My GTS 4AGE WILL start but WON'T STAY ON

[im2bad4ya]

Hey everyone. FULL DISCLOSURE: I am new to AE86's, this is my first one but I'm mechanically inclined. I also own a 1.8 Corolla among a few other toys.

So I got this car as a project. I was told that it just needed a fuel pump. The car cranks, turns over and starts but then dies shortly thereafter and I've had a car that did the same in the past that ended up needing a fuel pump. So in my quest to fix this car I came onto a surprise, this car NEEDED MORE than a fuel pump. Pic of the tank dropped and what came out of it:




So I took the tank to a radiator shop to clean out all the gunk and rust that was in there and I ordered myself a new fuel pump. I cleaned up the fuel pump bracket and sender bracket that was caked in rust and put everything back together, but the results are the same.

Click this pic so you can see a video of the problem.



I noticed that the EFI relay was extremely hot, so I could have an issue with that and will swap it out with a known working relay. I also read on some other forums and threads that there is a specific ground wire that needs to be hooked up (not sure if to a sensor or the engine block) that makes the fuel pump function with the key in the ON position, maybe someone can clarify this for me.

Along with swapping out the EFI relay I will also get a new fuel filter and try using starter fluid to see if the car stays on or not. Is there anything else I should be checking or anyone can lead me in the right direction? I also have a spare MAF and both give me the same result, doesn't stay turned on.

[aceforever]

Could it be the fuel pressure regulator?

[MisterJerk]

"that makes the fuel pump function with the key in the ON position, maybe someone can clarify this for me."

jumper the Diagnostic plug. this will put the engine into diag mode and will bypass the AFM fuel pump switch.

I think you need the FSM(link to it is in my sig)

Kind of sounds like the car is running off the cold start injector.
with all the crap in the fuel tank, check the fuel filter. should replace it, maybe flush the lines as well.
Also check if you are getting anything from the injectors.

[im2bad4ya]

So I've gone thru a few things and it's better than before but not yet 100%. I replaced the fuel filter and now the car stays on longer but still not the way it's supposed to. I guess my next plan is to remove the fuel rail and clean out the fuel pressure regulator and injectors. I will post up a video of how it turns on before I do this so you guys can see the before and after fuel filter replacement.

Also I wanted to see if anyone knows where this ground clip goes:




I also inspected the ECU and there happens to be a burnt out resistor, would anyone know what this is for or if I can solder a replacement in?

[jondee86]

The R515 resistor.... read all about it here...
http://www.aeu86.org/forum/showthread.p ... 897&page=2

You jump the Fuel Pump test plug to make sure the FP stays running
when the key is ON.

Engine sounds like it is firing off the cold start injetor and then dying
because the main injectors are not able to deliver enough fuel to keep
the engine running. Could be clogged injectors ? You could try pulling
the fuel rail and injectors assembled together. Then take the injectors
out and tip the fuel from the injectors out on a clean cloth, and see
what comes out with the fuel. Brown/rusty mud would mean injector
cleaning is required.

Check the fuel rail as well.

Cheers... jondee86

[Deuce Cam]

I'm not sure what that ground is for, but the other end should come off the part of the harness that runs across the front of the valve covers next to the dizzy.

That ground wire broke on me once when I was detailing under the hood and the engine wouldn't start.

[im2bad4ya]

You jump the Fuel Pump test plug to make sure the FP stays running
when the key is ON.

YES!!! this was it! I jumped the fuel pump and car stays on. So I guess this means the COR under the passenger dash has to be replaced? Is it possible to take apart and fix or should i just get a replacement? Now that I know the engine stays and on runs I can start really fixing this car back up.

I added the video of how it runs with the fuel pump jumped:




Will also have to look further into the VTIS issue and a replacement resistor.

[jondee86]

Normally, when you crank the engine, the flap inside the AFM
opens and closes a switch inside the AFM that grounds one of the
coils in the COR to power up the fuel pump. Before replacing the
COR find the ground wire from the AFM and check that it is good.



Maybe its this plug that needs to be connected ?

Cheers... jondee86

[im2bad4ya]

Maybe its this plug that needs to be connected ?

Yeah, if you take a look at my original post I was trying to figure out what connects to this. I looked on my harness and didn't find the corresponding plug, maybe the plug itself is cut. I will look on the harness again but I know it would have been obvious and I would have seen the matching connector if it was there.

Also I wanted to see if anyone knows where this ground clip goes:

[jondee86]

Don't get too tied up with the yellow plug. The main thing to check is that
your AFM is switching 12V to ground when the flap opens. You should have a
seven pin plug on the AFM. Pin 1 should be a brown wire that connects to
ground with next to zero resistance. Pin 2 should be a green-red wire that
has 12V when the key is ON.

When you test the resistance on the AFM pins between Pin 1 and Pin 2, you
should see the resistance change from infinity to near zero as you push the
flap open by hand.

Cheers... jondee86

[im2bad4ya]

You should have a
seven pin plug on the AFM. Pin 1 should be a brown wire that connects to
ground with next to zero resistance.

This was my problem. That ground wire and connector that's supposed to to be on the harness that goes to the driver side comes from the brown ground wire on the AFM. It was cut on the harness so I made a new wire and connector (it's the red crimp connector in the pic). I'm glad to say my car runs on it's own now without having to jump the fuel pump or relay. Thanks for the help jondee.