Starting Problems,possibly fuel systemPic

Blue347stang · Mar 31, 2004

A couple months I re-routed my engine compartment wires and now my car won't start. I have spark, timing is set to 0. Now I had fuel pressure but after 10 tries, the fuel pump didn't prime and didn't have any fuel pressure. So I replaced the fuel pump relay and EEC relay but still nothing. I reset the Ertia switch and that didn't work. So I go back to the fuel pump relay, I checked it connected with a tester. The orange/light green wire has juice but the rest of the wires don't, even with the ignition on or off. Here is what I'm talking about:Fuel Pump Relay Diagram. Ain't I suppose to have power going to any other wires? Or did my fuel pump go out? or Is my computer fried? Thanx

By the way, This is on a 1989 GT 5-speed with a A9P computer.

cjones · Apr 1, 2004

you should have constant power at O/Lg.

you should have power at R/Bk. if you don't then check the EEC power relay.

T/Lg is grounded through the computer.

Pk/Bk goes to the fuel pump.

EEC power relay-
R/Lg : +12v in run/start
Bk/O : +12v all the time
Bk/Lg : ground
R and O/Bk : output power from relay (+12v)

Blue347stang · Apr 1, 2004

cjones said:
you should have constant power at O/Lg.

you should have power at R/Bk. if you don't then check the EEC power relay.

T/Lg is grounded through the computer.

Pk/Bk goes to the fuel pump.

EEC power relay-
R/Lg : +12v in run/start
Bk/O : +12v all the time
Bk/Lg : ground
R and O/Bk : output power from relay (+12v)

Thanx for the info, will check on the eec relay though it was replace, if not it could be the computer.

TheUser · Apr 1, 2004

for what it's worth dude, make sure your computer wiring connector is plugged in well...tighten that bolt up...mine wouldn't start and I tightened that up and it starts now...I took it off and didn't get it back tight enough

oh and shouldn't timing be set to 10-14 degrees BTDC? 10 is stock...

Blue347stang · Apr 4, 2004

OK I checked my EEC Relay and its working fine. Now the Fuel pump relay, the Pk/BK wire, which goes to the fuel pump and #19 pin on EEC has no reading, is this right? I even check the #1 pin on the eec, and it has power and it has a good ground too. Can it just be my fuel pump that it went out? I mean when my car was running the engine would spin over like 4-6 times before it started up. The fuel pump was installed in 2000 and it's from BBK (in-tank 255 lph), Whats a good pump I can buy? Can I go with a in-line pump and leave the in-tank pump?

TheUser · Apr 4, 2004

no reading doesn't mean bad fuel pump, it would have voltage whether the fuel pump is bad or not...if the key is on. You had the key on when you tested it right? Also, the pump primes when you turn the key on, and then shuts off, so you might have to actually have the car running and probe the wire Might also check the resistance (ohms) of the pink wire to see if it's just a bad wire.

Blue347stang · Apr 4, 2004

TheUser said:
no reading doesn't mean bad fuel pump, it would have voltage whether the fuel pump is bad or not...if the key is on. You had the key on when you tested it right? Also, the pump primes when you turn the key on, and then shuts off, so you might have to actually have the car running and probe the wire Might also check the resistance (ohms) of the pink wire to see if it's just a bad wire.

The key was on when I was troubleshooting. I checked the wires by the fuel tank and I also had no voltage. The fuel pump relay I installed was from Oreillys auto parts but I think they gave me the wrong one. The reason is this, I removed it and used my tester kit from school (eletronics) which has 12v,5v, ground and switches. I applied 12v to terminal #4 on the relay assuming that it's the battery. Then I applied 5v to #2 with that in mind I checked for voltage with my DVM. Well instead of getting readings on terminal #3 (Fuel Pump Terminal), I got on #1 (Self-Test/EEC pin #22). So I'll probably buy another relay.

cjones · Apr 4, 2004

try this,

ground the selftest connector (T/Lg) in the engine compartment.
turn the key on.
recheck voltages
(by grounding the self-test connector you are bypassing the 2 second key on ground of the computer and giving the relay a constant trigger signal)

Blue347stang · Apr 5, 2004

cjones said:
try this,

ground the selftest connector (T/Lg) in the engine compartment.
turn the key on.
recheck voltages
(by grounding the self-test connector you are bypassing the 2 second key on ground of the computer and giving the relay a constant trigger signal)

Won't that cause a short? I have voltage on the #1 pin/terminal (T/LG). Also another thing I notice was, when I checked the MAF,BAP,ect... voltage was real low. Maybe I fried the EEC? But then again I do have almost 12v to my coil and other stuff.

Idwitheld-1` · Apr 5, 2004

cjones said:
try this,

ground the selftest connector (T/Lg) in the engine compartment.
turn the key on.
recheck voltages
(by grounding the self-test connector you are bypassing the 2 second key on ground of the computer and giving the relay a constant trigger signal)

Great tip. I never knew this. Thanks!

cjones · Apr 6, 2004

Blue347stang said:
Won't that cause a short? I have voltage on the #1 pin/terminal (T/LG). Also another thing I notice was, when I checked the MAF,BAP,ect... voltage was real low. Maybe I fried the EEC? But then again I do have almost 12v to my coil and other stuff.

if you unplug the relay i bet you won't have power on the T/Lg terminal. if you do then you have more problems. that wire has to be grounded for the Fuel Pump relay to trip and give power to the fuel pump.

was the voltage on your sensors 5.0volts?? if so, don't worry that's reference voltage. on the MAF term. A = +12.0v, B = ground, C = Sig Rtn, D = Signal

Blue347stang · Apr 7, 2004

cjones said:
if you unplug the relay i bet you won't have power on the T/Lg terminal. if you do then you have more problems. that wire has to be grounded for the Fuel Pump relay to trip and give power to the fuel pump.

was the voltage on your sensors 5.0volts?? if so, don't worry that's reference voltage. on the MAF term. A = +12.0v, B = ground, C = Sig Rtn, D = Signal

Well I found out that the Pk/BK wire which goes to the fuel pump is grounded (-). I unplug the harness at the gas tank to see if maybe it was the pump that was causing that but it wasn't. Everything else is fine all the sensors and relays have the right voltage going to them.

Blue347stang · Apr 10, 2004

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