Fuel Economy

Tiny
HARRY P
  • CERTIFIED MECHANIC
Okay. I'm going to pick your brains on how to attack it anyways. I use my 2000 4x4 4 door automatic Blazer as a mail route truck. 5 hours daily, 55-65 miles of stop and go. Up to 650 stops. Low speeds. In those 55 miles, I'm burning 8+ gallons of gas. Most of it is idling time. I want some ideas of free or cheap things I can do to improve that mileage. Being a 2000, it's does not have to pass emissions inspections anymore, so hitting the cat has crossed my mind.

I'm also thinking of ways to cut weight without losing structural integrity and performance.

I keep my brake calipers and slide pins greased so they operate correctly and don't send to be sticking anywhere. Truck fires right up fast. I took the distributor call off and cleaned the contacts but there wasn't much there to begin with. Wires look decently new, though I've had this truck 3 years so I may look at new plugs and wires soon.

I tried changing my lead foot out but can only find lead replacements so that's not an option. What else you got?

I can ask in the s10 groups on Facebook but 8/10 of them will suggest dropping an LS engine in it and that's just not in the budget for a mail route car.

Really think about it please. With my type of work, small improvements can really add up.
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Sunday, August 1st, 2021 AT 12:22 PM

57 Replies

Tiny
CJ MEDEVAC
  • CERTIFIED MECHANIC
https://www.ebay.com/itm/353525752627?chn=ps&var=622816569928&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=622816569928_353525752627&targetid=1262779894009&device=c&mktype=pla&googleloc=9010629&poi=&campaignid=10459841973&mkgroupid=123050527180&rlsatarget=pla-1262779894009&abcId=2146002&merchantid=420524481&gclid=EAIaIQobChMI9e6JtNOQ8gIVQ5yzCh2bcQlYEAQYByABEgLqk_D_BwE

If that doesn't cut it, you might switch over to an early model Dodge Ram, This would probably handle the mild S.C roads really well in your region.
It may lack power over in my neck of the woods.

The Medic
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Sunday, August 1st, 2021 AT 2:05 PM
Tiny
HMAC300
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Fuellmileage is up to the driver on how hard hepresses the gas pedal. Keep air and fuel filters clean make sure your injection is working good as alot of those broke the spider and would leak fuel. Keep in 2wd as much as possible lastly you could change gear ratio would make it slower but you would also have to do both axles so expensive.
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Sunday, August 1st, 2021 AT 3:47 PM
Tiny
HARRY P
  • CERTIFIED MECHANIC
Guys I'm basically looking for places I can cut some weight to help out. I'm stopping and going 600 times in a day. My lead foot isn't making much difference there. I can granny drive it and not do much better. I've tried.

In the past I'd removed the back seats to create more storage space. While storage space isn't an issue anymore, it might help to drop that 100 or so pounds of weight. Maybe gutting the door panels?
100 I wasn't addicted to AC I'd drop that whole system. What if I put a higher temp thermostat? Like a 210? Would that help much? But then I'd be increasing pressure on older parts so maybe that's a no go.

I can gut the cat and put a non fouler on the downstream O2 sensor to keep the light off. I know that'll give me a little boost.

Where else can I cut some weight?
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Monday, August 2nd, 2021 AT 3:40 AM
Tiny
HARRY P
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Hmac, I know those things are generally true, but when you're driving 75 feet at a time, granny driving vs lead foot doesn't make a whole lot of difference. I promise. I've tested it. Maybe 1/2 gallon on the day but it cost me 1/2 hour extra of my life that I was not paid any extra for. So the cost: benefit ratio just isn't there. What I need to do is cut weight and get it where it burns less fuel at idle, because most of the day it's idling.
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Monday, August 2nd, 2021 AT 3:44 AM
Tiny
STEVE W.
  • CERTIFIED MECHANIC
Gutting the cat isn't going to do anything to help the mileage, they are very free flowing on them and if it's working it isn't changing the fuel mix. Higher temp won't help either as it's not designed to use the higher temps and will just stress the system more. My 02 averaged about 18 mpg normally, that's because the 4.3 was built from the 350, it's a reliable engine but wasn't built for economy. Plus you are driving about the worst possible way for economy short stops, on and off the gas. Takes a serious weight reduction to make any difference in those conditions. Not really much to remove that will help with that.

