I troubleshooting my L-jet system and the computer smells a bit burned, can someone suggest a good place to send for repair or replacement?

Also, can someone tell me how to test my duel relay switch...

For a rebuilt FI control unit, contact Fuel Injection Corporation, Livermore, CA or Ecklers Automotion, Titusville, FL.

Click to view attachment

What happens when you try to start the motor ?

Engine cranks over, getting spark with no fuel from injectors. Pump is new and runs when air flap opens. Fuel pressure is 35psi.

Thanks

Have you checked that the wires on the resistor pack are intact? They often heal off and cause these symptoms.

The wires look to be well connected. I ohm tested from the center wire to each resistor. I think they were all 6.3-6.5

My CHT sender has no siginal reading at the plug, and at pin 13 on ECU. I ordered a new one from Pelican. Could that shut down the injectors?

I would say no, that should not prevent them from firing. You could always grab a resistor at Radio Shack or Frys for a temporary CHT

If you have the part number from the computer I have a bunch of them I will sell for $75 each.

Are you getting 12volts at pin 10 on the ECU plug?

.......Also, check &-or clean injector grounds...top of motor,rear of engine(prongs)

If your CHT is open (circuit) your L-Jet won't run your engine.

I will check pin 10 when I get home today.

So the injectors wont fire if CHT is Bad?

I cleaned the spade connectors and tested ground. All are good at the block connection.

Part Number is 473 906 021 Let me know if you have one please

I have NO voltage at pin 10. I tested with key on and off...Nothing.
Does this point to something else I can test??
Thanks for the help!

Pin 10 powers on the computer, I'd hold off on obtaining a new ecu till we dig a bit further.

OK I will go to storage tomorrow!

Using L-Jet manual that Jeff provided, it looks like the next to check is the Relays. I replaced all three on the board. No power to 10.
Next is ignition switch. Need voltage at 86c and 88y to ground. I see 86c and 88y on wiring diagram but cant find them on the car. frustrating!

Thanks but don't rush. If I get power to terminal 10, the ECU may turn on. Hell i'm lost.

No Problem!

I have power tp 86c and 88y and 88z all are on the vehicle side. No power to 88a, 88c which are located on the L-jet side.
Of coarse I still have no power to pin 10 on ECU plug.

Any help is appreciated. I'm lost and out of options, short of replacing every part. I am concerned the harness may have a problem...

Bruce gave me your number so I left you a message.

If you have power at pin 88z and 86c, you should also have power at pin 88a and 88b when the ignition switch is turn to the on position.

With the dual relay installed, jump pin 88a or 88b straight to the positive battery post, then check pin 10 on the ECU for power

I just jumped 88a and still no power at pin 10. I'm testing 88b now

ok, no power at pin 10 when I jump 88b to battery positive. same result with ignition on or off.

Just as a sanity test, and to make sure you are using the right pins on the ECU, lets try measuring the resistance from pin 1 on the ECU to the negative side of the ignition coil. You should read 0 ohms

Here's a pic that you may already have
Click to view attachment

ok, checked pin 1 to coil negative, with ignition on and off. my ohm meter reads nothing. Same reading as when the meter is just sitting on the bench in ohm mode.
Is this correct? Looking at diagram, i'm checking the correct pins.

Okay, on the negative side of the coil, you should have a few wires attached to it. One of the wires should be white, do you see this wire? Keep the ignition switch off when doing this test. Go ahead and probe each pin on the ECU plug just to make sure

I do see the white wire on negative coil. Should I disconnect it? or just test from coil neg to each ECU pin? V or ohm's?

Electrically it should be the same, but if you want you can disconnect the white wire and insert a meter lead in the female terminal. We are measuring the resistance to a pin in the ECU connector. You should also verify that you have zero ohms when you touch both meter leads together.

ok i'm on it.

wow this seems random, but I checked twice.

pin 1 =0 ohm
2=12ohm
3=12
4=0
5=0
6=2.1
7,8,9=0
10=1100?
11=1100
12=1100
13=1100
14=12.2
15=13.1
16,17=0
18=.3
19=0
20=43.8
21-26=0
27=1103
28-33=0
34=77.6
35=0

this doesn't look good..

So with a meter lead inserted inside the female connector (white wire pulled off ignition coil) and the other meter lead inserted one at a time, but every pin on the ECU connector, you got these readings?

I left the white wire on the coil and attached the neg side of meter to it, then checked pins with pos meter lead. should I unplug white wire?

yes I need to unhook white wire. i'm on it now

It shouldn't matter. So we haven't infinite resistance from pin 10 at the ECU plug to pin 88a on the dual relay and you have some serious cross talk on pin 1 to every other pin, I think it's time to send your harness to Jeff Bowlsby.

ok, now all pins have 0 ohm resistance, except for pin 18=.4 ohm
this is with white wire unhooked from coil neg.

Something ain't right
PM Jeff to see if he can help with rebuilding or talk with Bruce to see if he has any used ones laying around

thanks so much for all the help!! I'll let you know how it goes.

Very welcome. If the harness was internally shorted like the numbers you showed me, especially pin one to other pins as there can be upward to 700 volts on that wire, I can speculate this taking out the ECU. Which may explain the smokey smell

I replaced harness and still no power to 10.
I think I may have a problem at coil wiring. Coil is new. Should I have 12V when I check across the coil? Also when I check coil neg to battery neg for continuity, it shows open. No ground at coil neg?

Thanks for your help Tim

Also, I do have 12V on the positive side of coil when checked to the battery ground.

At this point, I think you might want to remove the FI wiring harness completely from the car, and start checking that all of the pins connect to what they should--and don't connect to where they shouldn't! You can use a continuity tester or an ohmmeter. Make sure that each wire only connects to one thing in the ECU connector, and that it's the thing in the correct position.

--DD

I believe so. The control module requires input from the head temp sensor. Without it it's "no go".

Not a problem
Coil should have 12volts only when the points within the dizzy are closed. Speaking of which, you should never leave the ignition switch to the "on" position without the engine running. You run the chance of burning up the ignition coil and points.

Back to the basics here. Go ahead and check the resistance on pin one on the ECU plug to the white wire on the negative post on the ignition coil. It should read 0 ohms. After that, check the resistance on pin 13 on the ECU plug to the connector at the temperature sensor. This should also be 0 ohms.

After that, verify you still have 12volts at pins 86c and 88z at the dual relay (with the ignition switch on). If both voltages are present on those 2 pins, check to see if you have 12volts on pins 88a and 88b (you should). If not, put your meter lead on the positive side of the battery, and put the other meter lead on pin 85. This will test the ground on pin 85, it should show a solid 12 volts. If you have voltage there, but not at pin 88a or 88b then you have a bad dual relay.

You can still start the car even with a bad dual relay. By feeding 12volts from the positive side of the battery to pin 88a, you should see 12 volts at pin 10 at the ECU.

Report back with your findings

Thanks Tim,

Here are the results we got.

Pin one to white negative coil wire= No resistance, no continuity.

We can not access the Temp sensor plug at this time.

86c, 88z= Yes 12 volts.

88a, 88b= No voltage.

Pin 85 to battery Positive= 12 volts.

I will order a duel relay tomorrow and report after installing.
Thanks again for all your help!

Larry