Could my fuel milage be excessive

[THEBRAIN]

Could my fuel milage be excessive
05 pleasureway lexor rd chevy 3500.w/ 116K miles on clock, one carry on bag & laptop bag an sleeping bag.small tool box
No gear or water in tanks kindof lite by traveling standards.

This calculation isn’t exact. I had a tad less than ½ tank which is 15 gallons.
Cruised 155 miles mostly 2 lane black top county road.so that’s 10mpg.
This mpg seams off by 5mpg?
Maybe time for a complete tune up?
I have a new air filter an fuel flilter yet to install (will next nice weather day)

The engine idels an runs so smooth I didn’t think she needs new spark plugs.
Remember I don’t have much history of my new van.I believe GM says to leave iridium
SPs in for 100K mile is this true or false. You would think SPs in that long would be welded to heads.

Please advice on tune up parts like spark plugs I normalley use NGKTR55 on my
LS1 car, an my L33 V8 trailblazor.

What SPs are you Guys using w/ the GM 6 litre?
I'm planning on a decent SP socket this https://www.amazon.com/gp/product/B0...JRE9G6AY&psc=1

or is 6" the wrong lenght, was planing to remove front wheels an do SPs though wheel well.

thanks for advice.

I'll probably remove the roof AC, I think it's 85LBs.

photo yes my rear wheel needs clean an repaint untill I get nicer rims

edit my rear tire preasure was 75 and fronts where 55 both cold.
I have read preferred preasure is 80 rear 60 front. 5LBs couldn't lower the mpg down to 10 or could it?

[booster]

Two lane highways at 50-55mph usually would give us about 16+mpg in summer months. We like 80 and 65 pressures with stock size tires.


If it is running well and making good power I would try to get a longer, better, more accurate mileage test before going nuts. Go to a parts store and have them check for codes. Check for brakes, including parking brake, for dragging.


I think Pleasure-way uses the 3.73 or 3.93 rear axle instead of the more common 4.11 like the Roadtreks have, but unless you were in a constantly downshifting condition that shouldn't make 5+mpg difference.


Don't panic until you get more information, IMO. But if it really is 10mpg there is something wrong and you soon would have plugged catalytic converters from the rich condition.

[N147JK]

Are you saying you had about 1/2 tank then drove until it showed close to empty? If yes, that is a very inaccurate way to calculate MPG.

1. Fill the tank until it is completely topped off and note the odometer. You should be able to see the fuel filling the filler neck all the way up to the cap. Yes a very small amount may spill out onto the ground - not a big deal.

You need to do this because you MUST be able to refill the tank back to its original level exactly. If you just pump until it automatically shuts off, you wont get an accurate amount because different pumps will shut off at different levels. You have to confirm the level visually.

2. Burn the fuel off. The farther you drive, the more accurate the calculation will be.

3. Refill the tank, again completely topping it off - same as step 1.

4. Calculate your MPG.

BTW, you don't have to do the calculation on the very next refuel. You can go as many refuels as you want, just as long as you keep track of the total mileage and amount of fuel put in each time. When you are ready to calculate the MPG accurately, completely top it off as in step 1 and divide the grand totals.

[booster]

Originally Posted by N147JK

Are you saying you had about 1/2 tank then drove until it showed close to empty? If yes, that is a very inaccurate way to calculate MPG.

1. Fill the tank until it is completely topped off. You should be able to see the fuel filling the filler neck all the way up to the cap. Yes a very small amount will spill out onto the ground - not a big deal.

You need to do this because you MUST return the fuel level back to its original level exactly.

2. Burn the fuel off. The more you burn off, the more accurate the calculation will be.

3. Refill the tank, again completely topping it off, same as step 1.

4. Calculate your MPG.

Totally agree that is if that he was saying he did it is nothing close to accurate. I find the second half of the tank our our Chevy goes lower way faster than the first halft


I would add that for accuracy you have fill at the same pump before and after to be accurate.

