C-115 Yamaha killing after starting

[cblood]

In order to start this engine I have to put the fast idle in the max position and have to manually hold the choke in the max position. It will run as long as it is rev'd up and kills when put into gear! I have cleaned and re-cleaned the carb's and installed a new fuel pump. Could this be caused by a oil fuel mixture problem? The oil ratio was doubled and marvel mystery oil was added 4oz to 10 gallons.

 

[rodbolt]

Re: C-115 Yamaha killing after starting

test the compression and the spark, do a search on this site for home made spark tester.

 

[cblood]

Re: C-115 Yamaha killing after starting

I installed new plugs today and to the eye seemed to be firing well. I found the article about the spark tester and will try it in the am. I will also try and find a compression meter to check the compression! How much should each pull/push. Thanks any more suggestions are greatly appreciated.

 

[rodbolt]

Re: C-115 Yamaha killing after starting

all cylinders should be within 10 PSI of each other, no specific numbers are published. spark should be able to jump at least a 1/2"-7/16"th gap.

 

[Ray Neudecker]

Re: C-115 Yamaha killing after starting

If the compression and fire tests are done and if ok, you are back to fuel restriction. the next step will be to hook up to a seperate tank and line to eliminate them.

 

[cblood]

Re: C-115 Yamaha killing after starting

the compression test went fine all with in normal limits. I had to adjust my floats in the carb they were to loose and were restricting fuel I guess. After runing the engine in the drive for about an hour the lower unit began to rattle a little? Now for my next project!! Thanks for all the help.