Hello Merry Volvo People

I've got a weird one for you. My friend's '88 240 all of a sudden started exhibiting a very profound hesitation upon acceleration. Under load or not, when you rev up it hesitates like crazy- seeming almost certainly like a lack of fuel. No lean pop, just boggggggg… It does it almost right off the bat. If the engine is fairly cool it seems to rev fine for one or two minutes but then starts bogging again. The car IS drivable- if you are very gentle on the throttle and go like granny.

We've tested just about everything under the sun. Newish (but not known good) Air Mass Meter swapped in, coolant sensor and TPS checks at the ECU (good), most if not all of the other checks at the ECU a la Bentley Bible (good!), different fuel pump swapped in, new pressure regulator (it was leaking anyway but no dice). If you unplug the AMM it makes little difference. Do we have two bum AMMs? The one we swapped in was quite new from FCP Groton.

We haven't put a new in-tank pump in yet, but it acts the same regardless of how much gas is in the tank and it seems to be running if you listen in the filler opening.

Any ideas? Still a bad AMM? Is it possessed?

Many thanks in advance…

Jim
--
'58 PV444
'66 1800S
'67 122S Estate
'70 142S
'72 142E
'78 242GT
All are pretty and run except the '78 The irony!
http://www.olddeadvolvos.com