2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Grounding and fuel pins question

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Old Oct 10, 2005 | 03:30 PM
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Grounding and fuel pins question

Ok i have a couple of questions.
1. Car not running or runs when it wants to then shuts off. I tested the current with the key ON at the injector pins 3C and 3E and they are getting 12 volts. But at pins 3G and 3A, im getting 4.6 volts. I know grounds are susposed to be 0 volts so something is wrong there. I was wondering where the grounds are located, i heard they were located somewhere on the rear rotor on the passenger side but i have yet to find them. If anyone had them in a picture, it would be helpful.

2. See attached picture. The connectors in the FSM are not the same as mine, mine are reversed. I didnt check the bottom pins so i dont know if they are reversed but i am sure that the top pins are. Is that susposed to be like that?

3. Dealing with the solenoid resistor, if i have high impedence injectors, would the car start or not?

thanks in advance
Attached Thumbnails Grounding and fuel pins question-connector.jpg  

Last edited by Russ-R; Oct 10, 2005 at 03:39 PM.
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Old Oct 10, 2005 | 06:13 PM
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HAILERS
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The FSM looks at a plug from the WIRE side of the plug. The manual is correct.

So if the plug is on the ECU, the sockets/pin are numbered/lettered from the right to the left in a up/down fashion.

With the key Off, and you read to ground on 3E and 3G, what is your ohms reading? Something like 0.5 ohms or less is just fine.

The grounds for the ECU are on the top of the rear ROTOR housing on a ring terminal. About two inches left of the center line. Held on with a single bolt. Not readily seen without removing the upper intake/throttle body.

Last edited by HAILERS; Oct 10, 2005 at 06:20 PM.
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Old Oct 10, 2005 | 07:57 PM
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Originally Posted by HAILERS
With the key Off, and you read to ground on 3E and 3G, what is your ohms reading? Something like 0.5 ohms or less is just fine.
2 Things, isnt the ground 3A and 3G? But i tested 3A and 3G and both read .8 . So im guessing thats a definite sign that a ground might be dirty. But will that cause the engine from starting?

I'm sure the injectors are getting power since I read 12v at their pins on the plug. I've also check for spark, by taking out the spark plug and "grounding" it near the fender to a bolt and saw the spark. The only werid thing was the spark on one of the trailing coils was a little weak. Ive also tested compression but did it wrong by not opening the throttle at all and by not having it warmed up. It read 90 psi on both rotors. So im sure the engine is fine. I had the injectors cleaned ,installed a new fuel pump, and fuel pressure regulator.

While running earlier today, everything working normally, then it shuts off as if electrical power was taken from somewhere. My next thing to check would be the fuel pressure and see if it is sufficient. In the meanwhile, I was wondering if there should be anything else i should check.

Also my previous question wasnt answered, would having high impedence injector with the solenoide resistor installed affect the car in anyway?
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Old Oct 10, 2005 | 09:36 PM
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Man, I vacate the forum for four months and come back to find the same problems with everybody, lol...

Nice to see you're still around helping everyone out with your wit, Hailers

Check your rear rotor housing ground, as Hailers said. That terminal could be corroded to hell and you'd still get a strong 12v at the pins from the injector side of the harness. For some quick troubleshooting, physically ground the ECU ground pins via a jumper to a chassis spot near the ECU. If all of your problems disappear, your housing ground (or harness) is shot...
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Old Oct 10, 2005 | 11:19 PM
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Good to see Wayne out in just four months. How long is the probatiion time you have to serve? And do they make you wear an ankle bracelet???

Last edited by HAILERS; Oct 10, 2005 at 11:21 PM.
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Old Oct 11, 2005 | 12:12 AM
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Lol, I've been pursuing other hobby interests that require mucho money and research time...

RA Rebuild just passed 31,000 miles, everything's still good to go...

Looks like the guys got all the help they need with you hanging around, anyway
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Old Oct 11, 2005 | 01:10 PM
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From: Georgia
Turns out my grounds were bad like you said. Instead of taking off the intake manifold to clean it, i "tapped" into the harness that was easily seen and soldered a wire from there then grounded it. Just wondering if any long term damage from doing this?
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Old Oct 11, 2005 | 02:05 PM
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none
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Old Oct 11, 2005 | 08:56 PM
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K thanks for all your help. Mucho props HAILERS and WAYNE88N/A ^_^
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