New member, New problem... Hi and Help!

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Hey guys, I read through the stickies but didn't find an answer. This is a lot of info, but hopefully someone can help. I am new to this forum but have worked on cars as a hobby for 20 years. I am in no way an expert but not a rookie. I have a 99 XJ a 19 GX460 13 Tundra (supercharged) and this 89 62.

I picked up the 89 62 from Dallas a few months back, all original* (I'll get to this) with 250k on the clock. Cali car for 30 years with no damage or rust to speak of (except a spot right above drip edge). It started and drove ok on the 150 mile ride home... but painfully slow (I have been in 60s before, so not normal slow). One thing I noticed was the gauges all pegged intermittently on the drive home (Temp would jump to top of range, Fuel would jump to bottom of range) then come back to normal after a few minutes... seemed like a ground.

Fuel gauge would show empty at 3/4 of a tank.

Battery would drain after a few days (new battery, alternator works fine).

I was driving around town and everything went dead. I coasted to a stop. The truck would not start. I checked the fusible link (seemed ok) and the fuses. EFI fuse was blown. Replaced, blew immediately again, replaced, same thing. Got the truck home on a flatbed.

I did some research and assumed a ground in the fuel pump. I replaced the fuel pump, sending unit, fuel filter and pressure regulator. When I went to restart, the truck cranks but does not start. Seems the fuel pump is not getting power (0 volts across when key in any position). I wired the pump to the Lexus battery and it runs fine, so its not the pump. No EFI fuses are blowing now, and gas tank level works fine, but truck will not start. I even tried to start with fuel pump connected to lexus battery... no joy. I cranked it until the battery died and nothing. I charged the battery back and tried again... would not even turn over, no clicking, nothing. Let it sit overnight and it cranked in the morning, but would not start.

I traced the fuel pump wires (red and green and white and black) to the fuse block, and they are not getting voltage across them at any point downstream of the fuse block. However, measuring across the fuse location itself I get 12V on the EFI fuse fuse is good and I swapped it to verify). I also get 12V across "ignition", but only 6V across the "engine" fuse. The wiring is a bit of a mess under the dash as a previous owner installed a trailer wiring system (installed is used loosely) and an alarm system.

Does anyone have any idea what is going on? Why fuel pump is not getting any power and why engine will not start even with fuel pump powered externally? Why im seeing 6V across "engine"? And why this would happen suddenly? Also, EFI fuses are no longer blowing so I think I fixed that issue. So sorry for a long first post and I appreciate everyone's time.
 
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I did the cut a hole in the floor method for the fuel pump replacement so I have easy access for everything (previous owner welded on a tow hitch across frame rails so tank can't be dropped).
 
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Check engine light is on, pulled code 14 for EFI error. I am getting 12v to the EFI main relay and it "clicks" when I take the key to on. Still not getting any power to the fuel pump.
 
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Is there a way to check the EFI relay aside from just the "click" noise? I'll search how to test it
 
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Jumped them as you mentioned and now the fuel pump gets power and runs! So that is one issue. Still wont start however.
 
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Jumped them as you mentioned and now the fuel pump gets power and runs! So that is one issue. Still wont start however.
Also broke the hard line loose from the tank to verify fuel is being sent. Fuel is pumping.
 
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Ok this is getting more interesting. I could not get it to start with starter fluid so I pulled a plug and its not getting spark. So jumpering B and Fp gets the pump to run, but now I'm not getting spark. All fuses are still good
 
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Thanks for the help Godwin. Also to confirm, the fact that the fuel pump is not receiving power unless B/Fp is jumpered means the Circuit Closing relay (inside cabin, passenger side footwell) is bad, or does it mean EFI Main relay (engine bay top of passenger side fender) is bad?
 

Godwin

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Thanks for the help Godwin. Also to confirm, the fact that the fuel pump is not receiving power unless B/Fp is jumpered means the Circuit Closing relay (inside cabin, passenger side footwell) is bad, or does it mean EFI Main relay (engine bay top of passenger side fender) is bad?

Yes. You want the Denso from Rockauto 1988 TOYOTA LAND CRUISER 4.0L L6 Fuel Pump / Circuit Opening Relay | RockAuto - https://www.rockauto.com/en/catalog/toyota,1988,land+cruiser,4.0l+l6,1276613,electrical-switch+&+relay,fuel+pump+/+circuit+opening+relay,3380
 

klinetime574

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Anyone, any ideas?
Just have to ask since you didn’t mention it, have you checked the rotor and distributor cap? I’m willing to bet you have because you sound pretty “with it.” Just covering the bases here.

Another thought, to your knowledge is there any sort of kill switch installed?

I’ll be curious to know what the issue is. I’m just a 2F owner :)
 
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The kill switch thing is something I have seriously thought about. Thats a really good thought, and I just can't tell how to find it if there is one. The wiring has been spliced in about 12 places with multiple in line fuses and relays installed. I'll keep running continuities to see if there is a break or a disconnect. As for the distributor, everything looks ok, but it doesn't seem to be getting power
 

diesellibrarian

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If you're seeing 6v on a circuit, it's likely due to a bad ground creating resistance, so I'd start checking for that. There is at least one common ground bus behind the instrument cluster that can be damaged by a short circuit. It's basically a little plastic connector with a bunch of wires running to it. Mine was visibly burnt/melted. I found it when tracing the cause of my dead headlights. After cleaning up the burned connections in the ground bus, my headlights and signal lights started working normally.

If you are only running 6v on a circuit, it's likely that even a healthy relay will not work properly, if at all.
 

diesellibrarian

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This is the ground bus I'm talking about (see little orange thing at the back, above the steering column). You can see that it is fried. I removed the bottom of the plastic cap and removed the connector, which has several prongs (maybe 10 or 12), cleaned it up, and re-inserted it, and then taped it up. Been working fine since. I'm not sure which circuits ground at that bus, but might be worth checking. The only way to get to it is to remove the instrument cluster.

1664310741616.png
 
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This should help you with your problem.
Check for voltage at the relays,

#1 EFI relay input Red-Yellow wire 12v ( constant )
#2 EFI relay output Yellow-Red wire 12v ( with ignition on )
#3 COR input Yellow-Red wire 12v ( with ignition on )
#4 COR output Red-Green wire 12v ( with starter engaged / engine running )
#5 Igniter input Black-Blue wire 12v ( with ignition on )


If there's a kill switch this should help you find it.
Post your findings after.

88fj62 wiring engine.gif
 

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