testing power pack and timerbase& sensor ?

1976 Evinrude 70 horse Model 70673D Service manual shows a neon light tester for testing the Power pack and the Sensor. The neon light tester shown, is no longer available. In the manual it shows the light tester connected to all three coil screws on the power pack at the same time and tester has a switch on its side to switch from one place to another. Pretty much the same for testing the Sensor. My question is, can I use a single prong neon light tester and check each of the circuits separately and get the same results? I used an in line spark tester to check the coils. When the engine was cold/cool the coils all checked good. When the engine had warmed up coils were erratic. Good for a little while then bad. I think I need to check upstream of the coils. Hence power pack and then the Timer base & sensor. Is there another tool I can use to check these items? When I first get to the lake engine runs good. Planes out like it should. After about 10 to 30 minutes it bogs down. Only running on two cylinders.
1 & 2 sometimes and 2 & 3 other times.

Re: testing power pack and timerbase& sensor ?

I don't see why the neon tester wouldn't work, however, it will only show that there is power there and not how much power is there. To accurately test the ignition componants, you need a DVA meter. Then you can see how much voltage you are really getting. Your problem does sound like it's an ignition issue. Coils can do that. The're fine while cool, but stop functioning when warmed up. I guess it's because they build up a resistance level that stops there function.

Re: testing power pack and timerbase& sensor ?

I found additional problem I don't understand. Engine is shorting out. Spark is jumping from coil wire to metal part of plug. I was running engine in drive way with earmuffs for cooling when I saw the spark jumping on two cylinders. Any explinations would be appreciated. Noe all three plugs ar new L77 F4 Champions.

Re: testing power pack and timerbase& sensor ?

If it's jumping from the wire then it's time to replace the wires.

Re: testing power pack and timerbase& sensor ?

Yep you probably gots bad wires.

Re: testing power pack and timerbase& sensor ?

The shorting appears to have been loose boots on spark plugs. I contacted Champion T/S
and that is what they said. I bought new boots and replaced them. Motor is now running smooth in drive way. I have not gotten it to the lake yet. Thanks to those that replied.
Does anyone know what the output voltage of the power pack is suppose to be?

Re: testing power pack and timerbase& sensor ?

cdielectronics.com...search engine..troubleshooting guide...will list those

Re: testing power pack and timerbase& sensor ?

Master Chief, Commander and Chief,
Thank you for your time and the information you posted. I think I was looking for the worst when all my problem was, is loose plug boots. I replaced the boots and wire clips yesterday and took the boat to the lake. It ran good. No misfire and still plenty of pep for a 35 year old boat. I have had a problem for two years. Engine ran very erratic. At times there were no problems. At other times it would just barely run. Three different boat shops didn't find it. I think they were all parts changers. Three new coils and lots of labor money. It now appears new plug boots fixed the problem. If it appears again the next time out I will get a DVA meter and check it out myself starting with the coils and working back to the Stator, timer base and sensor. People on both this forum and the Marine engine forum have made my day. Thanks to all. I think I'm back on the lake. Two years of frustration doesn't make for smiling face. Yesterdays results do.