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?

[TheCabinetmaker]

An inline pressure gauge will show pressure in the system, but that doesn't mean fuel is getting past the injectors.

[Groosh]

An inline pressure gauge will show pressure in the system, but that doesn't mean fuel is getting past the injectors.

Thanks. So if it firing on fluid the injectors are working but somehow I need to figure out if they are getting fuel. The fuel pressure gauge is off the right side rail. Any ideas on what to try next?

[r_towle]

Stick a pencil in the round intake end of the air-fuel meter.
Open the flapper door
You use the pencil to hold the door open, not to run the car, just to test
Turn on key to run
Do you hear the fuel pump?

[Groosh]

Stick a pencil in the round intake end of the air-fuel meter.
Open the flapper door
You use the pencil to hold the door open, not to run the car, just to test
Turn on key to run
Do you hear the fuel pump?

Can there be pressure in the fuel system but no fuel? Maybe the filter or something is clogged before the gauge?

- Fuel pump works

[timothy_nd28]

Rich's test is a good one, it's testing if your fuel pump turns on and it's also testing if part of the dual relay is working.

[jim_hoyland]

And the 6 pin connector is plugged into the AFM ?

[Groosh]

Rich's test is a good one, it's testing if your fuel pump turns on and it's also testing if part of the dual relay is working.

The relay isn't working as far as I know but I'm jumping the fuel pump right now. Power is getting to the relay properly from the ignition but not turning on the pump. Will that alter something else?

So if it fires under starting fluid, has fuel pressure but apparently no fuel, maybe it's as simple as a clogged filter?

[timothy_nd28]

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?

This comment has me concerned, what was de-wired? The dual relay does many things, one being the fuel pump but more importantly it turns on the Ljet computer.

[emoze]

NO - if it fires on start fluid but won't run

- the injectors are either stuck or not pulsing - put a NOID Light on the injector plugs to narrow it down

if it firing on fluid the injectors are working but somehow I need to figure out if they are getting fuel. The fuel pressure gauge is off the right side rail. Any ideas on what to try next?

[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?

This comment has me concerned, what was de-wired? The dual relay does many things, one being the fuel pump but more importantly it turns on the Ljet computer.

The owner pulled apart the dual relay - fuel pump/injector side - which I had to wire back together because he said there was a "fuel pump issue" which I think is the relay. Everything else seems to be intact relating to the engine and the other half of the dual relay. The lights, radio and gauges are another story.

Oh. There is one black with green stripe wire that is not connected. Not sure where that goes? Please don't judge the wire connectors. I'm just getting it together so it runs and will clean this up later.

[ejm]

- Will fire with starting fluid

Oh. There is one black with green stripe wire that is not connected. Not sure where that goes?

The wire is for an oil temp gauge if your car has one. Did you drain the tank and put some fresh fuel in?

[timothy_nd28]

I'm not sure if I can see the jumper from 88Y to 88Z, other than that it looks wired correctly.

With the ignition set to on and the ECU connector unplugged, do you get 12vdc at pin 10 to ground?

What was the results with Rich's test with the pencil in the AFM?

[Twonicks001]

I know this sounds overly simplistic but it had me going for a week or so. Do you have 12v at the fuel pump plug? My plug was bad. When I cut it off and spliced in my own clips to the pump, I was in business. Just a thought.

Good luck.

[motorvated]

If the injectors are not firing, you might want to confirm that the ground wire from the fuel injection harness is connected to a good clean spot on the engine block (not on the fan housing), and be sure the injector resistor pack is installed and the connector is clean. If it's there, carefully pull the connector apart a few times for a better connection. Injectors don't get any power without the resistor pack installed and therefore won't fire. Wires can break off of the resistor pack too, so be careful with it.

[Groosh]

Stick a pencil in the round intake end of the air-fuel meter.
Open the flapper door
You use the pencil to hold the door open, not to run the car, just to test
Turn on key to run
Do you hear the fuel pump?

So I put a pencil in the door and did not hear the pump run. Not sure if I'm doing things right. I'm still jumping the fuel pump to run it but not getting injectors to fire.

[Groosh]

If the injectors are not firing, you might want to confirm that the ground wire from the fuel injection harness is connected to a good clean spot on the engine block (not on the fan housing), and be sure the injector resistor pack is installed and the connector is clean. If it's there, carefully pull the connector apart a few times for a better connection. Injectors don't get any power without the resistor pack installed and therefore won't fire. Wires can break off of the resistor pack too, so be careful with it.

The ground looks clean and the resistor pack looks good. The wires are not frayed and took it apart several times to hopefully get a clean connection.

[Groosh]

I'm not sure if I can see the jumper from 88Y to 88Z, other than that it looks wired correctly.

With the ignition set to on and the ECU connector unplugged, do you get 12vdc at pin 10 to ground?

What was the results with Rich's test with the pencil in the AFM?

The jump is there. I tried to unplug the ECU and test for 12vdc from any pin and did not seem to get any.

I also bought a new relay which came today. It didn't help. I did notice that the fuel ground from the relay is hot. I traced it to the motor where it is grounded and get a volts from it.

[r_towle]

Without more accurate testing I would strongly suggest your AFM may need to be replaced, and your wiring needs to be redone properly.

[timothy_nd28]

Adding new parts just confounds the problem. Remove the fuel pump jumper and re-install the old dual relay.

When you tested for voltage on pin 10 of the ECU connector, was the ignition switch to on?

If so, let's do one thing before continuing with further tests. On the ignition coil, there should be a single wire on the (+) side terminal. Remove this wire, and tape it off. It's bad for the ignition coil and points when doing tests with the ignition key set for on, but the engine not running.

After the wire has been removed, we need to measure some voltages at the dual relay. With the meter set to DC, put the black lead on the negative battery post. Now with the red meter lead, probe pin 88z, then 88a and 88b. Report back what you see. This above test is done with the ignition key set to the "on or run" position.