2002 Mountaineer, intermittent starting

[Ixonia]

For the last 1 1/2 years my Mountaineer has had problems starting every few months. First I had the crankshaft sensor replaced. Then it happened a few months after that. The alternator went out, so replaced that. The problem kept happening so I had the starter replaced.
When the issue comes up, the engine cranks, but it will not turn over. If I leave the car sit for at least 30 minutes it will always start, then I won't have the problem for a bit longer.
I have taken the vehicle right over to an auto mechanic after the problem and no error messages come up. The vehicle does not run ruff, and I have no other issues.

[shorod]

Welcome to the forum!

For future reference, if the starter is spinning the engine over but the engine doesn't start, the starter will not be the cause.

Has anyone checked the fuel pressure? Ideally you'd check the fuel pressure when the vehicle is in the no start condition, but understanding that isn't always possible, checking the pressure KOEO and KOER even when it does seem to be working fine might indicate a weak fuel pump or restriction in the fuel lines.

What's a bit easier to check when the truck won't start is for a spark or no spark condition. An inline spark tester is small to carry with you, inexpensive to purchase, and doesn't take much work to install and use. Knowing whether or not you have spark when the engine won't start will quickly narrow down the number of areas you need to investigate.

Which engine does your 2002 Mountaineer have?

-Rod

[Ixonia]

Thanks for your knowledgeable response. My engine is a 4.0 liter V6. It rarely happened and now this month it has done it 4 x. Yesterday, I went shopping about 30 miles away. I was in the store for 45 minutes and came out and it wouldn't start. It sounds like it is flooded, right away. It doesn't turn over. I walked to another store and came back 40 minutes later and it started right up. Sounds great while running. This morning I went out and it did it again. This time I opened the passenger door and listened for the fuel pump - but it was too noisy outside. I shut the door and tried it again and this time it started. I feel like it must be the fuel pump. Could some valve be stuck that causes it to flood? If brushes or a connection is corroded, would that mean I would have to replace the fuel pump?

[shorod]

If the fuel pressure regulator is stuck it could cause the engine to flood, but that would also cause issues during normal driving since he fuel pump should be providing more fuel than the engine needs. Measuring the fuel pressure though would show if you have a pressure regulator that is not working properly or if you have a fuel injector that doesn't allow the fuel rail to properly pressurize.

If the brushes in the fuel pump are bad or corroded, yeah, you'll need a new fuel pump. If there's a corroded connection, chances are good the corroded connection would be external to the fuel pump assembly and therefore you may not need to replace the fuel pump in that scenario.

-Rod