1981 Mariner 70 update

remmer38

Seaman
Joined
Feb 23, 2004
Messages
72
After all I did and rebuilt. I found that I had about half power at full throttle. After checking spark (owwie from me slipping) and all connections, coils, la la la, I found it not to be a problem. I read one post here that said a small tank fitting could be a culprit. Well after a trip to Wally world for replacements, I still had a problem. I took the boat out of the slip and decided to do the at night spark test. Preparing for this, I decided to do what I saw on another post and see if my new cleaned carbs were still to blame. So what I did was take of the air box cover and while running the motor gave a brief spray of carb medic in each carb throat. I might be wrong but with just a shortttttt squirt in the top carb, the motor died. Doing this to the bottom carb got no response or rpm difference. So before I take the front off the motor again to get to the carbs, does it sound like the bottom one isnt doing its job? My other posts had those guys telling it was a fuel starve problem. 1 carb working, easy start, sweet idle and troll. 1 carb not working, making the mid to top not working. Sound thinking? Thanks in advance. Also I put my hand over the throat of the top carb and the motor choked down but not when I did it to the bottom carb.<br />R Emmer<br />Update 11:28 pm. No one helped me. Im the only post with no response after an hour or so. Wow
 

remmer38

Seaman
Joined
Feb 23, 2004
Messages
72
Re: 1981 Mariner 70 update

Well. Thanks for all the help. Ill make sure to send christmas cards.
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,763
Re: 1981 Mariner 70 update

With a problem like this, I start with 2 tests. Number one is to check for spark.<br />Number two is to check the compression on each cylinder.<br /><br />With the info you have given, I would bet that you have low compression on one or more cylinders.<br /><br />Test compression.<br />If its low, decarb the cylinders.<br />retest the compression. <br />If its still low, its time to pull the head and examine the cylinders.
 

remmer38

Seaman
Joined
Feb 23, 2004
Messages
72
Re: 1981 Mariner 70 update

Good spark on all cylinders. Decarbed yesterday with sea foam as per the general outboard FAQ. Thanks for the response. Ill keep ya informed.
 

jim dozier

Lieutenant Commander
Joined
Jan 8, 2003
Messages
1,970
Re: 1981 Mariner 70 update

If you have spark on the bottom cylinder (is the plug actually sparking?) and squirting gas in the throat has no effect, it may be that that cylinder is not firing because it is already too rich and the additional fuel is just making it worse. If the cylinder was running normally like the top cylinder it will die and the rpms would change. If it was too lean, and it had spark, squirting some fuel in would temporarily pick it up. You may want to check the carb float to see if it is stuck open. Check the fuel pump because a leaking diaphragm can inject fuel directly into the cylinder intake port to which the fuel pump is attached causing that cylinder to run rich. Check your reed plate (rarely a problem). If you have spark, fuel, air, and compression (have you checked the compression?), it has to go.
 

remmer38

Seaman
Joined
Feb 23, 2004
Messages
72
Re: 1981 Mariner 70 update

I am singing the Funeral march for this engine. My mech had said compression was good. I went with that the whole time. I wonder what 0 psi meant to him on the bottom cylinder. After pulling the exhaust plate, I find I could move the bottom cylinder in the crankcase. Very bad. The top 2 cylinders were still at 135 so Im gonna part it out. Is there a good site other than ebay? Ebay I think will be the best. Thanks gentleman for the ideas. Drink a beer in this motors,, fish catching, pretty girl riding, etc history. Cheers.
 

jim dozier

Lieutenant Commander
Joined
Jan 8, 2003
Messages
1,970
Re: 1981 Mariner 70 update

Sorry to hear that, Ebay seems to be the way to go or you could post a classified here on iboats.
 
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