The 1/2 tank symptom sure points to a pre pump problem. You can see if it runs (independent of the Main pump) by removing Fuse 5 and jumpering +12V to the Right side Fuse contact. The +12V is available at the "hot" (Left) side of fuses 6 —10.

But even if it runs, hose rot as shown below will let the Main pump suck air when the level gets low.


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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I had a similar problem in a 700, with low gas and while accelerating in a right turn it would cut out. If memory serves (this was four or five years ago), I replaced the fuel pressure regulator and the problem went away.

Hard acceleration may put more load on engine systems than other operating modes including greater fuel flow or more demanding ignition conditions. So any weakness may show up here first. I think it could be an ignition or fuel problem. Just to eliminate the easy things first, check for air leaks, timing, and advance. Consider replacing ignition parts if that has not been done recently. After that, fuel flow, injector clogging / unequal flow rate, air meter movement, and compression. Try slowing revving the engine in neutral and watch for any points of sever shaking. People here can advise on ways to check these.