94 FD cuts off
07-13-22, 04:39 PM
#1
Junior Member
Thread Starter
94 FD cuts off
Please lmk if there is a better forum to post this question. I have a stock 94 that had the intake completely apart. Pulled it from a shop that was trying to gouge the hell out of me. Car was sitting over 10 years. Drained the gas tank and cleaned it out pretty good. Also replaced the fuel pump and fuel filter, plugs etc. Car starts up for a few seconds and dies. If we spray ether it will run all day but as soon as we stop the ether it dies a few seconds later. With ether, I can give it gas and the RPMs go up as normal. Has anyone seen this? Anything I should be checking or may have missed? I should add that the compression is very good and when we take the spark plugs out after they r not wet, so it seems to be a fuel delivery issue.
One other minor issue, there is a black wire that comes off the AC compressor with a thin white line on it. Not sure where this wire ends up. It went directly into the harness before but no idea where it ends up. Any help? Again, if I should be posting this somewhere else, my apologies and I'll be happy to post in the correct spot.
Thanks
One other minor issue, there is a black wire that comes off the AC compressor with a thin white line on it. Not sure where this wire ends up. It went directly into the harness before but no idea where it ends up. Any help? Again, if I should be posting this somewhere else, my apologies and I'll be happy to post in the correct spot.
Thanks
Last edited by krid23; 07-13-22 at 07:04 PM. Reason: Left out info.
07-14-22, 08:53 AM
#2
RX-7 Bad Ass
iTrader: (55)
You're in a good spot for this 
.
If the car runs on the ether it sounds like the fuel pump isn't running. There is a DIAG terminal under the hood on the driver's side shock tower, open that up and jumper F/P and GND with a jumper wire. Turn the key to On and the fuel pump should continuously run. You may want to see if it will start and run like this, if so it could be something with the fuel pump relay.
Also possible something is wrong with the fuel pump install itself. Did you put in a stock fuel pump?
Dale
.If the car runs on the ether it sounds like the fuel pump isn't running. There is a DIAG terminal under the hood on the driver's side shock tower, open that up and jumper F/P and GND with a jumper wire. Turn the key to On and the fuel pump should continuously run. You may want to see if it will start and run like this, if so it could be something with the fuel pump relay.
Also possible something is wrong with the fuel pump install itself. Did you put in a stock fuel pump?
Dale
07-15-22, 07:16 AM
#4
Junior Member
Thread Starter
Update: checked the fuel pressure and it's good. Looks like the injectors are not getting the pulse signal like they are supposed to. Need to figure out if it's the ECU or something else. Anything else to check?
07-15-22, 08:54 AM
#5
RX-7 Bad Ass
iTrader: (55)
If it has sat for a long time it's possible the injectors are locked up. First I would be 100% certain you have the fuel lines hooked up right, you will have SUPER weird problems if the lines are backwards (feed/return).
That said, it's a BIG JOB to get down to the injectors. They are buried under a mountain of brittle wiring and plastic. This is going to take some time to do right, and if you document and label you'll be just fine. Take pictures, make labels for stuff you unplug with tape, be careful and take your time.
The primary injectors are deepest in there, they are bolted to the center iron of the engine. They are the ones that are for idle and low RPM. The secondary injectors are in the bigger fuel rail that is bolted to the lower intake manifold, they kick in around 3000-4000 RPM and go to redline.
It's possible the plastic injector connectors will be SUPER brittle and will come apart. If so, you can buy new "shells" and pop the pins into the new plastic shell to fix the problem.
I would try and get both fuel rails out. If at all possible do NOT cut the fuel lines, Mazda used very high quality fuel lines and it is expensive stuff. Move the clamp back, spray WD-40 on the end of the hose, use hose pliers to twist the hose and work it back off the metal pipe.
You may be able to unbolt the rat's nest of solenoids and vacuum lines from the engine and pull it up a bit to get clearance. Remember you aren't trying to take EVERYTHING apart, just enough to get in there.
Once the fuel rails are out, leave the injectors in the rails and squirt some PB Blaster on the tips of the injectors. Get some jumper wires and hook 12v and ground to the 2 pins on each injector, using wires that have alligator clips is perfect for this. Tap the connection to the battery to give it full pulses over and over again, you should hopefully see the injector free up and move with an audible click. If so get some more PB Blaster in there and do it some more. Do this for all the injectors.
Removing the injectors from the rail is difficult, I've never found a clean way to do it. If you can get them moving then you are good. Once the car is running you will want to run some fuel injector treatment through the tank and help clean them up further. You could send the injectors out for professional cleaning/service but I don't know if that will get you much more than you can do on your own.
Dale
That said, it's a BIG JOB to get down to the injectors. They are buried under a mountain of brittle wiring and plastic. This is going to take some time to do right, and if you document and label you'll be just fine. Take pictures, make labels for stuff you unplug with tape, be careful and take your time.
The primary injectors are deepest in there, they are bolted to the center iron of the engine. They are the ones that are for idle and low RPM. The secondary injectors are in the bigger fuel rail that is bolted to the lower intake manifold, they kick in around 3000-4000 RPM and go to redline.
It's possible the plastic injector connectors will be SUPER brittle and will come apart. If so, you can buy new "shells" and pop the pins into the new plastic shell to fix the problem.
I would try and get both fuel rails out. If at all possible do NOT cut the fuel lines, Mazda used very high quality fuel lines and it is expensive stuff. Move the clamp back, spray WD-40 on the end of the hose, use hose pliers to twist the hose and work it back off the metal pipe.
You may be able to unbolt the rat's nest of solenoids and vacuum lines from the engine and pull it up a bit to get clearance. Remember you aren't trying to take EVERYTHING apart, just enough to get in there.
Once the fuel rails are out, leave the injectors in the rails and squirt some PB Blaster on the tips of the injectors. Get some jumper wires and hook 12v and ground to the 2 pins on each injector, using wires that have alligator clips is perfect for this. Tap the connection to the battery to give it full pulses over and over again, you should hopefully see the injector free up and move with an audible click. If so get some more PB Blaster in there and do it some more. Do this for all the injectors.
Removing the injectors from the rail is difficult, I've never found a clean way to do it. If you can get them moving then you are good. Once the car is running you will want to run some fuel injector treatment through the tank and help clean them up further. You could send the injectors out for professional cleaning/service but I don't know if that will get you much more than you can do on your own.
Dale
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