misfiring 1986 140 evinrude

[dcolpitts]

long story try to make short, vro failed. temp sensors limited the engine to about 2200 rpm. stopped engine. replaced vro and engine starts.idles. misfiring just above idle as it tries to plan out,then starts to stall.pulled plugs shecked compression. 1 cyl not firing plug was like new conditon. checked coil with meter ok, did spark test on coil will arc about 1/2".<br />carbs were rebuilt and fuel system replaced at same time as pump. enough background, does it sound like head gasket. compression was 95psi in that cyl compared to 110-115 in others. sorry for the detail, seems to help in long run<br />thanks for help in past

 

[Joe Reeves]

Re: misfiring 1986 140 evinrude

Okam.... It's possible that the head gasket is slightly flawed due to being hot. It sounds like you may have had a overheating warning rather than a VRO failure warning? How long did you run that engine after the warning horn sounded?<br /><br />VRO warning = Beep every other second.<br /><br />Overheat warning = Beep is steady and constant.<br /><br />Overheating could have caused gasket failure, and if just a slight failure, that would allow a slight amount of water enter the cylinder which would, of course, foul the spark plug.<br /><br />Bottom line.... Remove both cylinder heads and inspect the pistons, cylinder walls, sealing surfaces of the block and heads, gaskets etc. Install new gaskets if all looks well and torque the bolts to 18 to 20 foot pounds.<br /><br />Start with the left center bolt, then the center right bolt, then down to the next lower right bolt, then in an ever widening circle.<br /><br />Let us know what you find.

 

[dcolpitts]

Re: misfiring 1986 140 evinrude

thanks for reply joe. found out the alarm is not fuctioanalfor heat of oil. antoher project. did a 2nd compression test and was 108- 120psi on all syl. pulled heads, small amount of wear on the low compression cyl. the top cyl on the port bank was clean and the cyl below almost as clean. starbord bank both had carbon deposits. you were right on the overheating. I ran the motor about 2 minutes when it slowed down the first time. the vro failed with too much oil, piston broke not repairable. it may have overheated with too much oil? will order new head gaskets and keep posted<br />p.s. removed plug in faulty cyl and engine started and idled as good if not better, had plug attacthed ground at same time good spark