Printable Version of Topic

Posted by: smveril Nov 3 2019, 01:28 PM

I have a 73 2 liter that I am near the end of the restoration.

We are trying to get the car to run. The engine is rebuilt, it has a Bosley fuel injection harness.

We pulled two injectors and we saw no fuel flow. The fuel pump runs and we have fuel pressure. We then removed the ECU and checked the pin outs on the ECU cable per Paul Andres schematic. One thing we found was the start signal from the ignition switch was 10.5 volts. It should be greater than 12 volts (pin 18 and ground).

What could cause the low voltage to the ECU?

Thanks,
Mike
.

Posted by: Bleyseng Nov 4 2019, 04:02 PM

Does it start on starting fluid?

Posted by: sixnotfour Nov 4 2019, 04:08 PM

fuel lines backwards

Posted by: smveril Nov 4 2019, 07:53 PM

It will run on starting fluiid. We did check the fuel lines but it may make sense to measure fuel pressure. But we are getting 10.5 volts to the ECU instead of 12 volts. So the fuel injectors do not enough power to run.

Posted by: smveril Nov 4 2019, 08:17 PM

So, I am looking for ideas that restrict the ECU from getting 12 volts power

Posted by: jcd914 Nov 4 2019, 10:21 PM

The power to the ECU from the starter circuit is so the ECU will power up the fuel pump while the engine is being cranked over. The ECU probably does not need the full 12 volts in order to power the fuel pump.
Does the fuel pump run while cranking the engine?

The starter circuit is notorious for low voltage to the starter.
Many people have added relays or the Ford start solnoid to get the starter to engage. I have never heard anyone having an issue with the low voltage to the ECU from this same circuit.
The ECU gets battery voltage it uses for operation from a different circuit bia the power supply relay on the engine compartment relay panel.

Check fuel pressure.
Check the 3 ground wires at the top rear of the engine case bolt.
Check for voltage pulses at the injectors, a mood light is the simplest way to check this.
Check the connector for injector points in distributor, needs to be tight.

Jim

Posted by: porschetub Nov 4 2019, 11:10 PM

or bad ignition switch ?????.

Posted by: 914_teener Nov 5 2019, 11:04 AM

I agree....or bad or loose ground strap.


Ring out the bat terms for voltage drop from the switch backwards.

Posted by: smveril Nov 5 2019, 05:50 PM

The fuel pump does run. I replaced the ignition switch about 6 years ago when it failed.

I will check fuel pressure. I did clean all the grounds when I pump the engine back in the car.

Thanks for the other suggestions. I will try them.

I have another question. The new injection harness had the coil wire labels switched. Could that damage the ECU.

Thanks,

Mike

Posted by: 914_teener Nov 5 2019, 06:20 PM

? What lead of the FI harness plugs into the coil terms? Post a Pic.

Posted by: jack20 Nov 8 2019, 12:18 AM

Confirm that the female trigger points plug is making good contact at the distributor.