What powers the injectors?

surfdogskier · 09-27-2019, 03:14 PM

I have spark. I have gas. Gas is flowing. But my injectors are not shooting. They are new but I have not checked voltage. She ran great there for the last couple weeks in the neighborhood. I do not see any fuses blown. Need a little help.....Thanks!

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Your sig says 72, so I will assume your car has D-jetronic FI.

The D-jet injectors are always grounded at the multiple ground point on the crankcase seam on top of the motor near the flywheel end. Power is supplied by the ECU when the ECU is telling the injector to open, and turned off when the ECU is telling the injector to close. (L-jet is the opposite, as are most modern systems.)

In the stock setup, the D-jet ECU is what tells the fuel pump to run. So if the pump does pump, the ECU is actually working. That's good news. (Listen for the ~1.5 second "buzz" from the pump when you turn the key from "off" to "on".)

If the injectors are never opening at all, then look for unplugged wires. There are several that can cause that, from the aforementioned grounds to the MPS plug to the injector trigger points in the front of the distributor.

--DD

dr914 · 09-28-2019, 10:58 AM

use a noid light to see if all four injector leads are providing a signal, and if not then look at the ground leads on the back of the block as Dave suggested, make sure the trigger points are plugged in as well as the air pressure sensor

surfdogskier · 09-30-2019, 03:37 PM

I took out one of my injectors and it is not spraying. I dont have a noid light but I am going to get one. I do have fuel and my fuel pump is running. I do have spark. Just not supplying through the injectors.

I had her running fine last week but now this. I cant see any lose connections. Driving me nuts!

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Stop and look for wires that are unplugged. Particularly white wires. Double check all of the connections in the engine bay where white wires plug into something. You may have a connection that looks OK but isn't making good contact.

The three top suspects: The ground, the manifold pressure sensor, the FI trigger points. At least check those three.

--DD

surfdogskier · 10-01-2019, 10:32 AM

Quote:

Originally Posted by Dave at Pelican Parts

Stop and look for wires that are unplugged. Particularly white wires. Double check all of the connections in the engine bay where white wires plug into something. You may have a connection that looks OK but isn't making good contact.

The three top suspects: The ground, the manifold pressure sensor, the FI trigger points. At least check those three.

--DD

Dave, once again, you Da Man! Evidently one of the white wires I pulled and repinned wasnt making good contact. She cranked right up after doing what you said. Now I am going to clean them off real good with some degreaser.

Again, Thanks for your help...Jason

surfdogskier · 04:20 PM

Oh my gosh!!!! She is back to doing this same thing all over again. No power to the injectors. She ran fine one evening, parked her. Next day she would not start. I got spark. I got gas in the lines. Fuel pump works like it should. I took the distributor out and cleaned the trigger points to see if that would help. All wires are connected. MPS connected. All vacuum lines connected. I bought a noid light set up and they are definitely not getting power.

What else could it be? Something on the relay board? Bad relay?

This car is driving me insane. I am about to go duel carbs and drop this piece of **** fuel injection if I can't get this thing running.

dr914 · 10-09-2019, 09:31 AM

if the pressure sensor is plugged in you are getting a switching signal from the trigger points, the ground leads are tight and the fuel pump is running momentarily and stopping when the key is first turned to the on position and the head temp sensor is providing electrical resistance and is plugged into the harness, then try substituting the control unit and the pressure sensor. Power to the noid is cranking only (make sure that there is steady power to the positive 15 side of the coil when cranking

surfdogskier · 10-11-2019, 06:49 AM

Quote:

Originally Posted by dr914

if the pressure sensor is plugged in you are getting a switching signal from the trigger points, the ground leads are tight and the fuel pump is running momentarily and stopping when the key is first turned to the on position and the head temp sensor is providing electrical resistance and is plugged into the harness, then try substituting the control unit and the pressure sensor. Power to the noid is cranking only (make sure that there is steady power to the positive 15 side of the coil when cranking

i don't have extras of either to switch out.

surfdogskier · 10-11-2019, 07:40 AM

I am done dealing with fuel injection. I don't trust it. To many issues. I have spent to much time on it and tired of sinking more $$$ into it. Converting to carbs and selling the fuel injection.

dr914 · 10-11-2019, 08:50 AM

we can test the parts for you if you send them

remove the injection, wear the engine out, and devalue the car 2500

surfdogskier · 10-11-2019, 05:41 PM

Quote:

Originally Posted by dr914

we can test the parts for you if you send them

remove the injection, wear the engine out, and devalue the car 2500

Thanks Doc but I'm not in it for value of a car. Nothing I am doing to this is original. Matter of fact, I will be rhino lining the entire exterior of it jet black. The car will be blacked out completely. No chrome. My friend has one with carbs and loves it. No hassles. It is just a matter of trust with this car now. I never know when I go to get in it what is working or not. At least with carbs, I will pretty much where the issues are. Not in it for performance or gas mileage. I have other projects to get on with after this.

If I change my mind, I will take you up on your offer.....Thanks