No injector pulse

MK3MKB

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I thought I had posted about this before but I couldn't find my thread.

I picked up this Supra after the previous owner rebuilt the engine from rod knock but couldn't get it to start. Car sat for ~10 years. 7M-GE, manual. I'm not getting a pulse to the injectors. I've probed both sides of the connector and there is no voltage change. So far I have found no fuel pressure to rail, replaced pump with walbro 255, cleaned fuel tank, now have fuel to the rail. Also replaced the ignitor. Verified spark, checked continuity from distributor to plug, and confirmed ground on intake. I can get the car to start for roughly 2 seconds but it's running off the cold start injector. I don't think it matters, but the clutch needs to be bled.

Any help much appreciated.
 

figgie

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The 7m-ge supra is very simple, ignition switch feed the injectors 12v+ while the TCCS grounds the pins.


If you don't have 12v positive at one of the pins, then you will have to verify wiring.
 

f00g00

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There is a switch in the AFM that needs to close which provides ground to the circuit opening relay. That will keep the relay open after you start the car and it powers the fuel circuit. Check the flapper on the front if it moves freely on the AFM and if it does check pins 1 and 2 for continuity with the flapper open.
 
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A70nut

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Does the car have voltage at the power wire for the injectors? Have you checked lack of pulse with a noid light?
 

MK3MKB

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I found my problem. Turned out to be a faulty ECM.
 

MK3MKB

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How'd you figure that out? I'm not much on diagnosing so the answer will be helpful :)
Short answer, I knew I had power and ground so it had to be a signaling problem. All diagrams lead back to the ECM. I found one on eBay cheap and tossed it in, all is well now.

Long answer, I used a test light on both pins of the injector and light wasn’t coming on. I confirmed ground to the intake, confirmed fuses good. I also wasn’t getting fuel to the rail but the fuel pump was coming on when the flapper on the intake was open. I replaced the fuel pump thinking it was bad internally. When I pulled the tank down it turns out the pump was starving because the tank was so rusty. Ended up spending the better part of 5 hours cleaning the tank up. So now I had power, ground, and fuel but no signal. I remember reading somewhere the ignitor, and distributor played a part in signaling. I had continuity between the plug and Sauter Points on the distributor. I tried another ignitor because I had no way to test it (required a 5 volt source to one wire). I took to reading wiring diagrams and The injector wiring lead back to the ECM so I found an auto ECM on eBay for $45 and after some cranking the car fired up for the first time in 10 years.

I just picked the car up a few months ago but I was working on it slowly because my wife was pregnant and I was also getting the house ready. I actually ordered the fuel pump the second week of October and my son was born a whole month early on October 29th. Needless to say I didn’t have time to get back to the fuel pump until late November. Previous owner had supposedly rebuilt the engine because of a rod knock and couldn’t ever get the car to start after reinstalling the engine. Pushed it under a tree and it sat there for 10 years. He said he kept popping the efi fuse, there were several blown fuses littering the engine bay. I think he messed with the wiring and had some things grounded that should have been getting power.
 

debrucer

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Short answer, I knew I had power and ground so it had to be a signaling problem. All diagrams lead back to the ECM. I found one on eBay cheap and tossed it in, all is well now.

Long answer, I used a test light on both pins of the injector and light wasn’t coming on. I confirmed ground to the intake, confirmed fuses good. I also wasn’t getting fuel to the rail but the fuel pump was coming on when the flapper on the intake was open. I replaced the fuel pump thinking it was bad internally. When I pulled the tank down it turns out the pump was starving because the tank was so rusty. Ended up spending the better part of 5 hours cleaning the tank up. So now I had power, ground, and fuel but no signal. I remember reading somewhere the ignitor, and distributor played a part in signaling. I had continuity between the plug and Sauter Points on the distributor. I tried another ignitor because I had no way to test it (required a 5 volt source to one wire). I took to reading wiring diagrams and The injector wiring lead back to the ECM so I found an auto ECM on eBay for $45 and after some cranking the car fired up for the first time in 10 years.

I just picked the car up a few months ago but I was working on it slowly because my wife was pregnant and I was also getting the house ready. I actually ordered the fuel pump the second week of October and my son was born a whole month early on October 29th. Needless to say I didn’t have time to get back to the fuel pump until late November. Previous owner had supposedly rebuilt the engine because of a rod knock and couldn’t ever get the car to start after reinstalling the engine. Pushed it under a tree and it sat there for 10 years. He said he kept popping the efi fuse, there were several blown fuses littering the engine bay. I think he messed with the wiring and had some things grounded that should have been getting power.
The long answer is informative and gives me something to think about. I'm about to embark on re-installing my ECM that's been sitting on the shelf that long (ten years). I opened it once to peek at the level of the technology, and closed it back up. My goal is to run on an Aduino, Speeduino, but I have to get it running on OEM setup first, then switch over. It's going to be a challenge, so every bit of technique is important to me. Thank you.

Congratulations on the birth of your son! My daily-driver was a '67 Austin-Healey Sprite when my first was born. At least the Supra is a 4-seater:)