Removing and installing 700/900 sending units can be tricky. If your sending unit isn't fully seated down on the tank flange then that's likely an installation problem. Yours should have the spring loaded barrel. You need to keep the barrel pulled up off the bottom until the face is flush on the rubber collar before tightening the plastic collar then release the barrel. It's described in the FAQ how to use a loop of fishing line to accomplish this. This was a trick that Spook used and told us about. I've done this project a number of times over the years, so here's the way I do it:

o You loop the fishing line around the bottom of the barrel clip and run both ends up through the return line nipple. Pull the barrel all the way back by hand then tie the lines around the nipple to hold it. You need maybe 4'-6' of line. A super strong thread or fine string can also be used.

o Now install the sending unit, going through various gyrations of angling it and turning it to get it into the anti-slosh bucket without knocking the filter sock off. It will take a few attempts. Look down with a flashlight first to see what you're up against.

o Keep the face of the sender pushed flat on the rubber collar while you install and snug up the threaded plastic collar with the other hand.

o Install and moderately tighten the metal ring clamp around the plastic collar so the collar can't expand and jump threads during final tightening. Now tighten the plastic collar as hard as you can by hand. If the plastic collar is allowed to expand and starts jumping threads then the threads will start to strip and it will need replacement. The 700s (leastwise up to my 1989) didn't come with a metal ring clamp, so if needed get a 4" *stainless steel* ring clamp at a hardware store. Originally, Volvo called for a new plastic ring to always be used until they figured the ring clamp trick.

o For a final tightening, with a non-sparking drift (foot long wood stick) held at a 45deg or so angle against the collar tabs, use a hammer to tap around the plastic collar to tighten it another 1/8-1/4 turn (depending on how hand tight you got it, just 1/8 min and no more than about a 1/4 turn) then do a final tightening of the ring clamp.

o Undo the fishing line to release the barrel and pull one end up through the nipple to remove it. Reconnect the hoses and you should be good to go.

o To ensure there are no leaks, dry the area around the flange thoroughly before installing the hatch. Over the coming days and especially after you next fill up, stick you nose around the rear wheels and smell for gas vapours accumulating up under the fenders. Once or twice check underneath to see if there are fuel stains on the side of the tank (will typically be the axle side). End the project by re-opening the hatch to verify that the top of the tank remains dry.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now