it somehow.

Still not sure how much will be able to be viewed.
 
I am not familiar with your vessel, and the position of the tank, but if there is any access aperture, you can use a mirror to see within, and use a torch for illumination.

That is, a battery operated illumination device, and not an oxy torch with flame.

Use a flame and there would definitely be no need to drain the tank.

Bruce.
 
Go purchase a hand oil pump, the one merc sells to hand pump oil out of the engine. it has a threaded end (garden hose thread).

then go to a lowes or home depot or local hardware store and get fittings to reduce the threaded end so you can install a 3/8 to 1/2 diameter tubing to.

This is a safe way and very effective way to get ALL the fluid out of the tank.

Also you should add a good length of tubing to the uotput side so the bad gas goes overboard to a collection tank of some kind.

here is a pic of the pump.
 
crank the bow of the boat as far as you can, buy, steal, borrow a dc auto fuel pump.

Put 5-6 feet of clear hose with a clamp on both sides of pump.

Remove the fuel pickup, it the one where the fuel hose connects to a 90 degree fitting. That fitting screws off " and is actually a anti-syphin valve " one way valve. A fuel pickup tube with a screen on it will come up with the fitting.

Clean the screen on the end of the pickup tube and blow thru and inspect the valve make your it's clear and not gunked up and working.

Then inset the inlet hose to the dc pump into the back bottom corner of the tank and pump out all the fuel and gunk. Turn off the pump, pull hose.

Close up the tank and your done there.

Then if equipped change element on the fuel water sep.

Fuel pump might have a screen. And the fiting that enters the carb has a screen.

Make sure your tank vent is clear and your done.
 
the_tassie_devil said:
I am not familiar with your vessel, and the position of the tank, but if there is any access aperture, you can use a mirror to see within, and use a torch for illumination.

That is, a battery operated illumination device, and not an oxy torch with flame.

Use a flame and there would definitely be no need to drain the tank.

Bruce.
Click to expand...


Interesting thought on the torch idea, and it could potentially cure all the previous problems I have had with this engine and all, but would it really clean out the whole tank :D

I had a chance to look at the tank earlier today, and it is set up to use one or two lines (for twins I guess) so I hope one of them will come out without a problem.
 
kghost said:
Go purchase a hand oil pump, the one merc sells to hand pump oil out of the engine. it has a threaded end (garden hose thread).

then go to a lowes or home depot or local hardware store and get fittings to reduce the threaded end so you can install a 3/8 to 1/2 diameter tubing to.

This is a safe way and very effective way to get ALL the fluid out of the tank.

Also you should add a good length of tubing to the uotput side so the bad gas goes overboard to a collection tank of some kind.

here is a pic of the pump.
Click to expand...

Good ideas.

I think my mechanic uses a DC pump of some kind, and was intending on saving the fuel for some other application he has that is not finicky about fuel.

I still may end up doing this myself before it gets back to him to install the engine so I may look into the manual pump you suggest.
 
chiefalen said:
crank the bow of the boat as far as you can, buy, steal, borrow a dc auto fuel pump.

Put 5-6 feet of clear hose with a clamp on both sides of pump.

Remove the fuel pickup, it the one where the fuel hose connects to a 90 degree fitting. That fitting screws off " and is actually a anti-syphin valve " one way valve. A fuel pickup tube with a screen on it will come up with the fitting.

Clean the screen on the end of the pickup tube and blow thru and inspect the valve make your it's clear and not gunked up and working.

Then inset the inlet hose to the dc pump into the back bottom corner of the tank and pump out all the fuel and gunk. Turn off the pump, pull hose.

Close up the tank and your done there.

Then if equipped change element on the fuel water sep.

Fuel pump might have a screen. And the fiting that enters the carb has a screen.

Make sure your tank vent is clear and your done.
Click to expand...

So the fitting is attached to the fuel pick up inside the tank?

It looks like there are approx 6-8 small bolts or hex head screws that attach a round plate that the elbow screws into (will look tomorrow, and take a pic if I can).

I am pretty sure that my mechanic just sucks the fuel through the normal fuel line so I will try and remove the pick up and clean it all up as that seems to make more sense. Of course I can only do it if he continues to stall and does not get to it first etc

If I can get to it first, and manage to source a suitable pump will this method remove most or all of the gunk, or does it need to be "scrubbed" somehow?

Guys I was really getting a bunch of crap into the intake system last time this boat was actually running in 07, and I want to try and eliminate all of the potential problems before setting the new engine.

It has been a five year ordeal and the cost has risen well above the value of the boat (the sinking market has not helped either lol) and I just do not want to have headaches in the future with things that could have been avoided inexpensively or much easier while the engine was out.

I guess I am saying it would be a whole lot better to get it right now while I have the room to work in the bilge, and before whatever may be left out would be able to damage the new engine etc.

Thanks again to everyone for the suggestions.
 
sandkicker said:
Mechanical or electric fuel pump on the engine?
Click to expand...

It is a mech pump that bolts up directly to the block.

Some more specs in case it helps

Original mark IV 7.4 330 454 v8 mercruiser w/2 pc rear seal.

Replacement "supposedly" a similar year truck block 4 bolt mains, flat tappet cam, 2 pc rear seal, .030 0ver, now with pretty much new everything (internals and externals).

This is the older/simple style that is normally a pretty good workhorse etc that does not have too many bells and whistles like the newer mpi or efi stuff, but also being such has less to go wrong as well.
 
the one with the plate is the sender door. You can pump from the door also but then you won't be cleaning and inspecting the one way valve. And no don't let him pump from the same line you use to feed the motor he will just crap up the valve and the screen.

If you have time you can wash it out with a little gas and pump that also out.
 
chiefalen said:
the one with the plate is the sender door. You can pump from the door also but then you won't be cleaning and inspecting the one way valve. And no don't let him pump from the same line you use to feed the motor he will just crap up the valve and the screen.

If you have time you can wash it out with a little gas and pump that also out.
Click to expand...

Sorry for the delay, but been a little busy with a host of new engine troubles :(

Anyhow I was told "it was done the right way" and he "does it that way all the time".

Was not there to witness so I can only hope it continues to deliver mostly clean fuel. So far no water is showing up in the separator filter, and only a small amount of granular particles.

I am still battling a vibration problem, and yesterday it managed to loosen up the hose to fitting crimped connection on the remote filter line so I am busy trying to get one of these made and installed.

Fun, fun fun lol
 
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