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fuel pump issues

Well, the TC quit and it's got no PSI at the fuel rail and i cant hear the pump priming. For the second time now i am going to drop the tank to have a look. It's got a brand new 230 walbro in it too. If this pump is bad, I might splice an in-line pump somewhere more accessible(like some mustangs have) or cut an access door in the trunk floor, cuz this is frustrating. Has anyone here ran an external fuel pump and how'd you do it? Oh...and i JUST filled it up.....nice.

fuel pump issues

Reply #1 –
Is this a ?
Old Grey Cat to this.88 Cat, 5.0 HO, CW mounts, mass air, CI custom cam, afr165's, Tmoss worked cobra intake, BBK shorty's,off road h pipe, magnaflow ex. T-5,spec stage 2 clutch, 8.8 373 TC trac loc, che ajustables with bullits on the rear. 11" brakes up front. +

fuel pump issues

Reply #2 –
Dude, check this out,,,helped me out...ALOT!!!!! (thanks to jcassitty)


locate yellow wire up at starter solenoid (feed to fuel pump relay)
locate fuel pump relay (upper rt side of trunk)
locate inertia switch (typically located just on the other side of your license plate area in the trunk)
Inertia switch gets power from a splice and then back to the output of the eec relay via the black/yellow wire.
Loate EEC relay (upper right hand side of instrument panel)
Identify the wiring plugged into the fuel pump relay
yellow (from solenoid to input relay contact)
Pink / black (from relay output contact to fuel pump input)
the fuel pump ground is obtained by the orange wire.
Red wire (relay coil input from inertia switch)
tan/light green wire (this wire is the key, ground supply to the fuel pump relay)
the tan light green wire is supplied a ground from the eec alone and nothing else.
Note the feel of warmth or not on the fuel pump relay after the car has been running for a while.


How it works,,,,,,,,,,,
key is turned on, the eec relay contacts close and power is delivered to the inertia switch and the EEC.
The eec now sees power.
the inertia switch is passive (a little ball sits in a seat and pretty much shorts the switch closed)
power comes out the inertia switch and travels through the coil of the fuel pump relay.
the eec knows it has power so it provides a ground to the fuel pump relay tan/light green.
magnetism takes over and the relay contacts are sucked together.
Now the yellow wire from your starter relay delivers power up through the fuel pump relay and out to the fuel pump.
the fuel pump sees power and it gets a ground from chassis.

I time delay kicks in and if the car is not running , in 3-5 sec, the fuel pump will stop running.

TO BYPASS THE TIME DELAY>>>for trouble shooting reasons.....................
locate your eec self test connector up near the driver side strut tower.
have your key off
ground the TAN light green wire (does this color sound familiar?)turn on your key
now your fuel pump will run full time without the engine running.

Turn your radio on to Any AM station that has very little static (try to not be in a garage with flourecent lighting)
wiggle the wire harness along the fuel tank, the inertia switch, the fuel pump relay, and possibly even the eec relay.
Listen for pops and crackle as you wiggle/pull test wiring. If you hear pops in an isolated area, there is your high resistance problem.

turn radio off
mesure voltage up at the starer solenoid (yellow wire)
measure the voltage at the yellow wire back at the fuel pump relay (input power)
measure power at the red wire fuel pump relay coil input (from inertia switch)
measure the voltage at the pink/black wire (relay output to fuel pump in)
measure power on the input to the inertia switch (red)
measure power on the output of the inertia switch (red)
make sure no power exists on the tan / light greed wire., measure for resitance from the tan/light green to frame ground

document your above voltage readings and let us know what you find.

