Hows it going guys?
1998 Ranger XLT
4.0L OHV
2WD Auto
Stepside

Anywho, so i'm starting to slowly go through my truck. There are a few things that i could really use some assistance with. I'll start off with the Fuel Guage reading. Anyways, my fuel gauge has always been off. I will fill the truck up and the pump will kick off, leaving my gauge between 3/4 and full. I always thought it was the sending unit. The previous had replaced the sending unit and pump assembly right before i got it from them. So today, i decided to see if my tank was actually full. So i went to the gas station, and put some gas in. Keep in mind, the tank was just filled up, to where the pump kicks itself off. I began filling it some more and it would kick off every .50 or so. I kept going until i out about 2 more gallons in it. Once back in the truck, the gauge actually read full! So my question would be, whats kicking it off prematurely and not letting my tank get filled all the way? I mean it seems like it kicks off about 1.5-2 Gallons too early. Would it possibly have something to do with the Evap hoses back there? maybe something kinked or crudded up?

Next up would be my rear-end noise. Around 15MPH i can hear a shearing sound coming from between the center of the vehicle to the rear. I cannot pinpoint it. I've had it on the lift and had the drums and tires of while the vehicle was set on cruise control. It seemed to get really bad around 40MPH and you could really hear it. I'm starting to get vibration around that speed on the highway. I've checked the balance of the tires and they are all good. I did a rear-end flush about 5 months ago and didn't notice anything abnormal. Could it be a pinion bearing or wheel bearing? I've tried moving the driveshaft around to check for play, and it seems to be within spec (hardly any movement).

Thirdly- I'm getting the dread PO171 and PO174, I'm luckily shooting to do the Upper and Lower Manifold gaskets tomorrow. My question being, how many of you guys actually just replaced the Upper Gaskets and had good luck with that being your problem? I've already ran a smoke machine on it, and replaced my intake tubing because it had a tear in it, but it didnt fix the problem. I recently replaced the EGR tube as well. I did notice the Valve Cover gaskets were getting a little seepy, so it may be a good idea to just do the whole shabang. I have all the gaskets needed.

Sorry for the book, but hopefully someone has some guidance. I've searched through numerous posts, but none really answered my direct questions. Thanks guys.

 

P0171 and 0174 usually means MAF sensor is dirty(needs to be cleaned) or PCV Valve hose is leaking.
Computer reads the amount of air passing thru the MAF sensor, then bases the 14.7:1 air:fuel mix on that reading.
After air:fuel mix is burned computer reads if the burn was Lean or Rich based on Oxygen levels in the exhaust, reported by O2 sensors.
If Lean computer adds more fuel until Oxygen levels in exhaust are correct.

If computer feels it is having to add too much fuel above its calculations, on BOTH banks, it will notify the driver by setting codes 0171 and 0174
Engine is never running Lean, that's just the way the computer reports its concern

If MAF sensor is dirty it will under report the air flow
If air is entering the intake without going thru the MAF sensor then its the same as under reported air flow, vacuum leak.

If fuel pressure is lower than it should be that will cause the same codes because fuel flow is less than computer expects.
1998 Ranger 4.0l should have 60-70psi of fuel pressure

Since you have BOTH banks reporting as Lean then it wouldn't be O2 sensor related, chances of both O2 sensors having a problem at the same time is very very long odds.


The vent hose in/next to the filler hose is what allows you to fill up the tank without pump clicking off.
It allows the air out as the fuel goes in, if the air get trapped then fuel backs up and pump clicks off.
If vent hose is clogged up a bit then when filling most of the air can get out the Filler hose but as you get to the top the filler hose gets covered by fuel and without good air flow on vent hose the fuel backs up.

Over filling a gas tank on newer, 1995 and up, vehicles can damage EVAP system.
So be cautious about filling up too much.



Nothing on drive train noise/vibration, you could try new U-joints, not expensive to do

 

Thanks for the input! Well i got a chance to replace the Upper and lower manifold gaskets today as well as all the Injector O-Rings and the Fuel Rail Gasket/Valve Cover Gaskets. everything went pretty smooth and i cleaned everything with a parts cleaner. Drove it home no problems. I did find a small coolant seep (looks like its coming from the rear of the gasket on the drivers side. Im suspecting the gap of the gasket where the manifold and head mate together. i used RTV, i guess just not good enough.) I checked my fuel trims and my SFT are pretty good, ranging from -8 to 8. Thats within spec. On another note, the LTFT is still around 25%. I'm starting to think its time to change the O2 sensors. I'm installing a new fuel filter Monday, and i'm hopefully ordering a new coil and wires soon. They appear to be original and with close to 200K they are probably ready to be changed. Thanks.

 

LTFT(long term fuel trim) will take a few weeks to come down after P0171/174 code are cleared and the reason they showed up in the first place is fixed.

I think a Ford scanner can reset LTFT but not a regular scanner.
LTFT wouldn't be much help if it changed very quickly.

Its purpose is to keep engine air/fuel mix current as an engine/system gets older, engine will always get/have small air leaks, start burning a little oil, fuel pressure drops a few pounds, just normal aging.

LTFT is also used at start up before O2 sensors get to 650degF

O2 sensors will be reasonably reliable up to 100k miles, after that you may notice MPG dropping a bit, then is the time to change them, they will pay for themselves over the next 100k miles in better MPG

 

Thanks RonD. I appreciate the help. I'll be doing Upper Control Arms this upcoming week. I'll let you know how it goes and check my filler tube.