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1986 Mercury 25HP XD Will Not Run

C

c116005

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[FONT=&quot]1986 Mercury 25HP XD

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[FONT=&quot]Can only get it to momentarily hit one time when I first start to work on it, then nothing, not even with ether/spraying fuel in carb[/FONT]
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[FONT=&quot]Plugs seem to be dry[/FONT]
[FONT=&quot]
[/FONT]
[FONT=&quot]Compression Cold is 98 on both cylinders/no leaking[/FONT]
[FONT=&quot]Just replaced both crank seals and wear sleeve[/FONT]
[FONT=&quot]Has Spark - Just Replaced the Stator because I thought spark might be weak/really good spark now[/FONT]
[FONT=&quot]Trigger resistance seems normal at 780[/FONT]
[FONT=&quot]Replaced one coil[/FONT]
[FONT=&quot]Flywheel Key is intact[/FONT]
[FONT=&quot]Carb Rebuilt[/FONT]
[FONT=&quot]Replaced both exhaust manifold gaskets to fix water leak into lower cylinder[/FONT]
[FONT=&quot]New Fuel tank, Lines, Filter[/FONT]
[FONT=&quot]
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[FONT=&quot]Any ideas?[/FONT]
[FONT=&quot]Thank you in advance[/FONT]

 
flyingscott said:
Get a different gauge and re test? Do you have spark? Has the carb been rebuilt recently?
Click to expand...

I retested the compression a few days ago with a different guage, 98 each cylinder. Yes, have a great spark, recently replaced Stator. The carb has been rebuilt recently, i Sent it off to a rebuild service. I cannot get engine to hit on starter fluid or when I spray fuel in the carb.
 
Pull the transfer port covers off to look at the rings. 98 psi is not good good compression. Did you put the correct base gasket on? If you put the wrong one on you will cover the pump pulse port. Are you sure they put the right gaskets in your carb? And was it assembled with the correct gaskets?
 
flyingscott said:
Pull the transfer port covers off to look at the rings. 98 psi is not good good compression. Did you put the correct base gasket on? If you put the wrong one on you will cover the pump pulse port. Are you sure they put the right gaskets in your carb? And was it assembled with the correct gaskets?
Click to expand...

I read 90-100 compression when cold was good. The base gasket is the same as before. I actually sent the carb back for a second rebuild when I wasn't getting fuel the first time. They told me to buypass the carb by spraying fuel directly into the carb to rule out any carb problems. Will not hit with fuel sprayed into carb or with starting fluid.
 
If the wires to the cil are reversed, it will backfire and fight you when you yank the cord.

Here's something to look at: The reed cage assembly has a rubber seal that has been know to leak. If that's the case it won't run. Also, when you put the carb on, be sure the little hole in the gasket (that operates the fuel pump) is lined up correctly.


Jeff

PS:I had one of those with low compression (but higher than yours). It ran but weakly.
 
fastjeff said:
If the wires to the cil are reversed, it will backfire and fight you when you yank the cord.

Here's something to look at: The reed cage assembly has a rubber seal that has been know to leak. If that's the case it won't run. Also, when you put the carb on, be sure the little hole in the gasket (that operates the fuel pump) is lined up correctly.

Jeff

PS:I had one of those with low compression (but higher than yours). It ran but weakly.
Click to expand...


Yep, just pulled the reed block and that rubber seal was in bad shape... thank you.
 
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