your known good or "standard" voltage reading will be what was documented at the yellow wire at the starter relay.
Any voltage lower by 1.5v or more should be the focus of your troubleshooting.
your car should not be running during any of these tests.
88 sport,TW heads, comp xe270hr, cobra u/Tmoss ported lower, 65 mm throttle body, under drives,smog delete,
1.7 roller rockers, cai, k&n, bbk adj regulator, 76mm Pro-m,all MSD ign. MSD dist,18° base timing, 3g alt.1 5/8 ceramic headers, 255lph walbro, 2.5" h-pipe, flowmasters, silverfox valvebody, 3.73 gear,
http://i216.photobucket.com/albums/cc154/flipnbird/DSCF0185.jpg ( RIP : ( )

fuel pump issues

Reply #3 –
It's an 88 TC...holy smokes, i'm gonna have to read that a couple times!  So far I dropped the tank and the pump bench checked good.
I then had my assistant turn the key to "on" while I checked voltage thru the fuel pump connector. I saw 12 volts but it was only for a split second. The IRCM is closing the solenoid when I turn the key on...at least I hear it. The first thing I did was bypass the time delay and the pump wouldn't run.  Thanks for the above...i'll check it out tomorrow.  The car shut of but restarted, but the second time nada.

fuel pump issues

Reply #4 –
Quote from: lakenheath24;236318
It's an 88 TC...holy smokes, i'm gonna have to read that a couple times!  .


oh well,, might as well give up,, send er to the s heap,, its all over now,, no turning back,, the sky is falling,, might as well not get out of bed tomorrow,,,,,,,,,,,,,,,,,

But then you woke up and remembered ,,,,,,,,,You are an american!

fuel pump issues

Reply #5 –
What are you talking about...I ain't quitting, I'm just getting started!


  I get up EVERY morning...0530...because I get to make sure 54 F-15 Eagles are fed, watered and ready to go kick some ass. :beatyoass:

fuel pump issues

Reply #6 –
okay here's what i have..
1. Ran ground wire from EEC test port to battery ground. Solenoid clicks but pump doesn't run.
2. Checked for volts at TPS (got 5 volts w/key on).
3. W/pump still grounded, turned key to "on" and probed pink/black wire. test light comes on.
4. Checked inertia switch.  Ohms check between 2 pins were zero.
5. Checked inertia switch connector. One pin was infinite and the other was 1 ohm. 
6. Lastly, I grounded the fuel pump relay and ran a long wire to the hot side of the inertia switch. Pump ran as advertised.
Now what?!
The only thing I notice different is that the yellow turbo light doesn't light when i turn the key on. If i turn the ignition on and off 2/3 times it must be getting some fuel as it will fire but not run.

fuel pump issues

Reply #7 –
You aint gotta tell me nothing bout birds,, been there , done that a zillion times.:D :bowdown:


Your post is vague,


Quote from: lakenheath24;236394
okay here's what i have..
1. Ran ground wire from EEC test port to battery ground.
[COLOR="Red"]What color wire?[/COLOR]
[COLOR="red"]chassis ground right near the connector would have done just fine.[/COLOR]

Solenoid clicks but pump doesn't run.
[COLOR="red"]What solenoid,, are your talking about, relay?[/COLOR]

2. Checked for volts at TPS (got 5 volts w/key on).
[COLOR="red"]Why did you do that?[/COLOR]
what color wire?

3. W/pump still grounded, turned key to "on" and probed pink/black wire. test light comes on.
[COLOR="red"]Where, at the relay????  ok,, good so far, this tells me that the fuel pump relay yellow wire is getting power up to the input,,,, and the output goes directly to the fuel pump on the pink black.  This means that the inertia switch is making contact, the eec has supplied a ground to the relay and there is power up to the inertia switch via the EEC relay.[/COLOR]

4. Checked inertia switch.  Ohms check between 2 pins were zero.
[COLOR="red"]Technically meaning "shorted" correct?

was this with the inertia switch plugged in or not?[/COLOR]


5. Checked inertia switch connector. One pin was infinite and the other was 1 ohm. 
[COLOR="red"]Instructions did not say to do this,, and you lost me.[/COLOR]

6. Lastly, I grounded the fuel pump relay and ran a long wire to the hot side of the inertia switch. Pump ran as advertised.
Now what?!
[COLOR="red"]HOw,, what wires,, what color,,, lost me[/COLOR]
[COLOR="red"]I assume you ran a jumper wire from the output of the fuel pump relay directly to the input of the fuel pump,,, specifics again,, you prob bypassed the relay and the inertia switch.[/COLOR]

