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Old 03-05-2018, 04:38 PM   #76
PromiseRing
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No test light unfortunately. A test light and a noid light kit are on the to-buy list.

Just looked over the wiring diagram for the RSR. Black is a constant ground. Red is a constant 12v. Blue+yellow is a switched and fused 12v. Green+red is straight to each injector Orr??? Anything right to the LH box itself? Kinda confused on that. Going to check continuity on each of the 4 wires during the next no start.
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Old 03-05-2018, 05:06 PM   #77
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You should stop and get/build a test light.

The last test lamp I bought cost $1. It's in the trunk of my daily.
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Old 03-06-2018, 11:32 AM   #78
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Today it started fine, got to op temp, then parked for 1hr-1hr30min. Then a crank no start. I bypassed the RSR by jumping the 12v RED wire to the RED + GREEN wire and it did nothing. So the relay itself is not at fault here, but rather the wiring?

Waited like 5 minutes and it started right up.
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Old 03-06-2018, 02:03 PM   #79
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The fuel pump relay triggers the RSR. The fuel pump relay is grounded through the LH ecu.
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Old 03-06-2018, 02:34 PM   #80
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The fuel pump relay triggers the RSR. The fuel pump relay is grounded through the LH ecu.
So ground should be good since I know for a fact that the fuel pump relay is good and turns on both pumps reliably as it should.

Today when we had a no start again I grabbed a jumper wire and ran it from + post to the red/green wire and the car started. Itís startinf to look more and more like a + wiring issue. Once clean new relays are installed along with new + wiring to the battery, we will see how it goes.
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Old 03-07-2018, 02:12 PM   #81
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I had a similar issue with a car I had just redone. Was sudden and very random. When I got it running, I started jiggling all the wiring around the injectors and one of the tightened grounds moved. Turned out the bolt that grounds the injectors to the intake had stripped - could tighten it fine then a little more and it was slightly loose again.

Another idea to throw at the wall.
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Old 03-07-2018, 02:51 PM   #82
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During a no start, I used jumper cables to run from injector ground straight to the negative battery post. Made no change. I also just did IM gasket and some other stuff and made sure the grounds were clean and tight.

Parts will get here today but not sure if I’ll have time to install them.
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Old 03-07-2018, 03:29 PM   #83
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Dude bro. Why would you short the injector ground wire?
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Old 03-07-2018, 04:45 PM   #84
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Dude bro. Why would you short the injector ground wire?
What? Theyíre grounded to the manifold. I figured the ground might be shoddy so I grounded it directly to the battery. Is this a problem?
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Old 03-07-2018, 05:48 PM   #85
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Quote:
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What? They’re grounded to the manifold. I figured the ground might be shoddy so I grounded it directly to the battery. Is this a problem?
You are incorrect.
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Old 03-07-2018, 07:36 PM   #86
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You are incorrect.
so why are there injector grounds on the mani/rail? All I did was ground the ground bolt to the negative post.
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Old 03-07-2018, 09:01 PM   #87
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Quote:
Originally Posted by 15A View Post
I had a similar issue with a car I had just redone. Was sudden and very random. When I got it running, I started jiggling all the wiring around the injectors and one of the tightened grounds moved. Turned out the bolt that grounds the injectors to the intake had stripped - could tighten it fine then a little more and it was slightly loose again.

Another idea to throw at the wall.
Did you figure out that a 1/4" bolt is just enough larger than 6 mm to fit?
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Old 03-07-2018, 09:04 PM   #88
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Quote:
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What? Theyíre grounded to the manifold. I figured the ground might be shoddy so I grounded it directly to the battery. Is this a problem?
LH ecu switches the ground to fire the injectors. There is 12 volts to the injectors supplied by the RSR.
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Old 03-07-2018, 09:06 PM   #89
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Quote:
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so why are there injector grounds on the mani/rail? All I did was ground the ground bolt to the negative post.
There are many electrical parts on the engine that require grounds. Sensors.
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Old 03-07-2018, 09:06 PM   #90
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Quote:
Originally Posted by lummert View Post
LH ecu switches the ground to fire the injectors. There is 12 volts to the injectors supplied by the RSR.
So what are the 'injector' grounds for if LH controls the ground, and also what harm did I cause by grounding something thatís already grounded?
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Old 03-07-2018, 09:09 PM   #91
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Quote:
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So what are the 'injector' grounds for if LH controls the ground, and also what harm did I cause by grounding something thatís already grounded?
You didn't hurt anything by grounding the intake manifold to the negative battery post.
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Old 03-07-2018, 11:20 PM   #92
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You didn't hurt anything by grounding the intake manifold to the negative battery post.
The Idk why zvolv said that
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Old 03-08-2018, 01:05 AM   #93
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Hoping this helps the 740. I’m very unhappy with how ugly butt connectors are.



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Old 03-08-2018, 07:16 AM   #94
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don't know if it has been adressed in this thread, didn't read it all but...

the 7/9 have the dizzy at the back of the head. The gap between paravan and hood is right over the dizzy cap. there is a rubber seal located between paravan and hood to prevent rain water leaking on top of the dizzycap. But on older cars this might not work very well anymore because of degraded rubber seal or dirt. Water might drip down onto the dizzy cap and might get in between the black cover and the red cap itself. This might lead to poor starting in damp conditions.
It's worth a closer inspection.
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Old 03-08-2018, 12:39 PM   #95
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Quote:
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The Idk why zvolv said that
What makes the injectors operate?
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Old 03-08-2018, 02:02 PM   #96
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What makes the injectors operate?
A grounding signal from LH?
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Old 03-08-2018, 03:11 PM   #97
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Yes. Low side controlled. Some cars are high side controlled, but not commonly. So by you jumping the ground side directly to ground all you would be doing is opening up the injector to 100% duty cycle.
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Old 03-08-2018, 03:19 PM   #98
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Yes. Low side controlled. Some cars are high side controlled, but not commonly. So by you jumping the ground side directly to ground all you would be doing is opening up the injector to 100% duty cycle.
I thought the two grounds on the intake manifold needed to be good clean grounds. Considering they are grounded 100% of the time as far as I know since they are grounded to the engine and the engine is always grounded to the battery. So by running a direct ground Iím pretty sure I didnít actually change anything at all. This is all irrelevant anyway but now you got me thinking
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Old 03-08-2018, 03:52 PM   #99
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Those grounds are for the LH box I believe. For some electrical reason, like noise or in interference or some ****, they ran them all the way back up to the intake manifold instead. They are NOT the ground for the injectors, but since they come out of the injector wiring harness bundle I knew that's why you believed that.
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Old 03-08-2018, 03:59 PM   #100
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Quote:
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Those grounds are for the LH box I believe. For some electrical reason, like noise or in interference or some ****, they ran them all the way back up to the intake manifold instead. They are NOT the ground for the injectors, but since they come out of the injector wiring harness bundle I knew that's why you believed that.
I didnít really care what they were for, I just knew they were supposed to be good clean tight grounds, so thatís what I did. I did NOT directly ground the injectors, but rather gave the LH box a good clean ground.
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