Cheap, crimp-on connectors destined to fail

Hey there, time traveller!
This article was published 07/04/2007 (6756 days ago), so information in it may no longer be current.

QUESTION — I have a 1989 Ford F150 with electronic fuel injection EF1 that stalled out and would not restart. The diagnosis at the shop was no voltage to the high-pressure fuel pump. The wiring was replaced (spliced) using a Tap Splice connector — a low cost common connector (blue plastic) sometimes called a scotch lock for unstripped wires in this high current application. In addition the new wiring gauge they put in was not a 12 gauge as was put in by the factory. It was a lower gauge.

For a few days the fix worked but the stalling returned and got progressively worse as time went on. Recovery sometimes meant waiting overnight or longer for the vehicle to start again. After returning the vehicle many many times to the shop and much expense as they kept telling me it was something else, I had to take it to another shop and the true nature of the first repair was revealed. The second shop removed the Tap Splice connector, soldered the wire connections, weatherproofed the splices and the problem ended never to return again. I have been told that the first repair would never have lasted and that it was a temporary fix at the least, a badly thought out one at best.

My questions are: was the first repair destined to fail? Should Tap Splice connectors have been used? Should the wiring be upgraded to 12 gauge at some time in the future? Do you have any other suggestions or comments?

ANSWER — In my opinion, these cheap, quick, crimp-on electrical connectors designed for use on unstripped wiring are some of the worst aftermarket electrical parts ever supplied. I originally saw them used to attach trailer wiring into vehicles, and even in those applications they would work intermittently due to corroded contacts, loose connections and even broken wires. Problems occur even quicker when they are exposed to dirt and moisture.

There are many good crimp on connectors that have heat-sealed insulation around the connector to keep moisture out, and there are some crimp on diagnostic probe connectors that are filled with a self-sealing jell that work well, so not all crimp style connectors are bad, but those “Tap Splice” connectors, as you call them are terrible. They should have only been used in an emergency, and even then it would be preferable to strip insulation and solder the connections. Were they destined to fail? You bet!

As for the replacement wire size, it is usually good practice to replace any wire with the same size as originally equipped, but much depends on the length of the wire run. 12-gauge wire is capable of carrying 20 amps (typical maximum current for the fuel pump) for a distance of 20 feet. If the wire was only 15 feet long, you could use 14-gauge wire and it would still work. A short three-foot repair could be done with wire as small as 18 gauge, but usually a wire closer to the original size is used. If the wiring repair on your truck is a short length, you shouldn’t need to install a bigger wire gauge.

QUESTION — I wonder why, in this day and age, we’re still running on inflated tires. With suspension systems as good as they are, I’ll bet we could run on solid tires and barely notice the difference. Or, if that’s not true, why not fill tires with foam rubber with 35 pound density.

ANSWER — Suspension systems are much better, but even many of the best suspension systems are now using “air springs” (rubber bladders filled with air) to smooth out the ride. Air inside the tire is still one of the easiest methods of providing a smooth ride.

Solid rubber tires are used on some industrial applications, mainly to prevent flat tires, and there have been several concept wheel/tire combinations from manufacturers that used solid tires on a flexible wheel to provide ride quality, but these have only been experimental. As for 35 lb. density foam inside the tire, it would probably work for a short time but I suspect the foam would quickly wear out as it flexed. Air is still the best — for now.

Jim Kerr is an experienced mechanic, instructor of automotive technology and member of the Automobile Journalists’ Association of Canada. You can e-mail questions to Jim at the address below.

kerr.jim@sasktel.net