Typical Differential Kit with Positraction

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A few years back, my brother's trusty truck would not start. I hopped in and realized it would crank over just fine but would not start. I pulled a plug wire and saw spark, then put a fuel pressure gauge on the rail and saw nothing. Ah Ha! I swapped the fuel pump relay, but nothing. I checked the rollover switch; it was OK.

At this point, I decided the fuel pump must have given up after its 200K miles of faithful service. I went through the somewhat arduous task of removing the bed to access the top of the fuel tank and replacing the rusty fuel pickup assembly and pump.

Proud of my diagnostic skills and feeling satisfied, I put the bed back on and turned the key, it cranked over but would not start! I stared at the dash in defeat and noticed something missing, there was no CHECK ENGINE light illuminated while the key was in the ON position! I scanned a schematic and realized the computer had an independent ground that went to the battery. When I traced the wire it was lying in the rust under the battery.

Apparently when my brother replaced the battery years earlier, he left the wire off, and it made ground contact through the battery tray...until that weekend. As soon as I reconnected the wire to the ground terminal, the truck started right up.

Lesson learned: Look for all tell-tales before diving into more involved work.

Ryan in Maryland

Tell us about your most infamous auto repair blunder or unconventional fix. Use your woe to help others avoid similar mistakes or share off-the-wall solutions that worked (at least for a while!). Please email your story to flamur@rockauto.com. Include your mailing address and if you would like a RockAuto T-Shirt (please let us know your shirt size) or Hat if we publish your story. See the T-Shirts and Hats under Tools & Universal Parts in the RockAuto catalog. The story will be credited using only your first name and your vague geographic location (state, province, country, continent, etc.) so you can remain semi-anonymous!

Federal mandates required a new safety enhancing part be installed on cars sold in the USA by 1963. Checker began installing the new part early, in 1962, after they used up their inventory of old parts. What was this safety enhancing part?

A. windshields made of safety glass
B. tubeless tires
C. amber colored front turn signal lenses

Answer below

I have read manufacturer tips about checking ground connections before replacing electronic parts. I have even written articles about checking ground connections, adding ground wires, and using voltage drop testing before replacing parts. But despite all my wisdom, I still went ahead and unnecessarily replaced the Engine Control Module (ECM is Ford's EEC-IV) on my wife's 1993 Ford Tempo when the ECM really "just" had a ground connection problem.

A Hemmings article on Ford's EEC-IV says it is known for "extreme sensitivity to ground circuit issues" and "a high-impedance ground would drive it crazy." Rather than feeling too guilty for not practicing the grounding rules that I preach, I feel like the "crazy" EEC-IV has taught me additional Yoda-level grounding knowledge that is valuable to owners of other computer-equipped vehicles.

Parts that temporarily "fixed" the problem

1. With grounding problems, new parts may bring relief, but that relief may also be increasingly short lived. A grounding problem can persist for years. Replacing parts can temporarily fix/hide the problem for years as well. Disconnecting/reconnecting electrical connectors, removing/reinstalling mounting bolts and/or a fresh, completely in-spec. part might be enough to improve the ground connection. But, the root-cause grounding problem might still be there and possibly worsening.

The fuel pump in my wife's Ford would stop (no sound from fuel tank). A new Ignition Starter Switch fixed the problem for a few years and a new Fuel Pump fixed the problem for a few more years, cleaning the electrical connector on the Body Control Module (BCM contains the fuel pump relay) fixed the problem for another fourteen months, replacing the BCM fixed the problem for two days, replacing the ECM fixed the problem long enough for one round-trip to the grocery store. Forums are full of posts from Tempo, Mustang and other Ford EEC-IV owners with nearly identical stories. They gradually replace all the major parts connected to the circuit, reporting temporary success after every install. Sometimes, they start replacing the same parts for a second time and those new parts fix things for an even shorter period of time or don't help at all.

