Fuel pressure and spark but won't run Options

[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.

[timothy_nd28]

So you have 12volts on pins 14,15,32&33?

[Groosh]

Thanks to all of Tim's work, I have a repaired fuel injector harness back in the car. Thanks Tim!

The last we left it, I was at the following trying to test the ground.

Okay, jump pin 85 at the dual relay to the negative battery post. Redo same test as above.

Heard the relay click for the first time and got 12 volts on 88a and 88b.

[Groosh]

Well, I started back at the beginning of our testing.

After taping off the positive lead to the coil, I tested as follows:

- Ignition switch on
- Negative lead from multi meter on battery
- Positive lead touching the following:

88z - 12 volts
88a - 12 volts
88b - 12 volts

88d - will run fuel pump with 12 volts jump wire from positive terminal
86c - will get 12 volts with jump wire from negative battery terminal

[timothy_nd28]

Try deflecting the air flow meter flap with the ignition switch on, does the fuel pump engage?

Also, measure pins 14,15,32 and 33 by having the ignition switch on, and the meter set for DC volts. Put one meter lead on the negative battery post, and the other meter lead in the ECU sockets 14,15,32,33.

[Groosh]

Try deflecting the air flow meter flap with the ignition switch on, does the fuel pump engage?

Also, measure pins 14,15,32 and 33 by having the ignition switch on, and the meter set for DC volts. Put one meter lead on the negative battery post, and the other meter lead in the ECU sockets 14,15,32,33.

Yes, fuel pump engages with deflected air flow meter and key switched on.

With the meter set to DC 50 and key on, I'm reading 12 volts at ECU sockets 14,15,32,33.

[timothy_nd28]

Cool, much better results than last time.

[timothy_nd28]

Car is almost ready to run. I would do one more test to verify the injectors do still work and are spraying fuel. Unclamp all injectors from the manifold, leave the fuel lines attached and electrical connectors plugged in. Find a way to put mason jars under each fuel injector. Set the ignition switch to on and temporarily open the airflow meter flap or jamb a screwdriver inside to keep the flap open.

With a wire, attach one side to the negative battery post. Take the other side of this wire and probe pins 14,15,32,33 at the ecu connector. Watch the fuel injectors as you do this. It should be a mist of fuel spraying, make sure all spray patterns look the same.

Next, take your voltmeter and set it for resistance. Probe pin 13 at the ecu connector while the other lead is on the negative battery post.

Finally, reassemble and prepare the car to start. Make sure you reattach the power wire back on the ignition coil and you remove the screw driver from the airflow meter.

[Groosh]

Car is almost ready to run. I would do one more test to verify the injectors do still work and are spraying fuel. Unclamp all injectors from the manifold, leave the fuel lines attached and electrical connectors plugged in. Find a way to put mason jars under each fuel injector. Set the ignition switch to on and temporarily open the airflow meter flap or jamb a screwdriver inside to keep the flap open.

With a wire, attach one side to the negative battery post. Take the other side of this wire and probe pins 14,15,32,33 at the ecu connector. Watch the fuel injectors as you do this. It should be a mist of fuel spraying, make sure all spray patterns look the same.

Next, take your voltmeter and set it for resistance. Probe pin 13 at the ecu connector while the other lead is on the negative battery post.

Finally, reassemble and prepare the car to start. Make sure you reattach the power wire back on the ignition coil and you remove the screw driver from the airflow meter.

Well, I'm not seeing any fuel come out at all. I first tested this by cranking the car over with little jars under each injector. Only cylinder #2 had a little fuel mist and then it didn't do it again. I tried again by jumping the negative battery post and probing the pins and did not hear or see any sign of fuel coming from the injectors. The fuel pump was running.

[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.

[timothy_nd28]

Cool, not sure what your issue was with the previous test. Button the injectors back up and verify you still have spark. Try starting the car

[Groosh]

Cool, not sure what your issue was with the previous test. Button the injectors back up and verify you still have spark. Try starting the car

I think we are missing something. The injectors do not fire when plugged into the ECU. They only fire when we jumped them. Could my ECU be bad? I tried pulling an injector and no fuel comes out when everything is put together. Additionally, I don't think I have spark anymore. The car did run on starter fluid in the being. But now it doesn't and looking for spark from a pulled plug reveals no spark.

[timothy_nd28]

The ECU uses the spark signal to fire the injectors. When doing the previous tests, I had you remove the power wire off the ignition coil. This was done to protect either your ignition points or your pointless module. It's bad to leave the ignition on with the car not running, as it will ruin the points.

We need to address your no spark condition. Do you have mechanical points inside the distributor or is it a electronic module?

[Groosh]

The ECU uses the spark signal to fire the injectors. When doing the previous tests, I had you remove the power wire off the ignition coil. This was done to protect either your ignition points or your pointless module. It's bad to leave the ignition on with the car not running, as it will ruin the points.

We need to address your no spark condition. Do you have mechanical points inside the distributor or is it a electronic module?

I love how much you know Tim! The points are mechanical.

[timothy_nd28]

Verify you do have 12 volts present at the positive terminal of the ignition coil when the ignition switch is set to on. Measure this by probing the + terminal of the ignition coil and probing the negative battery post

[Groosh]

Verify you do have 12 volts present at the positive terminal of the ignition coil when the ignition switch is set to on. Measure this by probing the + terminal of the ignition coil and probing the negative battery post

We have 12 volts at the coil.

[timothy_nd28]

Remove the distributor cap and rotor, and manually spring open the points while trying to take a picture. Post the picture if you can, I'm wondering if the points are burnt

[Groosh]

Remove the distributor cap and rotor, and manually spring open the points while trying to take a picture. Post the picture if you can, I'm wondering if the points are burnt

[timothy_nd28]

Yah, time to replace them.