FZR400 Starting problem

Hey everyone...

Got a question regarding starting problems...

Bike in question: 1987 Yamaha FZR 400

Symptoms:

engine sounds to be cranking.. but never fires


Other information:

I have noticed that when ignition is on; and I set kill switch to run
that I do not hear the tick tick tick that I think should be the fuel
pump?

I've been through whole whiring loom and can not find any loose
wires/connections, nor any visible blown fuses.

What do I need to look at? does this sound come from the ignition unit
under the seat or from the electrical fuel pump itself? How can I test
either? Which is more likely to be the issue?

any help is much appreciated!

 

There are contacts inside the pump that de-energize the solenoid when
it reaches a certain position, and then a spring returns the solenoid
core to its original position and the contacts close again,
re-energizing the solenoid coil. The process repeats endlessly and the
fuel pump will go tick tick tick.

A solenoid type fuel pump goes tick tick tick until it builds up enough
pressure against the float valves in the carburetor to stop the
solenoid from moving.

This is not the best way to operate an electric fuel pump in a vehicle
which may fall over on its side and keep pumping gasoline while the
rider's leg is pinned under the machine.

So the electric fuel pump is digitally controlled to stop the pump when
the engine isn't running.

Some motorbikes have a resettable tipover switch, but Yamaha didn't
install one of those.

If your electric fuel pump system is like my FZR-1000's system,
there's a
5-second timer built into the digital igniter unit that runs the fuel
pump just long enough to fill up the carburetors.

The digital igniter gets a "run" signal from the pulse generator to
keep the fuel pump running while you're riding the motorcycle.

The reserve function is a switch on the left hand lower fairing that
sends a signal to the digital igniter unit to override the five second
timer and keep the pump running.

A wire runs from the digital igniter unit to the coil of a dual
function relay under the left hand side cover. I would expect to find
12 volts on that wire for five seconds after I turned the ignition
switch on.

One function of the relay is to control the fuel pump, the other
function is to enable the starter solenoid.

The way my FZR-1000 is wired, if I have power to operate the starter, I
have power to the fuel pump and power to the ignition coils, because
they both run off the same fuse.

You might try working the reserve switch to see if the fuel pump runs.

If that doesn't do the trick, try bypassing the fuel pump relay, which
is probably built into the same plastic box as the starter solenoid
enabling relay.

In order to test the digital igniter, you'd probably have to find a
Yamaha $tealer$hip that has an igniter tester.

If you suspect the fuel pump is the problem, try disconnecting it and
do an ohmmeter check to see if you have continuity through the solenoid
coil. You can check to see if the pump runs by applying 12 volts across
the pins of the connector.

 

Do you have a manual with troubleshooting charts? That'd be my first
step.

Testing the fuel pump itself should be fairly straightforward: pull the
outlet line, put it into a container, and turn the key. If no fuel comes
out, you need to look at your fuel system (bad pump, clogged filters,
bad tank valve/vacuum lines, etc.). If fuel comes out, you need to
determine if it's enough (Factory service manual should have this info;
I don't know whether or not the aftermarkets would).

In any case, it's worth going over your electrical system checking all
your connectors when the bike is this old. Make sure things are actually
connected, make sure connections are clean and tight. HTH!

--
Later,
John



'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

 

Thanks for the feedback guys!

In terms of the reserve switch on your FZR1000 I can not locate this on
the 400..

will grab a voltmeter to check out voltage...

Thanks again.. will let you know how it goes..

 

That model seems to have a vacuum operated petcock with a lever to
select reserve, so the reserve switch wouldn't be used.

So I would check out the relay to see if 12 volts is getting through to
the pump.

Check the wiring diagram in your owner's manual for details like color
codes of the wires.