fuel injection problem on 1975 v12 jaguar

Hi,

I am working on 1975 v12 jaguar . Injectors are not working. I have power across both terminals on the injectors. I have changed the trigger board for upgraded 4 wire with the correct rotor. I have done continuity test on ecu, injector amp and changed out the manifold absolute pressure sensor.

Done a visual on ecu and tested for power and grounds. The amp looked okay but have not been able to test it. The injector system is live because when I operate the throttle turntable the appropriate injectors work. Any help would be greatly appropriate. 

Hi Unknown,

I cannot follow your description. You have power on injectors but they do not operate ?

Have you verified whether both hall sensors give signals to ECU ?

thank you for your response
please how do you check check that at ecu
i have run a magnet over the board and it does click

Hi Unknown,

it is good manners here that we say hello and sign with our first name. That allows others to adress us personally.

Use an oscilloscope and check on line from hall sensor to ECU what signals you have.

Hi,

My name is Phil and I work at British Sports Cars in California.

This car was towed in as it stopped running on the freeway. Our customer says it slowly started loosing power and cylinders until it fully stopped running. When I crank the car over I get now pulse at the injectors. If I turn the ignition on and spin the distributor in my had I do get the injectors pulsing. Here is a video I made to show you what is happening. Any help would be greatly appreciated.

Hi Phil,

okay I have seen the video. So you have a pulse of injectors when you turn distributor finger manually but not when cranking. That is odd as there must be some (not all injectors) injecting during start, meaning pin 18 receiving +12V. And that should be independent of hall sensors as we want engine to start. So please check what is happening on pin 18 and whether you have minuimum +11.5V on pins 16, 24 versus pin 11.

Also please attach an oscilloscope somehow to pin 13 and 14 to see pulses from hall sensor. Magnet can fade and they have a short time only to make hall sensors operate. If they are very weak they could create pulses on manual spin of distributor finger but none during cranking. Just fishing for possible reasons.

Last you can monitor what happens on line 3 and 4 to amplifier. That is where Bosch ECU hands over to Lucas amplifier.

My name is Justin and I am helping Phil with this car. He has asked me to upload this video with what he has found. Thank you very much for the help.

youtube.com/shorts/i3r2aDM6hXs

Hi Justin,

is that the signal from the 2 Hall sensors to ECU? It should be a rectangular signal but with slow frequency. There is a pull-up resistor in ECU and closed Hall sensor pulls it down to 0.

What about distance of finger to hall sensor board?

I believe I had my scope set on the wrong setting when I did the video as it was set to AC and not DC. Doing the same test in DC I am not getting anything. This is a new scope to me so I am still figuring it out. Is there a good way to test the trigger board from it 4 pin connector?

I have been brought on to sort this out as Phil has become frustrated.

Hi,

well I cannot help with this oscilloscope. You can only measure with board being connected.

You are sure that you have a finger with magnet bilt in? It should create pulses in Hall sensor. Magnetic field goes down by distance. So if distance  of board to this magent in finger is too big, it might not work properly.

Yes the rotor does have a square magnet in the back side of it. It is a very strong magnet as I just checked it. I will get the trigger board closer and see if that makes a difference.

The car was running just fine for several months after we rebuilt the engine. The client took it down the freeway for about 30 minutes and on an up hill climb it started missing cylinder until it stopped completely.

I believe I am correct in having the scope set at DC current when testing?

Can I use the scope to test directly at 4 wire connector at the trigger board?

Hi,

DC or AC does not matter for a real oscilloscope. What do you want to measure on that connector when it is off? No power ? no signals.

What I am wanting to do is test the hall sensor at it 4 wire connector to verify I have a good hall sensor. I am not sure how to do this? If I can verify it is good I can then work my way back but I need to know I have a good hall sensor first.

I have tested the hall effect sensor from the 4 wire connector. It is testing bad and giving a wave form very similar to the video I sent you. It jumps up to 7 volts when the magnet is over the board but then doesn't drop off as the rotor is turned pas the board. On occasion it will drop down but to .180 volts.

Hi Unknown,

not knowing how you tested, it should be 0V when magnet induces Hall sensor while ECU is connected and under power.