My 91 exhibited similar problems, and it was rust debris from the fuel
tank plugging up the FRONT side of the fuel pump. The 86-91 models have
no separate fuel filter before the pump. (these is a nylon screen inside
the pump) The rust bits simply piled up against this screen and
partially blocked fuel flow. the best fix would be a large capacity
filter ahead of the pump, but the temporary fix was to squeeze off the
fuel line with a real hose pincher pliers, take the hose loose from the
front of the pump, and flush the bits out with an aerosol can with a straw.
Worked for me!
Al Brase

-- Dan Roberts wrote:

>My 89 Westy 4 speed won't exceed 55mph. I'm stranded in Houma, La., far from Wisconsin home. Here's the short story. The van's first symptom was poor gas mileage. Next, it began slowing, eventually refusing to go faster than 40 mph at times.
>By the time we reached Houma, La, I knew I had to get help or risk being stranded on a remote section of highway.
>
>Here's what I, and later a mechanic, have done:replaced fuel filter, replaced oxygen sensor, replaced distributor cap and rotor and replaced Oxygen Flow Meter. It runs better at city speeds but still won't run at highway speeds. At about 3,500 RMS, it stalls out as if it is fuel starved.
>
>The mechanic has run tests of the fuel pump, oxygen sensor, catalytic converter (found no blockage) and ignition timing. He and I have searched for kinks or leaks in the fuel system and compression lines. I've probably missed something, although he has worked on it for several hours and has tried to keep me informed of what he's doing.
>
>I desperately need some help from you List members. My wife has to be in Dallas Sunday morning. If you can offer any suggestions, please....
>
>Dan R.
>
>
>