Bad Gas in my 59 Lark 35HP? Hopefully...

[clarky711]

Greetings,

Ok, my 1959 Lark 35 HP engine ran great after a good tune up. I recently replaced the points/condensors, fuel filter, plugs, water impellor, all lower unit seals, etc. Compression is 115 and 117 for the 2 cylinders. The ground wire on the coils (replaced recently and in good shape) was worn off a little, exposing some copper, I taped them off so there should be no shorting.

After the above maintence was done, the engine ran great for 7 hours with no problems. As I was alomst out of gas, I filled it up with almost 5 gallons of 87 octane, added oil, and it ran horrible. I have a 6 gallon plastic tank and I run the engine at 24:1.

The engine will idle rough, and will not go above 1/3 throttle. When I attempt to go beyond that the engine just bogs down and starts to stall. I pulled the plugs and they were decent, but I replaced them anyway. Still bad.

So do I drain my tank and start with fresh gas? Will the mixed gas hurt my jeep (I was thinking of putting it in my jeep when the tank is low and diluting it will fresh gas)? Or do I pull the carb and rebuild/clean them. Are there any additives that will cure bad gas or is this a cop-out way of attempting to fix this problem.

Thanks in advance for your help.

Mike

 

[tashasdaddy]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

you are now running ethanol gas, if the gas lines were not changed to the new, alcohol proof hoses, the old ones are likely dirting your carbs. alcohol proof rubber. clean the carbs, you may have to do it more than once. also did you check spark?

 

[clarky711]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

Oh yeah, I forgot to mention that I did replace all of the gas lines with fuel hose from Napa Auto. I assume that these are acholol proof, right? Also, both cylinders are getting good spark. I think that it was funny that it ran good until the last fill up.

What are the symptons of an older 2 stroke engine running on bad gas?

Thanks again.

Mike

 

[tashasdaddy]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

you have them, i would clean the carb. filling the tank may have stirred stuff in the tank. are your carb adjustment knob easy to turn. if so they could have gotten disrupted. http://forums.iboats.com/showthread.php?t=167352

 

[cakopernik]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

This sounds kind of like what happened to mine. Im thinking bad gas too but not for sure. new plugs, good compression clean carbs and all. Still runs like crap. Im going to check my spark tonight and try fresh gas and see if it helps. Ill let you know how my turns out.

 

[clarky711]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

you have them, i would clean the carb. filling the tank may have stirred stuff in the tank. are your carb adjustment knob easy to turn. if so they could have gotten disrupted. http://forums.iboats.com/showthread.php?t=167352

they turn freely, but not that free where they would loosen up on me. I'll try and reset them, but I guess I'll drain my tank and try some new gas.

does anyone think that 4 gallons of 24:1 would hurt my jeep if I put it in mixed with 10 gallons of regular gas? I hate throwing gas out with the price at the pump...

thanks.

 

[tashasdaddy]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

i would use 2 gallons to 10, save the rest for the next tank.

 

[Sea18Horse]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

It may shorten the life of your catalytic converter and your oxygen sensor but it won't do any imediate harm. It would be better in your lawn mower though. If you're concerned about damage just get a cheap plastic 5 gallon gas can and then just dump in a little bit at a time until it's gone.

That said, if you bought the boat gas at the same place where you get gas for your Jeep or at least a reasonablely busy station the chances of getting bad gas is nil.

If once you get new gas you find out it didn't help you'll just have to do some basic diagnosis. Once it acts up does the spark crap out? Use a spark tester to verify. It should be able to jump a 1/4 - 3/8 gap. plugging in a spare spark plug and touching it to metal isn't good enough. If that's ok then you'll have to see if it's fuel. When it craps out take a spray bottle of mixed gas and see if it picks up when sprayed in the carb throat. Good luck!

Cheers.................Todd

 

[samo_ott]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

Nowhere did you mention that you changed the coils. Have you done so?

And at the end of every boating season I dump all my old mixed fuel in my Jeep with no side affects so I'd do it. And as mentioned, maybe spread 4 gallons over 2 tanks to be safe.

 

[clarky711]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

Nowhere did you mention that you changed the coils. Have you done so?

And at the end of every boating season I dump all my old mixed fuel in my Jeep with no side affects so I'd do it. And as mentioned, maybe spread 4 gallons over 2 tanks to be safe.

I did not change the coils, as they look new. I did take them out and visually inspect them and there were no cracks. Both ground wires had a small amount of the insulation wore off of them to where you could see a tiny amount of copper. I taped these off and pushed them down to where they would not come into contact with anything. I don't think that should be the problem here, but ya never know. Tomorrow night I'll swap gas and see.

Does anyone recommend any type of additive for gas that would help? Or should I just swap gas and not bother with the additives... Thanks.

MC

 

[clarky711]

Re: Bad Gas in my 59 Lark 35HP? Hopefully...

you have them, i would clean the carb. filling the tank may have stirred stuff in the tank. are your carb adjustment knob easy to turn. if so they could have gotten disrupted. http://forums.iboats.com/showthread.php?t=167352

UPDATE: So about 2 weeks ago, I emptied the tank and put fresh gas in with some stablizer. Same thing, not running right over 1/3 throttle. So I remebered what Tashadaddy said and started adjusting the high speed needle and whola! She ran like a top. It's been fine since as I've been out about 6 times or so. I even put the old gas back in and still fine. Thanks again for your help!!

Mike