What’s this noise? Fuel pump?

[Glenfield]

Team,

Have had an incredible day or so road tripping from Chicago to West Coast. Got to the top of Independence Pass and then this whirring sound popped up. It sounds like the fuel pump whirr but far more pronounced. Loud enough that you can hear it in the cabin. Here are a couple of links to the sound. Would love any opinions / help.

https://youtu.be/Ojt-B7kix80

https://youtu.be/hFWlOK0ZKnI


Staying put for a week in Elks of CO so can hopefully work it out and get some good driving in.

Cheers,
Tom

[Glenfield]

Sorry, should have mentioned - after whirring began, car began to surge at idle on a hot engine (car had been driving 300 miles). If you gave it load then went to neutral, it would surge a handful of times then settle at 950. Would repeat for 15 or so second each time after cars had any sort of load

[proporsche]

it is you fuel pump

Ivan

[Glenfield]

Thanks Ivan.

When I pull the relay and jumper the fuel pump, it reverts to it’s normal noise. Still a buzz but not pronounced (and certainly not audible within car). Does that change your thinking?

For completeness:
- I replaced the O2 connector. That could explain hot surge. Could it also explain the buzz? Will pull it today and see
- Also have a front defroster fan seemingly going (heard it makes a similar noise but that’s in Carreras)

I should have said, it’s a 1980SC.

Thanks in advance for any help. Have a week to troubleshoot it before I set off through Utah and Cali to the coast (I hope ...)

[evan9eleven]

Tom, for what its worth my FP is about that loud all the time. ‘81 SC.

I’m at a loss to understand why jumpering it would reduce the noise... I guess you could replace the FP relay just to eliminate that as a problem.

[proporsche]

what color of relay are you using?
Ivan

[Glenfield]

Thanks for replies guys.

Using the original red relay. Swapped in a replacement red FP (911-615-108-01-OEM). Didn’t seem to change things last night but today, all was back to normal on the buzzing. Will take it for one more sundown shake with new relay and then swap in old relay to see if it comes back.

The surging hot idle began when excess buzz began. That continued today despite FP settling down. Possible coincidence only and I have two issues to track down?

Cheers,
Tom

[proporsche]

ok Tom ,how old is your fuel filter? There is a date if you do not know on the filter it self.i`d say replace it...
Ivan

[Glenfield]

Thanks Ivan. Fuel filter is a couple of months old. Know they don’t make em’ like they used to though so can go there once others are exhausted.

Took it for a shake down and the Uber-buzz returned ( killing my buzz in the process). There with old relay and new. Swapped O2 relay with a new unit and no change either.

I think the hot surging is a separate issue. I was running rich in Chicago. About 45% duty cycle. Now at 8000’, with less air, can I assume that’s tipped me richer and beyond the point that ECU can correct smoothly? Would make sense as it only popped up once I crossed Independence Pass into the mountains. Also, car runs same but at a lower idle RPM with 02 sensor disconnected (at fixed 50% duty cycle).

I’ll get an FP and check valve expedited from our host in case that’s where I land on the buzzing.

Cheers,
Tom

[Glenfield]

I got my buzz back! Good buzz ...

Seems it was the fuel pump on it’s last legs. Was interesting as the problem was intermittent leading me to suspect a few other culprits and clutch at a few straws (including a dodgy re-wiring of an alarm). Replaced the pump and look to be good to carry on to California. Wanted to close it out and thank Proporsche for the steer.

Here’s a couple of thank you presents.




Sorry about these last two.