I have a '75 1.8L L-Jet that has sat for a while. Its my parts car, but I'm trying to get it running now.

When I got it, the fellow told me the double relay was bad, so I replaced that. Fuel lines were also totally gummed at the tank, so those have been changed, tank cleaned and fuel filter replaced. I also had the fuel injectors tested and cleanded. I had also found a shredded "stray" wire, which turned out to be the engine temp sensor (under the engine sheet metal), which was replaced.

The car will "fire" when I spray starting fluid in the intake. I don't have a pressure guage, but the pressure is sufficient to blow an improperly clamped fuel line off the fuel rail (I had an injector out, and some fuel must've sprayed into the hole, causing a "sputtering" near-start). I pulled the injectors to see if they were spraying, and they are not.

When I manipulate the AFM flap, I can hear both the fuel pump as well as a "hissing" sound from the pressure regulator (but can not see any leaks).

Troubleshooting these type issues is not my strength so any help/advice on where I need to look next would be greatly appreciated.

Double check the connections on the resistor pack. It should be a silver piece located next to the double relay. The connections often become brittle and break off.

I had 3 out of 4 wires break on the resistor pack. Check it

Thanks, guys...I have been wondering about that piece, as the plastic plug is badly corroded from battery acid, but it appears that the spades are still making good contact - I'll give them a closer look and try cleaning them up a bit more.

[quote name='wrightee' date='Sep 2 2012, 02:42 PM' post='1732801']
[quote name='jsayre914' post='1732799' date='Sep 2 2012, 02:36 PM']


I had 3 out of 4 wires break on the resistor pack. Check it
[/quote]

Resister connections are all solid - like I said before, the plastic plug is pretty ugly due to battery acid corrosion, but all of the spades make solid connections and all wires are intact.

you should be looking where the wires are solderd to the tubes inside the metal housing, this is where they snap off. not at the wire connections

heres an example

Wires are all connected - though I can see two that are beginning to "wear", but are still 80% intact (a few strands on the side are broken, but not enough to keep the current from flowing).

While I don't believe this is the source of the non-start issue, I will put this on the list to replace due to the wear...anyone have any idea if the harness side plugs are available anywhere?

Okay, reconnect everything that you had removed. Let's start at the beginning.

Now pull the main ECU/brain connector off. We will test these injectors manually, without pulling them or having a noid light. With this massive connector off of the brain, obtain a small length of wire. Ground one side of this wire to either chassis ground or the negative post on the battery.
Locate at the ECU connector pins 14,32,33 and 15. With the ignition switch to the "key on" position, go ahead and ground pin 14. You should hear a click from one of the injectors. After you verified an audible click, go ahead and ground pin 32 and listen for the same results. Do the same procedure for pin 33 and 15. These are your 4 fuel injectors. If you have audible clicks on each injector, it proves that your resistor pack is working, and part of your dual relay.

When performing this test, be sure to not leave your ignition switch to the "on" position for very long. You will damage your points or coil.

Click to view attachment

Thanks Tim,

I did not hear any clicks after testing at each of these pins.

I'll let the pro handle this...Tim_nd helped me out a while back. He knows his L-jet!

Good luck!

Check pin 88z at the dual relay, you should have 12vdc hot at all times, doesn't matter if your key is on or off. For this test, you can go ahead and disconnect the relay from the connector, or you can slightly pull the connector away from the relay so that you can try to sneak a meter lead to 88z.

If you have 12vdc present, then check pin 88b with the ignition switch to the "on" position (relay must be inserted) . If you have 12vdc present on pin 88b, you should also have 12vdc present on pin 10 on the main ECU connector.

Ok, those all check out - 88z has power w/o key in, 88b good with key at "on" and power at pin 10 on the ECU as well.

Excellent, I think we are homing into the problem area. With the key "on" check the common pin on the resistor pack. I believe it's the top middle pin. Leave the the resistor pack plugged in. The common pin will have one wire running back towards the ass end of the resistor pack. This pin should have 12vdc present, as this is the same wire of 88b on the relay connector you tested earlier.

If there is 12vdc present on the common pin on the resistor pack, go ahead and measure voltages on every other pin on that resistor pack connector (resistor pack still connected)

I'm getting 12vdc on all 5 pins.

Do you have the white wire connected to the coil (-) terminal?

--DD

Okay, measure the voltages on the ECU connector at pins: 14 to gnd, 15 to gnd, 32 to gnd, and 33 to gnd.

Yes, white wire is on neg side. This car has a "CompuFire" ignition in place of points.

14 = .03
15 = 0 (nothing)
32 = 12vdc
33 = .03

BTW, I really appreciate you taking the time to walk me through this.

No prob,,all of those pins should have 12vdc. I've made a couple of assumptions here, so don't get offended. Are all the fuel injector connectors plugged onto each injector? We know one is plugged in, and making continuity,,this is why your measuring 12vdc at the ECU connector.

With the one pin on the ECU connector reading 12vdc on the previous test,,if you apply ground on that pin, do you hear a click?

I would suggest pulling off each injector lead, then re-seating each connector with a slight wiggle, to ensure a good electrical connection. Then retest those pins at the ECU plug to see if you have any more 12vdc pins. If you have the same results, (one out of 4 has 12vdc),,then pull off each injector lead and probe one of the 2 contacts. With the ECU plug still unattached,,,one contact will measure nothing (at the fuel injector connector) the other should be reading 12vdc.

