79 Idling Problems

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Fri Nov 10, 2006 7:17 pm

The '79 that I just bought idles rough, and doesn't die when I unplug the idle solenoid.

Here's a question... If the idle solenoid is removed from the carb, and then the car is started, should gas come out of the hole where the solenoid should be? I assumed it should, but it does not.

Also, is fast idle speed on a '79 set by turning the screw on the fast idle dog? In my manual, it shows where the "fast idle adjustment" screw is, but states that it is inoperative/bypassed for carbed '79-80 models.

I've got to get this thing runing smooth and smogged by this month's end, and I'm a little low on funds right now, so I can't afford a shop rebuild.

So Cal Mark · Post by **So Cal Mark** » Fri Nov 10, 2006 7:49 pm

the idle cutoff solenoid has the idle jet on the end of it. If the solenoid is loose or removed the engine will idle so rich that it won't run. Fuel shouldn't come out of that hole, but it's nearly impossible to run the car with the solenoid out anyway. If you take the solenoid out, pull the idle jet off the end. You may find the pintle has been cut off. That's the cheap way to fix a bad solenoid!. If the car is idling rough, remove the plug wires one at a time from the dist cap and see if one cylinder doesn't make any difference. That will be the cyl causing the rough idle.

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Fri Nov 10, 2006 10:26 pm

My idle cutoff solenoid is new. I bought it the day after I got the car when I couldn't get the old one to click.

When you say that one cylinder is making the engine run rough, I am confused... could a carb problem cause just one cylinder to run differently than the others? Aren't they all getting the same mixture since they're fed by a single carb and manifold?

I've already replaced the plugs and wires, as well as cleaning the cap& rotor.

When I start the engine, it revs to over 2k rpm, then after I give it a little gas, it settles down to the 1k range, regardless of wether or not the idle solenoid is energized or not. Or rather, wether or not the idle solenoid is even installed. When I drive it, it wants to die when I put it in neutral, drops to 0 (zero) rpm for a second, then bumps back up to 1k.

So Cal Mark · Post by **So Cal Mark** » Sat Nov 11, 2006 12:39 am

since you replaced the solenoid, does it have the idle jet on the end?

racydave · Post by **racydave** » Sat Nov 11, 2006 7:21 pm

There are other items that could cause a rough idle. How does it run when driving? If you had a specific eng miss you could tell. Or maybe there is something affecting all cyls. Ive seen timing cause a rough idle. Vaccume leaks can also, usually if the system is lean, you can cup your hand over the carb to restrict air flow, if the rpms pick up, it is probably lean. If your float is set to high, you will be rich and have exessive fuel. Bad or old gas will cause the same. I removed all old gas from my 79 first!!!

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Sat Nov 11, 2006 9:21 pm

It runs great over 2500 rpm. Lots of power, smooth, no backfiring or exhaust popping. Under 2500, it stumbles and wants to die but just barely doesn't.

The idle jet I bought was complete, including jet. The jet # on the end was 55, and the original was 50. I've tried running it with both jets and that was when I discovered that it also runs without the idle solenoid installed.

Today I'm getting a gas smell while driving, so I'm going to pull the carb, replace the rubber gas lines and clean the carb.

So Cal Mark · Post by **So Cal Mark** » Sat Nov 11, 2006 9:39 pm

if the car runs without the solenoid connected, it must be getting fuel from the main jets while idling.