2002 F225 Yamaha - Cranks, but will not start..

[FlyGuy714]

Hey guys,

Scenario:

2002 Yamaha F225 4 stroke with 900 hours - has had every scheduled maintenance and just had a full service @ 800 hours this past winter replacing all fuel filters, water/fuel seperator, spark plugs and rebuilt the water pump.

Issue: Motor has been working excellent, rarely it would not crank on the first try recently, but always fired up perfect on the 2nd try. This past Sunday while running home from the Islands, the motor cut out like it was losing fuel slowly and will not re-start. It'll crank non-stop and sounds good, but seems to not be getting fuel to actually fire up.

So far I have checked the 10micron fuel filter and water/fuel seperator and also the "common" 3-pin connector issue with no luck. I do hear the fuel pumps turn on when the key is turned to "on position".

Is the fuel pump I hear with the key in the "on" position the VST or low pressure feed pump?

Can a clogged VST filter, "F" filter, or such be the cause?

Any suggestions of where to look first? Should I be able to hear the high pressure VST pump turn on?

Any ideas or tips would be great, I'm going to take a serious look this weekend and put in some time.

[boscoe99]

The pump you hear run for a moment when the key is turned on is the high pressure pump.

The low pressure pump feeds the high pressure pump. If the low pressure pump fails then the motor is not going to start or run. The low pressure pump does not operate until the motor is running.

Pump the bejeesus out of the primer ball. You are trying to force fuel through the system to the vapor separator tank wherein the high pressure pump lives. Turn the key just to the on position. Then turn the key off. Pump the primer ball until it is goodntite.

Then see if the motor will start. If so I would suspect the low pressure pump as having failed.

[FlyGuy714]

I tried pumping the primer ball like crazy with no effect. That was the first thing I tried after the motor quit.

It does seem like the primer ball isn't really getting "firm" like it used to. I never remember it becoming completely hard, but it seems to almost get firm and then be right back to squishy again after I stop pumping it..

Pumped it a ton and it didn't help the motor start at all, same crank, crank, crank and sounds like it has no fuel.

[boscoe99]

Well if the primer ball cannot be made to get rock hard like a ****aged school boy, and if you suspect it is lack of fuel, then it might be lack of fuel.

Remove the primary fuel filter and pump the primer ball. Does fuel flow freely to the filter?

Open the drain screw on the vapor separator tank and pump the primer ball. Does fuel flow freely out of the drain?

Mist some gasoline into the intake system and see if it fires.

Or better still put a fuel pressure gauge on the fuel system schrader valve and see if there is about 45 psi of fuel pressure when the key is turned on.

Plumb a six gallon fuel tank to the motor and then prime the fuel system. See if it starts and runs well. If so, the problem is backwards to the boat.

[FlyGuy714]

Thank you Boscoe, I'll start that troubleshooting first! Appreciate the tips, I've got some mechanical know-how but I'm knew to boat ownership. Looks like this is a perfect time to become more knowledgeable about my outboard and all its components.

[boscoe99]

The more that you know about your boat and motor the less that will go wrong with them.

[rodbolt17]

well barring a timing belt failure, its most likely loss of fuel or loss of spark.
the ECU and ign both have a fuse.
are they ok?

easy way is spray a bit of starting fluid and crank it, if it tries to fire it is sparking.

then it is on to fuel,is it contaminated with water?
you can drain a sample from the VST.
you can use jumpers and manually turn on the lift pump.
you have to use a guage to check the HP pump.

there are NO sensors OR switchs that will shut the engine off. don't even go there.

[FlyGuy714]

well barring a timing belt failure, its most likely loss of fuel or loss of spark.
the ECU and ign both have a fuse.
are they ok?

easy way is spray a bit of starting fluid and crank it, if it tries to fire it is sparking.

then it is on to fuel,is it contaminated with water?
you can drain a sample from the VST.
you can use jumpers and manually turn on the lift pump.
you have to use a guage to check the HP pump.

there are NO sensors OR switchs that will shut the engine off. don't even go there.

Fuses all looked ok. I have checked filters for water contamination and it looks good.

I did not have any quick start spray or what not to test if it'll fire with some starter fluid sprayed in the throttle body.

I'll test this first tonight!

Also - I have not tried to drain or look at the VST at all, as I am not that familiar. But I'm reading up on simyahama on how to go through the VST to atleast check the filters and such.

Thank you for the tips guys!

[FlyGuy714]

Ok, finally got down to the boat and did a few checks.

Motor did not rumble or pop at all during the starter fluid test. Fuel was flowing properly at the bulb and up to the on engine filter. The bulb is pretty old, so I'm going to order a new one anyways. I'm pretty sure my initial thought of being a fuel issue is incorrect.

Next, I used an inline spark tester and it seems that the plugs are getting a very weak spark. The test light barely flickers on, much less than when I've used them on cars in the past. Just a light flicker, not enough to pulse the whole bulb.

I also forgot to mention that I've seen the voltage jump to 15.5/16 volts at times when running for extended periods of time. The Yamaha gauge will blink the battery voltage and show its over charging.

What are the symptoms of a shot voltage rectifier or something similar?

[rodbolt17]

look at the regulator driver connectors, what color are they?

check for 12v at the ign coil primaries.
check peak voltage at the ign coil primaries.

this motor uses a 12v ign system.