L-Jet issues, Injectors not injecting Options

[echocanyons]

Hello,

I have a 75 1.8 with L-jet, it seemed to be running fine aside from a possible bit of a hard cold start.

I was driving it and suddenly the engine died, I looked in the engine compartment and the negative battery cable had popped off.

It has getting good spark.

The injectors do not pulse at all and can't seem to figure out the root cause of the problem.

I have tested the dual relay and have installed a new resistor pack, thinking that this was the issue, but still no luck.

I do know the fuel pump is working (I did not test the pressure) the AFM seems to be functioning.

The white wire connected on the same side as the condenser on the coil.

Could the battery cable thing have toasted the ECU?

How exactly do the injectors get the signal to fire? They are all batch fire right?

Are the injectors pressure driven in as much as they will not fire if there is not enough pressure or will they drip fuel?

I don't remember but do the injectors "click" when the recieve the electrical signal to fire?

(IMG:style_emoticons/default/confused24.gif)

[echocanyons]

If the injectors are fired by the breaker points (as stated in the factory manuals), does this mean if my points were fried that the injectors would not pulse? (IMG:style_emoticons/default/idea.gif)

[underthetire]

You are correct, batch fire. Injector points will cause this problem. If you have an old analog meter, you can see the injector pulse. A digital meter is not fast nough to pick it up. I use a old Simpson 260, or my Fluke scopemeter. The ECU will control duration. Check on Brads website, he has the best FI troubleshooting guide available.

[IronHillRestorations]

If it has the original AFC injection, there are no injector points.

I don't know the L Jet really well. IIRC this could be the resistor pack.

[echocanyons]

Yes its L-jet, stock so no injector points. I was thinking along the lines of the distributor points because that, as I understand it, is where the signal for the injector pulse originates from.

The resistor pack was replaced with a new one while troubleshooting and still didn't fix it, I considered the resistor pack and the dual relay first and now have pretty much excluded them.

[Dave_Darling]

That white wire that hooks up to the (-) terminal on the coil carries the ignition points signal to the FI system and tells it when to open the injectors. All four open at the same time, in fact.

My first thought would be that the white wire is unplugged, but you said it's plugged in. I would check for other wires that are unplugged as well, particularly grounds, the air flow meter, etc. I would also think about what could have gotten knocked loose when the battery became disconnected or what else could have happened at that point--such as, what did you touch when you put everything back together?

--DD

[ClayPerrine]

There is an additional power wire that comes from the positive battery post to the double relay. If it is broken, the injectors won't fire. Also the fuel pump won't work if the wire is broken.

Do this.. open the air flow meter with the key on. Does the pump run???


If not, you have a relay or power feed problem With your mentioning the battery cable, you probably broke that power feed wire.

[echocanyons]

I examined all of the wires and connections and didn't see anything that looked worrisome.

I tested the fuel pump by moving the AFM and the fuel pump is turning on.

I'll have to check the power wire that attaches to the dual relay.

Unfortunately the car is ~200miles away from home now so I can't do much until I get it home.

[r_towle]

Check wire going from the positive side of the battery to the dual relay that controls the injectors and the fuel pump.

Check the middle pole on the multi resistor pack...right next to the dual relay. see of that pole has power.

Check that the white wire is in fact producing 12vdc in time with the points...its a batch fired system...

Rich

[echocanyons]

Check wire going from the positive side of the battery to the dual relay that controls the injectors and the fuel pump.

Check the middle pole on the multi resistor pack...right next to the dual relay. see of that pole has power.

Check that the white wire is in fact producing 12vdc in time with the points...its a batch fired system...

Will do, I think I have a good basis to start.

I will post my findings

[echocanyons]

So after testing a few more things I nailed down the problem to the ECU, thanks to some great members here, BTW thanks a ton treemn and ZX-niner, I was able to get an extra and some spare parts.

I plugged it in and it fired right up.

My guess is that it was getting ready to croak for a while as there is no more having to let it crank for a while before it starts, it fires basically on the first time.

I understand that these things are pretty robust and don't usually go bad but in this case it did, so if all else fails L-jet owners, check your ECU.

A big thanks to McMark too for going out of his way to help me.

[echocanyons]

So I dissected the bad ECU to try and pin down the exact point of failure.


There is nothing apparent that I could see, no real signs of water damage or burned circuits.

I really don't have the equipment, know-how to test the whole thing.

[echocanyons]

on second thought is this corrosion on the left side of this picture? Could this be the issue?

[sean_v8_914]

looks like old solder flux to me

[zx-niner]

Glad to hear my old ECU worked after sitting for a number of years. I know the L-Jet system catches flack but I've always been happy with the way it runs when you get it sorted.

[jim_hoyland]

Here's a L-Jet test: http://manuals.type4.org/ljet/components/ljet10.htm

Looks pretty organized

[mightyohm]

My guess is that the battery cable falling off caused the charging system to go open loop, sending the system voltage through the roof. The high voltage fried something inside the ECU. The damage probably won't be visible.

I should go into the ECU repair business. (IMG:style_emoticons/default/biggrin.gif)