I recently did a soft rebuild on my 94 3.0 4runnner. Had an issue where I literally had no gusto. No power to go up even the smallest of hills. Seemed to idle fine, and rev fine but it just wouldn't go. I replaced and adjusted all the usual things.. Too many to list. Did a compression test and found low compression on cylinder 5. Confirmed a blown head gasket with a bore scope. Coolant in cylinder 5. Figured that was my issue, so like I said I did a soft rebuild. Everything but pulling the crankshaft and pistons. ARP studded the heads. Crossover relocation, the works. Got her back together and she ran like ˟˟˟˟. Like, exactly the same as before I tore it down. Disheartening to say the least. After a few jumpy sputtery runs around the block she died on me completely in the road on a descent hill I was barely creeping up anyway. Crank no start.
No power to fuel pump.
Testing
COR ohmed out and has continuity where it should and is receiving power. EFI relay has ohmed out, continuity where it should and bench tested ok, swapped with starter relay and still cranks.
Every time I've had an issue with this thing and pulled the codes, it's always different code.. each time I fix that problem, I have another that always manifests as no power to fuel pump. This engine is turning out to be 10lbs of ˟˟˟˟ in a 5lb bag.
Code for intake air temperature sensor. Replaced the VAFM. Fixed that code. Still no power to fuel pump. Checked continuity while cranking between COR and VAFM and have continuity. Have continuity through ground to VAFM and after. EFI fuse is good and has good power across it. Battery voltage in diag port between B+ and FP is great. Jumped the terminals and STILL no power to fuel pump.
Code for ECM losing communication to Igniter. Back probed ECM and found no fault at the igniter. Ohmed the ignition coil, within spec. Ohmed distributor and that's within spec as well. Applied power directly to fuel pump with cold start injector cracked and pump works fine. Pulled up a list of all the ground points in the engine compartment and inside the cab and inspected and cleaned every single one and checked continuity and they're all good. Still no power to fuel pump. I've spent hours studying forums and All Data and wiring diagrams. Decided to inspect the ignition switch and found its retaining screw a bit loose. Pulled it, disassembled, cleaned the contacts, reinstalled and still crank no start and no power to fuel pump.
Here's where it gets interesting.. while I had my head shoved up under the dash dicking around with the ignition switch, I saw a relay mounted to a tab above the steering column and guess what that little bastard said on it? "Fuel Pump Relay, Made In Japan

"
WTF? LITERALLY NOWHERE IN ANY FORUM OR IN ANY WIRING DIAGRAM I FOUND, WAS THAT RELAY. But get this, because I work at a shop, I have AllData. I found a test procedure for that relay. No description of it, no mention of it anywhere in any bit of any fuel system data I found, just a testing procedure for a fuel pump relay that was clearly not the EFI or the Circuit Opening Relay. Disassembled it contains a diode and a resistor and the test procedure confirmed its bad.

I will be replacing this in a couple days when I get paid again. I will post my results.

Is this relay an anomaly? Why wasn't it listed ANYWHERE? The Haynes manual was useless, AllData was useless, Google turned up nothing, YouTube also was less than helpful, and the 2nd gen Facebook group page knows nothing of it saying that the COR is the relay..
Very spurious.

 

So, I fixed my 4runner. I had really aspastic and sporadic intermittent connections to the fuel pump hanger itself. I think that the wiring was damaged inside its sheath, right at the connections. I replaced the ground and re-riveted it to the pump hanger, but because the positive power wire went through some sort of ceramic insulater, I double shrunk a new wire with marine grade heat shrink, found a drill bit exactly the same size, drilled and de-burred a hole through the lid of the pump hanger. I pulled the wire through and it was a really tight fit. I then put another bit of heat shrink above and below to keep the wire from slipping and them for good measure I put some Toyota brand FIPG above and below. Now it runs well.

I also discovered that the Fuel Pump Relay under the driver side of the dash isn't directly connected to the fuel pump. Its a relay used by the ecm to control the fuel pressure to regulator via the VSV for the FPU system. Not sure why it's not actually in the wiring diagrams but yeah, that's what I dug up.