[THEBRAIN]

Originally Posted by booster

Two lane highways at 50-55mph usually would give us about 16+mpg in summer months. We like 80 and 65 pressures with stock size tires.I prefer to travel very early to avoid other ppl on the road average speed 65 on 4 lane 75 unless a local gets in front of me a drives 55 I'll definity air up the tires to 80 rear & now 65 in front please recommend a decent portable compressor none of the gas stations have air anymore all the hose's have been cut by malicious folks


If it is running well and making good power I would try to get a longer, better, more accurate mileage test before going nuts. Go to a parts store and have them check for codes. Check for brakes, including parking brake, for dragging.I resolved the only code I had the front O2 sensor on pass side can I elevate each wheel and spin by hand to test the brake drag?


I think Pleasure-way uses the 3.73 or 3.93 rear axle instead of the more common 4.11 like the Roadtreks have, but unless you were in a constantly downshifting condition that shouldn't make 5+mpg difference.
according to my code lable I have 3.73 gear ratio I should have mentioned that I started at sea level stopped at 260' above sea level Florida panhandle isn't flat it's hilly so this was a uphill trip back


Don't panic until you get more information, IMO. But if it really is 10mpg there is something wrong and you soon would have plugged catalytic converters from the rich condition.

Originally Posted by N147JK

Are you saying you had about 1/2 tank then drove until it showed close to empty? If yes, that is a very inaccurate way to calculate MPG.yes just under 1/2 tank each notch on guage is whorth almost 2 gallons drove all the way to empty last notch but before the reserve yellow light came on. I agree w/ you an Booster about not being arcurate next trip (same trip) are you Guys saying there was much less than the 16 gallon which is 1/2 tank? I'm kindof used to the mileage being calculated by the vehicle

1. Fill the tank until it is completely topped off and note the odometer. You should be able to see the fuel filling the filler neck all the way up to the cap. Yes a very small amount may spill out onto the ground - not a big deal.

You need to do this because you MUST be able to refill the tank back to its original level exactly. If you just pump until it automatically shuts off, you wont get an accurate amount because different pumps will shut off at different levels. You have to confirm the level visually.
yes I do this next trip
2. Burn the fuel off. The farther you drive, the more accurate the calculation will be.

3. Refill the tank, again completely topping it off - same as step 1.

4. Calculate your MPG.

BTW, you don't have to do the calculation on the very next refuel. You can go as many refuels as you want, just as long as you keep track of the total mileage and amount of fuel put in each time. When you are ready to calculate the MPG accurately, completely top it off as in step 1 and divide the grand totals.

yes I will do but all things considered including avg speed I should be getting much better milage.
like I drive her sensibly not taking off hard and not racing to the red light just ahead ect. I bet she gets better going downhill when arriving.thanks N147JK I will report back after next trip scheduled for 3rd week in Feb.

Originally Posted by booster

Totally agree that is if that he was saying he did it is nothing close to accurate. I find the second half of the tank our our Chevy goes lower way faster than the first halft yes all GMs are like this due to the fuel tank level sensor.


I would add that for accuracy you have fill at the same pump before and after to be accurate.

are you saying same pump# at same gas station? I do usalley get fuel at the same place but rarely get to use the same pump. thanks Booster for advice
edit I want the van running efficiently she's hitting on all 8 no codes but something needs adjusting. also I should have mentioned I wasn't towing just cruising in van.if I was towing it would be even less proballey 5mpg which is unaceptable.

[SteveJ]

Me, personally, I would not jam the tank all the way to the top. In some vehicles, yours?, this can ruin the evaporative cannister.

I would fill the tank to where it shuts off, go drive enough to at least use a 1/2-3/4 tank, then return to the same pump to fill in the same way.

Perhaps not extremely accurate but should be pretty close.

