how do i test the ecu????

[Verne Smith]

I can not determine if my ecu is bad or my regulator. All of the grounds are good, I have 12 volts going to my fuel pump power lead. I nave checked against my enitire wire diagram and found no issues or breaks. Is there a test I can do to guarantee the ecu is bad or the regulators??? 1996 mariner150 mag. Efi

 

[jeffersondodson561]

Re: how do i test the ecu????

Replacing the ECU should be a lengthy process. After all other tests are done. What are your symptoms? If you are having runabiltiy issues, I would check for some sort of mechanical issue. Some times the symptoms are clear enough to warrant immediate replacement but not always. Testing the fuel pressure regulator in pretty straight forward. Fuel pressure should drop when vacuum is applied to reference hose. Also a damage/out of place hose cannot cause problems with fuel pressure.

 

[Verne Smith]

Re: how do i test the ecu????

I have good compression. I have good spark (New Switch Boxes). I have 12.8 V comming from the ECU to the fuel pump. I do not have 12V at the positive terminal of the fuel pump. I can ground the fuel pump and make it run and pump. Is the pressure regulator responsible for activating the ECU, and if it is not, what is. I have power going to the ECU and comming out, I just dont have any activity or signal.
I have a 96Mariner Magnum 150 EFI.

 

[Faztbullet]

Re: how do i test the ecu????

If you dont have 12v at positive it would not run if grounded. The driver board in the ECU controls the ground to the the fuel pump and you should have 12v at positive terminal at pump when key is switched on.If you have no ground the driver has failed in ECU.

 

[jeffersondodson561]

Re: how do i test the ecu????

If you can ground the (-) side of the fuel pump and make it run you have voltage at the fuel pump. What are you using to measure? Test light multimeter? I would really inspect all grounds of the ECU. I would disconnect battery and do a continutiy test on all of the grounds from the ECU to the Block, should have minimum resistance. What happens if you take the negative lead off the fuel pump, hook up your multimeter set to ohms and record the resistance once key is turned on? If you hook a jumper lead from ground to the fuel pump negative side and run the engine, record the resitance of the ohm meter. Once key is turned on fuel pump should run for about 10 seconds. After doing this and you have verified that you are not getting (-) coming from the ECU to the fuel pump it would appear that the ECU has failed.

 

[Verne Smith]

Re: how do i test the ecu????

I was under the impression that both sides of the fuel pump were positive and the ECU breaks the ground to activate when needed. I have 12V at the positive (red wire) to ground. I can remove the red wire from the pump, and ground the terminal and get the pump to run. I can use a digital multimeter from the red wire to ground and I get 12.8 volts. I cannot run the engine. I can remove the battery though and will do this ASAP. Thanks for your help, I was starting to wonder if anyone would reply. One last thing, how can i test the ECU, and do either of you happen to have a diagram of the terminals in the ecu harness? Thanks Again for all your help..