Early 88 Merkur Scorpio Restoration Project

[FocusSVT]

These are the days thru the hour glass

HA!!!!

Yes they are

[FocusSVT]

Haven't had much to update these past months. Drive the car a lot. A/C worked like a champ all summer long. Here is a short list of things I have dealt with.

1) Found out the headliner material is really too thick. It caused a lot of stress on the overhead console and caused it to crack in half. When I replaced it I made sure to add a little room to the bracket so the stress is reduced on the console.

2) Been fighting a weird slow to start condition. Cranks fine, but doesn't catch for several seconds, or will catch after second flip of key. I think I have it narrowed down to a bad check valve in the fuel pump. (Doesn't hold pressure when turned off) I may just install a check valve inline where the soft line goes to the fuel rail. It needs replaced soon anyway.

3) Diagnosed an intermittent failing ECT sensor this weekend. The short version is the ECT would fail in just a narrow range of temperature, below normal operating temperature, but not when it was totally cold. Result was, the car would run fine when first started up, but as it was warming up the sensor would fail at a certain resistance, causing mayhem with the ECU, even to the point of stalling and be hard to start again, and then as the engine kept warming up the ECT would resume normal function. Pulling codes would reveal a stored code of 51. ECT out of range. Nothing in active memory. I cleared the codes and waited till the next morning. I started the car and let it warm up. Ambient temperature outside was in the low 40's. Sure enough, after 5 minutes of warming up, the engine started idling erratic and trying to stall. I kept my foot on the pedal to keep it running and after another minute or two it settled down. I shut it off and pulled codes again. The Same code 51 showed up. I had replaced the ECT a year ago or so with an Autozone part with a lifetime warranty, so I pulled the sensor and got an exchange. Popped the new one in, and the car runs great. No more crazy idle and stalling issue.

4) If finances allow, I am going to take the Scorpio to Jeff this spring and let him re-paint it. That should be very exciting.

Nothing else much going on, too much work, and the kids are growing up too fast!

[blugg]

For #2 it's very possible the rubber "J" shaped fuel line on the fuel pump to fuel sending unit may have a small spilt. What this may cause is some of the pressurized fuel to piss back into the tank. Had this happen. Replacing rubber line solved issue

[FocusSVT]

For #2 it's very possible the rubber "J" shaped fuel line on the fuel pump to fuel sending unit may have a small spilt. What this may cause is some of the pressurized fuel to piss back into the tank. Had this happen. Replacing rubber line solved issue

Based on your comments and my suspicion that the check valve may have failed in the fuel pump, I went ahead and replaced the pump with a new assembly I have been holding onto for a couple of years.







After a quick trip to parts store to get new retaining clips for the fuel line connectors at the pump, car starts right up, no leaks, and the fuel system is holding pressure now. When I get some time I will try to figure out if the pump was leaking at the pickup like Jeff suggested, or if the check valve is bad.

[FocusSVT]

Here is an interesting issue I have had with the Scorpio that has really reared its ugly head this last week. Over time I've had a recurring issue where the ECT will "go bad". At one point after replacing it, the ECM still showed it as bad and showed the IAC as bad also. I think it was Ed or Ken that suggested I unplug the ECM and re-plug it in. Thinking that it may have had a slightly bad connection after being in the same position for 25+ years. That seemed to work like a charm for the last year or so. Earlier this fall, I started experiencing random rough starts, and as it would warm up the car would stumble and try to die. The ECM stored an ECT out of range and when I tested the ECT sure enough, it was reading about 2x the resistance at temperature as it should. Replaced it and the car ran fine. The first cold snap we had back in November I started seeing a similar issue.

This time it would start fine, and when it got to a certain temperature warming up the ECM would go crazy and the car wouldn't run right until it warmed up further. It even left me stranded on the side of the road one morning. The ECM stored a code saying the ECT had an open circuit, I think it was code 52. After the car fully warmed up it was fine. I thought, since the only thing changed in the system was the ECT, maybe it was a faulty unit. I got it at Autozone, so it was under warranty. Got a new one, replaced, and the problem went away for a week or two.

Last week, started car up and it sounded horrible. Wouldn't idle, ran like crap, and finally died. Wouldn't restart. Didn't have time that day to diagnose, so I left it alone until Friday. Pulled codes on the car again, and got the ECT out of range again. It was a stored code and not a present code, it was also above 40' outside so I don't think the code was thrown because of it being too cold.