Do this for each fuel injector connector, keeping in mind that one contact will read 0, and the other will read 12vdc.

Okay, thanks - I'll have to run through this tomorrow and I'll post what I find then.

Thanks again, Ed

Needless to say, the wire harness and some of the plugs are in poor/marginal condition.

After fiddling a little more, I did get voltage to read on pin 33, so both 32 and 33 show voltage at the ECU plug (cylinders 2 and 4).

I got a good voltage reading at the plug for cylinder 3, but still no reading at pin 15 after reconnecting, and only a very marginal reading (about .6 to .8 volt) at the cylinder 1 plug.

I can not hear any discernable click at the injectors when I ground pins 32 or 33 as well. I stuck my head down in to listen better, as I do have a buzzer sounding with the ignition "on" since taking out the center console and unplugging those gauges.

Take off the 4 injector leads, and prepare 4 cups of Coke. Set the injector lead into each cup for about 45 mins.

Correction: Full voltage at #3 injector plug, but only about 7 volts at ECU pin 15 after reconnecting.

Pin 33 and 32 looks like injector 1 and 4. So if your getting voltage at the ECU connector at these pins, and you apply ground to these pins, you'll be able to fire them. I understand the inability to hear this in a noisy environment. You can remove injector 1 and 4 from the intake, and visually look for spray mist.

After the Coke dip for each injector connector, spray them down with ether or something, to remove the residue.

Correction, I may have read the schematic wrong. What you stated earlier about the injectors for what cylinders that corresponds with pin 33 and 32 maybe correct.

I'm going off a good diagram I found on Jeff Bowlsby's site with a hand-drawn schematic of the L-Jet wiring.

Click to view attachment

Also, I found this unused (green) wire, but I was guessing it was from the condensor that was pulled out for the CompuFire ignition

Nevermind that green wire, this wire isn't causing your car not to start. It goes to your oil pressure switch.

It looks like his pressure switch is already connected so the green wire would be something else.

It actually came FROM the coil and went no where

As I started digging around in the wire looms, I realized that someone has done some major surgery on the harness (cuts and splices all over). Since I have some broken connectors and a harness with questionable integrity, I decided its time to use the spare harness I had been saving to put in after my rebuild.

I'm replacing it now and will see how things look after that.

after installing this wiring harness, recheck those pins on the ECU plug that I mentioned earlier. You should have 12vdc on each of them.

OK - harness is in and I now have 12vdc at all ECU Pins

start it up, it should run

No luck. Seems like I still have fuel delivery issues. Found one hose to an injector that was clogged with new sludge (must have moved here from when I replaced the lines on the tank side).

Guess I need to check fuel pressure next? Is it normal to hear the pressure regulator make a sort of hissing sound when you move the AFM flap?

Remove the distributor. Hook an ground wire from the distributor to the engine. Spin the distributor with the key on. The injectors should click. If you can't hear them, put a automotive stethoscope on each injector.

Another alternative is to get a noid light and test the injector leads.



It is plugged in to the injector leads. If the light flickers, your injector circuit is fine.

They are available at your FLAPS.

Thanks Clay - I had seen these on ebay before, but never made the purchase. I'll try this later in the week. When you say ground the distributor, is there a particular place that this needs to hook to, or just connect a wire to the distributor body and then engine?

Just a wire between the distributor and the engine is fine. Normally the distributor would ground through its body, but when you have it out, it can't.

He stated in a PM that his fuel injector last chance filters were now plugged with old rubber bits/sludge. I'm thinking since he replaced his FI harness, that the injectors are actually firing now. However, the fuel injectors are now plugged with debris.
After he flushes out the lines, and re-cleans these injectors, it should fire up.

Following tim_nd's expert advice, I've narrowed this non-start problem down to seized injectors. I get a "click" from one, but the other three don't click. All show the same resistance, so I'm hoping that a good fuel injector cleaning/rebuild service may free up the stuck ones. Anyone have any recommendations on where to send them?

Also, I found this link that indicates most L-Jetronic injectors (from VWs) are interchangeable with mine, though the numbers on mine don't match up with this chart. The Porsche # is 0 280 150 102 and the VW # is 022 096 031C. Any of you L-Jet folks use any of these other injectors? (in case my bad ones can't be fixed)

http://www.ratwell.com/technical/Injectors.html

I had great luck with witchhunter.com in the past. They have great turn around time, and they give you a print out full of data on each injector.

Find a 1980s vintage Datsun/Nissan. They use a Nippondenso built licensed copy of the Bosch L-Jet. The injectors are interchangeable with the 914 L-Jet injectors, and you can get them at any FLAPS. My lookup found these: 1984 Nissan 200SX injectors.

52.99 each, brand new.

Update...had the injectors refurbished at MrInjector.us (good price and great service). All had shown good electric resistance, but no "click". Testing confirmed they were siezed/gummed inside, but they came back working after cleaning. Put them back in, and after a few cranks she started!

Thanks again to tim_nd who has provided a great deal of technical help to get another L-jet running!

Now, I just need to get it running well! ...and then fix the rust

now only about a month to work on it to get it ready to go to the ECC

Been wanting to attend this, so I can meet some other local folks afflicted with this "hobby"... but, unfortunately, I have a schedule conflict that weekend.