more on F225TXRD Fuel Pump Driver / ECM - Boscoe?

[boscoe99]

LIT-18616-02-76
1st edition, Sept 2003

I have a TXRD built 11/04
the only differences I can recall noticing:
carbon canister & associated venting parts
harness has the CL connector

That was the manual issued for an F200/F225TLRC. As you may have noted it has never been updated for later models even though they are of a different configuration.

More tomorrow.

[rodbolt17]

we have two pages of discussion on an issue that I could track down in 10 min even if my meter was in the truck.

first I know if the pump is running the yellow/red wire has 12V.

at key on ALL yellow red wires have 12V.

now I also know that the low pressure pump does NOT run at key on.
I also know the HP pump runs 3-5 seconds at key on.

the complaint was the pumps turn on and the low pressure continues to run.

so how do I do this with no meter?

common sense and training coupled with a tad bit o experience.

pump runs,means I have 12V and a ground path.
not supposed to have a ground path.
means the driver shorted internally.
the control wire from the ECU to the driver shorted or the ECM shorted internally.

so I did remember to bring my pick.
I unplug the driver connector,I remove the driver to ECM control wire and plug the driver in.
if the pump now runs at key on the driver failed.
if it does not run I reconnect the control wire at the driver and disconnect it at the ECM connector.
if the pump now runs at key on I know the control wire is shorted to ground.
if it does not I know the ECM failed.

its a digital circuit.
in 99% of digital circuits the ground path is toggled.
remember low lights the light.
means a ground path operates the device.

woulda been faster if I remembered my meter and jumper leads and a couple paper clips.

however in this case I would have isolated the driver in about 10 min.

it called knowing how the system is supposed to work and why isn't it.

trons is trons.
it really doesn't matter what the device is.

[boscoe99]

The driver - this is on the 2005 F225 - is an interesting thing,
a single solid state module mounted on the floor of the cowling base
that incorporates BOTH the LP and HP pump "relays"
(and ALSO has some function with the regulator/rectifier output)

It has 14 wires, in 5 connectors !

One, black, and heavier wire gauge than the others, is apparently the power running the LP and HP pumps

Anything is possible with Yamaha. And of course it won't be documented very well in any Yamaha manual. I looked to see what was to be seen. The more I looked the more confused I got. I had to give up.

Go and look at a 2002 F225. It uses the driver for just the LP pump. A separate relay is used for the HP pump. One called a driver and the other a relay. It is also the only F225 that does not have an output for an isolator lead to charge a second battery. Looks like Yam forgot about this (previous models had it) and then put it back in for the 2003 model motor. Just like they forgot to put a knock sensor on the HPDI's.

I learned just a wee bit in this exercise so overall it has been worthwhile. And interesting.

[99yam40]

Hi Rodbolt

ok, so its a theoretical question, not a practical one -

but the question is "exactly what is going on inside the solid state F225TXRD driver module,

is it different for the two pumps,

and why"



The symbology for HP pump invokes a classic magnetic relay - surely that's not what's in there, but the concept is recognizable

But what are they trying to convey, with different symbology, for the LP pump ?

and why?

I see and understand what you are asking but have no idea why they used a different symbol for the low pressure pump relay if that is what that is.
I believe it is just a miss print/mistake because I think the ECU should be turning the LP on and off when it wants it to run by toggling the ground just like the HP

[boscoe99]

I see and understand what you are asking but have no idea why they used a different symbol for the low pressure pump relay if that is what that is.
I believe it is just a miss print/mistake because I think the ECU should be turning the LP on and off when it wants it to run by toggling the ground just like the HP

Now that I think about it some more (my head hurts from over thinking) maybe it is because the HP pump is generally only turned on one time when the motor is used whereas the LP pumps turns off and on repeatedly when the RPM is below 1200 that results in a different type of relay?

Does the driver click when a ground is applied to make it work? Does it maybe only click when one of the two grounds is applied? If one clicks and the other does not maybe they are using a mechanical relay for one pump and an electronic relay for the other pump? Just a guess. And if the guess is correct I presume the electronic relay would be used for the LP pump. More cost but a higher reliability over time and usage.

In the case of the F225 for 2002 it uses one component (called a driver) for the LP pump and a separate component (called a relay) for the HP pump.