Fuel pressure and spark but won't run Options

[Groosh]

Hi. I recently bought a '74 1.8 and am looking for help to get it running. It has the original fuel injection and ran late last year according the previous owner.

Here's what I know after reading many posts in the forum and working on it. Thanks to everybody who contributes, I couldn't have gotten this far without your help.

- The dual relay is bad I believe. After wiring it all back up, there is power from the ignition to both the start wire and run wire but no power to the fuel pump. I'm jumping the pump currently to test
- All relays in the board work
- Fuel pressure gauge shows 35psi on startup. I didn't install this gauge but seems to work ok
- Will fire with starting fluid

I'm thinking I must be pretty close and suspect the car isn't getting fuel but the gauge shows pressure?

[timothy_nd28]

Since the injectors all have continuity, the problem lies in a short wire run from the injector's connector to the ECU connector. I highlighted a red box that illustrates the problem area


Since you already tested the FI connector of the two failed injectors, and confirmed that you have 12 volts sitting at one of the two pins, confirms that the dual relay is sending voltage thru the resistor pack and is making its way to the fuel injector. Missing voltage at the ECU pins 14 and 15 tells me that there is a break in a wire or a bad connection at one of the connectors.

You can remove the fuel injector connector and reconfirm that you do indeed have 12 volts present on one of the two pins. The other dead pin, you can check the resistance of that pin to the ECU connector, which will be either pin 14 or 15. You should read 0 ohms, but since you are not getting voltage on pins 14 or 15, you may read a high resistance. I bet if you were to jiggle the harness while measuring resistance, you may see things change with your meter.

Be extra observant at the two failed injectors, look at the wires and pins at the injector connector. Same thing for pins 14 and 15 at the ECU connector.

After all that, you have 3 options.

Send your injection harness off to Jeff Bowlsby for repair, or buy a known good used one, or if you are up for it; get a razor blade and split the outer casing of the injection harness and find pin 14/15 wires and repair it yourself.

[Groosh]

Since the injectors all have continuity, the problem lies in a short wire run from the injector's connector to the ECU connector. I highlighted a red box that illustrates the problem area


Since you already tested the FI connector of the two failed injectors, and confirmed that you have 12 volts sitting at one of the two pins, confirms that the dual relay is sending voltage thru the resistor pack and is making its way to the fuel injector. Missing voltage at the ECU pins 14 and 15 tells me that there is a break in a wire or a bad connection at one of the connectors.

You can remove the fuel injector connector and reconfirm that you do indeed have 12 volts present on one of the two pins. The other dead pin, you can check the resistance of that pin to the ECU connector, which will be either pin 14 or 15. You should read 0 ohms, but since you are not getting voltage on pins 14 or 15, you may read a high resistance. I bet if you were to jiggle the harness while measuring resistance, you may see things change with your meter.

Be extra observant at the two failed injectors, look at the wires and pins at the injector connector. Same thing for pins 14 and 15 at the ECU connector.

After all that, you have 3 options.

Send your injection harness off to Jeff Bowlsby for repair, or buy a known good used one, or if you are up for it; get a razor blade and split the outer casing of the injection harness and find pin 14/15 wires and repair it yourself.

Hmmmm... I have the injector harness off. I notice a pin on one injector pushed in but all the injector wiring tests good when I connect from the injector plug back to the ECU connector. I also test good from the restistor pack plug to the injector plug.

That being said, there are bad wires. But I'm not sure what to make of it all before I go slicing and dicing.