Won't Fire up with L-jet, WTF!!! Update on Page 2 post 35 Options

[dlee6204]

I skimmed through the rest of this thread but if I understand correctly, you aren't getting fuel out of the injectors right? Have you tested the fuel pressure when cranking? No fuel through the injectors seems like it would be no pressure, the resistor pack, or bad injectors and I know you have near new injectors.

[Black22]

3 NOS injectors 1 that was previously on engine running. Resistor pack checks good with key on and using a wire grounded from battery (-) and jumping to ECU pigtail connection 14,15, 32, 33 you can hear each injector click.

Fuel pressure is 29psi.

[Tom]

Mike,
How many wires do you have going into the left plug on the last pic. 85C should be ground, can you check that with a multimeter and get back?

[jim_hoyland]

The dual relay has a brown ground wire. Usually attaches to a spade on the engine case near the center. If it is in place, check it's continuity.....this is a common L-Jet issue

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[Black22]

6 wires. One at each terminal listed on the diagram. 88d, 86c,88z,88y,86(a) and 85 which is a ground.

You might have misread my post 88c should have power. 85 is ground.

At the car right now with meter & computer. What do you want me to check?

[Black22]

The dual relay has a brown ground wire. Usually attaches to a spade on the engine case near the center. If it is in place, check it's continuity.....this is a common L-Jet issue

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Yes, all grounds are connected at grounding point underneath intake plenum on block. Continuity good.

[Tom]

I admit that I don't know L-jet.
I see you have a petronix, was it running with that before? And are you running a Bosch blue? Could you have the wires hooked up wrong. My Bosch blus has a+ and - terminal and I hooked it up wrong at first, but I have points and D-jet. Not trying to point fingers, just saying sometimes we try so hard, we get things mixed up.
Tom

[dlee6204]

Doug, I don't have that ground wire in your last picture. I never had it and the car ran. Necessary?

Okay I figured it out. That isn't a ground wire. It is a jumper wire that connects to the battery(+). In Bowlsby diagram it connects to terminal "6" and then there should be a jumper between "6" and "2"

http://bowlsby.net/914/WiringHarnesses/Har..._74-75L-Jet.pdf

[Black22]

I admit that I don't know L-jet.
I see you have a petronix, was it running with that before? And are you running a Bosch blue? Could you have the wires hooked up wrong. My Bosch blus has a+ and - terminal and I hooked it up wrong at first, but I have points and D-jet. Not trying to point fingers, just saying sometimes we try so hard, we get things mixed up.
Tom

Pertronix has less than 600miles on it before rebuild. I have the Pertronix Flamethrower coil. I have a new coil and an old of the same make. Car will fire and run with starter fluid and/or gas in throttle body.

[Black22]

Doug, I don't have that ground wire in your last picture. I never had it and the car ran. Necessary?

Okay I figured it out. That isn't a ground wire. It is a jumper wire that connects to the battery(+). In Bowlsby diagram it connects to terminal "6" and then there should be a jumper between "6" and "2"

http://bowlsby.net/914/WiringHarnesses/Har..._74-75L-Jet.pdf

Yeah I have that diagram. 2 & 6 are jumpered. My harnesses are all in spec per Jeff's diagrams

[dlee6204]

Well I'm out. It seems like you've already checked everything else I would check. My only other advice is double and triple check everything. Hopefully you will figure it out soon. (IMG:style_emoticons/default/popcorn[1].gif)

[Black22]

Well I'm out. It seems like you've already checked everything else I would check. My only other advice is double and triple check everything. Hopefully you will figure it out soon. (IMG:style_emoticons/default/popcorn[1].gif)

Already Double and Triple checked... (IMG:style_emoticons/default/confused24.gif)

It doesn't make sense.

[jim_hoyland]

IIRC you can circumvent the dual relay by grounding III at the 4 wire connector on the rear of the relay board. The schematic at shows the grounding will enable the fuel pump relay ( unused on the L-Jet ) to power the FP. The middle two relay would have to be in place ( Power and FP)

A fuel pressure gauge is a huge assist when trying to figure out whether the dual relay/fuel pump are working.

See: http://www.pelicanparts.com/914/parts/Elec...lectric_73E.jpg

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[Mike Bellis]

Need a L jet manual?
https://docs.google.com/file/d/0Bzy-cXUDftd...en_US&pli=1

[pilothyer]

Mike....I had this identical problem with my 75 1.8 L jet. I kept overlooking the head temp sensor because it was "NEW" finally after expiring all other means, I checked it with an OHM meter it's resistance was so high it was as good as open. I unplugged it and connected a jumper wire to the wire going to the ECU (not the one going to the temp sensor) then attached the other jumper wire end to battery neg. (essentially the same as telling the ECU the engine was warm) Got in the car and started it right up. Later I replaced the "new" temp sensor with a good new one you can also check your by connecting your meter to the sensor lead and ground you should have less than 3000 ohms when cold.

[pilothyer]

3 NOS injectors 1 that was previously on engine running. Resistor pack checks good with key on and using a wire grounded from battery (-) and jumping to ECU pigtail connection 14,15, 32, 33 you can hear each injector click.

Fuel pressure is 29psi.

Fuel rail pressure for L-Jet should be 38 - 40 psi

[timothy_nd28]

Check the resistance on the ECU plug between pin 13 and pin 17. This is the temp sensor.

680F (2k – 3k) Ω
140F (7.5k – 12k) Ω
1760F (250 – 400) Ω

There is Ljet tech data out on the web, and I can't find it anymore. It explained how the ECU on the car would re-act to component failures. In example, a shorted aux air valve, or open aux air valve. It was a total list of every component on a L-jet system in a state of being shorted or open. Has anyone ever seen this?

[Valy]

I would check
1. Does the injector get a pulse?
if yes, check your fuel lines, maybe you reconnected something wrong.
If no, check the ECU connections, especially the ones from the dizzy points and from the AFM

[Tom]

Mike,
Reading over your thread again, it sure sounds to me if the injectors are not getting the signal from the ECU that is needed to fire the injectors. Looking at the prints supplied in your thread, that would be a varying length negative pulse. The injectors have positive to the thru the resistor pack continiously and when ground is supplied, the "fire".You said by grounding the terminals in the ECU one at a time you do get injector action. I wonder if something in your signal to the ECU to fire the injectors is not right. Can you try fooling the ECU by grounding the input to it from the points. Maybe disconnect the petronix terminal at the coil and use a jumper as a temp set of points to see if the ECU will fire the injectors. If it doesn't, then I am at a loss here with L-Jet, but if it does, then you have a direction to look.
Tom

[ClayPerrine]

My suggestion.


There is a white wire in the L-Jet injection harness that is supposed to connect to the negative side of the coil. If you just replaced the points with a pertronix, I would look and make sure that wire is on the negative side of the coil. If it is not, then the injectors never receive a pulse telling them when to fire.