car will not idle at all

[85GT-79FJ40]

OK so yesterday I fired up my 84 Capri 5.0 for the first time since about mid-January. When I put the car away back in November I had just reset the idle mixture on the then-new edelbrock 1406 carb. It ran smooth and idled at about 850 perfectly. When I ran it to circulate coolant after swapping the radiator in January it ran perfect. Then I discovered a coolant leak between the timing cover and block. I just fixed that. Now the car will not idle at all. Get it below 1200 RPM or so and it instantly cuts out and dies. I'm guessing it's something with the carb but it was perfect before. I drove it around my neighborhood and as long as I kept it around 2 grand it ran fine, plenty of power. Push in the clutch, dead. I'm a bit puzzled.

[Matt J]

I'd agree it has to be in the carb, especially where it's been sitting for a while. Probably something stuck or a bit of gunk got sucked into it after it sat for a while. I'm not sure if a stuck float would cause that, but it sounds like you're not getting any fuel at idle. If it runs well at higher RPM, that's probably all it is.

[86GreenStang]

Also check vac lines

[brianj]

Those Edelbrock carbs are about as complicated as an anvil- this is why I use them on everything. You should be able to pull the top off the carb(six or eight torx screws) and be able to check the floats, needle and seat, and everything else in ten minutes without pulling the carb. One thing I learned- a stock 5.0 Ford pump will put out too much pressure for the carb. It may be overwhelming the needle and seat and flooding out, but I would have thought it would have done it right from the get go. Is everything else still stock on the car?

[85GT-79FJ40]

It's still pretty much stock otherwise. EGR is gone and all the other emissions stuff is gone. Stock intake with the edelbrock spacer that covers the EGR plate hole. Right before I put the car up last november I set the idle mixture with a vacuum gauge and drove it, then parked it in the garage and put it up on stands. I almost think the idle mixture might be too lean. When I go to restart it I have to give it a little gas. Could be something in the carb too I suppose. Although it sat all winter in the garage with the air cleaner on. I'll have to look into it more later in the week when I have some time. This is the first edelbrock carb I've used myself. But I am pretty familiar with webers like on my FJ40. Same deal with those, just take the top off and you can see everything.

[PaceFever79]

Try running the idle mixture screws all the way in (count the rotation)

Then back them out 2 turns each and try to start.

If it idles, use the throttle stop to raise the RPM to about 800

Adjust mixture screws in/out to find maximum RPM, then tighten 1/4 turn.

Then adjust the idle speed using the throttle stop screw.

[PaceFever79]

If you get it to idle by the above procedure, I'd take a manifold vacuum reading,
just to make sure you don't have a vacuum leak somewhere.

[PaceFever79]

Also, if the above adjustment procedure doesn't work the idle circuit may be clogged...
(on Performer carb the mixture screws control the fuel flow not the air flow)

Remove the idle mixture screws and spray carb cleaner in the holes.

You can also use a wire or guitar string to poke into the hole and make sure it's clean.

Then follow the mixture adjustment procedure above.

[85GT-79FJ40]

Thanks for the tips guys. I started the registration process for it this morning. Have to pick up plates later this week and put insurance on it. I figured I would make sure it runs reliably before I get plates though.

[85GT-79FJ40]

Ok played with it again tonight a bit. Took out the idle screws, sprayed carb cleaner in there, put them all the way in, backed out 2 turns no change. Backed out another turn, a little better. Now that the car is registered and insured I cranked the idle up and took it for a drive up the road. It was kind of skipping and surging a bit so I decided to turn around about a mile from my house. And it died. With the nose hanging out in the road. Wouldn't turn over either. Waited about 5 minutes and it started up again. Made it into my neighborhood and it died again. Coast into driveway. Won't turn over. So I suspected the timing was off. Loosened the distributor and turned it counterclockwise a little. Fired right up and idles fine at 850. Funny thing is I have NEVER moved the distributor in this car and it ran fine last fall. So I get out the timing light and I can't make out any marks at all on the balancer. Go to move the distributor and get shocked. So I need plug wires for sure. But more importantly I need to find the timing marks on the balancer. But I'm getting closer.

