Car start issues + I'm confused

Alright first off, the usual:
1991 Mercury Tracer 1.9L manual hatchback with 276,000 miles.

And now the problem:
I have intermittent problems with starting the car. The thing is I know exactly what is wrong, problem is I have no idea how to fix it.

When the car starts: The fuel pump kicks on, and the car starts with no issues.
When the car doesn’t start: The fuel pump does not kick on, and instead the car’s cooling fan kicks on. The starter works perfectly–just the car doesn’t start.

Obviously the car is not starting because the fuel pump does not turn on. And here is what I have done so far:

  • Changed the fuel filer.
  • Tested the fuel pump by itself (hooked it up to an external power supply). Pump works perfectly.
  • Added fuel dryer just in case I got some bad fuel.

There is no pattern that dictates when this problem happens and when this problem doesn’t happen, it seems to be completely random.

The only idea I can think of is there is an electronic control system somewhere that is malfunctioning from time to time. But to be honest I don’t know anything about the electronic control systems in the late 80s, early 90s Ford vehicles, so I am completely stumped. If it helps, the problem has happened more when I’m on the last 1/2 a tank of gas. Above a 1/2 a tank and the problem happens less.

Any ideas?

In newer cars the fuel pump relay is energized by the ignition for only a few seconds to bring the fuel pressure up. After that it requires some indication the engine is rotating to energize the relay. In pre-OBD II cars this signal was sometimes supplied by the oil pressure sensor. Put a voltmeter on the fuel pump relay to see if the output goes high during starting.

My Dad’s 89 Tempo had a similar issue. It was a bad fuel pump inertial switch. It was supposed to disable the fuel pump in the event of a crash. A button to reset the switch was accessible through a hole in the passenger side kick panel.

Ed B.

I have had ignitions do weird things, like one Chevy where you wiggle the key and the radio cut out. When the radio worked, the wipers did not. In a rainy state, this was a problem.

In my 93 Escort withthe same motor as yours, the ignition failure would make it randomly not start (with increasing frequency). If barking up the fuel pump tree ultimately doesn’t fix it, I would look at replacing the whole ignition mechanism, not just the switch. It took my mechanic 3 ignition switches in the space of a year to figure that one out. Since then, starting has not been an issue for my car.

Get a wiring diagram and check for current flow. It might be convenient to start at the relay.

Woke up today a full tank of gas (1 mile on it), and problem now seems permanent. Usually I can walk away from an hour and it’ll magically work again, but its been over 12 hours now and nothing. But all this really tells me it is not related to the fuel level in the tank, nothing really revolutionary.

@frank438 The part you said about “increasing frequency” describes my situation exactly, plus the 93 Escort and my car have very similar parts, so I will start there.

Thanks guys.

Once you have ruled out the fuel system, and before you replace the ignition, try wiggling the keys when it acts up. Sounds silly, but that is how my my stereo installer found the ignition/wiper connection. I had the stereo replaced the day the problem first appeared.

I also vote for the inertia switch. I had the same problem in my '88 Escort many years ago. I went to the junk yard and bought a used inertia switch for $5. and it’s been fine ever since. Mine was more likely to act up during cool or damp weather. You also have a fuel pump relay that could be going bad, it’s located on or near the ECU bracket behind the passengers side kick panel of the console. There will be two relays a brown/black one which is the EEC relay and a green/black one which is the fuel pump relay.

Alright, I need some help understanding how the entire fuel system is wired. I am an electrical engineer by trade, so I’d like to think I could figure out how they designed this thing, but obviously I have no clue.

Tracing the wiring backwards from the fuel tank, here is how I think it is wired:

Fuel pump -> fuel cutoff switch (same thing as inertia switch?) -> inertia switch -> relay -> fuel pump fuse -> ? -> ?..

Am I on the right track? Or am I completely off?

That’s the right track

If you go to Autozone’s website, register an email address and plug in the car’s info you can get into their free online repair info. In there you will probably find a) a step by step for trouble shooting fuel pump power issues and b) a wiring diagram.