Fox T-Bird/Cougar Forums

88 XR-7 5.0. Engine cranks but no start. Do not hear fuel pump relay or fuel pump "prime" when key turned to on.
Ground the tan wire at self-test connector with key on, no relay, no pump. Thinking fuel pump relay, right?
At the fuel pump relay connector in trunk, jump yellow (hot at all times) with the pink (to the pump).
Pump runs, car starts. Still thinking relay. Replaced relay, no change. Checked red wire (voltage with key on) to the relay, nothing.
Checked inertia switch, not tripped. Unplugged inertia switch, has continuity across terminals. Shake switch, button pops, switch opens.
Jumper inertia switch wires (pink w/ black stripe), no effect. So now I'm looking at the red wire going to the fuel pump relay.
With relay plugged in, jumper from yellow to thin red with key on, relay clicks, pump runs, car starts.
Now what? Ignition switch maybe?

Here are the 3 evtm pages related. As you can see there is a splice and another connector involved, check there. C455 is located under the right side of the dash, possibly near the PCM, Splice S132 is located in the engine bay on the same side as the battery.  These places are where I'd check, you're looking for battery voltage on that red wire, check for a poor connection, damaged/pulled out pins at  c455, and look for corrosion in the splice when you find it.  You may also test resistance across the circuit from point to point in the circuit, but make sure the system is de-energized.  As a last resort, make an overlay, but keep it in the same circuit. find a good place where the circuit has good continuity to the relay and splice a new wire from there to a point in that circuit where you have good working power. You've got a lot of other loads in this circuit, so be careful what you cut.  If you cut anything, cut the circuit off at the down-circuit side of the overlay, and make sure to tape the loose end off and secure it to the harness safely.  Ideally, you'll want that overlay to be as short as possible.

Check for KEY battery on the PUMP RELAY COIL WINDING. If it is their ground the other side of the relay coil ckt. Does the pump run?? If so and you back probed the ALDL connector you have to go to the ECM pin 22 i think and back probe it with a test light to ground. If the pump does not run. You have an open circuit some where. If it runs the ECM is not providing a ground!!

Like I said, we troubleshoot the relay power circuit.  This last step in your post verifies a couple of things: The Fuel Pump, Relay Source Power, Relay Trigger (from PCM), and the relay itself.
And that points to an open in circuit 361 (R) since the engine runs when you're feeding power to the relay coil, I'd rule out trouble between the splice and the eec power relay, but check the splice for wire boogers, and check connector C455.

I appreciate the replies from all.  I do have an 88 EVTM.  So if I understand this correctly, if the red provides key-on battery voltage to the relay, the relay trigger from the EEC (on the tan) is ground?

Yes, but if it starts and runs with Y jumpered to R, we know that the PCM is sending that signal and it's working.

Copy that.  Plan to get on it again today.  Thanks again.

If jumping Y to R and it runs the inertia switch should be checked for power through it. If it is their go to the relay their should be 2 battery's feeding the FP relay. check to see which one has no battery, This is a simple slave relay circuit. One of those batterys is missing. Also check for corroded terminals on the relay plug!!

Straight battery on Y and key battery on R One has no battery. Test it !!!

Sounds like no battery on the R terminal. The Y should have battery all the time!!

@ Tom
Take another chance to read his entire post.

@ Tom
Take another chance to read his entire post.

WHY???? He has a missing battery.

The pump runs when he crosses the relay battery terminals. Relay energizes from constant battery so i am assuming the KEY battery is missing. Once again a simple slave relay circuit.

R battery energizes the relay coil. He says when jumped the relay energizes. So that battery is missing. When jumped from Y the battery energizes the FP RELAY. BINGO either the enertia switch is NG or the wiring is NG. Did he check the battery in and out of the ENERTIA SWITCH. Using an OHM meter is not the right way to test the INERTIA SWITCH. It might ohm out but not pass the battery. JUST SAYING. A simple test light will fix this issue in 2 seconds as to where the issue is??

Everyone step back and drop their weapons!
 