The only thing I notice different is that the yellow turbo light doesn't light when i turn the key on. If i turn the ignition on and off 2/3 times it must be getting some fuel as it will fire but not run.
[COLOR="red"]I dont know anything about this,,,,,yet[/COLOR]




Try to read the step by step and follow the instructions.
Im thinking you heard something click and you do have power up to the pump, so from there you need get a BFH and do it to it on the tank:D

fuel pump issues

Reply #8 –
I followed an old set of instructions I printed off NATO tech articles a year ago for my red t-bird.  Allow me to re-phrase my post.
First i ran a seperate wire from from the EEC test point to ground to make the pump run. It did not, but the fuel pump relay clicked on and off like it's supposed to. I clicked the relay on/off quickly several times in case it was stuck.
  It then said to look for the CEL to make sure the EEC is powering up and since I don't have one it said to look for 5 volts at the TPS between the orange/blk wires, and i got the 5 volts, apparently indicating the EEC was powering up properly. This is where i noticed that the yellow turbo light on the instrument cluster wasn't lit up like it normally is when i start the car.
  The next step was to trip the fuel pump relay(EEC test port to ground) with key on and back probe the pink/blk wire on the IRCM with a 12 volt light, which I did and it lit up. I assume this means the EEC is functioning properly.
 I then checked the Inertia switch and it checked OK according to the article. I disconnected it and got less than 1 ohm between the pins.(i think this is to make sure it isnt open even with the white switch pushed in). I then checked the wires going to the switch and 1 was infinity while the other was less than 1 Ohm. This step leads to the next step which is to...
 After determining which side of the Inertia switch connector is the power supplier, I ran a long wire from the battery to the hot side of the Inertia switch connector and the pump turned on and ran. The key was on and the fuel pump relay was energised with the afore mentioned ground wire.
 This is where the troubleshooting ended in the article. I will get voltages tonight for the test points listed above.
  I dont know if you read the original post or not but I had the tank down originally cuz i thought the worst(fuel pump). I pulled the pump and bench checked it and it ran when i hooked it up to a spare battery. I put it back in and had my wife turn the key on while i had my meter out checking for voltage at the fuel pump connector. I had 1 probe on each pin and when she turned the key to "on" i got 12volts for...i'd say...1 second. 

 Is there a ground somewhere I need to look for? This one has the dummy(me) stumped. :D

fuel pump issues

Reply #9 –
hey...anybody know where the chassis ground for the fuel pump is at on this car(88 TC)?  I see by jcassitys DIY that the pump gets the ground from the orange wire at the IRCM but where does it go from there?

fuel pump issues

Reply #10 –
Quote from: lakenheath24;236475
The next step was to trip the fuel pump relay(EEC test port to ground) with key on and back probe the pink/blk wire on the IRCM with a 12 volt light, which I did and it lit up. I assume this means the EEC is functioning properly.


This means the EEC power and fuel pump relays on the IRCM are picked. Having 5v on the TPS indicates the EEC is powered up.

Quote
I then checked the Inertia switch and it checked OK according to the article. I disconnected it and got less than 1 ohm between the pins.(i think this is to make sure it isnt open even with the white switch pushed in). I then checked the wires going to the switch and 1 was infinity while the other was less than 1 Ohm. This step leads to the next step which is to...
 After determining which side of the Inertia switch connector is the power supplier, I ran a long wire from the battery to the hot side of the Inertia switch connector and the pump turned on and ran. The key was on and the fuel pump relay was energised with the afore mentioned ground wire.


The pink/blk wire that you checked at the IRCM and indicated it had voltage is supposed to go to one side of the inertia switch. This is your hot wire to run the pump. Sounds like this is what you are missing. Check with your test light to see if one of the inertia switch connectors is hot.
If it is then your not getting through the inertia switch. If it is not hot you have a open circuit somewhere between the back and front of the car.
Since the pump runs the pump ground must be ok.

 
Quote
I put it back in and had my wife turn the key on while i had my meter out checking for voltage at the fuel pump connector. I had 1 probe on each pin and when she turned the key to "on" i got 12volts for...i'd say...1 second.


