Pelican Parts Forums - NPC- Challenging Volvo FI problem, need help

We have had an odd problem on 3 different Volvos,
14 years apart. The first car was a 1978 240,
the second car was a 1987 740 turbo and now we are
troubled by a 1992 740 turbo. The ’78 had CIS while
the 742’s have KE Jetronic. The problem in the '78
was solved by the crusher, but somehow, we managed to
fix the ’87(which I still have as a parts car (I live
in new Hampshire and feel the need to have a few)). I
need help with my ’92. Because I have had this problem
in 3 of the 4 Volvos that I have had, I assume that it
is very common.

The Problem…
Sometimes the problem comes on while driving but
usually begins when the engine is first started. It
will idle fine, and accept a little throttle but if
the throttle is opened more than a certain amount, the
engine bogs down as though it is running out of gas.
If the throttle is closed then the engine smoothes
out. Now the Strange part. If the ignition is turned
off, and then on again, power is instantly restored. I
don’t even have to shut the engine off completely,
just, click off, click on.

So we replaced both fuel pumps, mass airflow meter,
fuel pump relay, plugs and wires. It feels like a fuel
delivery problem to me but I am not ruling out
ignition. What parts are common to ’78 CIS and KE
jetronic? The only thing that I know of on the FI
side is the fuel pump relay. I don’t recall what the
78 had for ignition. What parts are affected by
toggling the key?

Has anyone seen this before? Any ideas?

Thanks for reading this far.

-Brett Anderson