Fuel tank capacity, fuel gauge accuracy 745 Wagon.
 

I've put 700 miles on my engine with the new head and am very impressed with the power.

One thing that doesn't make sense is the fuel tank capacity in relation to the fuel gauge. I've got a 1985 745 Wagon.

With the gauge needle just into the red portion of the gauge I filled up with 11 1/2 gallons. Does that mean I have 9 1/2 gallons on reserve? Do I really have a 21 gallon tank? What gives?

A 21 gallon tank at 30 mpg should go over 600 miles.

Fuel gauge
 

Hi. Mine is completely crazy. I know that all Volvos we had in family had their gauges inaccurate and somewhat unreliable. RedArrow the 740wagon has a completely crazy fuel gauge. I don`t know how and why but it works totally `upside down`. When I fill it up *full*: it stays in the very left side = empty zone (red). As fuel level in tank gets lower, it slowly starts going to the right side (full zone). It happens pretty much all the time consistently. It never worked `the regular way` since I bought it but it is accurate in some ways. Exactly good at least once: :) at the middle when I have half of my fuel left. I know the car so by now I exactly know how much fuel I have in the tank. I just have to look at the mileage counter and devide it by 25-28 if city driving or 32-37 if highway driving and it tells me how many gallons of B20 diesel I have missing from the tank. If they ask me at the gas station I always say it in Gallons and not in $-s and I`m always right how much it will take.

I think my Volvo 240GLED6 `84 had its fuel gauge working correctly. That`s an exception from all Volvos I drove.
But I think you have a 60Liter fuel tank. (~16G~) Mine is a `85 745 that has the `86 gas tank.
The most I drove it on one tank was 480miles (772km), then I put 14 US Gallons of fuel into the tank when I finally reached a gas station. I got 2*5G diesel in the trunk though...
Picture shows gauge position when I have about 3.5 Gallons of fuel *used*.

You might have a 19.8 gallon tank. Take a look at your tank and compare it to these pics:

Replacing a 15.8 gallon fuel tank with a 19.8 gallon tank 700
http://www.brickboard.com/RWD/volvo/..._tank_198.html

My gauge is inop; I fuel up when trip odometer gets near 400 mi., it will usually take 12-14 gallons, speedo/odo is ~7-8% optimistic (reads faster than actual).

I'll take a look at my tank tonight and compare it to the pictures you have.

My gauge does seem accurate, at least when the tank is full it shows full.

I suppose the confusion is between what's reported in the 1985 owners manual (21 gallons) and the amount required to fill the tank when it hits reserve.

I can do about 30 miles after hitting the bottom stop if I drive conservatively, and she needs a bit of a smack to wake up in the morning.

Manual must be wrong: 15.8gal is the spec I have for my '86 wagon, and IIRC true for the '85's as well. http://new.volvocars.com/ownersdocs/...gle_wagon.html

Later wagons had bigger tanks, 19.xx gallons I think. I had a '93 960 wagon one time that was in that ballpark. Later sedans with IRS had a different tank molded to fit around the different rear end that might have been larger too, but I don't think it was over 20gal. The only thing that *does* have 21-gallon capacity is an early (1983-1984.5) 760 TD sedan, which have a second auxiliary long-range fuel tank mounted above the rear axle just behind the rear seat back, which fills through the regular filler neck and acts as a transparent extension of the regular under-floor tank.... this eliminates the pass-thru on those cars but affords 21 gallons of capacity. Maybe you're somehow reading that figure instead of the correct one.

One time a few years ago I drove my 1983 764 TD from Seattle to San Francisco and back for a long weekend. I filled the tank before leaving Seattle, then only filled up twice while on the road, averaging about 31.5 mpg during the trip. That 600+ mile range is nice on long trips. :cool: Even the wagon with its 15.8gal tank does 400 miles easily, though -- no major hardship, really....

I'll get this sorted out this weekend. I've probably got the 15.8 gallon tank as shown on the volvocars.com site.

Come on guys, those tanks are Metric, 60L or 80L:p

60 or 80 liters, got the answer
 

Good simple answer 745turbogreasel. I drained my tank using the philips head screw/bolt at the bottom of the tank and measured how much fuel it took to fill the tank. It was a little over 16 gallons. I do tend to overfill my tank. 60 liters equals 15.85 gallons and 80 liters equals 21.13 gallons.

The owners manual that stated the tank size is 21 gallons was not the original manual that came with the car so some of the 1985's must have had the 80 liter tank.

ngoma's link to replacing the tank definitely shows the difference between the two tanks.

I'm fine with 16 gallons for now. That will give me 480 miles at 30 mpg, or at least over 400 miles with a little fuel in reserve.

My gauge is accurate. With the needle still inside the red portion of the gauge, just at the left edge of the red portion, there was still a little over 2 gallons of fuel in the tank.

I was starting to feel very inadequate there, with everyone talking about 15.8 and 21 gallon tanks... the most I've every got in mine was about 12.5 gallons!!!

Then I realised your gallons were all wrong! ;)