Logo
FULL SITE MENU

74 mercruiser misses at idle and on plane

B

bajabrothers

New member
"When we filled up boat had ha

"When we filled up boat had half a tank of 87 octane, we topped the tank off with 93 octane and put a bottle of octane boost. Ran great until a little under half a tank. Boat started missing. Is it possible that the fuel was to rich? We are hoping to replace the plugs and solve our problem. Will plug replacement solve our problem?"
 
Carb or MPI?
Could be dirty f

Carb or MPI?
Could be dirty fuel of filters.
Gas is not "too rich"; octane will make no difference.
Try new plugs and filters.
Look for water in the water separating filter.

Rod
 
"Thanks for the info guys, my

"Thanks for the info guys, my boat has a carburetor. Are there any additional filters other than the fuel/water separator filter? I didn't know if there was an additional fuel filter."
 
Should be a screen or filter m

Should be a screen or filter media at carb inlet also. Also check for condensation under distributer cap.

Kurt
 
Did you fill up at a gas stati

Did you fill up at a gas station or at a gas dock?

If a gas dock did you pick up something other than gas with the fillup

Maybe a bit o water.........
 
"There should be a filter scre

"There should be a filter screen at the carb fuel inlet. Remove the fuel line and unscrew the large canister. If it has what appears to be brown sand in it, that is granular fuel varnish that is probably inside the carb and circuits; may need a rebuild. If you have a mechanical fuel pump there is a filter in the dome. Electric pump also has a filter on the outlet side."
 
"Kevin;
Suggest you empty the

"Kevin;
Suggest you empty the contents of your water separating filter into a glass jar and look for free water on the bottom. If you see any water, you would be advised to drain your tank completely and remove all traces of water, then start with fresh filters throughout. That should do it.
Rod"
 
Back
Top