06 FX4 5.4 22k. Just got this truck in Nov. I've had no problems with the way it has ran since new (to me). Added an Edge and MBRP exhaust right after I purchased the truck. I bought it with +19K miles. So 2k of those have been with the Edge (on program 2) and with the exhaust.

I get home from work today, about a 8 mile drive or so. Pull in the driveway and feel the truck start shuddering. Put it in park and it feels and sounds like it's running on 6 cylinders. I expected it to start smoking at any minute. I check for CEL, none. I check the edge for codes, none. I take it up the rode and it's running like crap still, 6 cylinders or completely out of time. No popping out the exhaust but I can tell by the sound it's not all there. I give about 1/2 throttle and it cleans itself up some. At this point I notice the fuel gauge is down to 1/4 tank. It WAS just a little over 1/2. I go about a mile and turn around and notice it's idling normal now. So I get into the throttle a little going back home and it's back to normal now. I look down when I get home and the fuel gauge is back at 1/2 also.

Do these things still have sending units?
Fuel pump?
Fuel filter?
Bad Gas?

It is still under warranty and I may still take it in after I see what some responses are but it didn't throw a code and no CEL. Thoughts?

 

I'd say fuel filter first, run it and see if it makes a difference...start w the cheapest possibility...the dealer wont know anything unless a code was thrown...fuel filter is a cheap fix

 

x2 always go cheapest first, pop that fuel filter off, and see what your fuel looks like. If the fuel and filter look good, next is your fuel pump, and if not that maybe your invectors are dirty.

 

Also a good way to test your fuel pump/sending unit. Once you have the filter off, have a buddy turn your key on your truck to th on position, but dont start it. Let the fuel pump kick on and see what the stream looks like. If its weak, well you know its something in the tank, or your sending unit/fuel pump is going bad...

 

Thanks guys that was first on the list. Any idea why it wouldn't produce a code when running that bad? I've done quite a bit of searching but everyone else that had a similar problem the truck continued to run like that OR it threw a code.

I see MAF in the searches alot so that will be cleaned also.

 

This is why I was thinking sending unit because of the fuel gauge issue. What is considered weak? I really have nothing to compare too. T

Thanks

 

well if its still under warranty, reset it to stock, take the edge out, take it to the dealer and see if they have had any problems of the sort, maybe its a common problem to them, and see if they can get it fixed.

 

you guys are missing the obvious first step... put some dry-gas in it... with the warm/cold cycles we get this time of year you might have got some moisture condensing into the gas and that will make it run rough. So try that first (check the dry-gas to see how much gas it will treat... you might need 2 bottles)

I'm not sure what part of Kansas you are in, but I assume you must get some cold weather this time of year, right?

Then change your fuel filter (I agree that you won't be able to tell whether its a "weak stream"... I wouldn't bother with that... you'll just get gas all over)

If those don't solve it, I'd have a dealer check it out.

 

Could be COP's too.

 

Thanks for the replies and suggestions. Truck started and ran great to work today. Didn't go anywhere for lunch. I also set the edge to monitor fuel rail pressure before I left home this morning. It stay right around 39-40. Don't know what those numbers mean since I have no baseline but I just wanted to see if it was really jumpy. Busier than a one-legged man in an a$$ kicking contest right now so the filter is gonna have to wait until later on this week. I will put in some fuel additive when I fill up on the way home.

 

mxracer49, from your sig what's an HBRP SI/SO Exhaust? I'm assuming it's a typo.

 

You think a guy would read his own sig huh? Thanks!