Fuel Question?

[Rayski]

When I was young at the end of the day on the lake, my father would disconnect the fuel line to the motor and let it run out of fuel before we trailered the boat. He had a late 70's Johnson 50HP and it ran with no problems for about 12 years before my father sold the boat. I have heard twice on this forum not to ever let a marine engine run out of fuel. Was this a bad practice and we just got lucky all those years or has motor technology changed were this is no longer acceptable? Thanks for any input!

 

[Frank Acampora]

Re: Fuel Question?

That practice actually stems from small engines that were removed from the boat and put in the trunk. It was practical; it kept gas from leaking all over and stinking up the car. Engines left on the transom do not need this--PROVIDED the boat is used regularly.

My observation is that it takes longer than a week for fuel to evaporate from carburetors and leave an oil residue.

So for long term storage you would want to drain the carbs to prevent gum and varnish from forming. Short term storage--not harmful but not necessary--unless you are fastidious, and when tilting the engine for trailering, some fuel leaks out of the carbs. ----Just my view on the habit.

 

[Rayski]

Re: Fuel Question?

Frank,

Thank you for your insight! What are your thoughts on where I should go next with my Force 90 HP? I got compression reading on all 3 around 130 PSI, but my middle spark plug looks like it is brand new from when I replaced them 2 weeks ago. I am going to put in a fuel pump kit as soon as I get it in. I was told the check valves on Force motors can fold up and cause similar problems. What are your thoughts on the head gasket or exhaust cover gasket letting cooling water in? And if this is the case, should I just take it to a Force repair shop or with a manual is this something that I could fix? Thank you for your help?

Don

 

[pecheux]

Re: Fuel Question?

Rayski,

What Frank wrote is right on ... especialy the OB in car trunk part. Myself I presently dont run out fuel for storage anymore since the other side of the coin is that storing with gas in carb also means oil on internal engine parts over the winter months. BUT I do incorporate a mix of carb cleaner and stabill in the tank prior to last run, and I stop the engine with choke ON to load it with the mix.

 

[Frank Acampora]

Re: Fuel Question?

130 is reasonable compression, but need more info on possible problem. How "around" 130 is around? Does engine run poorly because of the "clean" plug? See, if water is getting into the cylinder and cleaning the plug the engine may run acceptably. However, if the plug is clean because it is not firing, then the engine will run poorly. So, first determine the reason for the clean plug--There's only three: Plug not firing, little or no fuel delivered to that carb (very bad), or water leaking into combustion chamber and steam cleaning the plug.

Now, with 130 on all 3 cylinders, I doubt if the head gasket is bad. If you had a big enough leak to pass water, the compression would be significantly lower. More likely, the exhaust cover gasket(s) would be bad in this scenario. First, see if the cover bolts are loose. If so, tighten them a bit and see what happens. Don't go so tight that you snap them though.

If you do go to replace the gaskets--there are two with a ss plate sandwiched between--be careful with the bolts. They do tend to corrode into the block and can give you trouble coming out. With me it is Murphy's Law all the way. The last bolt always snaps off.

 

[Rayski]

Re: Fuel Question?

I checked the compression again and got 130 on each cylinder. The motor starts fine and runs good but not with the power when I first took it out. It is running about 6 mph slower and about 700 rpms lower. I just got a fuel pump kit yesterday and will put on this weekend, but I don't see how the fuel pump would keep the middle cylinder from getting fuel? But one of the guys told me I should put in the plastic check valves because they won't fold up and cause problems. Also, someone told me to take apart the middle carb and clean. He said he had the same problem and this fixed it. I will check the exhaust gasket like you said also. Guys, I really appreciate all the tips and help. You guys are a wealth of information. I just want to get this bad boy running smooth so I can get out and do some striper fishing!!