First post, long time follower.

I bought a 1988 SR5 4runner with a 22re and auto transmission a couple weeks ago.

I bought it DOA, the previous owner said his daughter was driving it and it just died while going down the road. I figured it couldn't be that difficult to figure out.

The fusible link, and main 80a fuse we both blown when I purchased it. I replaced both, with appropriate wire.

It will run and drive with the fuel pump hot wired.

I can hear the COR click when it cranks, but it does not fire the fuel pump.

No power to the diagnostic port, so I cannot jump the FP to B+ or any other test of that nature.

I believed this to indicate the main relay, so I replaced it with a new Toyota unit from the dealer, no change.

I attempted to jump the AFM port, the wire smoked, and the 30a fuse underhood and EFI 15a fuse in the kick panel blew. I traced the AFM wires into the cab, nothing of concern on them.

At this point, I'm at a loss, I'm not a brilliant electrician, and I don't have a clue where to go from here.

 

Welcome to YotaTech.

You'll probably need some help from someone more familiar with the "early" 4runners. Do you have the round fuel pump test connector, like that shown here: https://www.4crawler.com/4x4/CheapTr...CheckConnector ? Do you have voltage to ground at either pin, with key-on? Do you have voltage to ground at either pin with your hot-wire in place?

On later models, the fuel pump is run by jumping Fp to B+. B+ is powered through the EFI (MFI) fuse. But if the EFI fuse is out, you don't have ignition either, so it won't run at all.

When you "jumped" your AFM, which wire went to where? http://web.archive.org/web/201209071...33volumeai.pdf (You obviously had a short to ground.)

 

Thanks for the welcome! Wish it were in better circumstances.

I do not have the round plugs pictured.

Excuse the mess as I try to chase or locate a short,



I do have voltage to the diagnostic FP area with the hot wire hooked up. I only have about 2.8v on the B+ side.

This is the AFM connector I bypassed going by the instructions I found online,I just used a loop of wire.

 

The 88 is a bastard of first gen and what became second gen, you should have the dlc1 on the battery distribution block.

The power wire to the fuel pump runs thru the cab, I don't recall off hand if that's under the seat or under the door threshold from on this. It's very likely you have a short to ground in this run of wire.

You can test for this by unplugging the fuel pump at the tank end and the COR. This isolates FP and you can do short to ground (resistance) checks from either/both ends.

 

I tested this by feeding the FP in the diagnostic port 12v from battery, the COR activated and the truck started.

I don't have B+ 12v at the port for some reason.

 

When you said you "hot wired the pump" I except most of us assumed you ran a wire from the battery to the pump and not "used the FP diagnostics port..

FP is down stream from the relay, you by pass COR not trigger it. You need to look at the schematic again.

You had voltage here (B+, on the FP connection) at one point, where you said you jumpered the fuel pump in the AFM (and showed the fuel pump diagnostics connector) and blew several fuses.

So now you have two problems, a shorted B+ and an intermittent short to ground on FP

 

I have never had voltage at the B+ or the FP in the diagnostic port other than when I fed it there with a wire.

Initially I did simply wire the pump to the battery,then I started working backwards.

It will run the same with a jumper in the FP port,or wired directly to the battery.

It will not run,and immediately blows fuses if the AFM is jumpered.

It does nothing if the AFM is hooked up correctly.

 

O-1 pin 1, R-1 pin 2 carry power for the pump. (R-1, pin 5 is the ground) Subject to some wear and tear from passengers, cargo, and rodents. Another point of contact and possibly damage is above the fuel tank.

 

Think you're hooking up something wrong at the AFM when trying to jump FC to ground.



The green FC (pin 1) wire only connects to the COR trigger wire and provides ground via the white-black.

Without going out to check these should be the outboard two pins, but you can check by probing the AFM by clipping the ohm meter and flipping open the vane. It should go from OL (open) to something near zero ohms immediately.

B+ comes out of your EFI relay, directly feeds the ECU and indirectly feeds some other things via a connector (I want to say N1?) A couple of easy checks are the DLC (up stream of the connector via a splice) and VSV's.

A known fuse popping issue is the B+ feed to the oxygen sensor shorting out

 

Not sure what happened, but I had a buddy come out with a fancy multimeter/probe thing, we tested the AFM, it passed, tested the main relay, passed, tested COR, passed. Looked for continuity, had it everywhere, pulled the starter trigger and cranked it, heard the fuel pump run.

So I guess whatever caused all of it is fixed. I pulled the upper intake to be able to see the harness better while checking for shorts, my plan is to slap it back together and roll.

Thanks everyone.

 

Buy a fire extinguisher, please.

 

I pay insurance every month for a reason.

Not really sure what part of everything passed every test is unclear to you, probably the same part that was unclear about how the wiring to the fuel pump was in tact and functional.

So, again, thanks for nothing.