1984 mariner in line 6 cylinder

[william haynes]

Hope someone can help me. I have a 1984 mariner in line 6 cyl. I just bought this engine and put it on my bass boat. motor starts easy. Got out on the lake and gave it throttle and it wouldn't get up on plane and tried to die. went back to the marina and pulled each wire off plugs one at a time to see if I get a rpm drop. I got a drop on #2 cyl. I bought new plugs and went back on the lake. Gave it throttle and it came up on plane and ran great for about 5 miles then seemed to be slowing down. fished for a while, caught some fish. Started motor up, gave it throttle slowly and it bogged down and wouldn't get up on plane. Had to idle all the way back to the Launch ramp. I had 12 gallons of fresh fuel. Don't know why it would run so well for so long then wont get up on plane. The motor has good spark at all cylinders.any help will be much appreciated.

 

[roscoe]

Re: 1984 mariner in line 6 cylinder

Every motor I buy gets a few things right off the bat.

Compression and spark test.

New water pump impeller.

Rebuild the fuel pump.

Not quite enough info for a diagnosis.

You say you got an rpm drop when you pulled the #2 plug wire.
You should have gotten an rpm drop when you pulled each plug wire. ??

At this point, it could be a spark issue, a fuel/carb issue, a flooding issue, or a fuel pump caused flooding issue.

 

[canoemang]

Re: 1984 mariner in line 6 cylinder

As mentioned above.. check for spark and compression before you go any further, also a good idea to read the plugs if all of them are proper brown color and one is clean like new.. check for water ingestion.

Also a good idea to go through the carbs if afore mentioned is fine and clean them and do a link n sync.

 

[william haynes]

Re: 1984 mariner in line 6 cylinder

Sorry I gave you the wrong info. When I pulled the #2 spark plug wire nothing happened. You will usually get a drop when you take the plug wire off the plug meaning it is good. I am getting a good spark at #2 cyl. I took the plug out and it was really wet like there was too much gas getting to the cylinder. I didn't check the other plugs after I found the #2 plug was not good, I just bought all 6 new plugs and it ran great. Came up on plane and I was doing about 45mph. I was thinking the needle and seat and float are bad and letting too much gas into the #2 cylinder. I have had this happen on another merchury 115 and replaced the float which was saturated and was not shutting the gas off and it ran fine. The # 2 cylinder is flooding for sure. The spark is great. I understand what you mean. I usually do the same thing you told me to do. My son has the same problem and he says he just disconnects the fuel supply from the engine,lets the fuel burn out, waits a few minutes then starts it up and it runs great until it floods out again. I am not a marine mechanic but have enough knowledge to repair most things on my engines. I have wore out three engines and know a little about them. If you need any more info please let me know. I appreciate any help you can give me.

 

[canoemang]

Re: 1984 mariner in line 6 cylinder

Probably not the best idea to run these out of gast.. 2 strokes get lubrication from the gas/oil mix.

If you think it is the float/needle/seat rebuild the carbs.. they probably all need it.