mercury 850 thunderbolt ?

[Mhydler]

Hi my name is Matt I am new to the boating world I have had to do a bunch to it like when I bought it it had been setting for 3 years and not running so when I got it I had got it started and ran it off of muffs for a little bit then shut it off then started cleaning the cob webs out and notice all the wires in the engine needed replaced and I have rebuilt the harness and have had it running sense for a total of 3 hours with water coming out of the places that it should so. I took it to the lake had it running for 30min + to look it over and all is good then went past no wake zone went to give it gas and with no other sounds it just shut down. now its hard to crank but if I hook it to a battery charger it will start and now water don't come out of the pee hole of the other places I need some help trying to figure out what it is sorry for the long post.

 

[Mhydler]

Sorry it is a 1976 motor 850. 85 hp

 

[Chris1956]

Matt, It sounds like you have at least two issues. Waterpump is likely bad, so replace it. New impeller, wearplate and 2 gaskets need to be installed.

Also, carbs sound like they are dirty. That would cause her to stall upon acceleration. The idle mixture could also be too lean.

 

[Mhydler]

Thank you I am taking it apart tonight and going to see what I can find

 

[Mhydler]

Well took the water pump apart and all looked well no chips out if the fins or anything shafts still turns but going this morning and getting new one while it's apart

 

[Kitimat_DoubleEagle]

K, you need to charge your battery, or you batter may be no good. On these ignition systems it runs off your battery, the stator on the motor only charges the battery, if you were running it on idle for a long time it may have not been sufficiently charging your battery. Hook the batter to a trickle charger for a day or so and check the voltage with a multimeter or try and different battery. I have a 1975 850 and this caused me issues last year... Also your stator may not be charging the battery, they go bad. I worn down battery will crank the motor over, but not fast enough and with a weak spark, causing the issue you describe.

If the carbs are to lean on the idle/mixture circuit, then it will stall out when you try and accelerate to get up on plane.


Your pee hole is likely plugged. Take the cowel off and pull the hose off where it connect tot hte water jacket, blow it out with compressed air, you'll likely blow a bunch of **** out. I had this problem, as well last summer, looked like a weak stream all the time, blew it out and now its good to go.


These old motors are simple once you learn em. You'll get it goin!

 

[SD_Redneck]

One thing to check while you have the lower unit off is your impeller key. If it is worn down a little bit, it will wear out the inside of your impeller and it will not push much water through your cooling system. Its a simple fix and will save you trouble in the long run. And they are like $2 for a new one.