Have 01 expy 5.4l 4wd 120,000miles. Problem started last month on the way to florida for vacation. Running great then feel a Hiccup just occasionally trying to figure out where its coming from, rear end, tranny, engine. Continued to occasionally hiccup the entire 12 days we were gone. Some days nothing then some days it would do it. Had me believing at that point a misfire. throwing no codes at all. Did all my maintenace before we left town except the plugs which I planned on doing when we got back in town. So original plugs 120,000 miles and COP's as well. Has new fuel filter, never have done anything but regular maintenace and brakes, no O2 sensors, IAC, injectors, misfires or any issues. drove fine the other day, started to hicup again got home, pick up wife and restart and its rough idle then dies and won't stay at idle now won't start. turns over fine now it seems like fuel issues. Just wondering where to start, have all new COP's on their way so I am doing plugs and COP's but not sure if this is even the problem, still no codes. Has anyone experienced similar problems? If so what did you find to be the problem, open to all suggestions, thanks

 

check ur plugs, not necessarily change them, but the plugs can tell a story of engine problems just by looking at them, even if u don't know take pix of them and post them up

 

Yeah, I am definitely changing plugs, since it is overdue anyway. Changing all plugs and all COP's hopefully it fixes problem, will post pics of the plugs and let you know my results by the end of the week. The problem was just irritating and couldn't pinpoint what the issue is and now I just might be overthinking it. We will see what the plug change does and go from there. Was kind of hoping someone had a similar experience with the hiccup that the engine was having, not throwing codes, etc. and see what they found to be the problem.

 

inadequate fuel pressure can cause the issues you are describing. You might have gotten a tank of "bad" gas along the way...but you said it has a new fuel filter



otherwise, my biggest suspect would be the COP's and plugs. Did you say they are the original plugs?

 

Well changed the plugs and COP's tonight, and still won't start, had a feeling that was not the problem, but it needed to be done as the original plugs had 120,000 miles on them. Putting a fuel pressure tester on it to see if that is the problem, do Expys have issues with fuel pumps? Might be the crappy new fuel filter from autozone, however we made a trip to Orlando from Memphis and back last month and it seemed ok just the occasional Hiccup. Checked for codes as well tonight, says no codes everything is passing so I am really just checking everything I can, all vacuum lines looked good as well. Hopefully its the fuel pressure and I can go from there.

 

Not sure if I am checking the fuel pressure wrong but loaned a pressure tester from Autozone. Hooked up the schrader valve adapter hooked up the gauge, turned the ignition to on (not start it) to test the fuel pump and I have 0 psi on the gauge, so unless I am doing something wrong it looks like my fuel pump may be shot or a fuse or relay, any input would be great thanks.

 

Well ended up being the fuel pump. Changed it out and have driven a couple hundred miles and no more hiccup. Not sure if the plugs and Cop's fixed the hiccup and the fuel pump was just another issue that happened at the same time. It would seem odd for the fuel pump to intermittenly mess up. I would think that it would just be good one day then bad the next. Anyways The issue is fixed and she seems strong as ever. thanks for the couple replies.

 

Same thing is happening to me. I already changed the fuel pump, when it wouldn't start. Changed the Filter too. changed the spark plugs, and wires and still the hiccups. Cleaned the throttle body too. Checked the battery cables, cleaned them and tightened them as well. It still running with the hiccups and very slow speeding up. Its been a stressful month. What am I missing?

 

How do you swap the fuel pump? I can' t find a post explaining this.

 

It's in the fuel tank. Three screws, few hoses. The important thing to know is that you need the tools to disconnect the fuel lines. They sell those at Auto Zone. If you buy only the fuel pump it should only cost less than fifty dollars, if you buy the whole thing with the gas meter (float), it should cost less than 200. Hope this helps!