f250b no power to low pressure fuel pump

[straitin]

i have a pair of 4 stroke f250b's, the starboard engine will crank but not start, there is no power to low pressure fuel pump with the key on and i have found that the high pressure pump is siezed, obviously i will replace the pump but my question is should i have power at the low pressure pump or does the ECM recognise a problem and keep the power off. no fault codes show up in the diagnostics.

[rodbolt17]

the lift pump does not run at key on.
only if the engine is running.

[straitin]

f250b no power to low pressure fuel pump

Thank you for your advice, i notice that the port engine runs a pump for about 5-6 secs, is that the high pressure pump?, the one that is seized and hence no pump noise. should the the low pressure pump show voltage at cranking?

[rodbolt17]

the hp pump runs at key on to pressurize the rail in a start anticipation.
the USCG says that electric fuel pumps shall not run at key on,that is why the various systems from merc,honda Volvo Yamaha and all others run the HP pump for 3-5 seconds at key on then shut it off.
some run both pumps at key on, Yamaha did not.

[straitin]

f250b no power to low pressure fuel pump

Thanks again, that puts my mind at rest, new pump should arrive soon and then back to the briny. These forums are really great places to get these type of questions answered. Good on yer mate!

[boscoe99]

"f250b no power to low pressure fuel pump"

To answer your questions directly, if power is to be considered as 12 volts, then both pumps are powered when the key is in the on position. That is, you will see 12 volts to the positive terminal of each pump with the key on.

The ECU applies a ground to each pump to make it operate.

Only the high pressure pump is grounded when the key is first turned on. For several seconds to pressurize the fuel system. While the motor is being cranked and if the motor is started within five seconds then the ground will continue to be applied so that the pump runs continuously. If the motor stops for any reason then the ground will be removed by the ECU and the pump will stop.

Once the motor starts and is running the low pressure pump ground is applied by the ECU, but for only 10 seconds out of every 30 seconds, when the engine RPM is below 1200 RPM. Once above 1200 RPM the ground is applied continuously so that the low pressure pump runs continuously. Drop back down to 1200 or below and the low pressure pump begins to cycle on and off again.

Don't get fooled into thinking that electrical power is applied to operate the pumps. It is the ground. Completely opposite of how many electrical circuits operate.

[fairdeal]

"f250b no power to low pressure fuel pump"

Once the motor starts and is running the low pressure pump ground is applied by the ECU, but for only 10 seconds out of every 30 seconds, when the engine RPM is below 1200 RPM.

even more "granular" -you know, Boscoe, how i love to pore over my SMs -

here's what the Yamaha 2003 F225 SM says:



Now, when Mercury wrote the 2002 SM for the Mercaha F225, here's what they said:




I haven't yet experimented.

The latter would be simple to dis-prove - if incorrect.

The former, a bit more of a project to explore fully....

[boscoe99]

the hp pump runs at key on to pressurize the rail in a start anticipation.
the USCG says that electric fuel pumps shall not run at key on,that is why the various systems from merc,honda Volvo Yamaha and all others run the HP pump for 3-5 seconds at key on then shut it off.
some run both pumps at key on, Yamaha did not.

For the record, for those that may come along and read this post later, it needs to be noted that the law that the USCG is administering with respect to electric fuel pump operations, does NOT apply to an outboard motor.

[boscoe99]

even more "granular" -you know, Boscoe, how i love to pore over my SMs -

here's what the Yamaha 2003 F225 SM says:



Now, when Mercury wrote the 2002 SM for the Mercaha F225, here's what they said:




I haven't yet experimented.

The latter would be simple to dis-prove - if incorrect.

The former, a bit more of a project to explore fully....

Is it possible that the Mercury ECU does not operate in the same manner as does the Yamaha ECU? I would assume that the black Yams were built to Mercury specifications which could vary from Yamaha specifications.

In a Yam do we agree that upon engine start and run (assuming the run is kept below 1200 RPM) that the HP pump runs continuously and that the LP pump runs for 10 seconds (immediately upon engine start), then is off for 20 seconds, then runs for 10 seconds again...

[fairdeal]

Is it possible that the Mercury ECU does not operate in the same manner as does the Yamaha ECU? I would assume that the black Yams were built to Mercury specifications which could vary from Yamaha specifications.

It is possible, AFAIK.

What the 2002 manual does show, is that Mercury was "taking no chances" in complying with EPA.

"presaging" the carbon canister which Yamaha put on the F225 in, what, the 2005 model?

the "black Yam" apparently had this right from day one:

[rodbolt17]

the merc version of the F225 is NOT identical to the Yamaha version.
I did a full service that included VST and injectors on a "blown up" merc F225 2003 model that the pumps operated identical to the Yamaha setup.
there were some differences in the VST and crankcase venting.

motor cam in with low compression on a hole.

other dealer wanted 9000 bucks to repair it.

a friend called and asked if I would look at it.

leakdown showed 85% leakage but the air was coming past an intake valve.

ran it on a mix of 1qt YEIC to 3qt of gas.

retested and leakage was less than 10% on all 6.

the issue was carbon on a valve seat/face.

but I did not observe a pump on for 3 min at key on.
I typically turn the key,wait for the pump to shut down and then start the motor.

[boscoe99]

When exactly did Mercury offer their version of the Yam F225?

Looks to be similar to the very first Yamaha F225 (no second battery output and a HP pump relay and an LP pump driver).

Mercury only shows one version.

[straitin]

f250b no power to low pressure fuel pump

Thank you to all those who contributed input to my post, i was not sure how the system worked at first but deduced something was not right when the sounds at "key on" where not the same,and the engine refused to start. After a lot of research it became clear that a lot of engines where suffering from electrical fuel pump failure, mostly of the high pressure pump after winterisation and the use of E10 fuel so that is where i started the investigation and found a seized pump. I imported these engines from the USA as a used pair (trying to find a pair of large HP engines in Australia is very difficult) so it made sense to start at this point.
It is good to know that there are people with a vast knowledge bank out there prepared to help, thank you all once again.
Ed

[oldmako69]

the merc version of the F225 is NOT identical to the Yamaha version.
I did a full service that included VST and injectors on a "blown up" merc F225 2003 model that the pumps operated identical to the Yamaha setup.
there were some differences in the VST and crankcase venting.

motor cam in with low compression on a hole.

other dealer wanted 9000 bucks to repair it.

a friend called and asked if I would look at it.

leakdown showed 85% leakage but the air was coming past an intake valve.

ran it on a mix of 1qt YEIC to 3qt of gas.

retested and leakage was less than 10% on all 6.

the issue was carbon on a valve seat/face.

but I did not observe a pump on for 3 min at key on.
I typically turn the key,wait for the pump to shut down and then start the motor.

What is YEIC?

[fairdeal]

What is YEIC?

A typo, I think -

Yamaha Internal Engine Cleaner - apparently "Ring Free on Steroids"

sold only to dealers?

the instructions show the tech dressed up like Walter White....