View Full Version : 84 S&S smell of fuel from exhaust

06-29-2009, 01:34 PM
Just converted over to electronic ignition this spring. The boat seems to run great at high RPM, but noticing some vibration at lower RPM, and the smell of Gas from the exhaust. Have check gas lines, carb etc. All but the gas tank itself. No gas in bildge, Seems to be no gas slick from exhaust. No gas smell when the engine is off.

Could it be a cylinder is not firing.
How noticable is that at idle?

What is the best way to check that? Pull all the plugs individually and check for spark? Do this while engine is running, or just crank a few times per plug.?

Could the IE have anything to do with it

Thanks in advance

06-29-2009, 01:39 PM
You can just put a timing light on each wire and that should tell you

06-29-2009, 01:40 PM
Also pull the plugs see if you have any wet ones, make sure they are all good, and the wires have good connections.

06-29-2009, 01:48 PM
You should be able to hear it miss at idle. Easiest way to test spark would be timing light, like flipper suggested. Move the clamp around to each wire while its running.

06-29-2009, 01:50 PM
I would still pull plugs and check them. I had a similar problem with my '85 and turned out to be a bad plug.

06-29-2009, 02:04 PM
Ok, Thanks guys. I will do both. I assume this would this be the cause of the Fuel smell

07-12-2009, 06:07 AM
ive had a similar smell for the most part of last season and never got to the bottom of it , in the middle of doing the head gaskets which were in bad shape and skimmed both heads , so not sure if the two are connected ??

07-14-2009, 10:38 AM
Thanks, Let me know if that solved the problem when you are done and back on the water

07-18-2009, 11:06 AM
Since you had the distributor cap off, double check and make sure the cap is installed good and tight. Check the condition of the electrodes for each cylinder in the cap. If it's old a tune up is a good idea (cap, wires, plugs). The timing light will tell you if you are getting fire to the wire but it's not a good indication if the plug is firing or if the wire is 100%. The best way to see if a cylinder isn't firing is to remove the plug wires one at a time when it's at idle and see if the RPMs drop the same amount for each wire. If the RPMs don't change on one or more wires, then that one isn't firing. It's best to use a pair of pliers with good insulation on the handles or get the tool at an auto parts store. Some times you only get a little "tingle" on your hand, but an old wire and pliers with no insulation might give you a good zap!
Good luck.