I need some ideas. It is a Yamaha atv. Battery shows 12.9 volts and
turns the engine over fine, but won't start. When I hook up a battery
charger it starts right up. Battery voltage when running is 14 volts.
Hank <~~~knows something has to be wrong
I too think its a battery issue. I recently had an auxiliary battery with a
bad cell. The surface voltage reading was about 12 volts, but as soon as you
put a load on it, it would go down several volts. In your case, the voltage
is enough to crank the engine, but if the voltage drops down simultaneously,
it may not be giving the coil enough voltage to make a decent spark
14 v running means the charger system is probably good, you could
check voltage as it starts, but its most likely a weak battery without
any capacity, clean all connections first it could be something dirty
corroded or loose now alllowing full amperage to the starter.
I did replace a battery cable, and clean the terminals and also the
terminals on the starter and solenoid no fix. I put in KNOWN good
battery, no fix. I haven't tried jumping from another battery. I did
find that the coil wire was twisted together and replaced it with a
connector, no fix. I hook the battery charger directly to the battery,
which is the only way to get it to start.
Starter turns just as fast with charger as without charger, or good
battery. The coil was replaced thinking it was a weak coil.
I am sooooo confused.
Hank <~~~never seen this problem before
I could be the valves need adjusting, there is a compression release
on most small engines that allow for easier starting but the valves have
to be adjusted to specs for it work properly. The added amperage from
the additional battery might be enough to over come the extra
compression. I've got an old riding mower with a twin cylinder B&S
engine and it takes a three year battery to start it when the engine is
hot, the one year batteries just don't have enough cranking amps. Check
out some small engine forums.
And it PMO that I can buy a car battery cheaper than the dinky battery
for my riding lawnmower.
I believe we've had the compression release debate before. It's
common for engines that are started manually. I'm skeptical his atv
has one but a look at an ipb would tell. Need the model number.
It sounds like a pretty strange problem. I would try taking some
voltage measurements while cranking. At the battery and also at the
ignition module. Most likely the 12v positive enters the ignition
system at the module. As well as pull a plug and watch it for spark.
Are you doing anything at all differently not related to the battery?
It almost sounds like there is some safety device not allowing the
engine to start. My motorcycle has a couple or so things like that.
On my bike those all won't let it crank either. I've not seen a
safety device that lets you crank the engine but prevents it from
starting. That would be sort of stupid as the operator could easily
run the battery down.
On Fri, 16 Jul 2010 17:10:42 -0400, email@example.com wrote:
I had a "dragging starter" once. Armature bushings were bad and this
seemed to cause problems. The starter and cable would get hot, acting
I measured the Amp draw as the starter turned over ... I forget
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