Queston about fuel pump not shutting off.

[Ruthlessone3k]

I know most cars prime the fuel system when the key is turned to on, but the pump normally shuts off after a few seconds. When I turn the key to the on position I can hear the fuel pump running, but it does not shut off till I start the car. Is this normal with CIS? (This is my first car with CIS so I dont know what to expect from it.)

[briano1234]

No that isn't normal, as it tends to sound like you have a fuel pressure leak, or the fuel pump relay is wonky.

[Ruthlessone3k]

No that isn't normal, as it tends to sound like you have a fuel pressure leak, or the fuel pump relay is wonky.

Thanks, that may help explain why my car is running so poorly. It has trouble starting at times and it has really bad misfires and hesitation while driving. So bad I cant really drive it.

[Ruthlessone3k]

No that isn't normal, as it tends to sound like you have a fuel pressure leak, or the fuel pump relay is wonky.

Well something is screwy with the relay, Someone decided to put the load reduction relay (#18) in place of the fuel pump relay (#62) Now I need to find find the proper relay to continue diagnosing the problem. I'd hate to think it might all just be caused by a bad relay.

[vanaguy]

You can just put a jumper wire in place of the relay for diagnostics.

[Ruthlessone3k]

You can just put a jumper wire in place of the relay for diagnostics.

Turns out, it is the frequency valve making all the noise, which is odd since I read that it runs off the O2 sensor and my car does not have an O2 sensor (nor does it have a bung on the cat to install one). I was under the impression it was CIS basic (1987 German spec cabriolet) which I wouldn't think would have a frequency valve since it does not have an O2 sensor, but there are some wires going nowhere and a few other things that make me wonder if someone has replaced some parts with the wrong ones. Maybe it is a CIS Lambda with the wrong cat installed???

[native-texan_in_tn]

Ah, this is the post I was thinking about while replying to your other post today... Yes, take a look on your manifold for an O2 sensor (bearing in mind that I'm operating off of knowledge based on American-destined cars only...). At least your frequency valve is buzzing... Mine stopped working a few months ago when I was preparing to move my car back home but it turned out to be a combination of the Lambda relay, as well as the fuel-pump relay.

[Ruthlessone3k]

Thanks, I'll check it out when I get off duty tomorrow.