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Skyvisions
Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 13205
Experience:  Toyota Master Diagnostic
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1991 toyota 4runner V6.Will not start.Tried FP to B+ nothing.

Resolved Question:

1991 toyota 4runner V6.Will not start.Tried FP to B+ nothing. Checked B+ to negative battery and B+ is not hot. Put FP to positive side and fuel pump comes on and has pressure.It decided to start.When it starts the B+ becomes hot.When I take the wire loose it dies. Now it wont start at all?
Submitted: 4 years ago.
Category: Toyota
Expert:  Skyvisions replied 4 years ago.

With the key in the on position B+ in the diagnostic check box has to have 12 V this voltage comes by way of the EFI main relay and 15 amp EFI fuse. When you turn the key to the on position make sure the EFI relay is clicking and you're getting continuity through the point contacts. Try swapping this relay with another relay to see if that supplies 12 V two B+ in the check terminal. Let me know if you find and we can go from here.

 

Skyvisions

Customer: replied 4 years ago.

How do I check for contunuity?

 

Expert:  Skyvisions replied 4 years ago.

You would need to energize the coil windings and then check with an ohm meter across the other two terminals. If the relay clicks when the key is turned to the on position the coil windings are good the next step would be to check for voltage to the relay. Make sure that you have 12 V at the EFI 15 amp fuse. Is your EFI relay a plastic case relay or metal?

 

Skyvisions

Customer: replied 4 years ago.

metal

 

Expert:  Skyvisions replied 4 years ago.

The metal relays give the pinned identification schematic on the side of it. You can pop the metal cover off it is just a lot more difficult than the plastic top cover. My suggestion would be to use one of the other relays that has the exact same configuration and plug it into the EFI relay position and see if that makes a difference with 12 V to the B+ terminal with the key in the on position. Let me know what you find. You have to have 12 V to the B+ terminal because this means that you have 12 V to the many other things that are controlled by the EFI system in order to make this truck run.

 

Skyvisions

Customer: replied 4 years ago.
When I first started working on this thing the other day B+ was not hot. Then the next day it was hot.So, I hooked up the fp to B+ and the pump came on. Then B+ was not hot and hasn't been hot since, unless i hook fp to the positive side of the battery and when it cranks the B+ becomes hot.Now it won't crank at all?????????/
Expert:  Skyvisions replied 4 years ago.

I understand all of this, the thing that makes no sense is how it could be hot one day and not the next, this indicates a loose connection or intermittent problem. If it currently does not have 12 V at B+ with the key in the on position this is a good sign because we can diagnose from here. Do you have 12 v at both sides of the EFI fuse with the fuse installed?

 

Skyvisions

Customer: replied 4 years ago.
I don't have my meter in hand but I do have power with test light on both sides of the efi fuse.If I have to have a meter I can run next door and get one.
Expert:  Skyvisions replied 4 years ago.

Test light will do for now. Does the EFI relay click when you first push it into the tabs with the key in the on position? With the key in the on position using your test light check all 4 female pins in the fuse box do 2 of them have power?

 

Skyvisions

Customer: replied 4 years ago.
yes the relay clicks and yes I have power on two of the four prongs.
Expert:  Skyvisions replied 4 years ago.

And you still have no power to the B+ in the check connector and you are certain that you have the EFI relay?

 

Skyvisions

Customer: replied 4 years ago.

no B+ there are a couple of other relays under the dash by the other fuse box that are the same.I tried switching them out yesterday to no luck.

Expert:  Skyvisions replied 4 years ago.

If you are certain that the relay is good and if you jumper pin two to pin four with a jumper wire in place of the relay this will supply 12 V directly to the white wire with a red tracer that goes to the diagnostic check connector box and the engine control computer and circuit opening relay. Make sure this is the case. Then you need to remove the engine control computer which is behind the right kick panel. There are two wire-to-wire connectors the rear ward one is the connector that this white wire with a red tracer goes through in order to power up the circuit opening relay and the B+ terminal and the computer. Check for power at this white wire with a red tracer at the computer and this wire-to-wire connector. Let me know what you find.

 

Skyvisions

Customer: replied 4 years ago.
I hope I can do this.Let me go try.
Customer: replied 4 years ago.

ok i just went to do what you said and only one pin is hot where the relay goes now?

 

Expert:  Skyvisions replied 4 years ago.

Which pin # XXXXX you post a picture of which pin or can you see which color of the wire from under the fuse box? Does the relay still click when put in with power to only one pin?

 

Skyvisions

Customer: replied 4 years ago.

no the relay dosn't click. Its the hole on the left closetest to the front end. it apperas to be green. hard to tell. Are we on to something now?

Expert:  Skyvisions replied 4 years ago.

Below is a picture and pin location and number 1 should have 12 V and is fed by the 7.5 IGN fuse and pin 2 gets 12v from the 15 amp EFI fuse which one are you getting power to at this time? Check the 7.5 amp IGN fuse and make sure it has power and is tight in the box.

 

Skyvisions

graphic

Customer: replied 4 years ago.
i'm getting power on the #2 pin. I'll check the ign 7.5 fuse . My wife is trying to work on this computer.Can i close this out and pick back up the conversation on my laptop?
Customer: replied 4 years ago.
7.5 was blown now got power on both prongs i blew it when i went out to jump the wires. i jumped 1 and 3 i think. I guess i need to do what you told me before, huh?
Expert:  Skyvisions replied 4 years ago.

Yes that would be a good place to start. If you jump number two to number four this supplies direct voltage as if the relay was engaged.

 

Skyvisions

Customer: replied 4 years ago.

o k ill do. i've got to change computers. I''ll figure out how to pick this back up so i can pay you. thanks

Customer: replied 4 years ago.
I'm back. I'm gonna try to do what you said. If it was your guess now whats the problem?
Customer: replied 4 years ago.
are you there?
Expert:  Skyvisions replied 4 years ago.

What have you found so far as to what I told you to check?

 

Skyvisions

Customer: replied 4 years ago.
i'm going to check now.
Expert:  Skyvisions replied 4 years ago.

My information and directions are only as good as your ability to do the checks and test and follow them with accurate conclusions. Let me know what you find.

 

Skyvisions

Customer: replied 4 years ago.
your a genuis. when i crossed the 2 and 4 pin b+ became hot and she cranked right up. I guess it was the relay all along!
Expert:  Skyvisions replied 4 years ago.

Everything starts and runs normally now?

 

Skyvisions

Customer: replied 4 years ago.
it appears so. thats the first thing i replaced when it wouldn't start.i got it at oriellys. must have been the wrong or bad one. now that i've replaced the fuel pump and my gas guage isn't working.(LOL) it was the stupid relay.
Expert:  Skyvisions replied 4 years ago.

Good luck, if you need anything in the future just ask for me Skyvisions, in the question and I will get back to you .

 

Skyvisions

Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 13205
Experience: Toyota Master Diagnostic
Skyvisions and 5 other Toyota Specialists are ready to help you
Customer: replied 4 years ago.
before i accept do you know what cause these trucks to be going along and all of a sudden start loosing power and the cough or backfire and then regain power?
Expert:  Skyvisions replied 4 years ago.

I have seen a few issues with ignition coils going bad and the description that you're referring to. This engine had a recall back in the day for bad head gaskets and has been an ongoing problem FYI.

 

Skyvisions

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