I have a 99 Ford 6cylinder 4.0 4WD. It has been acting up like hesitating while driving, bogs down like not getting enough gas. It broke down yesterday morning and would not start back up. Had it checked at the part store they said try to replace fuel filter, if that don't work try replacing the fuel pump. So had both replaced and now it still will not start. Has anyone had a problem similar to this or any idea what I could check next? Thanks in advance.

 

To review,
An engine needs fuel , air and spark at the right time in order to run.
If you don't mind telling us when the fuel pump was replaced did they confirm you had little or no fuel pressure? There are other possibilities for the fuel pump not to work and hopefully it wasn't replaced on a whim.
The better thing to do is to confirm that fuel is getting to the cylinders and this can be done by removing any one of the spark plugs and see if it is wet with fuel. If it is , then the next thing to check is for spark at the spark plugs. This can also be done by laying the removed spark on the engine with the wire connected to it and cranking the starter. If spark is available you should be able to see it at the plug gap. If no spark is available we can go from there, but we need to know these two things first.

 

It was reading low fuel pressure before replacing the fuel pump. So on Tuesday we replaced the fuel filter first that didn't help so we replaced the fuel pump Tuesday evening. After replacing we were able to drive it approximately 25 miles, then it sat for about 30 minutes and then would not start again. So had it towed Wednesday and purchased another fuel pump and installed it on Wednesday afternoon, drove it for a little over an hour - ran great no hesitation or any sign that it still had problems. Shut it off and restarted it 3 times with no trouble, left it sit over night and went out to start it this morning and would not start again. Still acting like it is getting no fuel. I will mention the check spark to the guy working on it, any other areas that we could check? Thanks

 

Update: Just for others reference. The problem ended up being the fuel regulator. When the guy working on it went to replace the fuel pump the first time he decided to remove the regulator on the fuel assembly (he evidently thought it was not needed). Well with this year and model I guess you have to have it on the fuel assembly so on Friday I purchased a complete fuel assembly and installed it and that fixed my problems. The truck runs much better than it has in awhile.