Yamaha C115TXRS

[mainefinn05]

Having issues, trying to save some trouble shooting. First run of the year it ran great. Last years filters and plugs. Runs after that as I approach 4k rpm it loses power or acts like fuel starved. Today i changed all filters and plugs. Same issue again. Noticed when i changed plugs one side was much more nicely toasted than the other. Good light brown compared to the other darker almost wetter side. Coils? Stator? Shouldnt be fuel starve after all new filters right? Thanks.

[fitz73222]

First, Isolate your current fuel system as cause for fuel starvation. Run the engine on a remote 6 gallon tank with a different fuel line and primer bulb. If the engine runs fine, start to look at a collasped fuel line from ethanol degrade or faulty primer bulb check valve(s) with your existing system; next verify that your fuel system is venting correctly by running the engine with the gas cap removed to allow the tank to exchange air and see if the engine now runs OK. Assuming you have a remote fuel filter thats not contaminated with water and debris from dirty fuel, I would change it if the above tests don't solve the problem. Try these things and let us know the results.

[mainefinn05]

I have some clear line around i am going to use to see if im getting bubbles.

[fitz73222]

I've run engines on clear fuel line and found that "some' bubbles are normal as the engine draws fuel through the primer bulb check valves when they open, close and re-open again depending on throttle position. You did not mention whether or not your primer bulb was trying to go flat above 4000 rpms.

[mainefinn05]

Primer bulb is not being flattened.  However a number of my connections are currently double zip tied.  Gonna by some real hose clamps and start there.  I have dealt with my primer bulb sucking flat last year.  Hasn't happened yet this year.

[fitz73222]

I would start with the remote fuel tank and then work from there.

[fitz73222]

The remote fuel tank is going to point you in a direction. If the engine runs fine on the remote tank you have a boat fueling issue; if the engine still runs poorly you have an engine issue such as as fuel pump diaphragm, filter or plugged carb jet. As you mentioned, the differnet spark plug colors are telling you something. If you are starving for fuel from a main tank issue;all the plugs would look lean but it seems that you have differences between cylinder banks which tells me and engine issue.

[mainefinn05]

Checked the new plugs yesterday. Even appearance. Remote tank is gonna take some chasing down.

[fitz73222]

You can run it out of a regular gas can, just stick a different fuel hose and primer bulb down in the bottom of the can and fasten it to make sure it stays at the bottom and change over your existing fitting to that line. Its just for testing...

[mainefinn05]

Jesus, must be sun baked. Never thought of that.

[dburr]

Jesus, must be sun baked. Never thought of that.

96 the other day, 93% humidity, trapped in a green Nomex flight suit for 14 hours. Sun baked is one way of putting it!!!

You can either put the fuel hose inside some copper tubing or if you don't have stuff big enough, use a few plastic spot ties and a piece of coat hanger and that will help keep the hose straight...

No idea how our Southern Brethren can work outside in this from April till October..    

[fitz73222]

No idea how our Southern Brethren can work outside in this from April till October..  

My Dad used to say " What's second choice?" The Florida summer is the Florida summer; we live here because of the winter!