1981 90hp mecury inline six

[hope761fish]

I am in need of help, I puchase this 90hp mercry off ebay, it was listed as being just rebuilt and bored out to a 110 hp,at pick up, the guy told me after it was rebuilt he put it on his boat and went to the lake and ran it , he said he made one big circle and notice steam commimg out the midsection, so he shut it down, a mechanic told him to check the water tube, anyway he had a car accident and is wheelchair bound, the motor had set for a year before i bought it, i change the tube seal, which had busted, but the engine won't turn over WITH THE SPARK PLUGS IN IT, you take them OUT and it turn over fast, put the plugs back in and the flywheel barely turn a quarter turn, I can put a pull rope on it and turn it but it's not fast enough to start the motor. I belive it just tight from new rings and then sittting all that time, anyone have any suggestion WHAT SHOULD I DO ? i don't want to burn the starter out trying to start it, IT GOT TO BE ANOTHER WAY, thanks for any help

 

[Barnacle_Bill]

Re: 1981 90hp mecury inline six

Is the battery fully charged? If so did you try a different battery or else have that one load tested. (even if it new) Are all connections very clean and tight? Look for signs of corrosion around the base of the terminal lugs. If you see any, replace them as they can corrode inside where you can't see it. You can also try jumping to the starter direct with jumper cables. If it still won't work right, have the staarter checked at your local auto electric shop.

 

[Chris1956]

Re: 1981 90hp mecury inline six

When the plugs are out, can you turn it by hand? Does it turn smooth? if so, you likely have dirty starter cables or a bad starter.

I would remove the transfer covers on the starboard side and inspect the pistons, rings and cylinder. The motor could have overheated and you will see the damage, likely on number 3 or no 1 cylinders.

Rebuild the waterpump, and clean and rebuild the carbs, and set the timing and link and synch. A OEM service manual will set you up.

 

[anna]

Re: 1981 90hp mecury inline six

hi , had simmilar problem with a 50 hp merc would only turn the starter fast enough to fire up when it was jumped from my car with the engine running as it was getting extra power to starter that way .problem was a bad starter.apart from other tips posted you could try that. good luck bill