Help.. 280ZX FUEL INJECTION ISSUE

[thomas280z]

'80 280ZX

Seems to be flooding real bad. It runs fine when it runs and then just cuts off like its an electrical problem. When I try to restart it, its so flooded, it wont start. I removed the fuel pump relay to prevent it from running, then it will crank eventually. I checked the plugs, they're firing. What I did notice is that the fuel injectors are firing erratically. I can hear them firing when the car is not running and the key is on! I did a search on this site and found an article about the "AFM" not sending the right signal to the ECU. What is thhe AFM? I noticed one thing that might have something to do with the problem. The dropping resistor/sensor for the injectors gets extremely hot. Too hot to touch after just a short period of running. Is this normal? Any help would be appreciated. Also, what tells the ECU when to fire the injectors. Is this triggered off the ICU located on the side of the distributor?

Thanks

Joe

[thomas280z]

Bump, can anyone explain how the Fuel Injection works. With the erractic firing of the injectors, I'm thinking a bad (or going bad) ECU. But I've heard the AFM (Air flow Meter) on these cars has a high failure rate. What are the symptoms of a bad AFM?

Thanks

[Organdonor]

These symptoms points more in the direction of the black box attached to the side of your distributor. I would first test and or replace this part before messing with the AFM.

Also the dropping resistor will get hot in a short period of time.

[thomas280z]

Well I tried that, that wasnt it. You are talking about the ignition module right? The little black box that bolts to the distributor? I did some more troubleshooting. The problem only crops up after it is run awhile and gets hot. When it started messing up, it smelled like raw fuel going out the exhaust. I cut the engine off, actually it died, I pulled the wires going to the injectors, connected a voltmeter, and I was reading 12v with the key on and the engine off. On all the injectors!!! Its just injecting fuel all the time!!! What would cause this?? The ECU?? Help!!

[mdbrandy]

Go to this thread:

http://www.classiczcars.com/forums/showthread.php?p=79140&mode=linear

In the third post, there is a link to the FI manual that might do you some good. Lots of troubleshooting stuff.

Or:

http://www.72hours.net/~zcar/280zfuelinjectionbook.pdf

[thomas280z]

Thanks MDbrandy, the manual was a great help. The manual states that the ECU completes the ground for the injectors, thus firing them. And seeing that the injectors are firing eractically, I suspected the ECU is malfunctioning. After replacing it, problem fixed. And Organdonor, I appreciate the attempt to help but your advice was way off. First, according the manual, the ICM that you suggested was the culprit, has nothing to do with the firing of the injectors. The firing of the injectors is triggered from the negative side of the coil. And also the dropping resistor does not normally get that hot as you suggested. Its was overheating in my situation because the ECU was grounding the injectors all the time, thus causing the flooding and the overheating of the resistor. Dont get me wrong, but offering no advice is better that offering bad advice.

[rcperez123]

I like the way you think,try this one.I have a 75 260z fuel inj but am not getting power to the fuel pump,I have spark but no power to pump.Also you mentioned that the Dist sends a signal from the neg side,what wire do you have coming out of the neg of the Dist. a photo will help.Thank if you can help!