BlakesZX

Alright so my car wont start at all. Battery is fully charged, were getting spark to all of the spark plugs and the distributor is working properly. I took all 6 plugs out and turned the engine over, cylinder 6 is gushing fuel, way more than it should in my opinion and all the others are not doing this, seems like they are shooting very little/misting which may be correct, another problem is when i take off the power to the injector for cylinder 6, the 2 leads too it are both positive, this was the same for the cylinder 5, did not check the rest. Is this normal? Also when i check with my meter im getting 12 volts on both leads on the injector with the car completely off and the key out? why is it getting power?

Any ideas? im completely lost and going in circles

FricFrac

The 280ZX has batch fire as in three injectors are in parallel with each other. When you disconnect one you still have two hooked up in parallel and your unplugged connector is looking at the other side of the other two injectors. The injector coil is just that - a coil of wire. A coil of wire is the same as the piece of wire that goes to the positive side of the battery. If you go from the positive side of the battery to one side of the injector connnector then through the coil (which is basically a piece of wire coiled up) out the other side of the connector and down the wire right to the ECU you'll see +12V there as well. The ECU turns ground on and completes the circuit firing the three parallel injectors. Disconnect all the injector plugs and measure both sides of your connector and tell us what it reads

You can test fire your injectors simply buy ground the other side of the injector but beware if it's in the car and there is presurized fuel in it it will squirt it out!

BlakesZX

ok ill run out and check these, do you have any idea why cylinder 6 is throwing so much fuel and the others are not?

FricFrac

Maybe 6 is fine and the rest are plugged.... does #6 dribble when it's off?

FricFrac

You can take the injectors out. If you check in the FSM I think it tells you to run the car and pull the plug on the fuel pump to depressurize the system first. Once the injectors are disconnected from the fuel rail and intake plenum you can back flush them with carb cleaner. You'll need to open them though to get the carb cleaner to flow through them. To open them you can use a 9V battery to turn them on. They aren't designed to be open all the time so only have it on as long as you need it to back flush. You should put a current limiting resistor in series with the battery - around 12 or so ohms which will draw about 1 amp if you are using a car battery to activate the coil. I think a 9V battery will probably limit it's own current because it can only put out so much. I've heard guys doing that before but I haven't tried it myself. If you do decide to experiment make sure the injector doesn't get hot.

You'll have to figure out hot to attach the nozzle of the car cleaner spray can to the nozzle of the injector. Personally I'd use some heat shrink with a meltable inner jacket but duct tape or something might work but the glue will probably break down pretty quick with the carb cleaner. That's OK though you don't need it on for long - just enough to back flush the injector. Once you back flush it if you can get the filter out take that out. If you have an ultrasonic cleaner that's a great way to clean them. If not let them soak in carb cleaner overnight them back flush them the next day and put the filter back in then dry them out and re-install.

BlakesZX

Ok i went out and every injector connector has 12-13v/side. With the exception of cylinder 1 which reads 12v and .1v Also on cylinder 4, with one 8v and the other lead reading 12v. The car ran this morning fine and I've been chasing an intermittent "no-start" problem which was originally a "hot no-start" problem. It has evolved into a complete no start! Of course I have to ask, Is this normal to have voltage even when the car is off and key is out?

BlakesZX

FricFrac.....I have alittle more info on my ignition issue. It DID run a couple of days ago. I took all the plugs out and connected them to the wires. As I cranked it over, I had plenty of spark on all plugs, I could see what I thought was an excess amount of fuel coming out of cylinder 6, and once everything was connected and back in place the car will not even pop off with starting fluid! Does this suggest the ICM and the ECU are good? If I'm getting fire on the plugs, what could cause it to not start? I want to try everythinmg before I pull the injectors. I want to think it's an electronic type issue more than a case of fuel since it ran one minute and not the next.

BlakesZX

ALRIGHTY....it's been a couple of weeks but SUCCESS! I followed your advice Fric and backflushed all my injectors after removing them from the engine. I used the 9v battery with alligator clips. The injectors never got hot but they did flow carb cleaner backwards like you siad. I didn't remove the screens but I did go ahead and put a new fuel filter in. I installed everything back in. I DID replace a couple other things, The TPS needed to be replaced causs the plastic insert for the shaft on the backside had cracked and broke from being brittle. I set it by the FSM by locking it down when the gage went to infinity. I also put a spare MAF in. I DID reset the old MAF by the post addressing the carbon track and adjusting the plate. OK, with all that being said, it did take awhile to fire off since the fuel system was bone dry and a new filter was added. I hit it with ether and it finally fired up!

My only problem now that DID NOT exist before is the suge i get at 1500rpm. There is a very slight miss at idle but once it's warmed up and I idle up to 1500, it wants to surge to 2000 and drop back to 1500. It just does it continuously until I rev it out to 3-4k and let it back down. SOmetimes it starts surging again and sometimes it doesn't The car won't surge at any other rpm.

Any thoughts???

FricFrac

Sorry but I missed your replies for some reason. You figured it out though. I'd look at the AFM (not MAF) again if you have a dead spot somewhere in the carbon track as well as the vacuum lines. The really should all be replaced if you haven't done that already....

BlakesZX

I have another AFM I can try and the hoses aren't very snug on their fittings. I'm gonna do those for sure. I'll get back to you but I'm glad I did pull all the injectors to clean them. The stuck one dumped enough fuel in that cylinder to fill up the crankcase and pour out the dipstick tube!!! I've changed it already and glad I caught that. The oil is clean and clear again!