[Beau]

Man Supra's piss me off, GM ignitions are awesome, you could hold the plug under water and it would still fire.

 

[FLINTSTONESKID]

May be unrelated and this only happened once but my car shut off on me the one morning during driving, thankfully i was just pulling away from a light and not driving on the highway, at any rate, i tried to crank it over and it wouldnt start. my buddy who was following me, puched me to the side of the road and we looked at the fuses, the relays and grounds and nothing. i then noticed that my fuel pumps werent turning on with the key. i grabbed the AEM from off the floor and jus jiggled it a bit and the car started up. there didnt appear to be any loose wires on the harness and it hasnt happened again but maybe it is worth looking in to.....anyway, good luck, this kinda stuff def sucks.

 

[ovey1]

did you unplug the aem from the wiring harness cause like some of the other guys said moving around the harness but I unpluged the harness and it started i was amazed. Just a thought get the new plugs in there and try this it might work cause the aem is a picky little bitch I also had to put padding under the ecu cause it would randomly kill the fuel and the car would die so hopefully it works for you.

 

[mac_05evo]

check all your grounds ..

I've already went over everything looking for loose wires but will double check again.

Mac,
Did the car even try to fire after the pumps ran? The fuel system should have built some pressure after they ran. With my car this was sufficient for the car to start for ~1-2 seconds. Do you have a fuel pressure gage? If you do look at it after the pumps run. It should hold pressure well long enough for you to get out of the car and look in the engine bay if that's where it is.

The next thing to do is try starting the car (be sure the active box is checked again) and record/monitor coil 4 while you are doing it. If it doesn't turn ON while cranking then that explains why you aren't getting fuel.

Daniel

The car just cranked over and over, honestly it didn't sound near as promising as what it had earlier in the week when it would start up for a few seconds. Unfortunately I do not have a fuel pressure gauge I did watch the Coil 4 parameter while trying to turn the car over and it would change from OFF to ON so it is kicking in. I may try to pick up one of those cheap fuel pressure gauges like Ron suggested and see what happens.

You pulled a plug, it smelled of gas. Its very possible they got fouled when you kept trying to start it. Its a turbo car, with very little gap. Replace the plugs with new ones

Pulled the plugs after a few mins of trying to start it and they all smell like gas...
I wiggled them around and unplugged and reconnected every coil connector but the car still won't start. I have all the plugs out of it currently and they all look fine other than being a little black and smelling like gas. I guess I'm going to try and swap them out and see if that has any affect but I'm betting it probably won't.

I'm going to replace the plugs in the next day or so when I have time. I thought I had an extra full set there at the shop with me but I only had 4. Also one of the coil connectors broke as I removed it and my only spares are at the house. The plugs smelled pretty badly of gas but didn't look to the point they were fouled.

did you unplug the aem from the wiring harness cause like some of the other guys said moving around the harness but I unpluged the harness and it started i was amazed. Just a thought get the new plugs in there and try this it might work cause the aem is a picky little bitch I also had to put padding under the ecu cause it would randomly kill the fuel and the car would die so hopefully it works for you.

I will take loose/wiggle the harness around next time I mess with it and see if that will possibly help. Thanks for all the input guys!

 

[Slither]

It doesnt take much at all to foul a plug when running a small gap, I used to have to replace mine every 2-300 miles or I would start to lose power out the ass before installing the DLI

 

[mac_05evo]

It doesnt take much at all to foul a plug when running a small gap, I used to have to replace mine every 2-300 miles or I would start to lose power out the ass before installing the DLI

Yeah I agree. I run a DLI as well but still change my plugs every 2-3k miles (basically every oil change).

 

[TurboPK]

i had this similar problem,i installed an Optima yellow top battery,and the problem never came back

 

[dave2]

To me if you undid the connectors again on your coil packs and your prpoblem got worse it has to be in that wiring harness. Mine was a bitch to get started just took a bunch of moving it around and finally I got it to make good contact but it finally started. You may trace that harness and see how it looks you may have a break in it somewhere. also you may get someone to crank the car while you move the harness and see if you can get a hit out of it. If it does you know where to look from there.

 

[mac_05evo]

UPDATE: About 99% sure it's fuel related. I replaced all the plugs, wiggled the harnesses/wires to the AEM and coil connectors and still wouldn't start. I can spray some starting fluid in the intake manifold and the car will start up and run for a few seconds then die, repeat process and bam starts right up again. I have a fuel pressure tester coming later this afternoon and will try to figure out how to use it. Anyone know where the little valve thing is on the BoostLogic fuel rail to hook the gauge up to?

 

[SupraWood]

Is coil 4 turning on when you crank the engine? Do the pumps prime when you turn the key to run before cranking?

Daniel

 

[Slither]

DIdnt you say the plugs were wet with fuel? That should rule out a pressure problem(since the starter fluid will get it to fire)
Bad gas maybe?

