1996 Yamaha C60 TLRU surging issues!

[Bretjames22]

Hey guys, I Have this 1996 Yamaha c60, throwing me for a loop! Motor cranks, idles, and runs great up until about 10-15 minutes into a solid run at 3/4 to full throttle then it starts to surge. Have changed all fuel components on engine including the hose, bulb, and tank! Also had carbs taken down and cleaned. Changed charging coil , coils, and plugs also any help would be greatly appreciated guys!

Originally the issue was no spark, thought it was cdi box but it wasn’t it was a bad charging coil. Before the charging coil was changed motor ran like a champ with no surging at all! I’m lost!!!

 

[racerone]

How does it run when someone operates the manual fuel pump when the surging starts ?

 

[Bretjames22]

How does it run when someone operates the manual fuel pump when the surging starts ?

No change, bulb stays hard the whole time it’s surging

 

[racerone]

Water in the fuel??----Perhaps revisit carburetors.----You have replaced diaphragm in fuel pump?----Checked valves in fuel pump?

 

[Bretjames22]

Changed fuel pump no water in the fuel either, like I said none of this surging started until the charge coil was changed

 

[boscoe]

Have the original coils and plugs been reinstalled?

 

[Bretjames22]

All of that is new

 

[boscoe]

New does not necessarily mean good.

Something new seems to have cured the old no spark issue. Something new might be causing the new surging problem.

It can be a problem when parts are thrown at a problem.

 

[Bretjames22]

Ohmed out the coils lastnight, all 3 checked out in tolerance. But one thing I did find, when I checked the ohms on the connectors comming from CDI box number one was 16.2 number 2 was 21.1 and number 3 stayed at 0.