fuel pump buzz and idle speed...

[Milo2361]

well to start this thread off i recently began hearing my fuel pump's buzz through the cab of the car... never had that before . always could hear it buzz a little while standing outside but never on the inside of my car. is it time for a new one?

second, after looking at it, cleaned off the electrical connections, etc, my car has a REALLY low idle.... sub 500 cold, ran it up to operating temp , then i parked it again and it was mabye hitting 600? all fuel pump hoses are connected and tight.

third. in addition to a low idle, my car has the acceleration of a VW beetle right now...(ok maybe that was a little exaggerated but it isn't what it was last week. or even monday.) i'm planning on an oil change and valve adjust. (3200 since last oil change, about 15k since last valve adjust, i can hear some knocking)

never really worked on a p-car before and now im baffled.... Also, my repair book (haynes or something yeah i need to get a bently but didn't want to spring $100) says the idle cannot be adjusted without "special tools".... never thought i'd own a car i couldn't adjust my own idle on....

was planning on a weekend trip but might not happen now

love the car but dont live the prices of parts!!! lol

[Scott R]

The "special tools" for idle adjusting are a 4mm hex key and a gas analyzer. You can make the key by trimming down a t-handle hex tool, and you can buy a gas analyzer. One just sold in the for sale section a few days ago. Of course all of this is pointless unless you check the fuel pressures, warm and cold to see whats really going on.

[Gogar]

First of all; about your fuel pump: Often times when your tank is almost empty and/or it is warm outside, you may be abe to hear your fuel pump more. Fill up your gas tank and see if it goes away. Totally normal.

On your car you can adjust the idle RPM with your fingers. Slightly to the left and forward of the air filter/housing you can see the throttle linkage, and there's a big fat slotted-head screw. That's the idle adjustment.

To adjust your idle MIXTURE you need a (3mm?) hex key. But I really wouldn't start there.

But, that said it sounds like there's something else wrong, It's possible you just need to go through and check everything easy. Fuel flow, timing, spark plug wires on the dizzy, on the spark plugs, etc. etc. etc.

And, a Bentley is a great resource, but it is based around the 84-89 cars. It could still be helpful to you, but not so much in the engine compartment.

[Milo2361]

its 25º cooler today, fuel pump no longer buzzes so i suppose that must be because it was about 90º the other day....

fuel flow good, timing good, --- my dad checked these out last night---

plug wires are new, checked all spark plugs and cleaned them, not so local wrench said check for vacuum leaks..... so i did, i think i may have found one....

on the distributor there's that little vacuum thing connected to the bottom of it... black line going into it on the right(close to the fan) red line coming off the left. both go to behind the air box. i pull the red one off, nothing happens, pull the black one off and the idle smooths and raises from 500 ish to normal. - - that to me means the red one has a leak.
i took it out for a drive with that vacuum off and acceleration was quicker through first and second but anything after that was still slow as hell... double checked everything was tight on the fuel pump

perhaps once i fix that vacuum it might be better? maybe fuel filter is going bad?

closest euro shop is an hour and a half away, and my trip this weekend was towards there anyway. might drop it off for the weekend or something

[Milo2361]

wow.... are you frigging kidding me.....

so i discovered a blown fuse after curiously wondering why my interior lights weren't on, or my buzzer wasn't buzzing... turns out that somehow, some way, the little 5Amp fuse that controls what the fuse box cover calls "total interior lights" somehow screwed with my engine. every thing is fine now???? someone must have jacked with the wiring in past years... only came with 5years of records and nothing with wiring was ever written...

[RoninLB]

I know very little of SC engine CIS.

I believe there is a CIS gizmo connected to the interior light circuit.

either check a wiring diagram or start a new "subject".


good luck

[GothingNC]

I think the Lambda brain is on the same circuit as the interior light.

[Paulporsche]

Congrats on solving your problem. There is a Bentley manual for 78-83 SCs. That's the one you want. Also check out Wayne's books, and use the search function on this site. The CIS adjusting tool is 3mm.

[tcar]

Originally Posted by GothingNC

I think the Lambda brain is on the same circuit as the interior light.

The Frequency Valve is also on the interior light circuit and that will really mess with your mixture.