Fuel issue questions...

when I’m driving down the old highway and to a lesser extent in town my truck is having fuel problems. So far it hasn’t left me stranded but it isn’t winter yet. Every winter whatever I’m driving goes out on me. Thought at first it was cruise control related but it does it now just driving around. You can tell it’s getting fuel starved momentarily then it’s good again. Tachometer drops RPM’s and back up again. No codes are coming up to check. I changed out fuel filter just after I got truck. Truck has had a rough life so not sure what it is. Vacuum leak? Fuel pump? Crap in fuel filter? Any ideas? Thanks in advance, I’m on lay-off, need to find job fairly soon and need truck running good.

 

This on your 2003 4x4? What engine? Is it losing power then will surge again?

 

Yup 2003, 4x4, 6 cylinder and automatic. When going down highway it seems fuel starved for a second then okay again. Happens about every minute or so. Driving around town it doesn’t seem as bad but today it seemed to do it more.

 

kinda sounds similar to what mine is doing but mine is a 2wd 4cyl and 1996.

if you have an OBDII scanner hook it up and look at your live data and see if your short and long term fuel trims are off. Your FSM should tell you the tolerances that are allowed for your engine but if those are off it could be part of your problem.

from everything I have read they are typically from a vacuum leak. I made a smoke box and had a leaking brake booster but they can find any leaks.

Main thing is try and hook that scanner up and check your live data

 

A couple of go-no go tests. I would pull of the fuel filter and dump what ever is in it into a pan, then blow through it backwards, then blow through it forwards. It should blow relatively easily. A fuel filter is either plugged or not and I doubt that it IS your problem. While it is off put a line on in line from the fuel tank/pump and put that line into a large jug and crank the motor over to operate the fuel pump. You are looking for volume and pressure. If there are no codes and it flows adequate fuel then this is going to be a problem until it breaks, then you can figure it out. Until then, you are guessing. Is it the system that controls the spark or the system that controls the fuel pump. If you can find the blue wire that runs under the DS seat harness and tap into that wire and wire in a 12v bulb... not in series. You are looking to see if the bulb goes out when the truck stutters, if it does then it is the electric control for the fuel system.

 

‘ every winter whatever im driving goes out on me ‘

where do U live

some regions get a different mix o gasoline seasonally

different alhy mix

some get additives like butane to help start ups

if its a mom/pops stationthat doesnt get many truckloads a day/week

U could be pumping old/stale fuel

 

Just my weird luck unfortunately... winter shows up and something goes wrong. It’s always something new and in another 10 years I will have done it all. More than one way to become a good mechanic!!!
Luckily I found this place to get some good help and pass on past experiences.

 

My Aunt passed away a few years back and she willed me her riding mower. Not sure why or how she new but I was needing a new mower when I got it. It had the same problem as my truck. Evidently at sometime they got some debris down in the tank. It would start doing that and you could see in the visible gas filter that there was a problem. Cleaned it all out and all was well but occasionally it gets a little more debris from somewhere. It’s a craftsman mower and has been a pretty good one. Has a weird shimmy when you throttle up to high. Only has two blades and there isn’t any play. Haven’t figured out what’s wrong with that... saves me money by not throttling up to high. Anyway I believe debris in tank/filter may be the problem. No lights so I’m gonna start there and do this too

 

Any more ideas? Keep them coming! Need to get it running well soon to find a job. Thanks!

 

Does it idle fine?

 

no codes?

 

Seems to be... a couple of days back I noticed a small puddle of antifreeze underneath. It turned out to be that I needed to add a couple turns on newly installed hose/clamp. It idled until it warmed up and sounded good while doing so.

 

have you ever cleaned you MAF sensor?

 

FSM order of operations; test fuel pump is operating. if good then check circuit opening relay. if thats good check the voltage between terminal 3 of opening relay and body ground, should be 9-14V when engine is cranked. if thats good, then your into the ECU.

 

Dirty TB,,,

 

Replaced less than 10,000 miles ago!

Throttle body cleaned during fairly recent valve shimming and valve cover seal replacement

No codes!
I’m sure a code will come soon though...
Until then I’ll look everything over.

 

Cleaned up and replaced all I could around April.

 

I would say don't get so fixated on a fuel issue. It may or may not be that. Troubleshooting is simply isolate & eliminate. Glamisman gave you an easy way to check the fuel system. If that is OK, then move on to something else. It's also easy to mistake ignition problems for fuel issues. Either one cutting out will cause the engine to stutter, stall or buck. You can also get a code without it throwing a CEL.

 

I have read this post from the beginning, unless I missed it, have you had the tank off / down ? Over the many years I was in a new car dealer service dept. people would come in with similar complaints. we found starvation caused by the " sock " or pick up being partially clogged, sometimes it was water in the tank that came in with the gas. or even a combination of these things, So lets do the cheap things first, verify the correct fuel pressure and volume as previously suggested, if all is as it should be wait until it is almost empty, and drop the tank, pull the sending unit / pick up once you get a look you will know what to do. As a safety measure I would replace the electric fuel pump, they can have intermittent shorts, at this point it is to easy, you don't want to drop the tank again, do you .
Good luck
Please keep us posted

 

OEM or aftermarket MAF?