2016 250 vmax fuel issues

[arctic 1]

Fellas in need of help, fuel problems with 250 vmax 4 stroke,
Engine runs then once fuel is burnt from vst it dosent refil, took out the exterior inline pump and hooked direct to battery it turns on but doesnt pump fuel , this all started with a burt fuse by the way, assuming that pump was no good i thought i could try just an ordinary inline pump to see if i could get the vst to fill but hooked it up with no luck.tested the power wires to pump and have 0 v ,should this have 12 v when key is on or only when vst is calling for it . Any input would be great

[arctic 1]

I forgot to mention if i pump the ball it will stay running does this mean the injection pump is good or is it just running off the ball?

[TownsendsFJR1300]

With the pump hooked directly to the battery and no pumping, that sounds like your issue.

To my knowledge, 12 volts is applied to the pump but the GROUND is toggled on and off to make the pump function by the ECU.

And yes, you pumping the primer bulb is doing what the pump should be doing..

[fairdeal]

...

seconding Townsends' guidance.
The primer bulb functions as a pump - but only when you are manipulating it-
when it is 'just there' it can not pump fuel on its own.

At key on, all the red/yellow wires should have battery power,
when the ECM wants the lift pump to run,
it provides the ground.
(doesn't run the lift pump at key on, just when engine is running)

[arctic 1]

Perfect just as i thought, i had it narrowed to the pump but having no power no power at the plug confused me but had much assumed the power wasnt continious, the next question is could i put in a inline low pressure pump to test to be sure before i spend 1000 bux on a new one?

[fairdeal]

looks to me that our gracious hosts boat.net sell the pump for only $554.

https://www.boats.net/product/yamaha...CB-24410-00-00


but I think it would be safe to 'test' with something like this:

https://www.amazon.com/HFP-PPN21-Yam...gateway&sr=8-1

[boscoe99]

Very strange that the pump turns without pumping gasoline. Assuming that you powered it such that it turned so as to pump gasoline and not the other way round. But it is what it is.

Over on a bass boat board I frequent they were replacing the HPDI mechanical pumps with a boat mounted electric fuel pump. Worked well. No reason you could not do the same.

Am I presuming correctly that you are going to install your test pump ahead of the existing low pressure electric fuel pump?

[panasonic]

Fellas in need of help, fuel problems with 250 vmax 4 stroke,
Engine runs then once fuel is burnt from vst it dosent refil, took out the exterior inline pump and hooked direct to battery it turns on but doesnt pump fuel , this all started with a burt fuse by the way, assuming that pump was no good i thought i could try just an ordinary inline pump to see if i could get the vst to fill but hooked it up with no luck.tested the power wires to pump and have 0 v ,should this have 12 v when key is on or only when vst is calling for it . Any input would be great

I would be trying find out what caused the fuse to blow before I did anything else, seeing that is the first symptom of this problem.

[boscoe99]

Forgot to mention. Don't keep running the HP pump dry of gasoline. That can harm it. Gasoline is used to cool and lubricate the innards of the pump.

As Pan noted, try and find out what caused the pump to blow. Could very well have been the pump going south.

[TownsendsFJR1300]

To add to the above, ^^^, pry that puppy apart and see what the pump itself looks like inside. You have nothing to loose and can only confirm .


Maybe a vane (I have no idea what the inside of that pump looks like) came off, locked up the pump and blew the fuse, s..t happens...

WP vanes, (especially on the smaller, older engines) come off and block cooling passages. Been posted her many times...

[arctic 1]

All valid questions , i was certian to test the pump with proper polarity and tried reverse for the heck of it,i even pumped the ball while on to see if it needed a primer ,when i leave it run i can kind of feel it jam periodicly , tonight i hooked up a small inline pump and it seemed to run fine, new pump ordered today, after the advice you guys gave i tested wires when running to make sure i had power and i did . So has to be the pump, once i remove when new once comes in i will tear it apart to see whats inside and post some pics, when i picked up the engine it was used only has 333hrs to be exact there was water in filters and actually running out of fuel line, i suspect water done damage to pump sitting over the winter . 900 through my dealer here in canadas arctic ,found what looks like a exact match on amazon for 125 so ordered that as well, walbro pump looks like its the same from a 94 honda prelude lol. Cant thank you guys enough for the help will keep posted , i have more questions about my brothers 90hp but will make another thread.

[arctic 1]

So fellas ,back again i finally received my new pump from my dealer since june. I have been running it since the first post with a walbro pump i found on amazon , it corrected my problem of having to pump the ball all the time but didnt take the problem away entirely.
so heres whats going on
Initially i had to pump the bulb all the time to make it run
installed the amazon pump the engine runs fine and at 1500 or greater rms no problems the thing runs like a dream,
when i putter or go to idle the engine eventually stalls and have to pump the bulb to go again.
i have been blaming this on the pump from amazon as it was off by part numbers from the oem , thinking it to be a shorter pull pump or something.
i installed my new yamaha pump yesterday to find i still have the problem.
what tells this pump to run? Is it the float in the vst tank or is it on a cycle from the ecm?
starting to think when i lost the original pump and fuse blew it fxed up the ecm?

[boscoe99]

So fellas ,back again i finally received my new pump from my dealer since june. I have been running it since the first post with a walbro pump i found on amazon , it corrected my problem of having to pump the ball all the time but didnt take the problem away entirely.
so heres whats going on
Initially i had to pump the bulb all the time to make it run
installed the amazon pump the engine runs fine and at 1500 or greater rms no problems the thing runs like a dream,
when i putter or go to idle the engine eventually stalls and have to pump the bulb to go again.
i have been blaming this on the pump from amazon as it was off by part numbers from the oem , thinking it to be a shorter pull pump or something.
i installed my new yamaha pump yesterday to find i still have the problem.
what tells this pump to run? Is it the float in the vst tank or is it on a cycle from the ecm?
starting to think when i lost the original pump and fuse blew it fxed up the ecm?

The Engine Control Unit (ECU) tells the lift pump to run. By applying a ground to the lift pump. The lift pump has positive power any time that the key is in the on position.

If the engine RPM is below 1200 RPM the ground will be applied for 10 seconds out of every 30 seconds. Runs 10 seconds, off 20 seconds, on 10 seconds.... Above 1200 RPM the lift pump is grounded continuously.

There is a check valve (I suspect it is really a pressure relief valve) between the output of the lift pump and the inlet of the lift pump. If the valve is failing such that fuel is being bypassed outside of design limits then that possibly could cause the VST to have insufficient fuel. You could easily block off the return flow of the fuel to see if the problem goes away or stays the same.

[arctic 1]

Thanks boscoe this makes perfect sense, i will get at it today and see what i come up with.will update once i know more

[arctic 1]

Boscoe is the check valve inside the vst tank ?