2.5L ('98-'01) 01 won't start when it sits

[computersoc]

I have a 2.5L 2001 Ford Ranger XLT, manual transmission, 242k miles. When I don't drive the truck for a month, the battery is still fine and it cranks but it won't start. The weather here in NY has been 32F. Randomly it will start when I keep trying it. Sometimes I have to wait 30 minutes.

The starter is new. Battery, spark plugs and spark plug wires are two years old. I've tried fuel injector cleaner too.

I couldn't start it at all yesterday. Today it was 50F and it started on the second try. I let it idle for an hour with some more fuel injectors cleaner in the tank. I shut it off and then when I tried to start it, it started but stalled out after a second. I tried starting two more times and it wanted to start but it didn't. I tried a few more times and it finally started. I revved the crap out of the engine maybe 10 times. I shut it off twice and it started right up each time.

What is likely the problem? What should I do so it starts reliably? When I drive it every day, it seems to work fine for the most part. This problem only comes up when I'm out of town and I don't drive it for a month.

Edit: also when I click the key, I hear the whir noise coming from the fuel pump, even when it doesn't start.

 

[pjtoledo]

check fuel pressure
check for spark, and the ground wires.

 

[86_FX4]

First, just as a dummy check I'd see if jumping it makes it fire right up everytime. Sometimes you might have the juice to crank, but have such a voltage drop that other things act up. It's not likely, but an easy check to do to confirm that your battery in cold weather is not the culprit.
-I've had my rangers do some weird things when the battery was on it's way out, but would still start. Not common, but I've seen it.

Other than that, same as pjtoledo suggested, check for fuel and spark. Some component is either weak/dying or the cold causes just enough shrink to bring about the issues, whether it's physical or electrical. But finding out what component is missing from starting (air/fuel/spark) will get you on the right path for troubleshooting/replacing anything.

 

[computersoc]

I tried jumping it and it didn't help. That was the first thing I thought of and figured it's low hanging fruit if that's the problem. Battery gauge also was showing fine.

How do I check for fuel pressure?

 

[86_FX4]

Buy or rent a fuel pressure gauge. You can hook it up to the Schrader valve on the fuel rail. I forget the pressures to expect, but Google definitely will remember.

Not that it's an accurate test, but back in the day I'd just press the valve in slightly with a screwdriver to have fuel spray all over me and the engine bay. That would confirm I certainly had pressure. The adult way is to get a proper gauge and confirm pressure is within spec.