Please help johnson 140 v4 not firing at all.

[phillnjack2]

1977 Johnson 140hp
crossflow v4
model 140ML77S

Hello folks
ill explain what me and a friend have done first.
We took the thermostats out and replaced with new ones and gaskets and springs etc
all that seems to be perfect
But now thengine just dont want to fire up !!!!!!!!!!!
Checked the park, its nice and string and crosses the required gap no problem.
we have 150 150 147 and 150 psi compression.
The plugs just seem to keep getting wet and no firing.
We have tried so much we have flattened the battery 3 times.

The ignition switch is fine and like i say a good strong spark with the plugs out.
what am i forgetting or missing that is stopping this beast from firing up. ?


here is our regime
we put the battery leads on, pump the fuel bulb till hard, give a touch of choke (tried choke every type of way possible).
Give it a touch of throttle on warm up lever ,also tried every way with the trottle and not even a sign of firing.
We have taken the plugs out and cleaned them even changed them for new ones, spun engine over to clear out any
fuel left in te block then started all over again.

The engine when last run back in september was running very good just bad thermostats so thats why we changed them.
we have stripped both carbs twice and cleaned everything possible,checked float levels and blown everything
out with airlines and even used carb needles to make sure all orifices are clean.

None of the timming has been changed or altered in any way, throttle linkages also have not been altered.

im now on the point of giving up as i must be missing something very simple to stop this engine from running.

please folk's any help will be good, just to get the beast started.
then i can get back to my own engine.




phill

 

[boobie]

Re: Please help johnson 140 v4 not firing at all.

What gap will the spark jump on an open air gap spark tester ??

 

[Will Bark]

Re: Please help johnson 140 v4 not firing at all.

Is the staretr spinning the engine fast enough to fire under compression?

 

[phillnjack2]

Re: Please help johnson 140 v4 not firing at all.

the spark is jumping about 1/4 inch (could this be too small )
Battery is spinning fast. definitely good enough to start an engine.

this engine normally fires up no problem, well i say no problem, it normaly starts,then dies straight away then starts and
runs like it should.
Weve tried new plugs and the old plugs cleaned up, the only thing left i can think is it needs brand new fuel incase this
stuff has got contaminated somehow.
The fuel i just found out is about 3 months old and was premixed 3 months ago at 50-1.

Could this actually be the problem ? surely it would still fire and maybe run a bit rich if someof the petrol has evaporated


I thought it was fresh fuel being used


phill

 

[Bob_VT]

Re: Please help johnson 140 v4 not firing at all.

Spark sounds weak..... I would pull the flywheel and clean all of the crud from under it. Corrosion on the pickup will rob you of a hot spark.

 

[F_R]

Re: Please help johnson 140 v4 not firing at all.

It has to crank at a minimum of 200 rpm to have spark. That's why somebody asked about cranking speed under compression. That motor should jump a 1/2" air gap spark with ease. Did you disconnect any wires when you were working on the thermostat? Reconnected properly??

 

[phillnjack2]

Re: Please help johnson 140 v4 not firing at all.

I will pull the flywheel and have a clean up, i was wondering about the spark as well.
maybe its not good enough under compression.

Yes the cranking speed should start this, its normally not too bad at starting.
I will try to find out what rpms we are getting from the starter.

I dont remember any wires disconnected and have checked and re-checked all the wires.
its realy baffling me why its not even firing at all.

The motor has been in the full tilt up position for about 2 1/2 months and im wondering if any rain has got under the
flywheel and caused any corrosion.

apart from the stator what else would cause a weak spark ? if it was just one cylinder i would of said a coil.
But there is just no sign of firing at all

im gonna get a gallon of fresh petrol rig up some short petrol pipes clean the stator and everything under there and see if that solves it.
it just seems so strange that before we done the thermostats it ran ok, maybe its pure coincidence, it is a very old engine
and we dont know its history to be honest.
My friend has only had this about a year i think and its definitely been sitting now for a couple of months in the damp english winter.


phill

 

[phillnjack2]

Re: Please help johnson 140 v4 not firing at all.

Well tonight we took the flywheel of and it was very very clean under there.
No signs of any dirt or anything wrong.
tommorow in daylight will have a good inspection and a bit of a clean to be sure.
We cant see any broken wires or anything that would caus ethe problem of a weak spark.
Is there anything i am not looking at ? something i am missing ?

One thing i did notice is the woodruff key dont seem to be sticking out the crank much ???
its almost level at teh bottom and only about 1/16th of an inch at the top ??? should this be a lot more ?
The woodruff key on my 60hp sticks out a lot more and im wondering if this could of slipped ?
The flywheel nut was very tight, i would say about 100ft pounds or more and the flywheel took a bit of
pursueding to come off but not too bad, only about 20 whacks with the hammer on the puller compared to about 50 on the 60hp.

The engine as i say was running good a couple of months back, and it was turned off when last used it didnt stop on its own etc.

tommorow will also get fresh petrol and try with that as well after giving the magnets on the flywheel and stator a clean up.


phill

 

[Fed]

Re: Please help johnson 140 v4 not firing at all.

Did you check for the 'half inch spark before you pulled the flywheel?
Could the key have sheared off & you are only looking at what's left of it?

 

[emdsapmgr]

Re: Please help johnson 140 v4 not firing at all.

Wet spark plugs when trying to start the engine indicates you've got fuel but no spark. Have you taken a fuel sample to test for any water in the fuel? If you put an inductive timing light lead on all 4 plugwires while (with the plugs in the block) cranking, do you get spark? A sheared flywheel key would cause a "no start" situation, but usually you'd get some misfiring or backfiring indicating the timing is off. You may find the electrical/ignition troubleshooting information at this website helpful: cdielectronics.com. They list some output voltages which are very helpful when used to diagnose ignition problems. To test (isolate) for problems (shorts) with the key switch/control box wiring issues, disconnect the big red plug inside the lower cowling. Jump the starter direct from a known good battery with automotive jumper cables. The engine should crank normally. Check for cranking spark.