1990 16V 740 with long range tank option. I’m curious to know more about it!!!!

Clive740

I recently bought this 740 with, what I’m told, is a factory option long range tank.

I believe it is a 20L second tank, giving 85L total.

Can anyone tell me more about this set up? Was it factory or dealer fitted option?

Are there any issues with these tank options that I need to know about before I do any long trips etc ?

The fuel gauge is faulty, which I know is a common Volvo problem. It reads full when the tank is freshly filled, but starts to read unpredictably the further the car travels.

It is puzzling me how a single gauge is supposed to measure the level in two tanks at the same time?

Could the tank option be contributing to my gauge fault?

Im a bit of a fussy bugger at times, so I would like to solve the faulty gauge issue if possible. OR is it just not worth bothering?

Any information and advice is welcomed.

Cheers

Clive740

I should mention, the car had a full tank when I picked it up. Because of the gauge issue, I filled it up again after covering 300 kms to see if the fuel it took corresponded with the kms traveled. It took 27L to the first click. So that seems about right.

carnut222

That tank was common and factory-fitted in many 740s in Australia in certain years - I think most 740T had it and obviously the 16V since yours has it. The main issue with it is the hoses that join the fuel filler and tanks together. The hoses can perish and when you fill the tank to the brim, they are submerged in fuel, so you’ll have a massive fuel leak if they’re not in good condition. Other than that, there’s not a whole lot more to know. The main tank and the aux tank each have a fuel sender, and the instrument cluster has a screw that’s removed (or added, I can’t recall) to connect the circuit so the gauge works appropriately regardless of the tank configuration. Hope that helps! I had an 88 740T with this tank and had to replace one of the perished hoses. It wasn’t particularly easy to access!

asiandriver

Standard equipment on all Australiana market 740 sedans and 1st generation (82-87) 760 sedans.

Main fuel tank capacity is 60L, with auxiliary fuel tank the combined capacity goes up to 82L. However the capacity of the auxiliary fuel tank alone is only 15L, the remaining 7L lies in the top of the main fuel tank which is an expansion space & cannot be filled when the auxiliary fuel tank is not fitted.