Tweet
So now that I finally figured out how to post:
Using Yamaha Factory Manual 290294 (P/N 62F-28197-Z6-C1)
1993 Yamaha Pro 60 TLHR. Starts and idles good. *****s good. Jumps out of the water strong. Good RPM for a couple of hundred yards, then the engine starts to miss (cut out and shutter) on all cylinders. Backing the throttle off clears up the problem momentarily, but as throttle is increased, the shutter returns.
Manually closed the fuel enrichment valve. No change. Removed the air silencer to reveal a steady flow of fuel at WOT through the main discharge tubes in all of the carbs.
Removed and cleaned fuel system - no major oxidation inside the carbs. Not a fuel flow problem. 5 psi at *****ing speed. Vacuum at 1". Ignition timing at (previously set) + 7 and - 22 - good.
Good water flow at "tell tale" (impeller replaced 50 hrs ago). Cylinder head cooling jacket is warm (not burning hot) to the touch at speed.
Tested thermo switch. "On" at 80 C (book spec 84 - 90 C) and off at 67 C (book spec 67 - 74 C). The "on" temperature was close to spec, but still a slight concern. Removed the thermo switch from the wire harness. Retested the engine. Same miss as before.
Removed and tested the oil (injection) tank level switch. Black and green wires (resistance) were OK at 0 ohms - straight or reversed polarity; and the black and green/red test indicated 10 ohms (book spec 640) and infinity (other polarity); not "deflects once, and returns to infinity" - as described in the factory manual. Before I replace the level sensor with a new part, I visited an outboard wrecker to measure one of his float switches. Same results (readings) as the "original float switch". Coincidence? Two junk switches? Maybe. Not that Yamaha says to check the resistances with the (in this engine) bullet connected diode (diode - individually is good) connected to the Green / Red wire, but I am thinking that thought as I am write this post.
An interesting note: Seems as the engine gets warmer, the miss occurs sooner, and at lower RPM (2000 - 3000 - ish). As the shuttering was happening, I hooked up the thermo switch harness leads to simulate an overheat condition. Shutter was unchanged - that is - it didn't get worse.
I have not experienced a running engine over heat or low oil warning condition, so I don't know if the shutter is a result of a warning circuit being activated.
Tested pulser coil, charge coil, and crank position sensor. All - within specs. Performed the same tests on hot engine. All still within specs.
Tested CDI box (analog meter) with the following results: Charge coil circuit - all within specs. Pulser coil circuit - all within specs except W/R and B @ 17.5 K (book spec 37.5 - 1000 K). Crank position sensor - all withing spec except B and L/W @ 15 K (book spec 2.7 - 7.0 K), and B and L/R @ 0 ohms (book spec 8.9 to 20 K).
So guys, what do you think? Float switch or CDI box? Is there any way to disconnect, bypass or jump the oil tank float switch? Possibly connect Green to Black?
Anyone ever experience similar symptoms?
Ideally, I would like someone to actually measure an oil tank float switch from a 50, 60 or 70 hp (they are all the same) and tell me the results. Is the Factory Manual giving incorrect numbers?
I am finding trouble shooting with a Yamaha factory manual to be extremely challenging - in that Yamaha just tells you what to do; they don't ever explain how the particular component works, and how each component interacts with the others. Agree or disagree?
Any experienced help will be appreciated.
riverseaent@hotmail.com
Using Yamaha Factory Manual 290294 (P/N 62F-28197-Z6-C1)
1993 Yamaha Pro 60 TLHR. Starts and idles good. *****s good. Jumps out of the water strong. Good RPM for a couple of hundred yards, then the engine starts to miss (cut out and shutter) on all cylinders. Backing the throttle off clears up the problem momentarily, but as throttle is increased, the shutter returns.
Manually closed the fuel enrichment valve. No change. Removed the air silencer to reveal a steady flow of fuel at WOT through the main discharge tubes in all of the carbs.
Removed and cleaned fuel system - no major oxidation inside the carbs. Not a fuel flow problem. 5 psi at *****ing speed. Vacuum at 1". Ignition timing at (previously set) + 7 and - 22 - good.
Good water flow at "tell tale" (impeller replaced 50 hrs ago). Cylinder head cooling jacket is warm (not burning hot) to the touch at speed.
Tested thermo switch. "On" at 80 C (book spec 84 - 90 C) and off at 67 C (book spec 67 - 74 C). The "on" temperature was close to spec, but still a slight concern. Removed the thermo switch from the wire harness. Retested the engine. Same miss as before.
Removed and tested the oil (injection) tank level switch. Black and green wires (resistance) were OK at 0 ohms - straight or reversed polarity; and the black and green/red test indicated 10 ohms (book spec 640) and infinity (other polarity); not "deflects once, and returns to infinity" - as described in the factory manual. Before I replace the level sensor with a new part, I visited an outboard wrecker to measure one of his float switches. Same results (readings) as the "original float switch". Coincidence? Two junk switches? Maybe. Not that Yamaha says to check the resistances with the (in this engine) bullet connected diode (diode - individually is good) connected to the Green / Red wire, but I am thinking that thought as I am write this post.
An interesting note: Seems as the engine gets warmer, the miss occurs sooner, and at lower RPM (2000 - 3000 - ish). As the shuttering was happening, I hooked up the thermo switch harness leads to simulate an overheat condition. Shutter was unchanged - that is - it didn't get worse.
I have not experienced a running engine over heat or low oil warning condition, so I don't know if the shutter is a result of a warning circuit being activated.
Tested pulser coil, charge coil, and crank position sensor. All - within specs. Performed the same tests on hot engine. All still within specs.
Tested CDI box (analog meter) with the following results: Charge coil circuit - all within specs. Pulser coil circuit - all within specs except W/R and B @ 17.5 K (book spec 37.5 - 1000 K). Crank position sensor - all withing spec except B and L/W @ 15 K (book spec 2.7 - 7.0 K), and B and L/R @ 0 ohms (book spec 8.9 to 20 K).
So guys, what do you think? Float switch or CDI box? Is there any way to disconnect, bypass or jump the oil tank float switch? Possibly connect Green to Black?
Anyone ever experience similar symptoms?
Ideally, I would like someone to actually measure an oil tank float switch from a 50, 60 or 70 hp (they are all the same) and tell me the results. Is the Factory Manual giving incorrect numbers?
I am finding trouble shooting with a Yamaha factory manual to be extremely challenging - in that Yamaha just tells you what to do; they don't ever explain how the particular component works, and how each component interacts with the others. Agree or disagree?
Any experienced help will be appreciated.
riverseaent@hotmail.com
Comment