Bad for fuel pump to be on w.out engine on?

...As when key in position II to power the radio? Need to monkey w.the radio and don't want to run it in II if it's bad. I'm assuming the buzzing I hear when in II and engine off is the fuel pump.

 

You don't want it running if you're not going to start it. Do you have a fuel pump cut off switch under the dash? Mine has one. Not sure if they were factory or done aftermarket? It's tucked up under to the right of the steering wheel....

FWIW, YMMV!

JIM

 

Hmmm...might that be what that little (apparently aftermarket) switch under my dash is?! I pulled it out not knowing what it was - looked like an antitheft of ignition kill switch. Let me go check that....

EDIT: switching it seems to have no effect. The pump is loud, right? The continuous buzzing? Now that I think about it I switched it back and forth while trying to ascertain it's function while the car was idling and it didn't stall it out. But, if the pump goes out or is shut off would residual fuel keep the engine running more than a few seconds?

 

Couple seconds at best.

IF you have to work on the car with the key in Pos.II, pull the fuse to the fuel pump, fix what needs fixed and put it back in....(with the key off ofcourse. )
I would trace that toggle switch to figure out what that is while you're there...don't want any loose hot wires floating around under there.

JIM

 

IF you are talking about your 328, the fuel pump will NOT turn on unless it sees vacuum caused by the engine turning over. If your fuel pump is running with your engine off on a K-Jetronic car that is VERY bad. I see in your profile you have an 1986, probably with an O2 sensor feedback system. The buzzing you hear may be the frequency valve on/near the Kjet fuel distributor, and not the fuel pump if the car is running well.

 

Yes, when you're upside-down and unconscious, with parts of the fuel system sheared off, it's best if the fuel pump isn't still running.

 

Mine's got a switch too. Undeneath the dash, right above the center console, on that flimsy plastic strip that covers all the wiring (the red flip-cover on the photo). Always figured it to be aftermarket.

Of course, there is no comparing a carb 308 to a FI 308/328....

Hans
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On a CIS car, yes, it's bad to have the fuel pump running without the engine on. The injectors are squirting fuel the whole time the pump is running, and fuel builds up in the intake manifold. That would make the mix way too rich, and you can't start it until the fuel evaporates. (Experience from after I did the pressure checks on my CIS system.)

Is it a swiss model? (From the spare parts catalog, the '88 swiss market model has a different relay load-out.)

Check your fuse panel labels, and see if there's a relay (bottom left, under the "fuel pump relay") marked "fuel injection pump starting" or some such.

Or see if there's a blue connector on the air meter body.

On the US models, turning the key to "on" activates the (s) fuel pump starter relay. From there, turning the key to start will activate the (r) fuel pump relay. Once the AFM plate leaves its rest position (engine drawing air), the AFM safety switch removes ground from the coil of relay (s), and ignition power runs through relay (s) normal position to keep relay (r) active, and the fuel pump on. If the engine stalls, the AFM plate grounds the safety switch, relay (s) activates, and the fuel pump is cut off until you hit the start position again.

(It follows from this that you can't push start a US model -- no fuel delivery without the starter, or the safety switch disconnected (at that blue plug on the AFM).)


I'd think most of the 328s would be similar on this.

In the parts catalog, it doesn't like the euro models have a frequency valve. So if you're getting a loud buzzing with the key "on", you may want to check if your fuel pump safety switch is connected and operating.

CIS cars run a lot of fuel pressure, and if the car flips over and stalls, you'd probably want the fuel pump to shut off on its own.
(This arrangement sounds complicated, but it's more clever in operation than the "inertial cut off" on my Alfa, where you have to go under the hood to reset it.)

 

Technically, not true. If the metering plate in the fuel distributor is not being opened by airflow, no fuel is delivered to the injectors, pump or no pump. In fact, the accumulator maintains fuel pressure in the fuel system as if the pump was on even when the car is shut off. The metering system in the fuel distributor turns off the injectors.

But like all have said, in a 328, you should not be hearing the fuel pump with the key in position 2. You are probably hearing the frequency valve. However, if you want to test it, just pull the fuse for the fuel pump in the fusebox. It is well labeled and on its own fuse.

Birdman

 

If the engine isn't running but the fuel pump is then the fuel will certainly not be going through the injectors. There's a fuel return pipe that basically re-routes the fuel back into the fuel tanks.

I ran my 328 for many months with a faulty safety switch which meant that the pump was running in the pos II position and never had any problems.

The worst that you'll do is run the battery flat if you leave it on for too long !

 

Pull the fuse.........