Rough idle and shuts down...

[radiopilot]

Hi, last week I removed the carbureator in order to get to the bolt for the replacement starter, but when I installed everything back including the correct hose placements (vacuum hoses) the car now idles rough, I have to step on the gas pedal to get the car to run past 2000 rpm otherwise if I let go of the pedal the car dies... I rechecked the hoses but can't find where it's connected wrong, one thing in order to connect the wires to the starter I had to remove the oil filter and the fuel pump to reach the nut, but I installed the fuel pump correctly as far as I can tell.

Like I said the car runs great as long as the car is pushed over 2000 rpm.. out of ideas as to what is causing the rough idle and cutoff, the idle solenoid does work, it makes the click sound...

Thanks for any help...

Nick

[mbouse]

what year car?

[radiopilot]

Mike,

The car is the 1980, with the 28/32 ADHA carb.

one thing I forgot to mention, the carb was rotated some when removing it, could the float have stuck somehow?

Nick

P.S. just saw the post... Happy Birthday Mike

[mbouse]

did you hook up the distributor vacuum to the base of the carburator or to the intake manifold? it should be on the base of the carbuetor, and never the intake manifold.

are you sure you didn't crack any of those plastic colored tubes?

[radiopilot]

I took a picture of the engine bay before I removed any hoses, it's correctly installed all the hoses, the bolts holding the carb in are tightly installed, I also followed the hose installation per the shop manual, all the plastic hoses are intact, not split or cracked, the distributor hose is correctly installed at the base of the carb... like I said it's installed correctly... but the engine is rough.

[So Cal Mark]

did you remove the intake manifold or just the carb? If you're looking for a vacuum problem, it has to be below the throttle plate. So, check the brake booster hose. If you had the intake off, you may have damaged the gasket when re-installing. Try removing the spark plug wires from the dizzy one at a time to determine which cyl isn't firing

[radiopilot]

Mark... I just removed the carb, the intake manifold holes were covered to prevent any debris from falling in. I will try removing each plug but the car was fine and was running perfect prior to removing the old starter, no other parts were removed except the above mentioned items... I tell you I'm stumped on this one... everything checks out (hoses, electrical connections, etc..).

If one cylinder was out wouldn't it be out when revving the engine past idle? It runs fine past idle (1800-2000 rpm and up) but it dies out when I let go of the gas pedal, throttle linkage is installed correctly.

Nick

[rlux4]

Radiopilot, I feel your pain man. Mark: seems to me he was on the right track suspecting the carb. If it was upside down, would that cause the float to become bound up somehow, or a needle jet to jar loose?
Ron

[mbouse]

until the process of elimination begins, it can't end.

Thanks for the birthday greetings.

not opening the carb, i'd not suspect the carb itself first off. I've pulled a functioning carb and returned it to the intake more than once w/out issue. But, anything is possible. removing the top from the carb can be done to inspect the float w/out pulling the carb from the intake.

How about a clogged fuel filter? when you replaced the fuel pump...did you change the filter. Could the engine be starved for fuel at idle?

[racydave]

Im with Mark on this, It sounds carb or vaccum related. Fuel starvation is for demand situations, pulling revs... Did you replace the base plate gasket with the reinstall? Spray just a little choke cleaner at the base of carb, and the rpns jump, its a vac leak! Double check the booster hose and fittings.

[radiopilot]

OK.. I can't work on the car right now as I'm preparing for my trip to Florida.

But I'll try removing the plate cover for the carb float and see if things are fine, perhaps somethings amiss there... also I'll try the vacuum hoses/base of the carb by spraying some choke cleaner and see what happens.

All the hoses have the clamps tightened and as far as I could see no cracks anywhere, in fact I replaced a new crankcase breather hose with a new one (old one cracked during the starter replacement) but it was running fine before, can't see why a new hose would cause problems there.

Could I have installed the fuel pump wrong, but if I did the engine would not run good at any rpms? I did not install a new carb gasket, but used gasket sealer on the gaskets.

Nick

[racydave]

Carbs, gas and some kinds of sealer dont mix.

[radiopilot]

Carbs, gas and some kinds of sealer dont mix.

Agree, but this stuff is good for fuel, plus it's downstream of the carb (at the base of the carb towards the inlet) and not being 'sucked' into the carb.

I'll try the above remedies this weekend... see if it helps.

Thanks

[So Cal Mark]

I doubt the float is stuck, you would have severe flooding in that case and the engine would still be loading up at higher rpms. A large vacuum leak will sort of be masked at higher rpms. You still need to determine if it's just one cylinder or all that are affected. It is possible that when you turned the carb upside down that dirt in the bottom of the float bowl was dislodged and clogged the idle jet. If the fuel pump was hooked up incorrectly, the engine would have quit once the float bowl was emptied. Breather hose won't affect how it runs either

[radiopilot]

OK... the float is not stuck, there is no loose connections, there is no leakage at the base of the carb, etc.

What did find is that the choke plate on the top of the carb is not working like it should, is there a vacuum line that pulls this
choke plate shut on a cold engine? I notice that when I start the engine, I have to hold the plate at a particular position (not fully closed but a slight opening) and the car runs fine, as soon as I give a push on the accelerator the plate fully opens and the car begins it's erratic engine behaviour, as soon as I push the choke plate closed the engine begins a normal rpm without jumping around... anyone know what's going on?

I decided to stay home today and work on this...

Nick