Hi, I have a 94 940, non turbo wagon(175K). It runs well, except recently it started to stumble while at highway speeds. I will be driving at 70-75 and it will suddenly stumble like the fuel is being cut off, then continue driving fine. This has gotten worse and yesterday I drove home on city streets and parked it. Around town it drives fine, idles fine, runs cool and no CEL lights. Any thoughts? Thanks.

 

if its acting like this under load - I would look at your cap, rotor, wires, and spark plugs - maybe rpm sensor.

 

Fuel filter could be getting restricted. Fuel pump may be getting tired, suffering under load...

And, yes, all tune up possibilities should be eliminated, NOT RPM sensor--not involved in this...

 

Ok, picked up all the mentioned items, I'll install in the next day or so and see what happens. I did notice that speedo occasionally drops to zero, then starts working normally again, don't know if its related. Thanks.

 

my 91' 240 Wagon did that exact thing just 2 weeks ago, I thought it was low on fuel or something and was sipping air and perhaps the fuel gage went out...

as it turns out the fuses got corroded. I cleaned them up and its been fine ever since. The culprit was the main fuel pump fuse.

 

Speedo is no part of that.
240 fuses, electronics are old school, 940's much more modern, trouble free. Totally different set ups.

 

Update. Installed, plugs,wires,cap,rotor,main pump,fuel,air filters,oil cap and whatever that thing is that bolts onto left front inner fender. So far so good. Although the fuel pump sure is noisy-was that foam sheet supposed to be wrapped around pump?

 

What brand of pump did you get? Was the old one in the foam sheet?

 

A noisy main pump may be an indicator of a failed in-tank pump. The tank pump fails and puts a greater load on the main pump - thus the noise. This can cause fuel starvation under load and also cause the main pump to fail prematurely.

 

I don't remember the brand, but it was made in the USA. The original pump didn't have the foam. It came with the new pump.

 

The pump I replaced was very quiet. The new pump was noisy immediately after install.

 

well, replaced the in tank pump too-pump under car is still noisy and the car still stumbles and nearly cuts out at highway speeds. Could the fuel pump relay cause this? Are there separate relays for each pump? Is there a fuse for in tank pump-if so, where is it? Thanks, very frustrating as I love the car.

 

There is only a single relay for the pumps. Usually the relay failures occur when the solder joints crack on the little circuit board. If it were me, I'd remove the relay and resolder all the joints to eliminate that possibility.

If the engine is totally cutting out on the highway, I would check the crank position sensor. There really is not test for it but you can inspect it for cracks or flaking insulation. They tend to fail intermittently - usually when the engine is hot.

 

So, not the relay, possibly the solder joints. I changed the CPS and it seems like it may be a little better. Really only happens at speed on the highway. Around town it runs great. Still will run perfect, then stutter for an instant at freeway speeds, then continue as if nothing happened. Sometimes worse than others.

 

The solder joints to which I refer are on the circuit board in the relay. The symptoms don't really sound like a relay problem. Are there any engine codes?

 

No CELs , how do I check codes?

 

This site should tell you how to retrieve codes:

https://www.brickboard.com/FAQ/700-9...agnosticCodesi

 

Still dealing with this. What is the diagnostic connector and wire? I have an OBD fault reader but that doesn't apply to my 940. The car runs great and does it primarily when I'm cruising at freeway speeds (70-75) and ease off the throttle. Having the AC on seems to make it worse as well as do hotter days. It doesn't do it at all for the first 5-10 minutes of driving. The car always starts easily(hot or cold), will smoothly accelerate without issue and otherwise runs fine. It does "hiccup" when stopped at a light, again worse with AC on.

 

stumbling problems at mild throttle settings, like steady cruise speed are most often ignition related. cap, rotor, wires, spark plugs all should be in good condition, if they are, the problem could be your coil is breaking down, or the power module, or you have some flakey wiring.

 

The cap,rotor,plugs,wires are all new. I think I replaced the power module too-the thing on the front left,inside inner fender?
I have not replaced the coil though.