This is normal operation. The EEC will only keep the fuel pump relay picked for 1-2 seconds with the ignition in run if the engine is not running.

fuel pump issues

Reply #11 –
Quote from: flipnbird;236292
Dude, check this out,,,helped me out...ALOT!!!!! (thanks to jcassitty)


locate yellow wire up at starter solenoid (feed to fuel pump relay)
locate fuel pump relay (upper rt side of trunk)
locate inertia switch (typically located just on the other side of your license plate area in the trunk)
Inertia switch gets power from a splice and then back to the output of the eec relay via the black/yellow wire.
Loate EEC relay (upper right hand side of instrument panel)
Identify the wiring plugged into the fuel pump relay
yellow (from solenoid to input relay contact)
Pink / black (from relay output contact to fuel pump input)
the fuel pump ground is obtained by the orange wire.
Red wire (relay coil input from inertia switch)
tan/light green wire (this wire is the key, ground supply to the fuel pump relay)
the tan light green wire is supplied a ground from the eec alone and nothing else.
Note the feel of warmth or not on the fuel pump relay after the car has been running for a while.


How it works,,,,,,,,,,,
key is turned on, the eec relay contacts close and power is delivered to the inertia switch and the EEC.
The eec now sees power.
the inertia switch is passive (a little ball sits in a seat and pretty much shorts the switch closed)
power comes out the inertia switch and travels through the coil of the fuel pump relay.
the eec knows it has power so it provides a ground to the fuel pump relay tan/light green.
magnetism takes over and the relay contacts are sucked together.
Now the yellow wire from your starter relay delivers power up through the fuel pump relay and out to the fuel pump.
the fuel pump sees power and it gets a ground from chassis.

I time delay kicks in and if the car is not running , in 3-5 sec, the fuel pump will stop running.

TO BYPASS THE TIME DELAY>>>for trouble shooting reasons.....................
locate your eec self test connector up near the driver side strut tower.
have your key off
ground the TAN light green wire (does this color sound familiar?)turn on your key
now your fuel pump will run full time without the engine running.

Turn your radio on to Any AM station that has very little static (try to not be in a garage with flourecent lighting)
wiggle the wire harness along the fuel tank, the inertia switch, the fuel pump relay, and possibly even the eec relay.
Listen for pops and crackle as you wiggle/pull test wiring. If you hear pops in an isolated area, there is your high resistance problem.

turn radio off
mesure voltage up at the starer solenoid (yellow wire)
measure the voltage at the yellow wire back at the fuel pump relay (input power)
measure power at the red wire fuel pump relay coil input (from inertia switch)
measure the voltage at the pink/black wire (relay output to fuel pump in)
measure power on the input to the inertia switch (red)
measure power on the output of the inertia switch (red)
make sure no power exists on the tan / light greed wire., measure for resitance from the tan/light green to frame ground

document your above voltage readings and let us know what you find.

your known good or "standard" voltage reading will be what was documented at the yellow wire at the starter relay.
Any voltage lower by 1.5v or more should be the focus of your troubleshooting.
your car should not be running during any of these tests.


This write-up is for 3.8 , 5.0. and earlier Turbos but not for 87, 88 turbo.

fuel pump issues

Reply #12 –
unreal...i jumpered the inertia switch plug for the hell of it and guess what...starts right up. I'm happy and pissed at the same time. the first thing i did was push the white button in to reset it. oh well it's fixed!:D

fuel pump issues

Reply #13 –
you da man!!!!!:bowdown:

Im still not sure how you had power to the fuel pump with an open inertia switch but maybe Ill compare the turbo wiring and see whats different.

fuel pump issues

Reply #14 –
the only reason i even thought to try it was because the plug looked like it had shorted at some time or other...it was brown and slightly melted on the end.....no idea how that could happen to that particular switch. At least I am dusting off my troubleshooting skilz with this car! My guess is that as soon as voltage hit the switch it shut off...allowing a bit of voltage through but not enough to juice the pump.