 

[TRINISPEED]

On my last SC300 the pumps would prime and i even disconnected the fuel line and saw the gas coming out, but the car still wouldn't start.
I did the 12 volt direct power to the pump and it cranked right up.

 

[mac_05evo]

Is coil 4 turning on when you crank the engine? Do the pumps prime when you turn the key to run before cranking?

Daniel

Yes and yes to both of those questions. I can turn the pump on manually as well but it still will not start.

 

[mac_05evo]

DIdnt you say the plugs were wet with fuel? That should rule out a pressure problem(since the starter fluid will get it to fire)
Bad gas maybe?

The plugs weren't really wet but smelled highly of gas and were nice and black. I suppose it could be gas, you never know? I had just filled up maybe 20-30 miles prior to all of this starting.

On my last SC300 the pumps would prime and i even disconnected the fuel line and saw the gas coming out, but the car still wouldn't start.
I did the 12 volt direct power to the pump and it cranked right up.

How do you do the 12 volt direct power to the pump?

 

[Slither]

Honestly man, until you get a way to check for fuel pressure/injector firing and spark I would not replace anything else at this point.

 

[Slither]

The plugs weren't really wet but smelled highly of gas and were nice and black. I suppose it could be gas, you never know? I had just filled up maybe 20-30 miles prior to all of this starting.


How do you do the 12 volt direct power to the pump?

If you search back some posts of mine, you will see where I done a writeup to run all your gauges, pumps, etc.. off of one relay. I just use part of that distribution block to send the signal to twin 30 amp relays to turn on the pumps. I dont rely on my AEM to turn them on for me.
LET ME EDIT THIS PART FOR YOU A LITTLE CLEARER. What you want to do is use an add-a-fuse to a fuse that gets 12v(power) when you cycle the key forward. Run two wires to your relays where the AEM hooks into it now. This makes them cut on whenever the key is cycled forward

I am curious though, when you are trying to get the car started are you touching the pedal at all? Usually(on the EFI cars I have worked on) going WOT while cranking kills all injectors(might not be the case for a supra though). With my car I allways give it about 1/4 throttle until the car fires right up with my AEM, or I will vary the throttle from 0 to 1/2 throttle or whatever. Sometimes I dont think my car would start if I just tried cranking it.
Also, when you connect to the AEM, are any of your parameters red in the troubleshooting tab?

 

[mac_05evo]

Honestly man, until you get a way to check for fuel pressure/injector firing and spark I would not replace anything else at this point.

I've got to pickup a small adapter for the fuel pressure gauge so I can tie it into the back my adjustable fuel pressure regulator.

If you search back some posts of mine, you will see where I done a writeup to run all your gauges, pumps, etc.. off of one relay. I just use part of that distribution block to send the signal to twin 30 amp relays to turn on the pumps. I dont rely on my AEM to turn them on for me.
LET ME EDIT THIS PART FOR YOU A LITTLE CLEARER. What you want to do is use an add-a-fuse to a fuse that gets 12v(power) when you cycle the key forward. Run two wires to your relays where the AEM hooks into it now. This makes them cut on whenever the key is cycled forward

I am curious though, when you are trying to get the car started are you touching the pedal at all? Usually(on the EFI cars I have worked on) going WOT while cranking kills all injectors(might not be the case for a supra though). With my car I allways give it about 1/4 throttle until the car fires right up with my AEM, or I will vary the throttle from 0 to 1/2 throttle or whatever. Sometimes I dont think my car would start if I just tried cranking it.
Also, when you connect to the AEM, are any of your parameters red in the troubleshooting tab?

I'll look into that, I believe I remember seeing that post of yours a while back. Honestly, I don't understand a lot of that type of stuff though unless I see it visually but I'll take a look at all of it and see what I can figure out. Thanks for the suggestion and being patient lol.

When I'm starting it I do not touch the pedal at all. I stumbled across the setting for what you're talking about in my AEM. My injectors are set for anything past 80% throttle (TPS) the injectors will not pump. Normally I do not have to touch the gas pedal at all and it starts right up. I've tried cranking it with no pedal, to the floor, half, etc and doesn't really make a difference. When it does start up, if you get on the gas immediately (before it dies) it will rev up fine. None of the parameters in the troubleshooting tab are in the red and so far I haven't ran across any parameters that do not come up with the proper readings/reactions.

 

[mac_05evo]

Also, at the adjustable fuel pressure regulator, I took loose both of the lines going to it. The line that comes from the top left going into the FPR gas flows out of it like crazy when you turn the key on. The bottom hose (return I guess?) nothing comes out of when you try to turn the car over. Could that mean anything?

 

[Krister]

I had the same problem, turned out one of the hoses from the fuel pump was had come off in the tank so there was no fuel pressure.

 

[mac_05evo]

I had the same problem, turned out one of the hoses from the fuel pump was had come off in the tank so there was no fuel pressure.

Were you getting fuel pressure at the fuel filter and/or regulator? I'm just trying to figure out where all this gas is coming from when I disconnect the lines lol.