3HP Lightwin fuel flow

[Dizz]

I have this 59 3hp running&starting very good.Took it to lake Friday,and by gps pushed my 12' x 36" jom boat 4.5-5.2mph.rpm`s sounded good,except after maybe 3 minutes full throttle rpm`s would back off aprox 500-800revs,as fuel flow wouldn`t quite keep up with carb.You could let it run low throttle for a couple min,and it would run full for another 2-3 min.
My strainer is clean as I can get it,looks good,fuel line clear,carb boul clean,tank clean.
Any ideas,It wouldn`t be float adj,could it?
It only slows down aprox .5mph.

 

[Joe Reeves]

Re: 3HP Lightwin fuel flow

The fuel filter within the tank may appear clean but usually it's restricted. The problem would have to be that filter OR the engine is starting to overheat.

The filter has been unavailable since 1995 but if it was available the price would exceed $45.00 (whew!). However I do have one left in stock should you need it ($31.00+ship). ReevesJ32@aol.com

 

[Molaker]

Re: 3HP Lightwin fuel flow

If you pump the primer bulb, does it catch back up? If so, you could be getting ahead of the fuel pump. You might try a fuel pump rebuild kit. But first, make sure your tank is venting properly.

 

[F_R]

Re: 3HP Lightwin fuel flow

Bust the sintered filter out and solder in a rolled up piece of brass filter screen. ("Bust" as in melt the solder and it will fall out)

 

[Dizz]

Re: 3HP Lightwin fuel flow

Where would you find the brass filter screen?When I open valve&vent it appears I have good fuel flow.

 

[F_R]

Re: 3HP Lightwin fuel flow

http://www.mcmaster.com/ is one place. A 12" x 12" piece wil fix your motor and everybody elses' for miles around. I'll let you wade through the mesh size specifications.

Yes, the symptoms of a partially clogged filter are as you described. Runs at slower speeds but starves at higher speeds. Or, runs at any speed with a full tank but starves with a partial tank.

 

[Dizz]

Re: 3HP Lightwin fuel flow

Molaker.this motor has an internal on top fuel tank,no bulb.
Thanks again,FR.I did a lot more cleaning,and will try again on the water before I go any farther with this.
These motors have low pitched props,I mean even with a bigger 14' alum boat,they will make full RPM`s.Good little motors.I have new coils,points&condensors,water impellor,fixed welded handle,new oil drain washers,clean carb.I cut the spark plug wires up a little to get to clean copper,
I`m ready to roll!
Are the Redline coils allright as far as you know?Later

 

[Scaaty]

Re: 3HP Lightwin fuel flow

Another problem might be just PAST the fuel valve filter, in the valve itself. I had one I worked on, cleaned up the filter real good, (gummed up with old gas), and still no good. Ripped it off, and the passage way through the valve was still pretty well gummed up. Well, not gum, more like tar...cleaned it out with a drill it was so tough
Darn right good motors..own 2 . straight and weedless drives

 

[Molaker]

Re: 3HP Lightwin fuel flow

Molaker.this motor has an internal on top fuel tank,no bulb.

After the experts responses, I figured that out. Sorry for the babble.

 

[Joe Reeves]

Re: 3HP Lightwin fuel flow

I understood your first post to indicate that the fuel flow wouldn't keep up, but I see now that you say you have a good fuel flow. If so, that in turn would indicate that the fuel filter is okay.

Is the cap vent functioning properly? Other than that, my thoughts would be a overheating problem.

 

[Dizz]

Re: 3HP Lightwin fuel flow

On the water,when it slowed I thought of clogged vent,opened gas cap and no help.


Not sure of the water flow I should be looking for.All I see is some water coming out of that vent outlet halfway up lower unit on front.It sputters a moderate light amount out of both sides that is hot.is their another place it should be coming from?I put water impellor in same way as came out,but that may not be correct.which way does it go,I have to tear it down again to see how it is turned.

 

[Dizz]

Re: 3HP Lightwin fuel flow

bump

 

[F_R]

Re: 3HP Lightwin fuel flow

The shaft turn clockwise. The impeller blades trail back. Now ones will self correct if you put them in backwards. you should not flip used ones over.

 

[Dizz]

Re: 3HP Lightwin fuel flow

Any ideas on how much water to look for,and is that double vent outlet on front of lower unit only place to see it?Thank`s

 

[F_R]

Re: 3HP Lightwin fuel flow

It should have a spray of water out the relief holes at all speeds. Most of the water goes out with the underwater exhaust where you can't see it..

 

[Dizz]

Re: 3HP Lightwin fuel flow

Thank`s,it does have a spray at all speeds.Would their be a thermostat on this engine?


On another matter,That flat cover plate that is on side of block with all the screws,mine was very loose&seeping oil.I finally had to use lockwashers.would a slight vacum leak thru this plate cause any real problems other that the oil mess?Thanks again for all the tips.

 

[Joe Reeves]

Re: 3HP Lightwin fuel flow

That flat cover is an exhaust baffle plate with red hot exxhaust in one area and water in another. Being loose would allow water to gain access to the exhaust and combustion areas and vice versa. This could set up a stalemate situation whereas the water flow would be stopped at a certain point.

I'd suggest that you replace the gasket that's behind that plate. If the problem continues, install a complete water pump assembly to eliminate any possible problems in that department.

 

[Dizz]

Re: 3HP Lightwin fuel flow

Will check it out,Thank`s