P0302 Mercury mountaineer 4.0 6cyl.

Question

2006 mountaineer 4.0 6cyl. 115,000 miles
Occasional hard start lately with one time p0302 code when running truck runs great no stumble no hesitation, just in initial start up worse when cold or shut down for length of time. I believe it is fuel pump,it started instantly when fuel was introduced directly into intake system.once started it restarts easily unless I don't start it for 12 hours then same I believe fuel pressure is low and pump begining to fail.

Answer 1

Hi there,

Usually a bad fuel pump won't cause a single cylinder misfire code. You can however test it to see if there is a fuel pressure issue when you attempt to start the truck. If the fuel pressure is dropping off from the fuel rail it can cause this type of issue. You may also have a leaking fuel injector on that cylinder. Flooding the cylinder after it sits, it can cause this issue