Random hard starting, rough idling

My fiancee has a 2000 Ford ranger XL pickup that she got in 2006 from an ex. It has 103,000 miles on it now, had 80,000 or so when she got it. At various times it takes spells where it doesn’t want to start when the engine has been setting overnight, and the only way to keep it idling is to keep a foot on the gas. It will keep idling very rough, almost stalling, until you’ve had it up to highway speed. Then it will run and start fine for the rest of the day. It does this in hot weather and cold weather, especially after a rain, but sometimes it will have days in the middle where it works fine. I don’t know what kind of maintenence has been kept up on this truck. The transmission fluid is dark, but I was recommended not to have it flushed because that might knock sludge loose and kill the transmission. I don’t know if that has anything to do with it anyway. I would guess it’s more likely something with the spark plugs, but I don’t know much about engine work. Any suggestions?

Check Engine light ever come on?


Only when the engine stalls out. Once it is running, no matter how poorly, the light stays off.

I think there may be a problem in the fuel system. Something like a fuel pressure regulator or injectors leaking gas into the engine as it sits. So when you start it in the morning, the engine is flooded. This explains why you must step on the accelerator to keep the engine running. To allow more air into the flooded engine. Once this excess fuel is burned off, and the fuel system produces enough fuel pressure again from the leaking regulator/injectors, the engine runs fine.

At this point, a fuel system leak-down test should be performed to determine if this is what’s happening.


Thank you. Is this test something that can be performed by any mechanic, or do we need to go to a specialist shop. And if this is the problem, any thoughts on what might be needed to fix it, or what a fair price for the repair might be?

Well! Here’s something you can check yourself.

Locate the fuel pressure regulator. This is just a small canister located on one of the fuel rails with a single vacuum hose attached. Before starting the engine, remove the vacuum hose from the regulator. If gas leaks out of this connection, that’s causing the flooding problem.