Loss of Power to HP fuel pump OX66

[captainpjt]

So I recently purchased a boat with a 2004 SX150TXRC 2 stroke OX66 on it. Ran it on muffs before I bought and then hauled it home and did a water pump and T-stats as preventative maintenance before using. After installing lower unit I fired it up and it ran for about 30 seconds just fine before sputtering out.

I quickly found out the HP pump has no juice so after reading some posts on here I am highly suspect of the relay on the stbd side of engine.

Any way to test this? It has a 4 leads coming out of it. There are black and yellow leads going to a waterproof 2 pin connector. The other 2 are individual leads with bullet connectors one being solid red and one red with yellow stripe. I read a previous post from rodbolt that stated any red/ yellow lead should have 12v+ with key on and the red yellow lead coming out of relay does not have 12V+.

Any other test method for this $200 part? From what I have read on here it seems to be a common problem.

[rodbolt17]

common?
nope.
I have seen 1 relay failure on an ox66.
black is the ground,yellow energizes the solenoid at key on, red is the 12V source yellow/red powers up the various 12 components such as the pump and the injectors.
easy to test,continuity on the ground,black wire.
12V at one wire to ground at key off battery switch on and 12V to 3 of the wires at key on.

[captainpjt]

Thanks Rodbolt for responding. I am just a bit confused on how to run the test?

I hooked relay back up to engine and with key on and everything connected except red with yellow stripe lead there is no voltage at red /yellow lead coming from relay.

The odd thing is that I put my meter to the the solid yellow lead going into relay ( which is actually a blue lead/white stripe on other side of waterproof connector) and it has 12.8 Volts whenever battery switch is on. It does not switch on /off with the key as you suggested it should above. Any idea why this might be?


If not relay, where else should I be looking for this issue? I traced hot lead for HP pump back to CDI and no power coming from CDI. Engine does crank and has spark. Checked 30 amp ATC fuse and (2) large fuses ( fusible link type things) on starboard side of engine and all ok. Also checked and cleaned CDI grounds.



thanks for assistance!

[captainpjt]

Ran test and it seems I have constant 12V at solid yellow lead going into relay regardless of whether switch ( ignition) is on or not. Any ideas?

[rodbolt17]

without a harness diagram in front of me, your relay has a ground,a constant 12v a switched 12v volt and a 12V output.
red/yellow wire is common to ALL devices powered up by the main relay.
the ECU controls pump GROUND path and supplys 12V to nothing.
can be tested like every other 12V relay ever made.
two pins control the relay contactor, the other two pins are simply current in and current out.
that's the only reason for a relay.
it allows a small operating current to control a much larger current path.

on the HPDI the relay s con*****ed by the ecu on the ground path side,cant remember without looking at it how the OX66 motors are but I imagine its the same.

typically on ECU switched devices its the ground path that gets switched.

hence the saying in digital electronics, LOW lights the light.
low being a ground potential.

[boscoe99]

Get a Yamaha copy of the service manual for your motor. Study the electrical wiring diagram very carefully. If you don't have a road map to guide you the journey may be very difficult. You can wind up being lost.

[boscoe99]

dupe entry

[captainpjt]

Thanks Rodbolt for all your advice and Boscoe too. I have a Yamaha service manual CD arriving monday. With the wiring diagrams and my Fluke meter, along with your greatly appreciated advice, Im sure will get this resolved. I will report my findings here once diagnosed to help others that may experience same issue.

Thanks Again!!

[sacmauinan]

So I recently purchased a boat with a 2004 SX150TXRC 2 stroke OX66 on it. Ran it on muffs before I bought and then hauled it home and did a water pump and T-stats as preventative maintenance before using. After installing lower unit I fired it up and it ran for about 30 seconds just fine before sputtering out.

I quickly found out the HP pump has no juice so after reading some posts on here I am highly suspect of the relay on the stbd side of engine.

Any way to test this? It has a 4 leads coming out of it. There are black and yellow leads going to a waterproof 2 pin connector. The other 2 are individual leads with bullet connectors one being solid red and one red with yellow stripe. I read a previous post from rodbolt that stated any red/ yellow lead should have 12v+ with key on and the red yellow lead coming out of relay does not have 12V+.

Any other test method for this $200 part? From what I have read on here it seems to be a common problem.

Thi?t k? mi?n phÃ* cho b?n vÃ* doanh nghi?p c?a b?n nhé!
S?c màu in ?n

[captainpjt]

Hello All,

Pleased to inform that it was in fact the relay. Installed new one today, turned key to hear the sweet sound of the HP pump, and off it fired and ran just fine!

thanks again rodbolt!!