As I said, I appreciate the replys. Now an update. Ran a replacement red key-on-battery to the fuel pump relay to get the car running. (Do not ask where it is connected, it is only temporary.) So the fuel pump relay functions as it should. I would assume the ground signal from the ECM is operating properly as the pump "primes" when key is turned on then shuts down if key is not turned to start. Now the way it is configured the inertia switch has no effect, plugged in or not. I KNOW THIS IS NOT CORRECT. So the inertia switch must be in that key-on-red between splice 532 and the relay in the trunk, if I'm reading the EVTM correctly. Those pink/blacks coming from the inertia switch change to the red (361) at connector 491, which I haven't found yet. So absent a bad wire and/or connection, I probably have a bad inertia switch.
 
....check the battery in and out of the ENERTIA SWITCH. Using an OHM meter is not the right way to test the INERTIA SWITCH. It might ohm out but not pass the battery. JUST SAYING.
 
Tom is correct, I only connected an ohm meter across the terminals of the inertia switch while it was unplugged and got continuity. So I need to go back and test for voltage in and out. By the way, the connectors are virtually pristine, that fuel pump relay suspended up there in that trunk keeps it clean I guess. It's back on the OE one for now.  I will crack this nut, because even though it is 24 years old, I miss driving this car, but I can't deal with a jury-rigged half-assed repair.

Good now all you have to do is either wire your test wire to the inertia switch and neaterize it and your safety switch will work. OR trace down the OPEN. Your choice this will also check if the inertia switch is working properly. Personally i bypass the switches in my car. And yes if the ECM is in control of the pump it will time out without an RPM SIGNAL FROM THE ENGINE. Thanks Tom

hwy73 incase you haven't noticed, the location of connectors and splices are listed in the back pages of the EVTM. The connector location will also give a page number for a picture of it.
C491 is a gray two terminal connector. It will have two red wires on one side and two pink wires on the other. Unplug it and jumper the two red wires together and you will eliminate the inertia switch and the associated wiring. This should help narrow down the search.

 

HOLD UP****
I am still suspicious of the EEC relay although it goes against what i will say below, The fact of the matter is that the EEC relay contacts are the power delivery guy to the splice point you called out "S532"
Adding the temp wire where you are doing so could in effect back feed this circuit and become the new power source for "S532" and make the failure of the EEC relay contacts transpartent to you.

Check the EEC relay that its coil is gettiing power and its contacts are sending out power

Usually people have the other problem, and typically they have power on the coil input but if they manuall ground the tan light green in the trunk the relay will work.
This usually means someone was jumping the relay in the trunk and back feed the EEE pin 22 with battery power, this will hose up your EEC.

To the quote i pulled from your post,
~the EEC relay energizes from your ign sw and then delivers power out to the EEC.  The EEC boots up and is then able to seek its logic ground.  The programed tables are dumped out to run your car , perform pulse width modulation tasks on your injecters and all that other stuff.
~the tan / light green wire is not actually a chassis ground but a ground that is logically switched on or off and is offered to the fuel pump relay.
Im just responding to this because it seemed like you wanted a second opinion and your corret the way you invision it.  Just wanted you to know you dont have the "normal" problem i usually see.  The only real "kinda" fix to the normal problem is to bond the relay connector tan/light green to chassis ground in the trunk.  The other fix is to replace the EEC.  The car will run normal in either situation.

Below is a check list of what you have done and verified, like said make sure the inertia switch has power in and out but i thought you already confirm it does not.

If you do not have power INPUT to the inertia switch the the problem is upstream of the fuel delivery circuit.
If you have power on one side but not the other of the inertia switch, then just jumper past the inertia switch and the car should run, jam a paper clip in the connector to test this.  Remove your temp power supply before jumping the inertia switch

I agree with everyones posts though, just chiming in

everything with a green dot means you've verified it, good troubleshooting!

matter of fact, to confirm my EEC thoughts,
-leave the temp power in place
-trip your interia swtch to open

~~your car should not run because the other parts of your car such as eec power input will not be present, but, your fuel pump will run.
++you can add a test light at one of your easy injectors red wire to ground and see that they injectors dont get power but yet the fuel pump is running.
~~or just check any random spark plug and you will have no spark,,
again this is with the interia switch open and the temp power jumper you have in place.

This is why I recommended to keep the overlay "in circuit" and before the inertia switch.  He's right, if you take power from another circuit, you may back feed the circuit.  This circuit includes such components as the injectors, so it would be good to test for power from the eec relay out until you find a ball of snot or a cut circuit.  I still suspect the circuit between S532 and the inertia switch, because if the eec relay were bad, the engine would not run.  The eec would not power up, the injectors would have no power, etc.  As long as you can jump Y to R WITH THE INERTIA SWITCH OUT, and have the engine run, I'd say your eec relay is validated.  You're almost certainly looking for a wiring problem.