[JTurbo]

Good progress. But you better hurry up, MU is coming quickly....

[85GT-79FJ40]

Found the marks on the balancer, painted a line at 10 degrees, installed some premium $20 Napa plug wires and after timing it I have it idling smoothly at 850 or so. Strange that this just kind of popped up after it ran fine last fall. The wires that were on it were Motorcraft wires. They could have been original I suppose. I haven't actually driven it since this but I plan going for a spin and putting some fresh gas in later today.

[85GT-79FJ40]

Took it for a ride and as soon as the choke kicked down pulling into a gas station it died. Put gas in it, stopped at a light, died again. Drove about a mile to a fellow gearheads house and it died again. But I think I may have found it. He thought maybe the vacuum advance wasn't working right. I attached my mityvac to the diaphragm on the distributor and it doesn't hold anything at all. Can't pull any pressure on it whatsoever. Seems to run fine under load when I have my foot in it but randomly won't idle whatsoever and steady at steady cruise it bucks like crazy. Any other tips?

[brianj]

My only thought would be, if the vacuum advance is not holding the advance plate, the timing could be randomly changing all over the place. I have seen this when people get the idea that they do not need their vacuum advance on their cars, and mechanically unhook it.

[85GT-79FJ40]

My only thought would be, if the vacuum advance is not holding the advance plate, the timing could be randomly changing all over the place. I have seen this when people get the idea that they do not need their vacuum advance on their cars, and mechanically unhook it.

This is what I'm thinking is happening. When it dies and I turn it over the engine makes some odd sounds much like when you're physically turning the distributor trying to get something to fire for the first time. And sometimes it idles, sometimes it doesn't. I'm just going to get a new distributor for it. I'm running out of time and the vacuum pot is like $22 and a whole reman distributor is $55.

[85GT-79FJ40]

So much for that theory. Pulled off the cap and rotor and moved the advance plate manually and it seems fine. Realized my vacuum pump was leaking with the wrong size hose on it and retried it with the correct size and the advance mechanism does work fine. Guess it's time to pull the top off the carb. Which really irks me because I just bought it in October! There must be something built up in there. Pulls fine at full throttle but bucks and surges at steady cruise and when decelerating. And usually won't idle. Seems to get worse when it warms up. It could be a vacuum leak too but from where? If the carb checks out I'll probably wind up yanking the intake off. It's only pulling about 15 inches of vacuum at idle. Steady but seems low. Getting to MU isn't looking good.

[mmb617]

Twice in the last 4 years I've run into a problem with my car when it wouldn't idle at anything below 1500 rpm. It would just slowly die unless you had the idle turned up that high, but it still pulled good once you were driving.

Both times the problem was a vacuum lead due to a blown intake gasket. In fact I just fixed the second one yesterday. After replacing the intake gasket it now idles just fine at 850.

Your problem sounds very similar.

[85GT-79FJ40]

Well it's running again. Just drove it for 45 minutes with no issues other than a very slight occasional surge at cruise. Which I suspect is a vacuum leak. With it running I was spraying carb cleaner around the intake looking for a leak and the driver's rear corner was leaking. Those two vacuum trees for the intakes were leaking. I broke both of them off with a hammer in disgust and they appeared to be spring loaded inside. Just sprayed it there with starting fluid and noticed no difference. I tightened the rear intake bolts a hair also. I think the biggest issue was the carb itself. When I pulled the top cover off the bowls had greenish chunky gunk in them Cleaned out the bowls, took the jets out, cleaned those, sprayed air through all the primary passages, and put it all back together. Put a fuel pressure regulator on it although I never had an issue without one before. At any rate it's idling smooth at 750, not stalling, and overall seems to be running fine now. I think I do have a slight vacuum leak but it will be fine until I can afford a different intake.