Breakdowns happen. One minute your engine is running; the next it isn't. What do you do? To illustrate the proper steps, I will relate a recent experience of my own. I was driving my 1991 Nissan Sentra SE-R on the freeway. The car had been off the road for quite a while-like two years-during which time I drove project cars (a Nissan Maxima and a Lexus IS300) and my '87 Buick Grand National. The Sentra had been recently revived for service as a project vehicle.
Everything was fine; the SE-R was cruising in fifth gear in the fast lane. The first indication that something was amiss was a sudden loss of momentum, much like the feeling when you go through a puddle of water at speed. It was a short "anti-surge" that was repeated moments later.
My first thought was I might have a flat tire, which would account for the apparent increase in rolling resistance. But the car didn't pull to one side and all seemed well with the tires. I decided to change lanes and gauge the tire's condition by the sound they made going over the Bott dots that separated the lanes. Everything checked out.
About a quarter-mile later the full seizure hit. The car lost momentum; pushing on the gas pedal made matters worse. Luckily there was a gap in traffic and I was able to get to the exit lane and down an off ramp. At the end of the ramp the engine was still running, but barely.
Again I depressed the accelerator and the engine tried to die on me. At the green, I made a quick right and another quick right into a commercial gas station-the unmanned variety. The engine barely idled and when I feathered the throttle, it died and wouldn't restart. The starter would turn the engine over but it would not fire to life.
Since I hadn't been driving the Sentra regularly, I had no tools. I called for help-SP Engineering had helped revive the car and the shop was fairly close; technician Jason Reinholdt was appointed to be the rescue team. While it was apparent I needed to carry tools in both my cars, I was left wondering what makes up an emergency kit-you can't tow a Snap-On tool chest behind you. What are the bare basics? This, too, will be clear as the drama unfolds.
Roadside diagnostics of an engine are reduced to checking spark and fuel. Diagnose these two items; if you don't uncover the culprit, you'll eliminate many of the possibilities.
Spark is first. Pop off a plug wire, insert a screw driver so it contacts the terminator and then set it against something metal (valve cover, etc). Crank the engine and observe. If a spark jumps to the metal, juice is getting to the plugs. If not, it would be time to move on to the coil, which is a new set of variables depending on whether the car runs an internal or external coil.
In my case, we had live wires, so it was on to item two: fuel. At the rail, remove the fuel line. Be careful as the fuel in the line may still be under a bit of pressure. Then find a container; we found an empty water bottle in the parking lot. Put the fuel line in and crank the engine. The fuel pump should prime the line when the key is in the accessory position and flow fuel as the engine cranks.
The Sentra did neither. In fact, we knew we were onto something when absolutely no fuel spilled when we first removed the line. The fuel pump seemed to be the culprit-a prediction I had based on the fact the engine died when pressing the gas pedal and the manner in which the engine cut out. When an ignition fails, it sometimes will be strong enough to idle the engine because it's under no load and firing at only 850 rpm, where it doesn't require the power that high-load and 4000 to 7500 rpm demands.
Why isn't the pump working? Before running out and buying a pump, a little more Sherlock Holmes action is called for. Is the pump getting juice? Our first stop was the relay box. The fuel system relay was removed and examined and no signs of its demise were present. Corrosion or burn marks are dead giveaways. Next was the fuse box in the dash. The fuel system fuse was in proper working order; had it not, we would've swapped it for a non-essential fuse of the same rating, like headlights or some interior function and gone from there.
We yanked out the back seat and removed the cover plate to the fuel tank, then un-plugged the leads to the pump. In need of a test light, it was time to don the thinking cap. With no lightbulb in the trunk, we popped out the dome light. I had my stock steering wheel in the trunk so horn wires were cut and scavenged. The wires were held against the leads of the pump plug and the other ends were held on the light. Turning the key to "accessory" got a flash.
But what about under more load? We cranked the engine and got light. Roadside diagnostics is like a posse pursuing an outlaw; you chase the problem incrementally until the culprit has no way out. We had chased the car's electrical current all the way to the fuel pump, checking the relays, fuses, the wiring to the pump and in the boxed canyon at the end of the trail was the pump itself; our problem could be nothing else. A NAPA store was four blocks away and minutes later, we swapped the pump. The engine started on the first try.
Emergency Kit Tools
Socket Set
Multi bit screwdriver
Pliers
Curved needle nose pliers
Test light/voltmeter
OE repair manual
Cell phone