Fuel Economy Slipping...!?

I have a stock 2013 Tacoma 4WD 4.0 L, 6 cylinder, Automatic 5-spd, Regular Gas truck. I'm at 175,000 km (108,700 miles) on the odometer right now. Problem is that I've started to notice the truck performing at a much lower fuel economy lately. Been travelling to the cottage over the last 5 years and its a 200 km trip and I usually burn just slightly over 1/4 tank of gas going one way. Nowadays for the same trip I'm burning close to 1/2 a tank of gas. This is close to double the amount of gas than I used to burn. Anybody have any ideas as to what is going on? I'm not doing anything out of the ordinary, not towing anything, or hauling anything super heavy. I've also been doing all the recommended maintenance at the dealer. The only odd thing that came up recently is that my Air Conditioning is not working, the light is flashing, so I turn it off and just use a little bit of heat which works fine. It's too cold for AC now anyway. Would appreciate if anybody has any insight into this. Thanks.

 

My guess is winter fuel. I typically see about 110 miles at 1/4 tank (slightly less than you) and for the past several tanks it’s gone WAY down... like 90 miles at 1/4 tank... summer months I average 320 - 350 (on a really good tank) and right now I can barely manage 290.

edit: not sure where you’re at geographically. Winter fuel might not be a thing where you are...

 

All others components being good, it'll be one to two things. 1st: fuel filter. 2nd: (less likely but has been found to be true) injectors. Well documented by the Aussies.

As well as in conjunction with what he said about the fuel change.^^^

 

I'm in Ontario, in the Greater Toronto Area... Never heard of "winter fuel". Thanks - will ask about it.

 

It just let's the engine start easier in cold weather. And has less energy in it

 

I think I would begin with some basic maintenance.

Clean throttle body and MAF
Change air filter
Change spark plugs
Change lubes in Diffs, Xfer case, tranny, power steering.....
Check the serp belt drive for dragging pulleys
Check tire air pressure.
Clear the truck of extra weight.
Check the Front End Alignment.
Verify tranny is shifting into Over Drive.

Just work to reduce any source of drag and friction.

I have essentially the same truck with 109,000+ miles. I get 19.* mpg in mixed driving, temperatures are ranging from 20F to 40F. When I'm running 60 mph in OD, the tach indicates about 1600 rpm.

These may or may not help.

 

How many time is "lately?" Its still possible that for the last two trips you just got an unlucky headwind.

 

A friend of mine with a very similar truck to the OP's had a very similar problem and brought the truck over for me to check out. Believe it or not, it was his front wheel bearings. And believe me, for wheel bearings to negatively affect fuel mileage, they have to be pretty bad. And his were. OEM Tacoma front wheel bearings (on 4WD trucks) are about a 100,000 mile item. I just replaced both of mine at 106,000 miles because one was just starting to go.

 

Fuel gauges are notoriously inaccurate. You need REAL numbers to know anything. What kind of mpg/kpl were you getting previously and what are you getting now?

 

Yes, wheel bearings can be a huge source of drag.

If this turns out to be the case, then you would be wise to change all the front wheel bearings on both wheels.

 

Are there any other symptoms to bad front wheel bearings besides bad fuel economy? Can I check it by lifting the front end and grabbing the wheel to see if there's play?

 

PCV replacement.

MAF cleaning.

TB cleaning.

Spark plugs.

The “fuel” part of the air/fuel/spark triumvirate isn’t usually a problem in Tacoma’s... so try basic items for the other two.

 

That is one way, but may not be definitive.

Lift the truck, remove the wheel, slowly rotate the the hub in both clockwise and counter clockwise. You are feeling for "bumps", drag, resistance in spots, listen for grinding or unusual sounds.

Worse case, pull the hub to access the bearings directly.

 

Play would indicate ball joint wear more than anything.

 

Yes. Generally speaking, they will make noise before you can detect play. The noise will generally be a humming sound that gets worse in corners. (That was my truck.) If they continue to get worse, you will be able to feel play (up and down and / or side to side) in a wheel when you jack the truck up. (That was my friend's truck.)

If it is a wheel bearing, as has already been said, you're better off replacing both sides plus the two seals on each side. After all, if one went, the other side won't be far behind. And be very careful of what kind of bearing you replace them with. There are many, many different brands out there with some significant differences is quality. Beware the cheap crap like Dorman.

 

That's what if you feel any play, you have to look closer to see where the play is coming from.

 

Unfortunately both the wheel bearings and ball joints suck on our Tacoma’s. Yay Toyota.

 

The wheel bearing on a 4WD Tacoma is a sealed unit with the hub pressed onto it, so you can't really pull just the hub.

 

Buy replacement hub assemblies from TW member 05Taco4X4

Unless you buy OEM from the dealer he’s the only guarantee that you’re gonna get OEM quality (Koyo) bearings that are pressed in correctly (there’s a long thread about it)

As a plus he ships very quickly, the hubs look great and are SUPER reasonably priced.

 

I hate that construction.

My GMC Sierra 2500HD had a similar build. Right front ABS sensor failed......$600 to replace the hub. The ABS encoder was buried in a sealed hub.

I guess I'm just old school. When you could pull the hubs, remove the tapered roller bearings, hand pack grease into the new bearings, press the races into the hub, reassemble with the castle nut and cotter pin. Total cost was bearings, seal and a bit of grease.....typically less than$25. Now, the repair is several hundred $$. Progress???