Sudden drop in MPG

[hgeranium]

For the entire time of driving my MJ, I've consistently gotten between 10-11MPG in the city and 13-14 highway. At the end of June, my fuel filter began to leak, so I replaced it, and my MPG for the next few tanks shot up to 13.5/17.5. I had that MPG for about a month before it came back down to my usual 10-11. I'm wondering if it is purely external factors/driving habits that have caused this

 

I drive pretty conservatively, not a lead foot but not like a grandma. Always have the trans switch on Comfort. It's not running rich, spark plugs confirm that. No major vacuum leaks. I don't run AC or vent air at all. Air filter is new and in good condition. I haven't taken them off to confirm, but the current injectors are yellow so I think they're the Volvo 746's.

 

I do live in a college town, so the timing of the MPG drop also coincided with the 'back-to-school crowd'; since August I've been in a lot more stop-and-go traffic. The heat also turned on for the summer around this time because of all that rain June-July.

 

I am also in the process of replacing all of my steering components (outer tie rods done, still have track bar and inner ends to install), so the alignment is eyeballed good enough to drive, but not professionally set. My alignment has never been correct since I've bought it since the steering components were so worn, but I figure it plays a role regardless.

 

I just wanted to see if I'm missing something. I've seen the long thread of the guy getting the best MPG possible, but I don't have the money or patience to fire off the parts cannon tuning up and optimizing. I know what it's capable of, but didn't want to assume external factors were to blame without some two cents from y'all.

[89 MJ]

Stock gears and tires?

 

Do you have a REM?

[Pete M]

stop and go traffic will absolutely kill mpgs.  

[hgeranium]

1 hour ago, 89 MJ said:

Stock gears and tires?

 

Do you have a REM?

Stock gearing and 30x9.5s. I put those tires on within a week of getting the truck

[hgeranium]

37 minutes ago, Pete M said:

stop and go traffic will absolutely kill mpgs.  

I figured as much. It’s just strange that my highway MPGs have taken a hit too. I frequently do a 180 mile round trip and even late at night with no traffic, I haven’t been able to replicate that 17.5MPG

[89 MJ]

Remember larger tires will throw off your odometer unless you changed the speedo gear. That doesn’t change your drop in fuel mileage though. 
 

If you have a REM, I’d recommend going through all of the values you have on that and compare them to expected values. 

[hgeranium]

8 hours ago, 89 MJ said:

Remember larger tires will throw off your odometer unless you changed the speedo gear. That doesn’t change your drop in fuel mileage though. 
 

If you have a REM, I’d recommend going through all of the values you have on that and compare them to expected values. 

I wish I had an REM. My heart says yes but my wallet says no  Maybe if somebody on here has a used unit