'89 525a quits. Apparently fuel. Self cure on cool down.

[Gene in NC]

'89 525a, 165k, quits. Apparently fuel. Self cure on cool down.

Hot day, 100 deg, after driving around town at noon, suddenly quit when slowing for corner at 20 mph. Cranking gets intermittent firing but no run.

Let cool down until 3:00pm. 1.5mi in town followed by 3mi on freeway at 70. Pulling onto off ramp, quit. Same no start symptoms.

Cooled down until about 7:00pm. Drove home at 60 without problem.

Car has history of intermittent stumbling at highway speed or in town 30 to 45 mph. Stumbles occur at light load with slight added throttle for incline. Worse when engine cold.

Sensitive to fuel quality. Problem started after years of running Texaco 89. Switch to Shell hi test greatly improved running. Use only Shell hi test now.

Really bad a couple of years ago. Set up test with fuel pressure gauge to windshield and test light from b+ at the fuel pump to dash. Stumbles showed drop of fuel pressure and power to fuel pump. With fresh fuel relay treated with contact enhancer, and the coming of spring the problem went away.

Stumbles returned in this late winter and finally degenerated to QUIT.

[genphreak]

Have you replaced the fuel filters regularly? Are they showing any signs of clogging? Maybe the fuel pump is dying- thus absorbing too much power and making the relay run hot/fail. Check the lines are good and also the vacuum line to the Fuel Pressure Reg. May be studd you've all done be4.

You and/or the PO haven't been using E10 or anything rought like that? Are the injectors still spraying correctly? At least check the appearance of the plugs... and let us all know how what the results are (or were...)