AE92 4AGE fuel pump fuse location

[BoostBoy]

Hey everyone,

Thank god forums like these are still around. This is my first post on this particular forum, but I have been a member of older ones for over a decade. Have also been a long time Corolla owner (have had a AE82, still have the 92, and had a Sportivo).

Anyway enough of the history lesson. My modified 92 has been sitting in my garage for 7 years. I have turned the motor over at various times and it’s always ran perfectly. In the last year I’ve had trouble starting the car and I really want to bring it back to life. The motor turns over, spark plugs spark, but the motor doesn’t start. My best guess is that it’s the fuel pump, as I can’t hear it turn on (it’s a Wahlbro 400hp pump). I’ve tried to find the fuse for the pump but no luck. My online research says it’s part of the EFI module, but maybe someone here can tell me for sure?

[SloRolla]

if you think it's the pump, pull it out and try it on a bench, with an external power and earth (not for very long so it doesn't burn it selfout)

[BoostBoy]

14 hours ago, SloRolla said:

if you think it's the pump, pull it out and try it on a bench, with an external power and earth (not for very long so it doesn't burn it selfout)

I'm pretty confident it's the pump, but thought it would be easier to check fuses first before pulling the pump out and possibly causing more damage.

After writing my post I did find a few wiring diagrams that showed a Circuit Opening Relay under the dash where the ECM is. Carbon can build up on the contacts which then stops it from making a proper connection. After cleaning that with a bit of sand paper I thought I would have solved my problem, but alas still the same issue :(

If there are no other fuses to check, I'll find a tutorial on how to pull out and test the pump. Thanks

[rebuilder86]

often the fuel pump does just die when sitting there. i wouldnt be surprised if it was that.
I've personally experienced it with my farm bashing pajero.
There is a connector somewhere where you short 2 terminals to activate the fuel pump relay.. This is from the MR2 manual but the same connector exists somewhere for you, so find it.
U should be able to hear the pump running when u connect these terminals, with the fuel cap off that is. If not, be certain the pump isnt running and its almsot certainly the pump itself. Relays fail from lots of use, pumps fail from no use or overheating.

[rebuilder86]

And to make it more complicated, the reason there is no actual "fuel pump relay", is because there are actually about 3 ahaha
so, the EFI main relay provides power to the fuel pump circuit opening relay (which to me is the closest thing to a fuel pump relay), which takes a second yes or no (on or off) signal from the air flow meter. (so that the pump turns off if the engine turns off and airflow stops)
But anyway, just connecting those 2 pins, bypasses the circuit opening relay and turns the pump on, sending all power needed through the wire u stab in to the connectors, so long as the EFI main relay is on (key is on)
The circuit opening relay is attached to wires on a yellow connector, close to the body of the ECU. so if this test successfully turns on the pump, but the pump doesn't work by simply turning the key to on, then locate this relay and replace it.

Edited December 27, 2017 by rebuilder86

[BoostBoy]

Mate you are a legend. This is exactly the kind of thing I was after. I did read elsewhere that I could short the Fp and B+ terminals (somewhere) to run the pump without actually pulling it out, so I will definitely try that and report back. Car has been sitting there idle for too long so it wouldn't suprise me either. Thankfully the actual engine hasn't seized. Yep should easily be able to test the Circuit Opening Relay as well while it's off the car, at least to see if the switch inside works. I've already found that one under the dash and it's easy to get to. I've heard replacement can be ~$100?? Not sure how true that is, but I'll cross that bridge if I have to.

Thanks again for the info. I'll report back with my findings.

[BoostBoy]

So I found the diagnostic plug and it looks like this 

I’ll try and clean it up and hopefully it will still work for me

[rebuilder86]

errrrrrm, has somebody put different coloured bubblegum in all the connectors???
Bugger that cut the wires and "macguyver jumpstart style it", like quickly touch them together and pull the AHHH face when you do it!

[BoostBoy]

Okay so this is what I have done so far after following the guides you posted (thanks!):

1. Shorted the terminals Fp and B+. Pump didn't turn on. I checked power going through the B+ terminal and all good.

2. Checked fuses EFI 15A, and AM7.5A and EFI main relay. All good. Relay closes as expected when powered on. I was unable to check Fusible link 1.25B as per the guide, because I don't know where that is?

3. Checked full operation of the Circuit Opening Relay as per the guide and it works.

4. Lastly I checked whether power was going through to the pump itself when Ignition was ON and I didn't get a reading? As can be seen from the pic below, I was getting no power to the blue/black stripe terminal, or the white/black stripe terminal (located underneath the back seat where the pump is). Should I be getting power come through on one of these terminals when Ignition is ON? I checked the white connector terminal too and no power to that one either. Indicates there's a break somewhere doesn't it?

How can I test the fuel pump itself on a battery? Do I leave it in the tank and just hook up power to the blue/black stripe and white/black stripe wires?

Edited December 30, 2017 by BoostBoy

[rebuilder86]

the pump.wont turn on unless the engine is actually running, oe the key has just been switched to on. (primes for a few seconds) can u get someone to turn the key to on for u while u monitor the connection with the multimeter. this will see if its getti g 12 v during those few priming seconds.

[rebuilder86]

but really when u jumpered that terminal it shouldve had 12 v then, did u test that connection when u had the jumper wire connected?

[BoostBoy]

Okay so turns out stupid me wasn't grounding the negative properly when testing. Retested simply by disconnecting the grey clip to the fuel pump with the 2 wires, then checking 12V at the terminal. The pump is getting power when the Ignition is ON. So now it looks like it's definetly the pump itself that is not working.

So what are my options now? Any way I can revive the pump?

[ke70dave]

nah just buy a new pump. 

Put old pump in bin:)

Any of the parts mobs will have one. try and get a reputable brand. Bosch if possible. 

[BoostBoy]

1 hour ago, ke70dave said:

nah just buy a new pump. 

Put old pump in bin:)

Any of the parts mobs will have one. try and get a reputable brand. Bosch if possible. 

It's not a standard pump. It's a Walbro 500HP. That might set me back $150-$200. I've seen a few youtube clips where mechanics have been able to revive a seized pump...I wonder if it's worth trying.

[ke70dave]

Is it just a standard 4age? If it were me id put an oem sx pump. 

Edited December 31, 2017 by ke70dave