Fast Idle

[blurple124]

Hi all,

Brought the spider out of the garage this weekend to put it in the barn for the winter months. It was running fine when I brought it home (minus the "starter motor not working" bit) and started right up when we push started it, but now it is "idling" at almost 3000 rpm....

Everything is stock, so as far as I know it should have an ADFA Weber on it (it is a '78 with the 1.8L). Any suggestions on what could be causing this?

[vandor]

First thing to look at would be if the throttle linkage is hanging up somewhere. If it is all smooth, it may be a malfunctioning water choke. It is on the rear of the carb, and has two smaller hoses running to it. Do those hoses get warm as the car warms up? They carry coolant, and as the coolant warms, the choke is supposed to open.

[124JOE]

carb gaskets dry up abit when sitting
if it was leaking just let it sit a day and they will thicken with the gas in it
or the intake might need re tourquing
ok i should ask if theres any leaks air,gas?

[blurple124]

There may be leaks. I recently replaced many of the engine hoses, so those should be taken care of. There are only two hoses missing: The mech. Fuel pump out line that you saw in my other post (but I have an elec. pump in place of that so it is irrelevant) and there is also a small place for a hose on the back side of the stock airbox. It almost looks like a vac or breather line, but I'm not sure. It is adjacent to the large hose that comes into the airbox.

We did just have the air cleaner off of it and the carb was sitting uncovered for a period of time so it could be gummed up a bit.

[So Cal Mark]

make sure the water hoses to the choke are getting hot, but it's common to find fast idle mechinisims all gummed up

[124JOE]

first it needs the air cleaner on for setting the idle
and second the hose thats gose to the air filter is from the ft side of the carb near the cam box down on the base

that is on my 32adfa

hope this helps

[blurple124]

Okay great, Yes thank you that does help. I will check the temperature when I get it out again in the spring.

Another thing I couldn't seem to find anywhere was the orientation of the air cleaner cover. I see an E and and I on it, which I could think stand for Intake and Exhaust, but I can't line those up with the actual intake and exhaust holes on the air cleaner. It must make a difference since there is a shield of some sort that covers something when it is on.

[So Cal Mark]

for cold weather operation, turn the lid to block the cold intake

[124JOE]

yes its a seasonal position thing

[blurple124]

Oh, interesting! They just thought of everything, didn't they? Except the whole rust-proofing idea!

[blurple124]

Just touching back on this topic again.

I took the carb off of the car and put it through a parts cleaner, which should help to clear up any stickiness that might have been affecting it before. I haven't replaced the starter motor yet, so I haven't had a chance to actually run the car yet, but I have a couple questions before I do that:

Is is possible that the idle solenoid on my ADFA has gone bad and it is causing my troubles? Is there a good way to tell if it has, if so what symptoms would I be seeing?

And:

When disconnecting the emissions equipment, I will end up bypassing the fast-idle system on the carb. My question is whether I want to put a plugged whose on this diaphragm inlet to maintain a vacuum or do I want to leave it like it is and eliminate the vacuum?




During inspection the rod coming out of the bottom of this device was not moving, should it be? Could this be causing the idle troubles?

[124JOE]

i removed mine and sealed the hole in the carb
as mine wasnt working anyway.

[blurple124]

Well, I've tried carb cleaner, and that seemed to have no effect. I did, however disconnect the idle solenoid on the side of the carb while the car was running and idle dropped to about 1400 and was running really rough. Any clues here?
What, exactly, does that solenoid do in the system? How do I run without it, or should I?

[blurple124]

Alright, more diagnosis on this subject.

I thought I had the idle speed adjusted incorrectly, so I fixed that. The choke is heating up.

I figured out how to make it happen, which, in my experience, is the first step in figuring out how NOT to make it happen.

When I accelerate the engine smoothly (by hand, hood open i.e. no throttle cables involved), bring it up past 3k, then let it settle down, it sits around 2100-2500 rpm. But, if I crack the throttle, accelerating hard, then let it settle down, it comes back down to the idle speed I have it set at.

Thoughts?

[Exit98]

Charlie,

Two things,

I've got a much milder version of your issue. Your throttle linkage is hanging up somewhere. Probably outside the carb. Follow it along. Is the return spring under tension for example?

But watch out for this too. (I have a 32 ADF by the way) there is a little half pulley on the firewall side of the carb and the throttle cable runs inside the valley of the pulley edge. When I manually advance my throttle from the engine compartment invariably the cable slips off the pulley. You don't see it so when you go to drive the car the throttle response is all weird. Make sure the wire is engaged with the pulley (assuming you have a similar set up to mine).

Good luck.