I have seen a minor increase (maybe 1 mpg) when switching to the newer individual injectors from the old spider units. Beyond that they just were not built for mileage.

Up here the current mail dude has two vehicles, one a 4X4 Nissan and the other is a Kia Soul The Soul stays parked at the PO and he drives the one needed for the conditions and amount of mail, like he was telling me, 80% of the time it's a few parcels and lot's of junk mail and such. The Soul is a LOT better on gas but isn't real good in heavy snow. So in the winter it gets parked in his garage and he runs the Nissan full time.
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Monday, August 2nd, 2021 AT 10:38 AM
Tiny
HARRY P
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Ok. How much dead weight do you think I could stand to lose? I dropped about 100 pounds of extra unused crap out of the trunk the other day. I'm going to remove the back seats soon. I was also thinking about dropping the hitch but I really do like having it there. It's nice to know I can randomly tow shit. Where else can I shave some dead weight?

If I were able to get my hands on a tuner for it and maybe drop the idle by 50 RPMs might that make a difference in the aggregate?

Basically guys, I know I need to buy something smaller. But that's not in the budget. Free/cheap improvements, however, are.
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Tuesday, August 3rd, 2021 AT 3:50 AM
Tiny
STEVE W.
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Rule of thumb is 10% weight reduction gives you 1% mpg gain, but that is over a longer test run, stop and go isn't likely to yield that. Lower idle won't help much as you then need to apply more pedal to get moving plus most tuners don't allow idle speed changes due to that requiring a remap. Low resistance tires made for mileage might help but they are also going to be stiff and slick compared to an all season. Sorry it's not more helpful but they were just not made for mileage.
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Tuesday, August 3rd, 2021 AT 5:16 AM
Tiny
HMAC300
  • CERTIFIED MECHANIC
To bad you can't get a hybrid as they only run on electric to about 6 miles an hour
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Tuesday, August 3rd, 2021 AT 8:02 AM
Tiny
94 TRANSAM
  • CERTIFIED MECHANIC
Youre kind of in a pickle but for your cost vs options I would say for the money and work your biggest improvements are, switch to full synthetic oil. That will give you a little and the biggest bang for your buck as odd as it may seem would be to switch to load range E tires and run 80 psi in them. Those 2 things will reduce a ton of load and drag. You would be shocked at the difference just the tires make. 32 psi in tires puts a heavy load on a motor. If you dont believe it just try pushing a car with 32 psi and then push one with 80. Massive difference. I switched my truck to load range E with 80 PSI and went from 15 to 19 MPG. It is alot rougher ride though. You can switch to syn in the diffs too. Frictional HP costs alot of gas.
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Tuesday, August 3rd, 2021 AT 9:19 PM
Tiny
HARRY P
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I've run the numbers guys. On a 55 miles route, I'm getting 8.2 mpg. If I can get that 10 mpg somehow, it'll save me $72/month. I'm not looking for much, just a little bit. So the back seats are coming out. Going to pop in a new fuel filter (I've put 35k on since I got it and haven't changed it yet so it's probably due). Make sure the gas cap is good. With 180k on it, gutting the cat might be in order. I've got a buddy with a welder that owes me a favor and I've got an O2 sensor non fouler to fool to CEL.

