Throttle cam adjustment

[stl]

I have a 18hp evinrude 1973. It has not been run in for years. I put in a new water pump,and rebuilt the carburetor. It still won't start. I do have spark on both cylinders. It started for a few seconds on about the third pull, but then nothing. I am suspect of the throttle cam adjustment Should this be done with the choke in or out? Could this even be the issue? It acted like it was flooded after the third pull, maybe I missed something on the carb rebuild. What do you guys think. Also there is a kill switch that the insulation on the wires is cracked and falling off. Could this be suspect? Thanks for any input.

 

[1730V]

Re: Throttle cam adjustment

DO NOT mess with that throttle cam unless you have a good OEM manual and understand it. That adjustment can detonate your engine in a hurry.

If you have spark and fuel, it should run. If the engine severely backfired, you may have sheared the flywheel key thus messing the timing.

DO NOT use starting fluid (ether). Use a spray bottle with fuel/oil mix.

 

[F_R]

Re: Throttle cam adjustment

A sheared flywheel key is a very real possibility, especially if somebody had it off and didn't use a torque wrench to properly tighten the nut. If those bare wires touch metal it will short out the ignition. A misadjusted throttle cam will affect mid range running (rough), but not keep it from even starting. It is adjusted with the choke in. The carb throttle plate should just barely start opening when the cam follower roller aligns with the mark on the cam.

 

[stl]

Re: Throttle cam adjustment

Is there a way to check if I have a sheared flywheel key

 

[HighTrim]

Re: Throttle cam adjustment

Is your throttle cam marked "START"?? If so, when the warm up lever on the control box is moved to the START position, the START mark on the throttle cam should center on the cam roller. If it does not, turn the stop screw in the control box in or out to obtain the proper adjustment. The warm up lever adjustment should be checked and redone if required when the engine idle speed is changed enough to require throttle cable trunion adjustment. But like stated, this is easier done with a manual. You will need a proper puller with grade 8 bolts to remove the flywheel, along with a strap to hold it.

 

[marcysibyll]

Re: Throttle cam adjustment

If it's got gas, spark and compression, god says it has to run. Go on the theory that it was running when parked. Check spark with a spark tester, specs will be in repair manual. Chgeck compression with a compression tester. If both of these are within specs, you have fuel problem.

 

[HighTrim]

Re: Throttle cam adjustment

I missed the comment you made about the kill switch wiring on my first glance, I would definately look into that before all else. Re wire it.

 

[stl]

Re: Throttle cam adjustment

Update, I adjusted the throttle cam correctly. I think this had little to do with the hard starting. I temporarly wrapped kill switch wires in electical tape and I finally got it to start. I got it idled down pretty well, except for a small backfire on occasion, which seems to get better the longer the motor runs. Any ideas on the backfire? I found out tonight from my brother in law that this motor has not been run in at least 12 years. I have a couple more questions. The original service manual says to use champion plugs uj4j. Champion web site says they no longer carry those but a suitable replacement is j4c. Do you think this is a good replacement. It seems like I have been told before by people on this site that the champion cross reference is not always accurate. Should I completley rewire the kill switch. I have some 14awg primary wire laying around will that work. Any help on the rewire or any of these other issues is greatly apreciated. Thanks again for all of your help so far

 

[rickdb1boat]

Re: Throttle cam adjustment

I would rewire the switch. The J4C's will be fine at a gap of .030...

 

[HighTrim]

Re: Throttle cam adjustment

Yes those plugs are fine. The misfire is usually plug related. Make sure they are torqued down to 18.5 to 20.5 ft/lbs when you install them. And yes, if that kill switch is arcing it will cause you problems.

 

[stl]

Re: Throttle cam adjustment

Thanks guys will that 14awg be ok. To rewire the kill switch. Can I fit it back into the connectors, or shoul I look for an original replacement?