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Discussion Starter #1
Ok, so I just bought this 1990 dodge cummins 350 and went up to vegas to get it. Before I left vegas I topped it off. Then I started towards phoenix and the truck made it all teh way to phoenix without ever stopping for gas. My question it this. When I got to phoenix the truck's fuel guage still read right between the 3/4 and full tank lines? Seems like it would have used a bit more fuel thatn that??? Im wondering if the guage is wrong? Or if these trucks just have huge fuel tanks and I had no idea.
What I do know is this. When I first picked up the truck from where I bought it from the fuel guage also read half way between the 3/4 and full lines. Then, after I topped it off it read above the full tank line. And it took $55 to top it off.

This is my first cummins and I'm just afraid of running it out of fuel so I want to make sure this fuel guage works before I go cruising around thinking I have fuel. How many miles do you get on a tank?
 

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When I fill up i only have 200 kms on my odometer, but also my speedo gear is the wrong one, and I have 33's on the truck so, I think im getting 400 km's (250 miles) to a tank. Costs roughly 50$ to fill up...ends up being about 20 MPG
 

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I routinely get 500+ miles to a tank (~30 gallon tank and I almost never dip below 20MPG per-fill average). I try to refill no less often than every 400 miles to prevent chances of fuel starvation in the hills.
 

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Well, the next time you fill up. You can figure the mpg, by how much fuel you used. Then you can go by the odometer. Don't trust the gauge.
 

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Here's my mileage log...I update it every tank. My truck has been parked for a few months, though...but I plan to be back with better mileage when I get this stick installed. ;)



This was with a stock 91.5 4x4 auto with 33x12.5 tires and a slightly turned up pump. I don't drive like crazy...but you can see some serious changes in mileage based on how I use the pedal. Oh and that's entirely around town mileage...haven't actually used the truck for a road trip yet.
 

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i just made a trip moving from oregon to wisconsin with my truck and i would fill up about every 350 miles. at my fill up point i would have about 1/4 tank left. since the highway drive here i might not see a town for 100 miles i didnt want to push it. lol
 

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I'm getting around 15-16 mpg right now. If I drive strictly highway I get 19-20.

@ 15-16 mpg I'm going around 650kms per tank (about 400 miles)
If I am on the highway and getting 19-20mpg I can go over 500 miles on a tank and still have room to go further.
 

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Here's my mileage log...I update it every tank. My truck has been parked for a few months, though...but I plan to be back with better mileage when I get this stick installed. ;)



This was with a stock 91.5 4x4 auto with 33x12.5 tires and a slightly turned up pump. I don't drive like crazy...but you can see some serious changes in mileage based on how I use the pedal. Oh and that's entirely around town mileage...haven't actually used the truck for a road trip yet.
i wish i could buy diesel where every you get it from. last time i filled up i had to pay $3.19:banghead:
 

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I usually fill up when I get just past 1/4 tank mark and it's usually between 320-390 miles. I average what the link in my sig shows.
 

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My fuel gage kind of does its own thing. :rof

I filled up this morning. This is a mix of city and highway.

214 miles came to 11 gallons of fuel = 19.45 MPG



I'll have a better run in a couple of weeks. I am going to a 1st gen meet in Iowa. :D
 

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I made a highway trip on my last tank of fuel and went 462.5 miles and used 21.8 gallons of fuel. Came out to be 21.21 mpg, and I drove against a strong headwind most of the trip, averaged about 70 mph, and used the air conditioner.

I don't have a heavy right foot so that probably helps a lot. :thumbsup:

Dawson
 

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On the highway I average 19.5mpg which was running about 65mph and holding 5-7psi solid.

Now after turning my starwheel back down I can run 65mph at around 2-3psi. I love my 12cm housing but if I decide to keep doing highway trips I might swap out for a 16cm. I still haven't installed my pyro.
 

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700+ miles per tank (13 gal)
oops wait, wrong vehicle...

truck gets around 23 with the tight converter and about a 28 gal tank. i think my topper helps too
 

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Discussion Starter #16
I'm just afraid of running out... what are the consequences if you run it completely dry isnt that major bad news? I'm going to go fill it up again and start clocking the miles and I will record how many gallons it takes to fill up. Do these trucks have standard fuel tanks that hold so many gallons? Or are they different per truck. I have a 1990 single cab dually with a flat bed. Also did the 90 come with a low fuel light? Maybe if the guage is off the light will still work at the right time? This way I can learn more about if the guage is accurate or not?
thanks
Ryan
 

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I'm just afraid of running out... what are the consequences if you run it completely dry isnt that major bad news? I'm going to go fill it up again and start clocking the miles and I will record how many gallons it takes to fill up. Do these trucks have standard fuel tanks that hold so many gallons? Or are they different per truck. I have a 1990 single cab dually with a flat bed. Also did the 90 come with a low fuel light? Maybe if the guage is off the light will still work at the right time? This way I can learn more about if the guage is accurate or not?
thanks
Ryan
I do believe these trucks all came with a 30-32 gallon tank. The low fuel light might not work if the gauge does not, as my gauge fluctuates while driving and when it passes a certain point the low fuel light will come on until the fuel stops moving around long enough for the float to stabilize.
 

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i bet its close to 400 but i keep adding new parts so im always "testing" them with wide open throttle runs and quick races on the highway.
 

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The low fuel is a different circuit in the sending unit.
 

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Discussion Starter #20
So did these trucks all come with a 30 gallon take? Since I have owned the truck I have refueled twice. The first time was 10.17 gallons of fuel and I went 149.3 miles. Then just tonight I filled it up again and it took 11.29 gallons and my trip odometer read 175.4 miles. Both equal about 15 mpg not that great but I don't exactly drive it real slow either I push the gas when i need to and travel at high speeds with high rpms on the freeway here in phoenix so its what Id expect.

So im guessing if I have a 30 gallon tank (if this is the stock fuel tank capacity) then I should expect 450 miles per tank with my driving habits before running out dry...

I am trying to figure this out because I am afraid of running out because the fuel guage seems fishy.

What would happen if I did run out? I have heard to NEVER do it but have never heard it explained to my why not to and what it does to the motor?

thanks again guys
 
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