[N147JK]

Originally Posted by SteveJ

Me, personally, I would not jam the tank all the way to the top. In some vehicles, yours?, this can ruin the evaporative cannister.

I would fill the tank to where it shuts off, go drive enough to at least use a 1/2-3/4 tank, then return to the same pump to fill in the same way.

Perhaps not extremely accurate but should be pretty close.

That's probably a good policy.. just try and average it out long-term. Definitely not worth doing any damage! One issue though is I can get 4 to 5 more gallons in my E250 van after the auto shut-off occurs, which is a lot of range.

[THEBRAIN]

Originally Posted by SteveJ

Me, personally, I would not jam the tank all the way to the top. In some vehicles, yours?, this can ruin the evaporative cannister.

I would fill the tank to where it shuts off, go drive enough to at least use a 1/2-3/4 tank, then return to the same pump to fill in the same way.

Perhaps not extremely accurate but should be pretty close.

good tip Steve.
even if my current calculations where off by a gallon or 2 my mileage still sucks.
will keep a close eye on milage. worst thing is I'm babying her. will report back. thanks

[booster]

Originally Posted by THEBRAIN

good tip Steve.
even if my current calculations where off by a gallon or 2 my mileage still sucks.
will keep a close eye on milage. worst thing is I'm babying her. will report back. thanks

IMO you could be off 5 gallons or more reading only the lower half of the gauge.

[jrobe]

Then the question is, should we worry much about fuel mileage when we buy a fuel inefficient van, load it down to the maximal GVWR and then buy it so we can travel long distances. For me the answer is no.

[GeorgeRa]

For folks interested seeing instant gas mileage a ScanGauge is a good tool, easy hookup.
https://www.scangauge.com/products/p...scangauge-iii/

[booster]

Originally Posted by GeorgeRa

For folks interested seeing instant gas mileage a ScanGauge is a good tool, easy hookup.
https://www.scangauge.com/products/p...scangauge-iii/

Yep, we have one. The problem is that you need to do an accurate fairly long term information gathering to get the fuel correction right. If you use the every tank adjustment it never, ever seems to stabilize and jumps all over the place. I logged a 2000+ mile trip with all the gas we used and never reset the fillup on the Scangauge so at the end, at the same pump, I could compare what it said we used compared to many fillup amounts. I then set the correction manually and never did the auto on again.

[N147JK]

Originally Posted by jrobe

Then the question is, should we worry much about fuel mileage when we buy a fuel inefficient van, load it down to the maximal GVWR and then buy it so we can travel long distances. For me the answer is no.

True, we will never see very good MPG in these vans no matter what we do. But in this case the OP is concerned there may be something wrong with his van. If so, it should be fixed.

FWIW my van comes in at about 1500 lbs under GVWR - fully loaded ready for the road! It's one of the reasons I love it. It's not overbuilt or overweight. It gets exactly what Ford says to expect.. 15.00 MPG.

[blackbourn3704]

Here's something you may want to consider in your calculations too. If you are running a generator to power your coach A/C remember it uses fuel too. Our Onan 2800 uses 0.4 gallons per hour and as we normally cruise at 60 miles per hour that means 0.4 gallons NOT consumed by the drive engine for each 60 miles of the trip calculations. For instance 600 miles in 10 hours using 45 gallons =13.3 mpg, but deducting 4 gallons for generator use = 600/41 = 14.6 mpg.

[JohnnyFry]

Computing mileage on partial tank readings is inaccurate because fuel gauges are imprecise at any reading other than full and empty. They are non- linear in between because fuel tanks have irregular shapes.

[Trav59KL]

Absolutely right. Gas gauges are not linear, or even close to accurate. In my experience at "one-half" on the tank there may be substantially less, or substantially more, than half the total fuel capacity of the tank. And on most cars, the gauge hits empty while there is still a gallon (or two, or three) in the tank. The only way to measure even close to actual mileage is to measure gas in and out at the pump.

