HI everyone, new to this forum, but not new to Toyotas, or the All-Trac.

I recently have been having trouble with our 1990 Corolla All-Trac, which has the 4AFE engine with fuel injection. I posted this problem to another Toyota forum but they were not any help, so I thought I would try it here for those of you with EFI experience.

Here is the background (I do not think it is relevant, but it might be), we have owned the cars for several years, I reringed and installed new bearings and seals several years ago and installed a rebuilthead (The engine was in bad shape when we got it).   it has been a daily driver since and has been reliable, but I accidentally overheated the All-Trac last winter (leaky hose) and than it needed a head gasket, it was still running but I parked it anyway. It sat for six months until a few months ago I finally replaced the head gasket, all went routinely, I replaced some bad hoses as well. It went back together normally and it started roughly and I found a bad vacuum leak around the number 4 injector grommet. I took it out and wiped all the grommets with RTV, put it all back carefully and it ran fine. I drove for about 40 miles, with multiple starts and stops, and all seemed normal. I parked it for a few weeks and arranged to have the windshield replaced (it is full of cracks), but that day it would start but would run weakly and than die out. I could not keep it running, even with pumping the pedal.

I check for spark and got a strong yellow/white spark, I squirted starting fluid into the intake and it started and ran strong for about 10 seconds. I repeated this several times, it appears only to run when there was starting fluid present in the intake. So it appeared no or weak fuel supply.

I replaced the fuel filter, no change. I replaced the MAP sensor (I had a spare one, and it is easy to change), same results. When I replaced the fuel filter the line had good fuel pressure, and when I turned the key I could hear the tank mounted pump running. And the fuel pressure returned to the injector manifold.

So I figured it could be the signal to the injectors, I checked all the system fuses, connectors,and even swapped out the system relays (I also had some spares).

I got a spare ECU from the local Pull-A-Part (only $10 so I thought it was worth a try), but it behaved the same with the replacement ECU. Since ECU failures are rare I figured that it was unlikely both were bad, even though both were used units.

I know sometimes the fuel pump can work but not develop enough pressure, and I had a spare pump from a Corolla tank I bought some time ago for my Tercel4wd EFI conversion. I was hoping to avoid it because you have to drop the gas tank to replaced the pump. After everything else failed to get it to start I went ahead and replaced the in-tank fuel pump. I bench tested the replacement pump first in a can of fuel, and a fuel pressure gauge on the outlet. With 12v it pumped to 70 PSI, so it appears good. After I put the new pump in the car started, ran good for a few seconds, went weak and than died out again.

I than replaced the fuel pressure regulartor from one off the 4age engine that will eventually go into my Tercel (they are slightly different design, but it fit and should work the same). And I got the same results.

So at this point I have replaced the fuel filter, the ECU, the system relays, the fuel pump, the pressure regulator, and the MAP sensor. I have doubled checked all the system connections, relays and system fuses, and all the vacuum lines. And it still acts the same, starts weakly and than dies out, runs with starting fluid in the intake.

I can not think of anything left to check or replace, and it is not like I am not familiar with the engine systems. Are there any sensors or other components that will not allow it run? AFAIK, even with failed sensors it will still run, just poorly.

Are there any other parts I should test or check or replace? I am stumped.

The service manual is all but useless.  thanks for any help or ideas.

Have you tried unplugging the MAP sensor to send the car into open loop?

Windsheild cracked?  Is there some rust around the winshield ?

Have you ever thought that water or moisture could get in your fuse box (kick panel)?

the only problem similar to yours that I experienced was related to my fuse box. When I start my car and I turn on my lights, the engine stopped.

I removed all my fuses, cleaned the fuses box assy and the problem disappeared... at least until today

I'm probably not a big help for you but it is something more to consider

It seems like the engine is getting fuel, are the injectors working correctly?  You can check them with a meter.
Are there any clogged or twisted hoses?
What about spark, idle, and timing?  

Sounds like you may have a large vacuum leak somewhere. You can trickle water along the intake manifold gasket and injectors to try to locate a leak. Check the brake booster vacuum line and the PCV vacuum line as well. Have someone try to keep the engine running while listening for a leak.  Good luck.

Could also be a stuck open egr valve.

Could be cables - solonoid - that sort of thing.. I mean you've checked the pump, changed ecu's. You're getting a good start but then it dies...solonoids can behave like that, So the ECU's sending the message alright. Pumps good but somewhere the signals getting f**ked up They handle the first signals but gradually get weak.

Check all your cables, have you got a voltage meter or do you know a sparky mate that can help you run some checks?