Logo
FULL SITE MENU

Mercury Blue Band stalls after 30 mins

M

myls29

New member
Hey guys, been reading these forums for a while now and decided it was time to post :)
So I've recently bought my first bout (1975 Swiftcraft Stilleto SR) its got a 1974 (I think) Mercury 850 Thunderbolt on the back (S/N 8017752 - Australian).

Bit of background, motor sat for 3 years before I bought it, I put a water pump kit through it and replaced gearbox oil. Been out of two runs since and starts fine, idles well, changes gear acceptably and runs great at WOT for about 30 mins (very rough time estimation) and then at some point will stall. At this point it seems to start back up okay but then has alot of trouble getting the revs up. I can put the throttle at what should be WOT and sits at about 2.5k revs, if I pull the throttle back and go again it sometimes gets up and goes fine and others the same thing happens. "banging" the throttle down seems to have a positive effect as does raising the idle lever also. It seems to be a throttle cable issue to me but I checked it out when I got home and seems to operate fine and is strange that it only occurs when the engine gets warm.

Any ideas would be greatly appreciated

Thanks, Mike
 
the motor may be getting hot...first thing i would do is check compression...then run without the cowl and see if you can hold a finger on the head for a count of 6 when the problem occurs.
 
..." runs great at WOT for about 30 mins "

Are you kidding! You think that it's an electric motor that runs WOT all the time? Next time give the poor thing a break and throttle it back a bit. You may have fried some pistons.

Jeff
 
Oops It seems I miswritten my statement, I definitely wouldn't run at WOT for 30 mins...
i should have seen it runs great in general for 30 mins including idle, slow speed and WOT portions ( not actually WOt avrually, bout 4.5k) but near enough
Compressions are good, 150 on all 4
 
reread the entry...does that motor have a distributor?...if it does it rides in a kind of band around it and has a grease fitting on it...if it hangs the timing wont advance...i have forgotten exactly how it is built but grease it...
 
thanks kimcrwbr1, I'll give that a go :) and no haven't checked actual WOT rpms as of yet

papyson - Next time i go out ill see take the cowl off as you say and touch test and report back. Good thinking on the distributor also, I'll suss is that

Thanks, Mike
 
Back
Top