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Couple of problems with b78 Merc

G

gpd4

New member
"I've got a 1978 Mercury B

"I've got a 1978 Mercury Black Max 200HP. We finally got a nice day and the wife let me play with the boat for a minute yesterday and much to my delight (and amazement) it fired right up on the muffs in the driveway. It wouldn't, however, go into reverse. The throttle-only button worked fine - I needed a little extra juice to get it started, and it shifted smoothly into forward, but it won't go into reverse with the engine running or turned off. The attaching points on the engine looked good (to me) and so I went for the control box...I guess it's bolted through the side of the helm, 'cause I got nowhere with that...

Late last season, I had a little trouble with the shifting into reverse, but I'd just have to jiggle the cable a little behind the control box and I'd have no problems for the rest of the day. What could cause this? Worn cables? Should I drop the lower unit and see if it will shift with no transmission there? Worn out control box?

Next problem relates to last season, too, but it spent some time in the shop because it seemed like it was dropping a cylinder or two under load. It would run great, then all of a sudden...not so great. I had new coil packs, stator, plugs, ect. put on it - the shop said they replaced basically everything except the trigger "because those almost never go bad" Could that be the problem?

Thanks."
 
"unhook the cable from the mot

"unhook the cable from the motor and shift it from there
sounds like worn cables

could be the trigger, sounds like u have a part replacing shop not a certified shop

get yourself a manual and a meter"
 
"Shift it at the motor? Or tr

"Shift it at the motor? Or try to shift it while it's disconnected?

As for the repair shop, no one around here wants to work on anything older than an '83 motor - and the "cylinder dropping" problem isn't constant, only sometimes, and only when under load...

Thanks."
 
"Thanks - I'll give that a

"Thanks - I'll give that a shot. If it will go into gear, would you say it's a bad cable? Or a bad control box?"
 
"George, I do not think Merc

"George, I do not think Merc made a 200HP motor in 1978(175 HP max?), It is likely newer. To adjust the cable, you should disconnect the shift cable, put both the control and the motor into neutral and adjust the barrell nut to fit the shift cable clamp."
 
"According to the title for it

"According to the title for it, it's a '78 - and the boat it came on is a '78 Terry. S/N 5090199 seems to fall right in there, too..."
 
Sure they made a 200 in 78 and

Sure they made a 200 in 78 and yes up to the 515 series # it is 78!
 
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