Starts but won't run

[BradF]

Have an 82 2000 that hasn't run in years. New tank, pump and filter with fresh fuel. Engine will start but only runs a second or two. Any suggestions on how to proceed next would be appreciated. Also, is the fuel pump supposed to run constantly. I'm used to a pump running for a few seconds when you turn the key to "run", then stops until you turn to "start".

[GeorgeT]

Sounds as if it's starting on the "cold start" injector and the others aren't firing. Check that you have power to the injectors, also the injectors may be stuck after sitting so long and need to be cleaned. The fuel pump should only run when the air flow meter flap moves but many owners rewired them to start running as soon as the key is in the "run" and "start positions.


You should get the Fuel Injection manual available on-line.

[BradF]

Thanks for your reply on this. I read over Brad Artigue's fuel injection guide and have gotten to the following:
1. There is no power going to the fuel injectors
2. The fuel pump runs with the ignition in "run" and "start".
3. The pump runs with the double relay, the AFM and the ECU disconnected.
You mentioned that owners would wire the pump to work that way. Is there a common way that is done?
4. Is there any thing to check that would prevent power going to the injectors besides a bad ECU?

[RRoller123]

There are 2 ground wires that are attached to the mounting bolts of the air plenum, driver's side. If they are not properly grounded, the injectors won't fire. You can see them, one at the corner, and the other at the next bolt forward, in this photo.

[BradF]

Thanks for the tip. I checked the grounds, they're good. I unplugged an injector and neither a meter or a noid light show power going to the injectors. The cold start injector is working. Does anyone know if any of the components connected to the ECU keep the injectors off?

[RRoller123]

Interesting that the CSI fires but not the 4 injectors. I would guess a couple of things (GUESS I said.... ) I am guessing that the CSI fires based upon the TTS, explaining why it fires but not the 4 injectors, so it may be that the AFM is not sending the proper signal, maybe connector bad, internals, whatever.

You might measure the injector signals back at the ECU, that would let you know if it is a break in the wiring somewhere downstream. Also might isolate the problem to the ECU.

Also check the TPS at the throttle plate. It should be adjusted such that you can hear it click just as the throttle is opened. It tells the ECU to shut down the injectors when the throttle is closed. (To prevent backfiring, such as might happen when suddenly pulling off of the throttle while up at highway speed, for example). If it isn't right, the Injectors might be permanently closed?

Here are some Bosch L-Jetronics references online: (I personally think the best one is the last one)

FUEL INJECTION DEBUGGING
http://www.hiperformancestore.com/Ljetronic.htm
http://www.njfiats.org/joomla/images/st ... BoschL.pdf

FUEL INJECTOR CLEANING:
http://WWW.OKINJECTORS.COM
http://www.witchhunter.com

FUEL INJECTION MANUAL
http://www.mirafiori.com/faq/fiatFI_may2002.pdf

FUEL INJECTORS CHART
http://users.erols.com/srweiss/tableifc.htm

L-JETRONIC MANUAL
http://www.hiperformancestore.com/Ljetronic.htm

L-JETRONIC
http://mastertechmag.com/pdf/1988/11nov ... ronic2.pdf
http://jenniskens.livedsl.nl/Technical/ ... tronic.pdf

L-JETRONIC FI MANUAL (FROM VW)
https://www.type4.org/manuals/ljet/index.html

BOSCH L-JETRONIC MANUAL – BEST ONE:
http://foxed.ca/rx7manual/manuals/BOSCH ... Manual.pdf

http://dtec.net.au/Tech%20Articles.htm

[BradF]

Thank you! I'll go over all this and post back with the results...

[76was124]

Manuals, as RRoller said, will get you there.

As I recall, the injectors are fired when the ecu pulls one side of the coils to ground. Even though there are separate wires and terminals on the ecu for each injector, the ground switching terminals on the ecu are all tied together on the ecu circuit board so it fires all injectors in unison. They don't sequence per cylinder.

Also I would strongly discourage any wiring changes to keep the fuel pump running when the key switch is on. Major safety risk if you are in an accident and the fuel pump keeps running.

[BradF]

My concern exactly with the pump running like this. It should only work when the AFM senses air flow so will need to correct this.
Seems odd the injectors all open at the same time. Why would you want to supply fuel to a cylinder that's not firing? Looks like I'll be chasing wire this weekend

[RRoller123]

One can just install an inertial shutoff switch (resettable) on the fuel pump power line. I got mine at Ford, and the connector at a local junkyard. The Ford parts manager said the sensors are all the same, so there is no variation for car mass. Wire it in line to the pump power feed, which is under the rear seat in my car. Bolted the sensor vertically to the rear wall.

So why do this? Well, I think ironically that it is probably safer than the original design. Modern sensor, very selective, reliable, resettable and sensitive, for one. Certainly more reliable than relying upon a 40-50 year old dual relay to run the pump.... Then there is the very real possibility that one could have an accident with fuel leak where the engine keeps running, and fuel will keep pumping......

Also, I like to hear the fuel pump spin up before the noise of starting kicks in. One can thus monitor the pump noise by itself, which aids in diagnosing issues, or observing imminent pump failure. Gives a second or two for the pressure to build and settle. There are a few inevitable air bubbles that work into the system, and you can hear the pump pass those in about 1-2 seconds and stabilize. Then there is slightly faster starting, not waiting for engine rotation to pull open the AFM flap and activate the pump. Plus there is always a risk when starting to fool around with existing (non-original but working) wiring that works fine and has worked fine for years. Anyway, that is my thought on all of this.

[NGK]

I have the same Problem my dad and I think it might be the computer is bad if you find out what your problem is let me know.

[BradF]

[quote="RRoller123"]One can just install an inertial shutoff switch (resettable) on the fuel pump power line. I got mine at Ford, and the connector at a local junkyard. The Ford parts manager said the sensors are all the same, so there is no variation for car mass. Wire it in line to the pump power feed, which is under the rear seat in my car. Bolted the sensor vertically to the rear wall.

So why do this? Well, I think ironically that it is probably safer than the original design. Modern sensor, very selective, reliable, resettable and sensitive, for one. Certainly more reliable than relying upon a 40-50 year old dual relay to run the pump.... Then there is the very real possibility that one could have an accident with fuel leak where the engine keeps running, and fuel will keep pumping......

This is a great idea! I certainly don't have any qualms about using parts that greatly improve the safety and operation of the car. I'll be using this tip for sure...and getting the injectors working.

[BradF]

I'll be posting results, for sure. Good luck with your project

[RRoller123]

There is also another thing to consider..... these AFM flaps are notorious for sticking. They could (possibly) stick open and allow the pump to keep running, certainly possible in an accident situation. I like the inertial shutoff switch/sensor, wired right at the pump power supply. And the sensor mounted on a vertical, rigid surface right near the pump. I think it is the best solution overall. But this is just my opinion. The forum has a tremendous wealth of knowledge, experience, and opinions here, that is the beauty of it. We read and consider it all and reach our own conclusions and make our own decisions.

Pete

[76was124]

Seems odd the injectors all open at the same time. Why would you want to supply fuel to a cylinder that's not firing? Looks like I'll be chasing wire this weekend

Simpler design, given the fuel is injected into the intake manifold vs directly in the cylinder, it all goes to the same cylinder that draws in air/fuel for for the next combustion. It doesn't go to any other cylinder as those intake valves are closed due to cam position. So then why four injectors vs one? I am guessing, but the fuel volume through four injectors atomizing mixes better and faster than same volume through one injector.