91 Mercury XR4 will not Idle

[goofy2me]

Motor will not idle until at least 2200rpm.<br />Carbs been clean 3 times thinking it is the carbs. Decarb motor and replace with new plugs(BU8H)and still will not idle. Running unit with new gas on a test gas tank. Will sometime not stay idle at 2200rpm. Can hit choke and stay on for a little bit and die out. Motor starts fine and will stay on for 10-15 second and die. Have ran motor in open water at 4500rpm and it run fine at high speed. Any help would be great.

 

[goofy2me]

Re: 91 Mercury XR4 will not Idle

Have Check all 6 coil and have fire on all.<br />Check compression and all are within spec(110).<br />Try the spray into carb while idling to keep it from dieing, but that did not help. Do not know what to try next. If anyone know what I can try,please let me know. Thanks

 

[jdkzrt]

Re: 91 Mercury XR4 will not Idle

Sounds like a timing advance problem. Actually, more likely stuck advanced, and not retarding when going back to low/idle speed.

 

[goofy2me]

Re: 91 Mercury XR4 will not Idle

Check timing and seem to be ok. Did notice that when first started that motor would not die until it would warm up. The motor would start with no problem after it die out. I have disable the oil injection. Would this cause the motor not to idle?

 

[goofy2me]

Re: 91 Mercury XR4 will not Idle

Also have check that all plugs are fireing good(1/4 inch when near block). Compression is also ok.