75HP evinrude running rough, bad gas?

markheth

Recruit
Joined
Jul 25, 2004
Messages
5
I have an older 2 stroke 75HP Evinrude, and when i was out last weekend, I went through 1 tank of gas, the engine ran perfect. When i switched to the other 2 tanks i have, it would not stay running at all.<br /><br />At first I thought it may be the tanks (they are old metal OMC tanks), so i sipohoned some gas from these tanks to the empty tank which worked before. No difference at all, would not stay running.<br /><br />When i took the gas cap off the other tanks, there was alot of suction inside the tanks, i thought that may be the problem, so i tried to let it run with the cap off... no difference at all :( <br /><br />So now i think i have some bad gas... it looks ok to me, but it was last years gas. <br /><br />Is there anything else that could be the problem?<br /><br />Would it run that bad if I had the mixture wrong? What it it was too rich or too lean?<br /><br />I'm running 50:1, is that ok?<br /><br />Thanks!
 

voodoo

Petty Officer 1st Class
Joined
Jun 23, 2004
Messages
258
Re: 75HP evinrude running rough, bad gas?

50 to 1 is good, too rich fouls plugs and carbons rings etc, too lean eats engines.<br />Gas that has sat 3-6 months unstabilized should be considered unusable.
 

markheth

Recruit
Joined
Jul 25, 2004
Messages
5
Re: 75HP evinrude running rough, bad gas?

Can i stabalize the gas, or is it gone? My 4hp works perfect on this gas, funny the 75hp was so sensitive about it.
 

PDS

Petty Officer 1st Class
Joined
Aug 15, 2002
Messages
239
Re: 75HP evinrude running rough, bad gas?

Gas is funny in 2 strokes. My chainsaw will run on 2 year old gas mix, but my old (76) 115 jonson won't run on gas that I bought 6 months ago. I suggest you loose the gas and start anew. You really can't renew the gas, but can burn it in a old carburated car or truck. Not recommened in fuel injected (oil is said to clog fuel injectors)My 2 cents. PDS
 

Todd Humphreys

Petty Officer 3rd Class
Joined
May 12, 2004
Messages
81
Re: 75HP evinrude running rough, bad gas?

Check to see if the pick up on that tank is partially cloged from rust or other debris. Those old metal tanks tend to rust a bit, and the rust (if it has water in the gas) can clog us the pick up screen over time. While you have all the gas removed look inside with a flashlight and remove the pickup tube and clean. Its worth a try!!! FYI :p
 
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