Fuel Pump Circuit Problems

[gearb0x]

Hey guys,

I'm at the pointy end of my first megasquirt conversion & I'm running into a little trouble with my fuel pump circuit.

The car specs & ECU mods are as follows:

- Toyota 4AGE 20v
- v2.2 PCB w/ error* daughterboard & glens garage Idle/spark board with the following options:
- Wasted spark
- 3 wire IAC
- Hall crank sensor w/ 36-1 wheel
- VVT, FAN, Launch Control
- Knock sense

Now I'm having trouble with the fuel pump not energizing. I have the loom & ecu setup for bench testing, I have checked continuity of pin 37 to the (-) of the fuel pump relay and all is good, if I earth pin 37 on the inside of the ECU case with the loom plugged in the relay triggers so Its not my wiring loom. At the moment I have the transistor Q3 out of the board and Ive been trying to test the holes on the board with the multimeter. I haven't tried replacing Q3 yet but I was wondering if there was anything I can check for with the multimeter while Q3 is removed to confirm if the transistor is toast or not

Regards,
Phillip Savage

[gearb0x]

Oh and I almost forgot, Its running the HiRes 10G code, I couldn't actually install 029y4 on it, I got all sorts of weird errors

[gearb0x]

also, the fuel pump relay is a 40A "with resistor" I'm not sure if the resistor makes a difference

Phill

[jsmcortina]

Do you have a stim you can test on?

Measure the voltage at R13. When the fuel pump is supposed to be on (2.5 seconds on key-on) this should be 5V at one end and ~0.7V at the other. When the FP supposed to be off I'd expect ~0V at both ends.

Have you tried cranking and are you getting any rpm?

James

[gearb0x]

It seems to be intermittent, while i was testing R13 i heard it switch the FP relay on then off when turning the ECU on.

When its not working I have 4.7v at one end of R13, when it goes low there is still 2v on it.

[gearb0x]

Its not on the engine yet and my stimulator is broken (raided parts for another project). Its runing a Hall sensor which I have bentch tested with a hole saw & a power drill fine, megatune shows its turning the fuel pump on when there is cranking but its still not energising the relay

[jsmcortina]

OK, check the voltages at that resistor like I mentioned.

James

[gearb0x]

OK at the moment it is 4.75v when the fuel pump is meant to be on, and drops to 0.45v when the fuel pump is supposed to be off on the CPU side of R13

On the transistor side it starts at 0.69v when the fuel pump is on and drops to 0.45v

[jsmcortina]

It does sound likely that the output transistor has been damaged and it is worth replacing. They are cheap.

James

[gearb0x]

Woohoo, on the 3rd go I got it, I think I kept toasting the replacement transistors with heat from being lazy and not sucking out the solder while testing

I sucked out the solder properly and its all good now thanks