Yamaha F115/Mariner 115 EFI won't start

[twirk_twirk]

So I tested the current to the VST pump today.

The multimeter only shows a reading for a split second when I turn the ignition key to the ON position.

I read 13.7v for a split second then nothing.

[twirk_twirk]

Check for power to the T/T motor, Probe blue and green wires when pressing up or down when you press up the blue is positive and green is negative,vise versa for down. try tapping the the motor with something (preferably not a sledge hammer) if you have power to it, sometimes the brushes stick.

Sorry for the crappy explanation just got back from the pub

LOL. Thanks greasyshaft. I appreciate your sacrifice. Thanks for helping out! I'll try that and post back.

[TownsendsFJR1300]

So I tested the current to the VST pump today.

The multimeter only shows a reading for a split second when I turn the ignition key to the ON position.

I read 13.7v for a split second then nothing.

Its going to show voltage to the VST pump until it builds up pressure then TURN OFF the power, usually a second or two.

Per an earlier post by Rodbolt, if the screen in the bottom of the pump in the VST is clogged with varnish, you CAN spray carb cleaner, thru the plastic tube (that comes with the can) all about and that should help.

In your 1st and 5th post you mention smelling fuel from the cylinders but the spark plugs are dry. Can you confirm if the plugs are getting wet with fuel?

[twirk_twirk]

Its going to show voltage to the VST pump until it builds up pressure then TURN OFF the power, usually a second or two.

Per an earlier post by Rodbolt, if the screen in the bottom of the pump in the VST is clogged with varnish, you CAN spray carb cleaner, thru the plastic tube (that comes with the can) all about and that should help.

In your 1st and 5th post you mention smelling fuel from the cylinders but the spark plugs are dry. Can you confirm if the plugs are getting wet with fuel?


Guess I'm missing something, why would you be checking/messing with the trim and tilt motor? Did that fail? It has nothing to do with the FI system and the engine is spinning over normally.. ??

So, the way i tested the VST pump voltage was, disconnect the wire connector to the VST pump and attach the multimeter to the wires to test (meaning the VST pump was disconnected). Logic tells me though that the 12.7 current should flow continually, however it only displayed on the multimeter for a split second, then returned to 0.

I guess the next thing to do is take off the intake manifold and disassemble the VST tank to check the pump and its screen. Perhaps I've burnt it out. Perhaps it just needs some carb cleaner like you mention. I'll try it.

The spark plugs are NOT getting wet. Perhaps it was all in my mind about the whole fuel smelling thing

I can also confirm that the injectors are functioning. I've run the injector test with the YDIS software and they are functioning properly. Also, I have plenty of spark, so what's left is I'm not getting any gas.

Tilt/trim motor. I mentioned it because it has failed and I thought it might be related to the VST pump not working since they are both electrical devices. I tested the voltage coming from the relay to the tilt/trim motor. Plenty of current there. I tried to tap the motor like greasyshaft suggested. Did not help. The motor does not respond to pressing up or down. I do, however hear a VERY faint click from the tilt/trim motor after holding the 'UP' switch in for approx. 2 seconds.

Oh and yes the engine is spinning over normally.

[rodbolt17]

your first clue that you need to study.
voltage does NOT flow.
current flows and is measured in amps.
the main relay supplies the operating voltage on the red wire any time the key is on.
the blue wire, ground path, is applied by the ECU based on engine signals.

[twirk_twirk]

your first clue that you need to study.
voltage does NOT flow.
current flows and is measured in amps.
the main relay supplies the operating voltage on the red wire any time the key is on.
the blue wire, ground path, is applied by the ECU based on engine signals.

Got it.

So, am I right in assuming that the split second reading of 12.7v could be a normal cut-the-power "response" by the ECU.

[rodbolt17]

t key on the main relay is turned on and the ECU "wakes up.
first thing its going to do is cycle the injectors once then apply a ground path to the fuel pump for about 2-3 seconds in anticipation of a start.
if the key is left on 12V remains at the pump but the ECU has removed the ground path.
no ground path,no current flow, no pump operation.

[TownsendsFJR1300]

Sounds like your on the right track.

I missed the sentence re the T&T so please dis-regaurd that earlier post.