1979 35hp Johnson runs great, gets hot,no spark?

[Jhals]

I have an electric start 1979 35hp Johnson long shaft, it has always run great until recently.It runs perfect for 45min to 1 1/2 hour, then completely dies and will not restart until it cools. I lose spark, or get intermittent spark, which electrical component is the likely culprit?

 

[brickthor]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

I would say the power pack or ECM if installed.

 

[StarTekh]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

hello, i would chk your coils ...

 

[rickdb1boat]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

I'd run it on muffs or in a tank and shoot a heat gun or hair dryer on the suspect part until I found which one was bad.

 

[Jhals]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

Is it possible to get these parts too hot and cause damage with a hair dryer? I don't have a heat gun.

 

[marinegrh]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

Id be curious to know when you had a water pump and stat change, yearly is recommended, then if that doesnt solve you problem, temp the motor with a melt stick, oy digital gun, and like above mentioned try to heat minimally some of the components on the engine ..<br /><br />good luck

 

[Jhals]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

The water pump seems to work fine, plenty of water always coming out of pee hole,when you say stat I assume Stator, costs 235 bucks not going to replace unless broke

 

[Xcusme]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

Jhals,<br />He is referring to the Thermostat.. 'stat'

 

[Jhals]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

Don't know when the thermostat was last changed, would that cause an intermittent spark problem?

 

[marinegrh]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

if your having a temp related problem, which it sounds like, you stat regulates the temp, try running the engine without it, the engine block, may becoming hotter then normal,/ does you warning system work?,/ causing a thermal, or temperature breakdown of an ignition component, just a thought

 

[marinegrh]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

had another thought, real quick, hows your wiring, is any of it touching the block, possibly shorting to ground?

 

[Jhals]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

I don't believe it has a warning system. I ran it with muffs last night for @ two hours before I could get the engine to quit, I immediately checked for spark and had none. The water coming out of the pee hole was cool when in neutral, but quite warm when I put it in gear. After the engine cooled @ 30 min, had great spark again.

 

[marinegrh]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

how much of a gap is the spark jumping, 7/16 is spec, keep us infoed

 

[Jhals]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

It had great spark at least 7/16, when it got hot it had zero spark.

 

[marinegrh]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

have you done an ignition test when the engine is hot, starting from the , seems when cold and parts are contracted, they work fine, but when warm and expansion is occuring you having problems, try testing them while the engine is still hot,

 

[StarTekh]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

sorry guys ...this reeks of badd coils , Mr Reevs sir...

 

[Jhals]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

John Star<br />Are you talking about ignition coils or A/C coils?

 

[Jhals]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

I don't know if there is a correlation, but right before I started having this problem, like minutes before, I hit a rock with the prop pretty hard?

 

[Jhals]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

Marinegrh,<br />After further inspection I found the red wire coming out of the rectifier to have a cut in it, I just touched it and it grounded (sparked) on the engine block. I will be replacing this tomorrow, could it be just that? I hope!

 

[StarTekh]

Re: 1979 35hp Johnson runs great, gets hot,no spark?

i would think u found your problem. coils and condensers...