1985 4Runner only runs on cold start injector

pappy

photosynthesizing
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FYI. Your injector connectors could be toast and crumble/break when you try to remove them. They are available aftermarket, and now is the time to consider replacing them. This connector also works for the cold start if you break it too. The nice thing is the pigtail gives you more wire to work with when fixing those splices. I seem to recall NAPA sells them, or you can get them here, Fuel Injector Connector
 
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Also, injectors 1 & 2 are wired together, and 3 & 4 are wired together. Hence, the splices.
Are the splices fairly close to where you can see the splits in the loom( just about where the loom runs under the upper intake manifold) Or are they spliced back farther?
 

pappy

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There will be four (5?) splices, if I remember correctly. I don't recall where they were in the loom. I just peeled everything back starting at the injectors.
 
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There will be four (5?) splices, if I remember correctly. I don't recall where they were in the loom. I just peeled everything back starting at the injectors.
Ok I will do that, I’m guessing 5? Are those 2 grounds that run to the intake spliced too maybe? Any idea what cost was on those connectors? I seem to see $4-$20.
 
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Thank you a ton for everyone’s help by the way! I know this will be an ongoing process so I appreciate y’all bearing with me!
 
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Both the grounds and signal will be spliced. The link I provided was $2 each, plus the ride.
Awesome! That’s a major relief! Thank you for the help! I’ll keep you posted on what I find as I dig in!
Do you know if the 6 pack noid lights that auto stores rent will fit our injector connector? Or any good cheap ways to create one? I would like to test at beginning and end of digging into the harness.
 
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Dude you need to check at the injectors with a volt meter before tearing the harness out.
What a waste of time if thats not your actual problem.


No offense but,
If you don't have a wiring diagram and dmm you need someone there to hold your hand.
 
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Dude you need to check at the injectors with a volt meter before tearing the harness out.
What a waste of time if thats not your actual problem.


No offense but,
If you don't have a wiring diagram and dmm you need someone there to hold your hand.
I’m not yanking a harness out without testing. Which is why I asked the noid light question.
Yes I have a dmm and wiring diagram which has gotten me this far.
 
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For what its worth I was able to repair those splices without pulling the harness. Its obviously not as easy doing the repair, but it was less time consuming in the long run.
 
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So I just re confirmed that I have 12v going into the injector solenoid resistor. That should show the circuit of power from ecu to ignitor to coil to distributor, back to ignitor and igniter to resistor is functional. I’m going to double check that voltage is coming back off of distributor pickup to ignitor. Then I’m going to pop the injector connectors and put noid light on to see if I’m getting command. I’ve also heard about people probing at the 10p connector at ecu. Top left wire and one next to it I should be able to see command from ecu, however I have read y’all about needing to use a paper clip, any clarification? My DMM probes don’t seem to want to fit into the connector so if I have to I will stab the wire and repair coating.
 
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I like it to use small T pins to back probe.
Ok thank you! Now there’s igf and ne that are being dealt with. Constant power in to ignitor, and the other is a pulsed ground coming from the pickup, to the ignitor, back to ecu, then from ecu on the white&red wires to the injectors to create the pulse for open and close. Am I correct on this?
Now with the pulse ground will it be completing the circuit for that moment of pulse? I believe so. When probing then I should be able to pick the 12v power wire associated with it, and the pulse ground then see at least a blip depending on my meter’s response time which will show where I am getting full command up to?

Also you seem more knowledgeable, maybe you are a.s.e? Any tips on verifying the signal from distributor pickup so I know pulse is being generated( I’ve read the pulse is generated off of spark, then sent through to be pulse for injectors)? Would same technique work for verification off of igniter?
 
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If you run off the csi, you don't have a spark problem.
You cannot really sample anything off the ignitor because it interferes with the signal.

Fact is the pickup in the dizzy sends signal to the coil/ignitor where the ecu sees it and fires injectors.

I think you need to verify that you afm is making the fuel pump run properly.
The FP is triggered by the COR during starting. The COR is actually like two relays in one. What happens is the starting signal activates the FP during cranking. once running, the afm activates the other pulling winding in the COR.
 
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If you run off the csi, you don't have a spark problem.
You cannot really sample anything off the ignitor because it interferes with the signal.

Fact is the pickup in the dizzy sends signal to the coil/ignitor where the ecu sees it and fires injectors.

I think you need to verify that you afm is making the fuel pump run properly.
The FP is triggered by the COR during starting. The COR is actually like two relays in one. What happens is the starting signal activates the FP during cranking. once running, the afm activates the other pulling winding in the COR.
How do I test the afm? I’ve replaced the COR with known good, the fuel pump is new. I know start up everything is right. I don’t have a spare afm to throw on, any tests that I can do? Can I hard wire the FP to send full flow? That way afm could just run air to see if it works? Idk if there’s a return or pressure relief like diesel trucks have.
 
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Here are a couple screenshots from FSM.
you can see the afm is simply a switch in this case.
The check conn is the two wire squarish conn near the two yellow conn on driver inner fender
Screenshot_20200408-103523.png
Screenshot_20200408-103621.png
 
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Going to get another afm to try or I can always sell it to my buddy. Hopefully that’s the issue, I tried his before replacing my FP.
 
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