Logo
FULL SITE MENU

1980 40hp mercury just got it all together and tried to frie it up but no spark

ok i now have spark but with plugs in it wont turn over the flywheel turns then as soon as its under pressure stops as if not enough power i'm charging the battery but i think its fine its not that the starter motor stops turning just that it cant turn it anymore when the plugs are out it turns over fine
 
Bad connections, a bad solenoid, or a bad starter. You can eliminate the first two by jumping the starter directly with some GOOD jumper cables.

Jeff
 
kimcrwbr1 said:
+1 on all the wires especially the ground sand them metal to metal and bolt them down good and snug. Sounds like good compression tho if the spark is hot enough your down to fuel and coolant. Is your gearbox full of oil and make sure the lower unit is under water before you start it It will burn up the inpeller within seconds is it dont have water to it. Take your time.
Click to expand...
yes it looks like too much compression it will not even turn over so no spark if i take the plugs out it cranks lovely even if i leave 1 plug in it will not crank what voltage and amp battery should i be using it seems like i dont have enough power to turn it over although it has a pull start on aswell but i got no chance of pulling that over with that compression any ideas?
 
Starter motors respond better w/a 10 wt. machine oil on the shafts and brass bushings. Grease hardens and contributes to poor cranking after awhile. If you want to use a grease use merc. 2-4-C. It won't harden and stays nearly liquid.
 
...just not when i run it through the start solenoid why?
Click to expand...
The internal contacts of the solenoid are fried. There isn't much to them; just a flat disk and a small post for the contact area. They will eventually weld themseves closed and the starter won't stop spinning or the contacts get burned up.
 
guyjg said:
The internal contacts of the solenoid are fried. There isn't much to them; just a flat disk and a small post for the contact area. They will eventually weld themseves closed and the starter won't stop spinning or the contacts get burned up.
Click to expand...
solenoid repaired but still slow turning over and a hot earth wire so will get some chunky wire tomorrow fingers crossed
 
ok. so with new chunky cables and sanding all posts were now turning over, so we have spark, we seem to have fuel and crank but no combustion??
 
What is the compression? Won't fire w/o it. You also need crankcase pressure to pulse the fuel pump and force the fuel/air mixture into the cylinder. If there is a seal leaking crankcase pressure it will never fire.
 
Back
Top