After a few minutes of warm up. Idle becomes unstable and searches. Very little power when driving. Sputters and misses. Sometimes will kick in if I get it above 3000 rpm. If I spray a little ether into the intake just above the mass sensor it starts running fine. I can then drive it and drives good. Shut the engine off and restart, drives like crap again. Squirt of ether then runs good again. What's going on here?

Working out the kinks on the she beast. Looks as though the very bad connection to the O2 sensor were really confusing the ECU. That damage was caused by the original water in gas rough running. I cleaned up the electrics, repaired the exhaust. Back to running decent now. Including through the 1/4 tank of gas where problems first started. TFG for the warm weather...

Also see - Vacuum Leak after airfilter change? 𖑀 𖑀] to read about AMM issues.

One of my troubleshooting mantras is WHAT JUST HAPPENED? Have you or anyone else done something to the car?

Check that work.

740s are known to have fuel pick-up issues when the fuel level is low.

With alcohol in the fuel, water is seldom the issue unless your fuel source is contaminated. Do not buy fuel if the station is getting a delivery as this can roil up junk from the bottom of the tanks.

On our "88 745 GLE this happened at 1/4 of a tank.

Fill your fuel up to see if the problem goes away.

Since we always kept a 1/2 tank of fuel in the car, we forgot about the problem, and about 3 years later it happened again - the fuel was low, and we never had the problem again (235K miles) because we kept the fuel up.

I have read that the problem can get worse, happening at progressively higher fuel levels over time.

Thx for this info, James. I'm taking all tips from this thread to get my 1990 745 running again. I was ready to change fuel filter and pump, but I'll do other things first.
Steve

Note that 740s have a small pre-pump that sits in the fuel tank. These are not as durable as the larger external fuel pump. When they go bad, you will notice stalling when the tank is low, particularly when making a turn or pulling out of a parking space - the fuel sloshes to one side of the tank and is even lower at the pickup point.

Sound like it is lean. Vacuum leak or hole in the intake ductwork ?

Greg

As riverbend indicates, air intake induction system (vacuum) leaks?

Bendix Rex ignition / Regina fuel control or Bosch LH-Jetronic fuel / EZK ignition?

If Bosch, Turbo or not?
https://www.brickboard.com/FAQ/700-900/EnginePerformanceSymptoms.htm

Check OBD codes?:
https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm

There's more in the FAQ.

Hope that helps.
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Thanks. NA redblock. Bendix Rex ignition / Regina. I think it had water in the fuel originally. Rough running hit twice like clockwork at a 1/4 tank. Second time I added some drier. Was interment like picking up pockets of water and improved of over time on the drive home. Found the O-ring on the gas cap was bad, replaced it. Still need to to the gas door hinge too. Long story... The exhaust definitely was damaged by the rough running.

Conceivable the intake was too. I'll look into that. Putting my hand over the intake above the AMM didn't stall out the motor, so maybe there' something there.

All this with that blizzard and a new girl friend is making this a slow process. Least I got the 960 too which I've be driving for now.