150hp XR6 erractic trigger?

[dr]

s/n OT579554. Two days on the water troubleshooting. Day one, motor started and good idle. Leaving no wake area, throttle applied, rpm and speed correspond. 30mph at 3k good, above hesitation. Looking at tach , rpm was erratic to max. Thinking rev limit kicking in. Loaded boat on trailer for home. Visual check sparkplugs, tight and not fouled. Looked at linkage and sync. All screws, stoppers, and locknuts, loctite secure. Walked through sync alignment, did not time or fired up, all screws bottom out when called for in alignment. All marks on levers, cams, screws correspond to set up picture in manual. I could manually move lever which advanced timing linkage at full throttle (engine off) Day two on water, same results, good start good idle, good power to 30mph at 3 k. Then rpm maxed out on tach, I believe max rev shut down again. Pulled up to dock and moved tach meter lead to 2nd Volt regulator gray wire. Upon start up, idle speed, Tach was at 5k. But I knew from sound it was not. Returned meter to 1st regulator same results. Took back boat to launch, enroute Tach returned to corresponding rpm per sound and speed. Again applied throttle, same results 30mph at 3k, above 3k tach maxed out and engine cut out, (rev limiter??) So question, is this a bad trigger or bad control module. any thoughts would help.

Dennis

[EuropeanAM]

Go through the RESISTANCE tests on the trigger. During each test, move the throttle from IDLE to WOT and back at least 3 times, and manually flex the trigger harness around. If readings begin jumping around during any of these actions (repeatedly), REPLACE THE TRIGGER.

Relatively common by this age, caused by degrading wiring materials.

[dr]

Thanks Don, yep! broken wire . Already in contact with Rhonda

Dennis

[JOE54]

+100 most never wiggle wires in testing went right over their heads

[dr]

Replacement trigger assy installed, ohm tested as specified in manual, but same on water results. Above 3k erractic RPMs then over rev activates; killing cyl firing. The bad trigger assy had a broken lead and worn wire insulation. Possibly grounding out . Thus next question, can this trigger wire being bad also played havoc with the Control Module?

Dennis

[EuropeanAM]

Doubtful. I'd recommend walking back through all of the tests again (keeping in mind that "new" does not necessarily mean "good").

[dr]

Trigger assy wires all good on new assy. They ohmed out as specified, Timing Advance linkage measured at 11/16. And rotates freely. All connectors are tight and visual inspection shows no other wires defective. Stator wires measured and visual, all good. 2 Volt regulators removed and inspected. No burns or color change. On water shows voltage charging battery. CDM harness wires okay. Plug wires okay. All plugs same color. Did not check on water, bias circuit. But shift switch is working. Bias comes from control module no adjustment. Next?

Dennis

[leonreno]

Have you tested voltage output above 3k rpms? Having the bad tach readings and cut out, bad regulators could be causing over voltage, and I believe that can cause a shut down.

[EuropeanAM]

Double check the grounds on the coil plate. Also make sure you are using ONLY NGK: BPZ8HS-10 spark plugs (and that none of them are bad, damaged, or have even the faintest of lengthwise marks on the porcelain surrounding the electrode).

Also make sure stator wiring isn't rubbing against something that might be shorting it out.

[dr]

Spark plugs are NGK as specified, grounds checked, pulled CDMs (look okay) and Ohm'd harness. All good. I don't have muffs, can this motor use it's garden hose connection near pee hole instead for test running in driveway?

[leonreno]

Not really supposed to, doesn’t always get enough water pressure and pump can burn up too. If you have a large tub or trash. An that fits over the lower unit you can use that, water level needs to be at or above the seam where the lower unit and mid section meet.

[EuropeanAM]

^^^^ +1