What happened to my mileage?

[Somemedic]

DSKchehy: you are going to be replacing your IP soon. Sell it or make the preperations.

Fuel on the rear tailgate sounds like the fuel that collects in the motor valley cause the IP is leaking and needs rebuilt. Get a bright flashlight and look on top of the motor. Suspect the injectors if the top of the motor is dry but I have a feeling it wont be.

Ive never had the injectors rebuilt but the fuel on the tailgate went away after the IP was rebuilt and the top of the motor is dry. You will also sometimes see fuel leaking out of the flex plate inspection cover weep hole.

Buy a good quality head gasket kit and start shopping for an injector pump rebuild shop. Might also get some rebuilt injectors at the same time. Id bet she'd scream after the rebuild.

Now you know what to do with that tax check. Around $1100 to farm it all out.

 

[ragedracer]

I currently run Power Service in every tank, have since I first got it. It's just disconcerting that I've lost 4-5mpg in the last 800 miles. Something must be wrong.

I would think if the engine were wearing out, I would see loss of oil, blue smoke, etc. That I'm losing no oil at all really steers me to somewhere in the fuel system.

 

[Screamin' Metal]

The General is right...it is probably that.....but maybe.....gotta learn to troubleshoot on these things.....

 

[ragedracer]

DSKchehy: you are going to be replacing your IP soon. Sell it or make the preperations.

Fuel on the rear tailgate sounds like the fuel that collects in the motor valley cause the IP is leaking and needs rebuilt. Get a bright flashlight and look on top of the motor. Suspect the injectors if the top of the motor is dry but I have a feeling it wont be.

Ive never had the injectors rebuilt but the fuel on the tailgate went away after the IP was rebuilt and the top of the motor is dry. You will also sometimes see fuel leaking out of the flex plate inspection cover weep hole.

Buy a good quality head gasket kit and start shopping for an injector pump rebuild shop. Might also get some rebuilt injectors at the same time. Id bet she'd scream after the rebuild.

Now you know what to do with that tax check. Around $1100 to farm it all out.

You might be on to something here.. When I get home, I'll check on the motor, BUT, I have noticed a drip coming out of the weep hole, usually just a drop or 2 after I park, but not continuous. I assumed it was a very small oil leak from the rear main seal. This started just about the time my mileage started going to crap.

Is it best to check shortly after a drive, or would there be fuel in the valley all the time?

Edit: Tax Check? HAHAHAHAHAHAHAHA!!! I'm self employed. I haven't gotten a refund in, well, I can't really remember the last time I did.

 

[Screamin' Metal]

How does the engine run....as good as its Been? Crank up OK? Does it smoke excissively on starteup? Does it pull as hard as it always has? Does it smoke bad doing it?

 

[ragedracer]

How does the engine run....as good as its Been? Crank up OK? Does it smoke excissively on starteup? Does it pull as hard as it always has? Does it smoke bad doing it?

It runs great. Very little smoke on startup. It starts quickly both from cold and hot. Pulls as hard as it ever has. Does not smoke much at all under load.

 

[Screamin' Metal]

Don't want to get your hopes up....sometimes the seal will allow air to be sucked into the system just enough to mess up the fuel milage good, so you've described. The General is right....your pump is probably on the downhill slide....but you might be able to change out that seal and drive it a little longer till you get your finances in order.

There's another thread on this issue......you can get you IP rebuilt for about $300 or so, and injectors you can buy, on a exchange basis, and do yourself. Changing the IP isn't bad for the strong-at-heart.....

 

[ROB L3]

i lost mileage when i used that ultra low sulfer crap.try a tank of off road fuel and see what happens

 

[Degosh]

also what kind of oil have you used in your last oil change, if you run dino oil on synth you will see a drop in mpg. another thing is did you check to see if you have sludge building up in your oil. maby not but when i see less mpg first thing i check is the oil.

 

[bobbed818]

Not to beat a dead horse or add to posts. Before you spend big $$$ on IP, injectors, etc, Try putting the smaller tires on it for a tank or so and just see what happens. I'm not saying your milage didn't increase, but I've never been that fortunate to get a lift, bigger tires, and better MPG. Also, I don't know if your t-case has a slip-yoke or fixed yoke, but if it is a fixed yoke I have seen them leak through the splines,washer, and nut.

 

[southdave]

dumb question your not in 4wd? or are your hubs locked?

 

[abarkus]

He has a fule leak on the return side

 

[ragedracer]

First: Merry Christmas!!!

I haven't had a chance to get out and check for a fuel leak yet. As to putting different tires on, I don't think that's it. If it were the tires, I would think I would have seen an immediate drop in mileage, not a slight increase at first, with a steady decline months later. I wouldn't even be concerned if I had lost 5 mpg all at once, it's when I lose a couple MPG each tank that I worry.

And to get off the original topic onto my TC leak. It's a slip yoke, and it seems to be leaking at the u-joint connection. In fact, it looks like the u-joint saddle is press fit onto the yoke, and the fit there has gone slightly bad. I might pull the u-joint off and run a weld around the press fit and see if that takes care if it. The slip yoke itself is dry, yet it drips all the time, even when just sitting still. There's no way for the ATF to make it to the "drip point" on the outside of the yoke. I even tried wrapping a rag around the yoke to see, and it was still dripping, yet the rag was clean!

 

[4x4 Forever]

If your rag stays dry around the slip, the only other way would be fluid coming out the end of the yoke. Your yoke/ujoint saddle piece should be forged out of one piece of metal. Also check for hole at the end of the yoke while your at it, it might have rusted through.

 

[Recovry4x4]

I believe there is a big tampon that is shoved down inside the slip yoke. When that goes bad stuff leaks out of the end of the yoke.

 

[TBigLug]

Something else to look at for grins, how's the tranny fluid? Maybe it's starting to get burnt and the trans is starting to slip. Might be just a little but enough to screw up your MPG's. Just a thought.

 

[ragedracer]

Something else to look at for grins, how's the tranny fluid? Maybe it's starting to get burnt and the trans is starting to slip. Might be just a little but enough to screw up your MPG's. Just a thought.

Tranny fluid is new and good. I changed it when I first got it last year, the stuff than came out looked new. When this leak developed, I pulled the pan, replaced the filter, replaced the yoke shaft seal, and refilled. So, no, it's not due to bad fluid.

 

[Screamin' Metal]

Hey....keep us informed of what you find! We'ew here if ya need use......

....................'When it positively, absolutely has to be destroyed overnight..........'

 

[4x4 Forever]

I believe there is a big tampon that is shoved down inside the slip yoke. When that goes bad stuff leaks out of the end of the yoke.

 

[kennyw]

Have you corrected the speedometer for the larger tires? If not, that may be the reason you thought your mileage increased with a lift and bigger tires... doesn't help or have anything to do with the slow decline though.