My "temp" red key-on overlay goes to the trunk and is spliced in at the fuel pump relay connector.  The original red is cut, so I don't think I would get a backfeed. Jcassity, I agree, if I had just tied in a new red, power could backflow through the circuit.  Now if you flip over to the 5.0 page of this circuit, there is the additional connector 491 which joins the pink/blk-s from the inertia switch to the red 361 circuit.  The car runs fine, everything else works, so I think I have it narrowed down to either the inertia switch itself, or the wiring loop from C491 to it.  I know I stated earlier that I jumpered the inertia switch with no luck, but I can't remember if I had the relay plugged in or not, so that is someting I have to verify, after returning the wiring to stock.  As it is now though, the inertia switch is bypassed.
One interesting thing though, my temp.,in-line fused, red key-on is connected at the fuse block at a point that is also "accessory-on".  So turning the key to accessory makes the fuel pump run.  Apparently the ECA creates that ground at pin 22 when it is powered down which trips the fuel pump relay if it is getting power at the red.  So I tried for a hot-in-run point at the fuse block but my initial attempt failed.  That red needs hot-in-run+start to keep the pump running as the engine cranks.  I did't have a chance to mess with it today, but I'm climbing in that trunk tomorrow in search of elusive C491!

Does the SES light come on when keyed??? If yes the EEC relay is working.  If no the EEC relay is KAPUT!!! If the back feed you performed is after the inertia switch and the inertia is tripped or removed you are not back feeding.

Check voltage at 37/57 of the ECM for battery when ignition is keyed. IS IT THEIR  YES EEC IS OK. Or is the SES light on when keyed  YES EEC IS OK!!! Install noid light in one injector connector crank does noid light blink?? Yes EEC OK. NO EEC KAPUT!!!

Best way to check the EEC relay is to see if the SES Light comes on with the ignition keyed. It supplies battery to pins 37/57 and powers up the ECM.

"Check Engine" light comes on with key on.  EEC relay can be heard clicking on under pass side of dash.  Engine starts literally on first crank, runs fine, "Check Engine" light goes out.  My plan is to reconnect stock red at fuel pump relay, remove temp red. Check for power on both sides of inertia switch.  If it goes in and doesn't come out, this would indicate to me a bad inertia switch.  If it goes in and comes out, then I will check at C491. If it comes out of 491 then the break is in the wire from 491 to the fuel pump relay connector which is literally across the top of the trunk from one side to the other.  If juice is not going into 491, then its broke between there and S532 going forward, which I guess is worst case scenario.  JHC, its taking longer to type out than to probably actually test, but tomorrow should tell the tale.

I haven't looked at mine in all this, but I seem to remember that C491 is the pigtail on the Inertia switch. C491 is where you're going to have your inertia switch disconnected from.  On 5.0L cars, between C491 and S532 is C455, which according to the location chart is under the IP on the right side, probably near the PCM.  Don't forget C455 in your check list.

Wire the dam thing to a KEY battery in series with a fuse and call it a DAY!!!!!!!!!!!!!!!

No sense in ripping the wiring harness open for this situation!!!

page 223 shows the location of c491.

Not a mystery.

HERE YOU GO> Connector C491: RH Front Of Luggage Compartment

 
well you should have siad that instead of "dont ask me how".

essentially you did end up performing the verification step and it proof tests as pass.

Jcassity what I meant when I stated "don't ask me where...." I meant tounge-in-cheek that I didn't want to admit how I "rigged" it to run. I know where I connected it, sorry for the confusion.  When the rain here stops, I should have an update.

Either way , i agree with Tom  but its nice to hunt down the break in the feed, you cant assure yourself it isnt gonna start arching at some point in the future.  You can fix with a bypass but what becomes of the feed when it decides to cause other issues.

its your call, doign the bypass gets you going sooner with the odds of the least risk.  I would gamble on the bypass and just make a note to yourself in your EVTM drawing what you did.  a few years from now your going to forget exactly what you did and how.

I had to take notes on what i did to jumper the Neutral saftey switch on the Kia sporage, connector was under the dash about 3 connections upstream of the range selector switch down on the automatic 4x4, would have had to drop the trans to get it out.