Can you think of any other spots I can drop weight? This isn't a family car, it's a workhorse, so I'm not real worried about interior cosmetics.
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Thursday, August 5th, 2021 AT 6:34 AM
Tiny
HARRY P
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Today I ran a route that's a bit longer (63 miles) with fewer stops. I also unplugged the AC compressor clutch because, whipped I don't run the AC while working, it does constantly cycle the system even with it off. I managed a whopping 9.2 mpg today. Maybe it was the reduction in stops, maybe it was the disconnecting the compressor clutch. I'm running the same route tomorrow and will leave the compressor clutch hooked up and see what it does. Should be interesting. Also, I took a dash cam video in case anyone was interested in seeing what I do from my perspective.
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Friday, August 6th, 2021 AT 5:17 PM
Tiny
STEVE W.
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The AC in that shouldn't cycle on unless the AC is in use or the defroster is on, if it is you have a controller issue.
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Friday, August 6th, 2021 AT 5:49 PM
Tiny
HARRY P
  • CERTIFIED MECHANIC
I've switched the controller out for a different issue but it still does that. My 2002 did it, as did my last 2000. I was pretty sure it was normal. I thought it was part of some moisture control junk they were doing. If memory serves they've done it on many models. Maybe I'm wrong though
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Saturday, August 7th, 2021 AT 11:53 AM
Tiny
STEVE W.
  • CERTIFIED MECHANIC
None of mine worked that way the 97, 01 and 02 only cycled if you are in defrost or AC or if you are running any part of that, the idea is that it runs the air through the AC system to dry it if you are running defrost so you don't fog or ice the windshield. The 85 and 92 I had didn't work that way though, those didn't use AC unless it was on. Understandable though as the 2.8 was anemic enough without the extra load and the 4.3 was better but didn't have that system. I had one with a 2.2 in it for about a week, that thing could barely get away from a stop sign. If you've ever driven one of the LLV mail trucks, they were better than the Blazer !
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Saturday, August 7th, 2021 AT 1:13 PM
Tiny
HARRY P
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Indeed I've driven both the 2.2L Blazer and the LLV. I use a LLV every other week on Sundays. I one managed to clock 0-60 (GPS verified) in under 17 seconds by working the shifter like an old 3 on the tree while literally standing on the gas. Honestly, the LLV is darn near perfect for what it does and I doubt they'll top it with the next truck. The new one may be nicer, but I see it being problematic and our "less-than-stellar" won't be able to handle it. I've literally diagnosed the LLV problems for them only to find the truck with the exact same problem the day after they had it in the shop for a week. And it would be as simple as a stuck thermostat. I can't wait to see what they can do with post 1980s tech and AC
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Monday, August 9th, 2021 AT 6:49 AM
Tiny
HARRY P
  • CERTIFIED MECHANIC
Speaking of LLVs, here's what's happened the last time I drove one. If I had to guess I'd say a mechanic didn't tighten the pulley bolts. Happened as I was merging onto I-40 (following GPS against my better judgment)
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Wednesday, August 11th, 2021 AT 7:33 AM
Tiny
HARRY P
  • CERTIFIED MECHANIC
Getting back on track here, if cutting 10% weight generally results in a 1% fuel economy bump, I would think that my type of driving would be doubly or triply helped, seeing as it's mainly going to go towards acceleration, which is all I do, allowing me to take my for if the pedal earlier. Also, a nice little side effect is maybe my brakes will last a little longer. No matter what I use, I don't get more than 3-4 months out of a set of front pads.
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Wednesday, August 11th, 2021 AT 7:52 AM
Tiny
MASTER ASE TECH
  • MEMBER
I second the 80 PSI in the tires. Without switching the tires, run the PSI as high as you feel comfortable with. Also remove any roof racks or other things in the air stream, and strip all the weight out.
Dump the mechanical fan for an electric model.
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Wednesday, August 11th, 2021 AT 11:32 AM
Tiny
HARRY P
  • CERTIFIED MECHANIC
I've thought about switching to an E-fan before but right now I'm just trying to go for free or dirt cheap mods I can do while saving cash to buy something else to use on a daily basis. Thinking I can get a little 4 cylinder beater car that runs good to use most of the year and just use the Blazer as a daily driver and run it only as needed on the route.

As for the tires, they're brand new and under warranty so I'm not into doing anything to them until I have to right now.
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Wednesday, August 11th, 2021 AT 1:09 PM
Tiny
HARRY P
  • CERTIFIED MECHANIC
I filled the tank the other day. Ran a route 2 days straight. Filled it up on the way back to the office at the end of the second day. 126 miles driven on the trip meter, 16 gallons of gas to refill. I swear it used to do better than that. I didn't always track it, but I used to be able to go through 2 days and not be sweating it with the gas light on at the end of the second day. Sometimes I could push halfway through a third day before the light came on.

I've got no engine light on, no codes, the air filter is clean.

I've got the day off Monday. Maybe I'll dig in under the hood and start a general tune up.
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Saturday, August 14th, 2021 AT 12:33 PM

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