'97 Moutaineer Intermittent Starting Problem

[glennet404]

Hello-


Been having this problem for the last 12 months or so - and hope somebody has some suggestions.

The vehicle is a '97 Mountaineer 5.0L with 130K miles and automatic transmission. Every 4-12 weeks or so the engine will turn just fine - but refuse to run. You continue to turn the key every 10-15 minutes or so and eventually to engine will start.

So far the only thing I've done is change the relays - that had no effect.
Once the engine failed to start while it was in my driveway - I hooked up my timing light to check spark to the plug - and when I told my assistant to turn the key - it started !!

So I've really been unable to identify whether its fuel or electrical in nature.

What I can say is that the outdoor and engine temperatures seems to have no effect. This problem has occurred on cold starts - on warm starts - on cold days and warm days.

Anybody have any ideas ??

Glenn

[shorod]

Fuel pump or crankshaft position sensor would be my initial suspects. But until you determine what you don't have when it won't start, everything's just a guess.

-Rod

[glennet404]

Okay - so the problem occurred again in my driveway.

Verified motor has spark.

Now for the unusual twist. The motor would not start after 6 or so attempts over several hours. I read where somebody had the same problem but was able to start the vehicle with the following procedure:

Depress gas pedal to floor.
Turn key to accessory position - and let it sit for a few seconds - I let it sit until the interior chimes stopped.
Then turn key to start position.

Guess what - it started.

I tried starting with my usual method of simply turning the key to start position only a few moments before - but it was a no go.

Could the extra few seconds on accessory be enough for a weak pump to build pressure ??

Any comments ??

Glenn

[shorod]

Not with your foot pressing the throttle all the way to the floor. When you go Wide Open Throttle (WOT) it puts the PCM in "Clear Flood" mode which shuts off the fuel injectors. So if it started, it started from fuel that was already in the system from the attempt moments prior.

If you wanted to build pressure in the fuel rail, and your fuel pump was working, you'd want to turn the key to the Run position for 3 seconds, turn the key off for about 5 seconds, then back to Run for 3 seconds, and repeat this another time or two before trying to start.

-Rod

[Mike2755us]

My 97' was doing the same thing. after i changed the fuel filter and put some injecter cleaner in the tank. i put in mid-grade fuel and it has been a month w/no problems. i hope this helps...