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]

Ok, I'm very glad that you did this test. First, we must rule out the simple, do you have fuel? What is the fuel pressure at the fuel rail?

A few tests ago you measured 12 volts from pins 14,15,32 and 33 to battery ground. This test proves that you have continuity from the ECU connector thru the wiring harness, the fuel injector itself has continuity, the wiring harness to the dropping resistors has continuity, and finally, the harness to the dual relay has continuity. All of this is a very good thing.

Even though each fuel injector show's continuity, this does not prove that they will work. Mechanically, these injectors could be seized or plugged full of (IMG:style_emoticons/default/stromberg.gif) . Let's do one more test just to prove that these injectors are working electrically.

These injectors are low impedance, I'm pretty sure they are around 2.5 ohms (correct me if I'm wrong). You also have a 6 ohm dropping resistor in series of each fuel injector (resistor pack). Using a simple equation I=E/R, we can solve for current on each injector circuit. Total resistance is around 8.5 ohms, voltage is 13, so we should see something around 1.5 amps.

Many meters will measure amperage's for DC circuits. The meter will usually have something that will say DC A, and they typically measure up to 10 amps. Make sure you don't have your meter set to DC milliamps, as this will blow the meter's internal fuse. Make sure the red meter lead is plugged into the correct port on the meter, DC amp setting usually has its own port.

Now, same test as before. Remove the power wire from the ignition coil, set the ignition switch to on, temporarily deflect the air flow meter flap or jump pin 88d at the dual relay to the positive battery post. Next, insert the red meter lead into socket 14 of the ECU connector, while the black meter lead is touching the negative battery post. You should hear a click at the fuel injector, should also see fuel spraying too. As all of this is going on, observe what your meter is saying, should be somewhere of 1.5 amps.

Repeat this for pins 15, 32 and 33.

If you are seeing 1.5 amps at each injector, and you have verified fuel pressure at the fuel rail, then you send off your injectors to WitchHunters for cleaning.

[Groosh]

Ok, I'm very glad that you did this test. First, we must rule out the simple, do you have fuel? What is the fuel pressure at the fuel rail?

A few tests ago you measured 12 volts from pins 14,15,32 and 33 to battery ground. This test proves that you have continuity from the ECU connector thru the wiring harness, the fuel injector itself has continuity, the wiring harness to the dropping resistors has continuity, and finally, the harness to the dual relay has continuity. All of this is a very good thing.

Even though each fuel injector show's continuity, this does not prove that they will work. Mechanically, these injectors could be seized or plugged full of (IMG:style_emoticons/default/stromberg.gif) . Let's do one more test just to prove that these injectors are working electrically.

These injectors are low impedance, I'm pretty sure they are around 2.5 ohms (correct me if I'm wrong). You also have a 6 ohm dropping resistor in series of each fuel injector (resistor pack). Using a simple equation I=E/R, we can solve for current on each injector circuit. Total resistance is around 8.5 ohms, voltage is 13, so we should see something around 1.5 amps.

Many meters will measure amperage's for DC circuits. The meter will usually have something that will say DC A, and they typically measure up to 10 amps. Make sure you don't have your meter set to DC milliamps, as this will blow the meter's internal fuse. Make sure the red meter lead is plugged into the correct port on the meter, DC amp setting usually has its own port.

Now, same test as before. Remove the power wire from the ignition coil, set the ignition switch to on, temporarily deflect the air flow meter flap or jump pin 88d at the dual relay to the positive battery post. Next, insert the red meter lead into socket 14 of the ECU connector, while the black meter lead is touching the negative battery post. You should hear a click at the fuel injector, should also see fuel spraying too. As all of this is going on, observe what your meter is saying, should be somewhere of 1.5 amps.

Repeat this for pins 15, 32 and 33.

If you are seeing 1.5 amps at each injector, and you have verified fuel pressure at the fuel rail, then you send off your injectors to WitchHunters for cleaning.

There is a fuel pressure meter on the rail. It reads about 50 psi but I have no idea if it is accurate. It does go up and down but I have never seen it settle at zero.

I tested all the injectors as described and they all fire a beautiful stream of fuel with about 1.5 amps on the meter set to DC A 10A.