[GeorgeRa]

Originally Posted by Trav59KL

Absolutely right. Gas gauges are not linear, or even close to accurate. In my experience at "one-half" on the tank there may be substantially less, or substantially more, than half the total fuel capacity of the tank. And on most cars, the gauge hits empty while there is still a gallon (or two, or three) in the tank. The only way to measure even close to actual mileage is to measure gas in and out at the pump.

I found my well calibrated ScanGauge II rather accurate. Built in instant gauges on some cars are reasonably accurate as well. For my Sprinter I keep spreadsheet with fill pump reading and milage, it is a good monitoring tool to see if things are OK.

[ChicagoTom]

08 chevy pw lexor, answers in upper case below

Originally Posted by thebrain

could my fuel milage be excessive
05 pleasureway lexor rd chevy 3500.w/ 116k miles on clock, one carry on bag & laptop bag an sleeping bag.small tool box
no gear or water in tanks kindof lite by traveling standards.
THE THING WEIGHS 9200 POUNDS, DON'T WORRY ABOUT IT

This calculation isn’t exact. I had a tad less than ½ tank which is 15 gallons.
Cruised 155 miles mostly 2 lane black top county road.so that’s 10mpg.
This mpg seams off by 5mpg?
WHY ARE YOU DOING THIS SIMPLY PRESS THE RESET ON THE DASH. UNLESS YOUR YEAR DIDN'T HAVE THAT?
maybe time for a complete tune up? I HAVE 155K ON MINE AND IT'S NEVER BEEN TUNED UP. PLUGS AND WIRES CHANGED AT 140K OR SO
i have a new air filter an fuel flilter yet to install (will next nice weather day)

the engine idels an runs so smooth i didn’t think she needs new spark plugs.
Remember i don’t have much history of my new van.i believe gm says to leave iridium
sps in for 100k mile is this true or false. You would think sps in that long would be welded to heads.

Please advice on tune up parts like spark plugs i normalley use ngktr55 on my
ls1 car, an my l33 v8 trailblazor.

What sps are you guys using w/ the gm 6 litre?
I'm planning on a decent sp socket this https://www.amazon.com/gp/product/b0...jre9g6ay&psc=1

or is 6" the wrong lenght, was planing to remove front wheels an do sps though wheel well.

Thanks for advice.

I'll probably remove the roof ac, i think it's 85lbs. Lol, don't remove the a/c, it won't make a difference

photo yes my rear wheel needs clean an repaint untill i get nicer rims

edit my rear tire preasure was 75 and fronts where 55 both cold.
I have read preferred preasure is 80 rear 60 front. 5lbs couldn't lower the mpg down to 10 or could it?

>>>>>>PW SAYS 50/80
HONESTLY THE REPLIES HERE ARE COMICAL

[booster]

Originally Posted by ChicagoTom

08 chevy pw lexor, answers in upper case below >>>>>>PW SAYS 50/80
HONESTLY THE REPLIES HERE ARE COMICAL

Roadtrek also says 50/80 and I will tell you why.


It is the recommended from Chevy for the base van before conversion. Just look at the original tire pressure plate from GM.


That recommendation is a best compromise for an unloaded cargo van up to a fully loaded cargo van so is not optimized for a narrow range of weights like we see in near fully loaded all the time class b vans.


If you read all the reviews of tires and pressures here and many other places for class b vans, I think you will find 60-65 in the front, 80 in the rear is by far the most common pressures that folks have found for the best handling/comfort balance.


We have run 50 psi in the past to compare and the handling was severely reduced IMO.


I also think it is pretty insulting to call people opinions comical.


By the way, GM recommends spark plug change at 100K miles. Why is OK to violate that, but not the tire pressure recommendations?

[booster]

Empty 2007 Express 3500 curb weight 5453#


Fully loaded to max GVWR 3500 9600#


Increase of 4147# which I guess is just a bit over "a couple of hundred pounds". 75% weight increase.