I measured the resistance of the ECT at the fuel injection harness connection on the left side of the intake manifold. I could see appropriate resistance values. I turned the key on and measured 5 volts at the sensor connector itself. My best thought is the ECT connector has a broken wire in it causing the loss of signal to the ECM.

This fuel injection harness that has the ECT, TPS, and all of the fuel injectors in it is kind of beat up. It has a couple of broken ends on it, so I thought replacing the whole thing would be good and I could further investigate any other wirings issues.

The donor harness had one broken clip on a fuel injector connector so I bought a BWD brand replacement last night. I soldered the wires together and then shrink wrapped them.

It is ready to go back in today. Otherwise I guess I will look at the ECM harness and see what I can there.

I hope this is it!

[Ed Lijewski]

Nice write up. Good luck that the issue is now resolved.

(Note: Trouble codes don't mean that a specific sensor is bad, rather that there is an issue somewhere in that sensor's system circuit. Remember that Ford "invented" the "wiggle test"...)

YMMV

[FocusSVT]

Well, that was a long weekend for no Bueno, ECM is not seeing the ECT sensor. I guess I need to investigate the harness at the ECM. I found and purchased a breakout box on Ebay tonight.

[merkurdriver]

Once I replaced an ECT and the rubber ring (form the old one) stayed in the vehicle harness connector...and the new ECT had a rubber ring in it as well.
Result = doubled up rubber rings and the voltage from the ECT being erratic / non-existant at times.
Might be a long shot, but can't hurt to check the connector and make sure there is not an old ring up in there.

[In XS 7]

Once I replaced an ECT and the rubber ring (form the old one) stayed in the vehicle harness connector...and the new ECT had a rubber ring in it as well.
Result = doubled up rubber rings and the voltage from the ECT being erratic / non-existant at times.
Might be a long shot, but can't hurt to check the connector and make sure there is not an old ring up in there.

X2, that is a very good point Mike.

[FocusSVT]

Once I replaced an ECT and the rubber ring (form the old one) stayed in the vehicle harness connector...and the new ECT had a rubber ring in it as well.
Result = doubled up rubber rings and the voltage from the ECT being erratic / non-existant at times.
Might be a long shot, but can't hurt to check the connector and make sure there is not an old ring up in there.

I will check that. Thanks for the tip!

[DPDISXR4Ti]

I don't know if the Scorpio is similar, but on the XR harness several sensors (TPS, VAM, IAC, etc) share a ground which is spliced deep in the harness near the battery. It is somewhat common for this splice to get gnarly and need refreshing on the XR. Might be worth investigating.

[Bob Weir]

Darren
Did you take the harness apart? The insulation of many wires in two harness' was so bad it was causing fault readings for the sensors.

My post "FI / Sensors Harness vs Sensors"

viewtopic.php?f=29&t=27563

[FocusSVT]

Darren
Did you take the harness apart? The insulation of many wires in two harness' was so bad it was causing fault readings for the sensors.

My post "FI / Sensors Harness vs Sensors"

viewtopic.php?f=29&t=27563

I had replaced it with a harness out of my parts car. Got the same results. I think I wasted a whole weekend. I am waiting for the breakout box to show up so I can further diagnose the wiring issue. I will let you know how it goes.

[FocusSVT]

So, a quick postmortem on the ECT wiring issue on the car. After working the prior weekend to replace the harness with a donor out of the blue car. Finished the install, ran codes and saw the same issue, open circuit, out of range on the ECT. What I failed to realize is this: I recently got an Innova code scanner that actually displays the codes instead of beeping them at you. In my frustration of the long weekend and lack of observational skill, I believe the codes I saw were stored codes and not current codes. I left the car in the garage and cleared the codes. That Monday I started it up and moved it to driveway so wife could have the spot. The car ran fine, but I didn't think much of it. I got the time last Friday to look at the car again and it started and ran fine. I pulled the codes and realized what I was seeing. The codes were gone, and nothing new showed up.

Bottom line, I think the new harness fixed the issue. It is running and driving fine. If it happens again, I have a breakout box now so I can further diagnose the issue. I have been driving it since last Saturday without issue.

Now, back to your normal programming.

[Bob Weir]

Great to hear the other wiring harness was the cure! And that you learned how to use a code scanner.

Out of curiosity, starting at the throttle position sensor, remove the tape wrap. I bet you're going to find some funky insulation and wires.

And I know you'll be "testing" the breakout box. It makes diagnostics so much easier.

Bob