Mysterious fan running-can't locate it...

[R22tech]

Car is 85 Targa- noise(sounds like a fan is running) coming from under the front of the car. It IS NOT the condensor fan motor behind the front spoiler, the freshh air blowers up by the windshield, or the evaporator fan motor in the smuggler's box. It runs only when the engine is running and all the time. I haven't heard it before and can't figure out what it is. I have an oil cooler in front of the rht/fr wheel- is there a fan in there? It started after I had an emissions test performed, in which I ran the car hard before I went, and they put it on the dyno for a minute or so during the test. Am I retarded, or is this mysterious fan noise something that needs to be dealt with.

Possibly dumb response, but is it possibly your fuel pump?

[Kurt B]

You didn't mention the footwell heater blowers behind the kick panels! Might sound like they're coming from the front, who knows.

Otherwise, could be the washer motors running overtime without water?

[KTL]

I'm with Dave. I'd guess fuel pump or footwell heater assist motor. I don't think you could hear the footwell assist outside the car? Oil cooler blower wasn't there until 87 although someone could have added that without too much trouble.

No, you're not retarded. You recognized a good deal on A/C belts when you saw it. If it's the fuel pump, you want to address it before you end up stranded at the video store where all your friends and neighbors will see how Doug's concours 911 broke down!

[avi8torny]

I can hear my fuel pump running and wonder if it's time for a replacement. The car seems to run fine. How can you tell before it strands you?

[KTL]

I don't think you can tell? Maybe some hesitation/power loss? They usually just stop working. My friend's 88 Blazer's pump just decided to give up during a stop for gas on his way to Yosemite. That had to suck, being from IL. Can't walk home from there!

The pump was loud as can be on my '95 F250 truck. Just figured since R22 hadn't noticed it before, it may be going south?

[Kurt B]

The footwell blowers are very quiet, but as they wear out as I'm discovering having just turned them on for the first time in god only knows how many years, the blades fall and rub against the housing, giving them a hum. ...Dunno.

[steve911]

R22tech--
check that both your heater levers are down (toward the floor) and that the fan switch between the seats is set to 0. I've found that even sligthly raising the heat levers turns on the footwell fan(s).

[R22tech]

I'm sorry guys, forgot to mention it is NOT the footwell blowers- Please guide me to the fuel pump; it could sound like a pump running.

[Formerly Steve Wilkinson]

The fuel pump is under the car, on the centerline of the fuel tank, right behind the bottom of the tank, up above the rectangular steel plate that protects it. Plate's easy to get off, but you'll be able to hear it with the plate in place, if it's making that much noise.

STephan

[cary]

Hopefully Mr.Walker will jump in here.

But all the other blowers should work with the key on.
The fuel pump only runs with the engine running. DME.

Could help your search.

[rattlsnak]

Hey, Im in Roswell also, we can meet after my sons school function tomorrow,. ill help you find it.

[ToyCollector]

Did you find it yet?

If you haven't pulled your mufflers yet (different topic), go to the next PCA event and you'll have your answer. Several cars running straight megaphones or Supertrapps. LOUD LOUD LOUD. Coming from me, trust me, it's LOUD!!!!!!

I need to take you out in the 930 with the top down so you can hear what I think is close to exhaust note perfection--for the street.

[Rick Lee]

You should be able to hear your fuel pump kick on when you turn your key to the "ON" position, but before you turn it all the way to crank the engine. I don't think hearing the pump is any cause for alarm. It's loud anyway, but I don't think I can hear mine once the engine is running.

[Jim Sims]

This is not correct; if the engine is not running (sucking air) then the fuel pump will not run in the "on" key position. There was never a fuel pump "pre-run" in any Porsche factory CIS system; a few early VW CIS systems had this feature but it was eliminated after a few episodes of fuel running out of the tail pipe. See: http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=54389&highlight=fuel+pump+prerun

Jim

[Jim Sims]

My previous post applies to the CIS cars only; I don't know what the DME cars do in regards to running the fuel pump in the "on" key position. Jim

If it's not the fuel pump, what am I hearing when I turn on the key in my 77 with CIS? Sure sounds like a pump running up to pressure.

[Jim Sims]

It is possible to make the pump run by modifying the wiring. My point is that none were delivered new wired so the fuel pump ran without the engine turning over and sucking air (cranking or running). One could jumper around the air meter contact switch in the CIS system for example (see component G19 in the '77 wiring diagram on pg. 295 of the1990 edition of Haynes Porsche 911 Automotive Repair Manual). Inari77S, perhaps in your car something like this was done to eliminate problems with this switch or to avoid replacing it as it is in an awkward location. This switch closes and completes the normal or key "on" position running circuit for the fuel pump when air is moving by the CIS metering plate. If it stays open (the contacts don't close) the fuel pump will stop running when the starter stops cranking. This is a safety "interlock" to prevent the CIS system from filling a non-running engine with gasoline. There is a separate circuit that runs the fuel pump while the car is cranking and only while it is cranking. Jim

Thanks, Jim,
Looks like I've got some wire tracing to do.

[rattlsnak]

Jim, close,... but if you simply unplug the sensor the pump will run all the time the key is on. The was a VERY common trick to cure hard starting due to pump prime loss.