2. It looks exactly like a desktop computer problem, but that might mean your old PC just had a grounding problem too. After a cold-start, the engine in my wife's Ford would run for about ten minutes and then the fuel pump would shut down. After a minute or two, the fuel pump would come back to life and the engine would restart and run another three minutes. The Ford's OBD I diagnostic connector conveniently has a pin that turns on the fuel pump whenever it is grounded. The fuel pump always ran fine with that pin grounded, so it was not the fuel pump overheating. (The ECM turns on the fuel pump relay by providing a ground, so manually grounding that OBD I connector pin might provide a good ground connection to the fuel pump relay that the ECM no longer has on its own.)

I guessed that an electronic component on the computer's circuit board was overheating, shutting off and restarting after cooling down. That is when I finally replaced the ECM and enjoyed one trip to the grocery store before the fuel pump stalling started again.

Old PCs and laptops also sometimes repeatedly shutdown and restart as they heat up and cool off. The last time I had a PC do that, I called the computer manufacturer and was told to unplug all the cables and hold the computer's power button in for thirty seconds to "drain away static electricity." The PC was not dead, it was just experiencing something similar to a grounding problem.

3. Accept the solution even if you cannot adequately explain it. I spent six long years studying electrical engineering, and I wanted an elegant solution. I had replaced, tested and/or cleaned every part, connector and ground connection I could reach. In the '80s, there is no way Ford Engineers could have known how well every ground path in their EEC IV designs would hold up after thirty years. I decided I would try to enhance their original design.

I took a 12 ft. long battery Jumper Cable (available at RockAuto.com!) and clamped one end to the engine ground near the battery, then with the ignition key on and the car in its broken state, I started clamping the other end of the cable to metal points all over the car while listening for the fuel pump to start up. I had some inconsistent false positives but finally found the sweet spot when I clamped the ground wire onto the large Spare Tire Hold Down bolt in the trunk. With that bolt grounded, the engine/fuel pump stayed running indefinitely and always started up immediately. I am guessing my jumper cable was providing a new ground path for the nearby fuel pump. Maybe the fuel pump's ground path had changed over time, sucking the life out of the sensitive computer's ground path at the front of the car. I would probably have to get my doctorate in electrical engineering to know for sure.

The jumper cables running over the roof of the Ford looked tacky, so I ran some heavy gauge Primary Wire I had on hand from the main engine ground to a new bolt on the firewall and then I ran more wire from the engine ground to three separate new bolts mounted near the spare tire well in the trunk. There was an unused hole and grommet in the right front door jam so the new cable installation is professional-looking and out of sight. All the heavy wire might have been overkill, but I wanted to make sure I did not inadvertently burn up a too-thin wire, and I wanted to be sure that both the computer at the front of the car and the fuel pump at the rear of the car had excellent, independent ground paths.

Tom Taylor,
RockAuto.com

To read more of Toms articles, click this link and choose from story titles on the Newsletter Archives page.

I have been able to get this 30+ year old Bronco back on the road with parts from RockAuto. It is a 1988 Ford Bronco II Eddie Bauer Edition with the 2.9l V6 and A4LD automatic transmission and electric shift 4x4. I found it through a web based classified ad in a towing company’s lot. It took some elbow grease and a few part orders from RockAuto, but it is now up and running.

I replaced the water pump, heater core, thermostat and coolant hoses, various sensors, ignition wires, all the A/C components, window motors, steering box, tie-rods, brake components, fuel pump, fuel pressure regulator and more. The list is extensive, but thanks to RockAuto, I was able to accomplish the task affordably.

The odometer says 95K, and I plan to drive the wheels off of it and order replacement parts when needed from RockAuto. Thanks and keep up the great work! Lots of us depend on the parts you provide.

Mike in North Carolina

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Federal mandates required a new safety enhancing part be installed on cars sold in the USA by 1963. Checker began installing the new part early, in 1962, after they used up their inventory of old parts. What was this safety enhancing part?

A. windshields made of safety glass
B. tubeless tires
Answer: C. amber colored front turn signal lenses

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