Evinrude 1981 70hp 70tlcim - Intermittent Spark

[Rerouter]

Hello. Have intermittent spark (seems to work for a few minutes at colder temps) and being less familiar with older magneto based systems wanted a second opinion if the power pack has failed

Checked all coils and leads - 0.2 ohms or less between coilpack socket and plug tip. Open to body. (Had 2 failed plugs and 1 poor lead that have been replaced)

All 3 coil packs measure 310-325 ohm to ground on the HV end. And 0.2-0.3 Ohm on the DC 12V side.

When cranking, see 5.6V DC on the jumpered yellow terminal feeding into the rectifier. And have confirmed rectifier is working.

0.5-0.7V DC being fed into each coil pack when cranking, which seems wrong to me.

The ground to the power pack is a little high. About 0.6 ohms. But connects to ground near the starter switch.

Ive replaced all connections to the terminal block as the yellow flat crimps had corrosion.

Yet to test the 2x 2 brown wire sensors to the magnetos. Have lifted the magneto and it does not appear to have anything loose.

 

[racerone]

First thing I would do is load test the battery.----Take starter apart for inspection , cleaning and ohms check on armature.

 

[ct1762@gmail.com]

Hello. Have intermittent spark (seems to work for a few minutes at colder temps) and being less familiar with older magneto based systems wanted a second opinion if the power pack has failed

Checked all coils and leads - 0.2 ohms or less between coilpack socket and plug tip. Open to body. (Had 2 failed plugs and 1 poor lead that have been replaced)

All 3 coil packs measure 310-325 ohm to ground on the HV end. And 0.2-0.3 Ohm on the DC 12V side.

When cranking, see 5.6V DC on the jumpered yellow terminal feeding into the rectifier. And have confirmed rectifier is working.

0.5-0.7V DC being fed into each coil pack when cranking, which seems wrong to me.

The ground to the power pack is a little high. About 0.6 ohms. But connects to ground near the starter switch.

Ive replaced all connections to the terminal block as the yellow flat crimps had corrosion.

Yet to test the 2x 2 brown wire sensors to the magnetos. Have lifted the magneto and it does not appear to have anything loose.

you may find the polarity is reversed on these, and its an AC reading if doing the test without a DVA adapter. if it sparks somewhat, you know the charge coil in the stator works. need a cheap DVA adapter to properly test primary terminals and sensor coil jumpers (use DC setting this time). just guessing otherwise.

 

[Rerouter]

Raceone got it. It ended up being a spot in the battery loom had corroded. New cables was the fix.

 

[ct1762@gmail.com]

Raceone got it. It ended up being a spot in the battery loom had corroded. New cables was the fix.

i didnt realize it was cranking slowly. hes right battery/starter issues are extremely common

 

[Rerouter]

I didnt either. But it was right on the margin. I forget the exact number. But if i flexed the cable the RPM bumped about 50 higher and it would then start. Thanks for the Help.

 

[cyclops222]

You now know all wiring is probably corroded. Replace 1 wire at a time to stop more erratic running. Reuse NOTHING that is still original. Very simple satisfying project. Then you will KNOW !!! It is not another wire somewhere causing problems.
Enjoy.

 

[ct1762@gmail.com]

You now know all wiring is probably corroded. Replace 1 wire at a time to stop more erratic running. Reuse NOTHING that is still original. Very simple satisfying project. Then you will KNOW !!! It is not another wire somewhere causing problems.
Enjoy.

great advice to be sure

 

[ct1762@gmail.com]

I didnt either. But it was right on the margin. I forget the exact number. But if i flexed the cable the RPM bumped about 50 higher and it would then start. Thanks for the Help.

no problem. another fun one is rebuilding the starter w. a new $15 brush kit to make it like brand new. very easy to do.