Access the inside cover to get to the top of the in tank pump. Most problems are found around all the fuel lines bundle inside this small space. On my 745t the metal lines going into the fuel tank were rusted. I had to buy a use assembly ( which worked for awhile)1 and just replaced.the in tank pump yesterday due to to filter sock deterioration jambing up the in tank pump. You'll find a tank fill hose, vent hose and the pressure hose and return hose. Check each one for splits and cracks and the metal line for rust.

Mine had a crack by the fuel sender.
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Paul NW Indiana '90 745 turbo 145 K

That is what I meant to say Sending unit cap. There is a rubber seal there

I found the cause and a little bit of nightmare-fuel. The main issue is that the fuel sender assembly was not seated into the tank and the bung nut was not really screwed on.

Also, it's a Regina car with a single pump... uh it *was*. Only it isn't anymore. My late friend did some weird stuff. I think he plumbed in a Bosch pump I gave him, but the fuel lines and wiring are all kinds of sketchy. It looks like low-pressure carburetor fuel line even after the high-pressure pump. SOooo... that will be an afternoon or more to fix. I'll make a post about that separately, probably.

Is the car registered and insured?

OIf so, do have a relationship with a garage?

Ask them to put the car on a lift and have them (you ?) - inspect the bottom of the car.

I took my '54 Chevy to the grace that issues inspection stickers and they put the car on one of their lifts for the mechanic and myself to inspect the bottom for $20. (direct cash payment to the mechanic involved)

I have stored cars for months under car covers outdoors and the cars have been kept in good condition for a couple of months during the summer.

These cars were kept on a clean, paved surface - storage on grass or soil can make the bottom of the car dirty and moist.

I have purchased several covers from Pep Boys (now O'Riley in my area) that work very well for the price - they are blue, non-woven fabric with a thin perforated layer of polyethylene.

First, I cover the car with a cheap, plastic, blue tarp that has been cut to just cover the top of the car, trimmed so that it just overlaps about 1 foot, then I apply the cover. This take care of moisture that has soaked through the cover when we have an extended rain.

Consider disposition (a sensitive topic) of the car as I have found that old Volvos that are not driven deteriorate faster than the old Volvos that I drive!

For me it was the rubber seal for the fuel pump "cap" that was bad. Never had fuel odor after replacing it

The return line on my 740 had cracked. Leaked when I topped it off.
Check around your injectors if they are wet.

Cracked gas tank gives overpowering odor in the garage. Similar to that experience when replacing the in-tank fuel pump. Check for any spilled fuel underneath car. The 700 and 900 (as in photo) series uses plastic fuel tank IIRC. Leaked fuel from old hoses don't smell as bad from experience.

Amarin.