Joined: Fri May 18th, 2018
Interests: vintage motorcycles, building/fixing writing
Reputation Points: 49
|Hello all! Wishing everyone a happy Thanksgiving and good times with family.
It has been awhile since I last posted on my original problem of the engine starting then reving and shutting down, but I wanted to make sure that I had it whipped before I chimed in again. As I stated earlier, my goal with this truck is to make it a reliable, good running daily use truck for as long as I need it. Since the truck was an original when I bought it, not much had been done to it over time. As a result, many of the service items (TPS, IAC, PCV, EGR...etc) needed to be replaced anyway. With the help of a local shop, we began the search for the problem. Along the way all of the aforementioned service items were replaced along with Spark Plugs, coil pack, wires, fuel pump and filter, and the MAF was cleaned along with the fuel injectors. Still no luck. Same problem persisted. Then I bought a Ford Factory Electrical, Vacuum and troubleshooting manual to give me access to wiring diagrams. After a skull session with my friend Ray at the shop, he suggested that I put a light bulb and socket in the fuel pump circuit. Since I had already eliminated the inertia switch and subbed a tip-over switch, I decided to go one step further and just put a digital volt meter in the line in parallel to be able to see what was actually going on. So, when I started the truck I would keep a beady eye on the volt meter and watch for clues. Lo....AND behold...the next time it acted up I watched the voltage reading and just after the engine revved up, the voltage dropped to less than 1 volt, but only for a split second and then it popped back up to normal levels, but it was long enough to shut down the fuel pump and the ignition switch had to be turned completely off and then re-started.
Long story short, after perusing the wiring diagrams, I discovered that the primary side of the fuel pump relay was powered through the PCM relay. Upon removal of the PCM relay it looked ok, but it failed the "Sniff Test". It had a burned smell about it. This whole thing had been an intermittent problem, so evidently the PCM relay was failing when it overheated and then working ok when it was not overheated. Since the replacement of the PCM relay in early September, the truck has not failed to start and run every time. I wanted to give it enough time to prove itself, because the old problem had bee recurring in one to two week intervals.
This whole adventure has played out over months and been nothing short of maddening. But....it does prove the theory that if you don't quit, eventually you....WIN !!!!!!!!
I have been an electrician forever, and I still enjoy building, repairing and creating projects. Do a little welding and fabrication. My two primary hobbies are messing about with vintage motorcycles and attempting to do my blog site justice (ridingmybucketlist.com)My wife of 51 years and I are in our 3rd year of travels in our motorhome.