Mercury 850

[Rikkie bell]

Iam working on old mercury for a friend it has 130pis on all cylinder but top 2 cylinder are not firing both wires have spark but won't fire the wires on sator we're very bad to point I had use a rotary tool to get to ware I could sotter to can the sator cause cylinders not to fire with spark

 

[Rikkie bell]

Iam working on old mercury for a friend it has 130pis on all cylinder but top 2 cylinder are not firing both wires have spark but won't fire the wires on sator we're very bad to point I had use a rotary tool to get to ware I could sotter to can the sator cause cylinders not to fire with spark

 

[GA_Boater]

Combined your threads.

Please use the period on your keyboard. Your post is extremely hard to read and decipher.

 

[Rikkie bell]

Combined your threads.

Please use the period on your keyboard. Your post is extremely hard to read and decipher.

I new to posting I'll try to do better in future

 

[dwco5051]

It would help if you could tell us what year the 850 is as the ignition systems are different depending on the year. A serial number or even a picture of the motor cowling would help.
Do I understand correctly that you have spark on the bottom 2 plugs only and not the top 2?

 

[Rikkie bell]

It would help if you could tell us what year the 850 is as the ignition systems are different depending on the year. A serial number or even a picture of the motor cowling would help.
Do I understand correctly that you have spark on the bottom 2 plugs only and not the top 2?

It is a1975. And I have spark on top to cyl. But it's only running on bottom to cyl.

 

[Rikkie bell]

It's 1975. I have spark on all cyl. But it's only running on bottom 2 cyl all cyl have 130 psi compression

 

[dwco5051]

It's 1975. I have spark on all cyl. But it's only running on bottom 2 cyl all cyl have 130 psi compression

Are the plugs wet with fuel right after it is shut down?

 

[Rikkie bell]

The top 2 have fule on them. The plugs look like new very white. They are perm gap. I pulled spark plugs wires 1 and 2 make no change but it will die when pull #3

 

[racerone]

Perhaps the carburetor is plugged.----No fuel going in also means no oil.----Do not run this motor until you determine the fault.----Or fuel pump diaphragm is ruptured and there is too much gas.----Or plug wires are on the wrong cylinder.

 

[dwco5051]

I had a 76 850 for 25 years and I still have a file folder full of notes on what I had worked on and maintenance. I seem to remember that 75-76 was when the change ignition systems was. Does yours have a distributor? Was the spark checked with a gap tester and were all four about the same intensity? Plug wires crossed?

 

[dwco5051]

I had a 76 850 for 25 years and I still have a file folder full of notes on what I had worked on and maintenance. I seem to remember that 75-76 was when the change ignition systems was. Does yours have a distributor? Was the spark checked with a gap tester and were all four about the same intensity? Plug wires crossed?

I was still typing I guess with raceone replied. Pay attention to his advice, he is much sharper on these motors than me.

 

[Rikkie bell]

1 and 2 have are wet with fule. I tried changed wires on 1 and 2 with no change. If I hold wires at end of plugs I can hear the spark jumping. I was thinking of stator because I had used rotary tool to get to the wires to sodter new wires on

 

[Rikkie bell]

And yes it has distribator

 

[Rikkie bell]

Spark Sound the same on #3 lower cowling is back on so I can't pull#4 wire I don't have a spark tester

 

[Rikkie bell]

I have turned idle mixture screws and it changed rpm

 

[racerone]

I believe the posts on the distributor cap are numbered.----Make sure wires are correct.-----Or mark TDC on flywheel for each cylinder.----Then check with a timing light.

 

[Rikkie bell]

Iam pretty sure the are in the right firing order.
I will pull all plugs and get TDC on all cyl tomorrow.
Thank you so much!!!. I'll keep working at it

 

[racerone]

How did this motor run for your friend last year ?

 

[Rikkie bell]

It ran but would die at ildle