Merc 70hp '90 bogs at WOT but OK with choke.

[woywoyboy]

Evening all, second run out with the above engine today. First time all sweet, today she bogged under WOT but when the key was depressed to enable choke, she went fine. I know this is a fuel restriction of some kind but from where should I commence troubleshooting ? On a lighter note, we did catch plenty.

 

[sharkcat]

Re: Merc 70hp '90 bogs at WOT but OK with choke.

Hi woywoyboy hows life on the central coast??You are right you have a fuel restriction.Running lean especially at WOT is VERY VERY BAD.it will cause engine failure I would suggest not to use the boat till the prob is sorted.Check the fuel tank for dirt,blocked breather.Check fuel lines/primer bulb & connections for blockages/air leaks.Replace filters if fitted (if not fitted get one,good insurance & not very expensive).Check fuel pump diaphram replace if there is any doubt.Clean out carbs & reset float levels.Reassemble Do a link & synch & you should be good to go.Your manual will tell you how to do this...you do have a manual dont you

 

[woywoyboy]

Re: Merc 70hp '90 bogs at WOT but OK with choke.

Tx Sharkcat, I've eliminated all possibility of blockage up to the hose leading into the carbs. Should I be able to blow air through this hose into the carbs ? I've tried with my mouth and can't but I'm reluctant to use compressed air in case I may damage some kind of seal.

 

[sharkcat]

Re: Merc 70hp '90 bogs at WOT but OK with choke.

I honestly dont know cos I dont like the taste of petrol & Ive never tried .But I would think that if fuel can get thru so can air.Are you sure you are blowing into the carbs & not the fuel pump..If you are blowing into the pump the diaphram will stop the air & if you are blowing into the carbs it sounds like a stuck neeedle..Re read my first reply & do that it will take a little time but it will work. & get a manual