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Fuel question for the OMC techs #8887964 05/02/13 02:04 AM
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Yellowcat Offline OP
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I have a 1977 evinrude 9.9. I bought it dirt cheap knowing it had spark and compression. I got it running with no problems at all. But it will not run wot in gear.

I am good friends with the best omc technician in the area. We looked at it today and its running too rich at wot. Fuel pump is good, carb is good. I can give ya more details if ya want. We checked ignition. Swapped coils and powerpack.

So its running too rich at wot. What could cause this? I am open to any suggestions.


Justin
63lb, 2 58lb, several 40's, 38lb, and several 20lb yellas.


Re: Fuel question for the OMC techs [Re: Yellowcat] #8888721 05/02/13 11:29 AM
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hopalong Offline
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float out of adjustment or sticking.
choke sticking shut.
look at # 3 and 9 on this diagram, either could be sticking and causing it. try running a can of seafoam in a gal of fuel mix and run it both wide open and idle, run it for a while then shut off and let sit for a couple of hrs then run again. do this in the lake if possible.

Last edited by hopalong; 05/02/13 11:30 AM.
Re: Fuel question for the OMC techs [Re: Yellowcat] #8888854 05/02/13 12:36 PM
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Yellowcat Offline OP
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Hopalong,
everything you mentioned is good. We are pretty much positive its not carb related or fuel pump related. Unless someone changed the orifice out to try to make it a 15 and didnt know what they were doing. The orifice in it is a 38. We are pretty sure the 38 is for a 9.9 and a 58 is for a 15. Does anyone know this for sure?
With it not being carb related, fuel pump or ignition. Could it be reeds?

Btw i got 90 psi both cylinders


Justin
63lb, 2 58lb, several 40's, 38lb, and several 20lb yellas.


Re: Fuel question for the OMC techs [Re: Yellowcat] #8888903 05/02/13 12:52 PM
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hopalong Offline
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can you rev it up in neutral?
if your sure the butterflies are working right then got to spark, may be that your dropping spark on higher rpm's, check timing @ wot.

Re: Fuel question for the OMC techs [Re: Yellowcat] #8889445 05/02/13 02:42 PM
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waydon1 Offline
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Yellowcat, 90 psi is borderline compression on that engine.. Try a differant gauge and/or do a decarb and test again.. A leakdown test will tell you a lot more about the condition of the cylinders than a comp test... Make sure the timer base is advancing all the way... Check WOT timing... Most of the time a reed problem will cause the engine to spit gas back out of the carb throat... Do a search on leakdown test to understand it... A factory OMC service book is a big help....The after market books can be wrong on some things....

Re: Fuel question for the OMC techs [Re: Yellowcat] #8891115 05/02/13 08:25 PM
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Yellowcat Offline OP
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Hopalong it will rev up until the timing plate hits the stop in neutral but it does not seem like it is reving up as high as it should. I know it will only reach a certain rpm because of the stop that is a safety for neutral. Checked coils powerack kv voltage timing at the spot where it falls on its face. All good. In the omc service manual it says for a bad reed it would backfire. Mine does not backfire though. Will check out a leakdown test

I know the guy that is helpin me with it WIll figure it out. Hes been workin on omc for 30 plus years and has never had one like this before

Thanks for all they help and suggestions. My ears are still open!

Last edited by Yellowcat; 05/02/13 08:26 PM.

Justin
63lb, 2 58lb, several 40's, 38lb, and several 20lb yellas.


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