By Brian Manley
One of the reasons I still enjoy repairing cars is because they can still surprise me. Sometimes it's the customer that creates the surprises.
The Story
I got the call one afternoon from a friend's father, Stan, who had been working on a 1986 Ford Ranger pickup for several weeks, on and off, without making things any better. The Ranger, which belonged to his next-door neighbor, had been getting poor gas mileage for months. This concern had progressively worsened, finally resulting in an extremely poor-running engine. Stan began “attacking” this car several weeks earlier by “trying to find out why it won't stay running.” He was also searching for an elusive, intermittent dead battery concern. Stan had replaced the distributor cap, rotor, plugs and wires, the No. 6 fuel injector, one cylinder head gasket and the intake manifold set and the starter motor.
The tuneup items were an attempt to fix the “not-staying-running” concern, but the fuel injector had been replaced because “the number six cylinder keeps filling up with gas.” Stan replaced the starter because his neighbor's son had put a clutch and a starter in it, and it hadn't started correctly since, emitting a gut-wrenching, steel-on-steel grinding with each pinion engagement. Stan pulled the transmission to check the work that had been performed on the clutch, and to make certain that the flywheel's ring gear wasn't damaged too badly. Stan found that the wrong application starter had been installed.
To make a frustrating repair even more aggravating, Stan, while working with the fuel rail and installing the No. 6 injector, had dropped a 10mm bolt into the intake manifold. So Stan did what any good neighbor would do: he pulled the intake and the cylinder head until he found the bolt, then reassembled it, using new gaskets. This is the part of “The Story” where Stan earned my respect for doing what he had to do, instead of shipping the car with a bolt rattling around inside the intake or the engine somewhere. I did cringe when he told me that he doesn't think that it did any damage to the engine. “Did you run the engine with the bolt in there?&3148; I asked. Stan replied, “Briefly.”
Stan then told me he had pulled the plugs out of the engine and cranked it over to check compression. Unfortunately, he had not disabled the ignition system, and when the No. 6 piston came up on the compression stroke, he had a fireball come at him that, he said, "barely missed my face!" He tells me the wiring harness had suffered some burns, but he thinks it might still be all right. After Stan made me laugh with the fireball part, I couldn't resist taking a look at this truck!
The Visual Inspection
As I popped the hood I couldn't wait to see how extensive the damage was to the wiring harness. Figure 1 shows a good close-up of a portion of the harness along the fender apron. This didn't look good at all; the plastic connectors had distorted enough to become misshaped, and some of the copper wiring was exposed. I had to remember that this was the result of the fix and not the root cause of the concern. Remembering what Stan had said about the gas in the oil, I pulled the dipstick to find the level was halfway up its length - and it smelled like fuel.
I stepped back from the engine for a moment to contemplate how this much fuel could be getting into one cylinder. The way the intake is designed on this 2.9 liter, fuel couldn't be coming from another cylinder's injector. Then it hit me. I noticed the manifold vacuum hose for the fuel pressure regulator was directly over cylinder No. 6. Figure 2 shows what I discovered when I pulled the hose from the intake port.
The Aftermarket Regulator
I sold Stan a replacement fuel pressure regulator and two oil changes; he was happy that I found a tangible reason for the excess fuel. When the part arrived, I found that it required me to remove the coupler from the original regulator and install it on the new one using hose clamps. This requires cutting the plastic hose from the original regulator without excessively scarring the barbed end of the coupler that is to be reused. Figure 3 shows the two parts side by side. Once I installed the new regulator and changed the oil, the 2.9-liter engine ran as it should.
Pressure Testing
When I replace any fuel system parts, I like to test fuel pressure after I'm finished to make certain the new parts are functioning as they should. This system showed 29-30 psi regulated and 36 unregulated. Figure 4 shows the new pressure regulator installed.
The Wiggle Test
Even though the engine was running and it performed well on a test drive, I warned Stan that, due to the extra crispy wiring harness, I should perform a KOER wiggle test with my scan tool. I was particularly concerned because many of these wires went to engine sensors, provided powers and grounds, and ran into the largest grommet in the firewall. Since I wanted to know what each of these wires did, I pulled my Jendham manual from my shelf and opened it up to the pin chart for the 1986 Ranger (Figure 5). I paid particular attention to any wires that would affect engine operation. I ran the test while wiggling all of the affected connections and wires, but there was no indication of an open or a short. I did, however, wrap some of the exposed wires with electrical tape to prevent an inevitable concern in the future. I told Stan the harness should be replaced as soon as possible to save his neighbor the grief of a breakdown. Figure 6 shows how extensive the damage was to the harness. If Stan doesn't replace this harness, I'll see this truck again - on the hook!
Testing for Parasites
The results of my initial parasitic drain test, 11.7 milliamps, were well within the acceptable range of 50 milliamps. I installed a battery isolator and went for a drive while running all of the accessories. Back at the shop I hooked up my ammeter, then opened the isolator switch to force all of the electrons through my meter. I still only had 12 milliamps. What could be causing this battery to go dead?
I performed a complete Battery/ Starting/Charging system test that revealed a strong battery, a good charging system and a starter negative cable with close to 2 volts voltage drop from end to end. Replacing the cable brought the numbers down to .3 volts. Did this cause the "dead battery" concern? Time will tell.
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Brian Manley is a vocational automotive instructor for the Cherry Creek school district in Aurora, Colo. He is an ASE master certified automobile technician and a former member of the National Automotive Technicians Education Foundation (NATEF) board of trustees. He can be reached at manley_brian@hotmail.com.
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Copyright (c) 1996-2008. Automotive Service Association. All rights reserved.
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