240z engine issues

[jordy240]

The car is running but it is much louder then normal, and I believe it is running on 2 cylinders.

What I have done:

Detached the belt to the smog air pump (left it off)

covered the air going into each carb seperately, the front one is not sucking in any air.

pulled wires to the spark plugs one by one, the front 2 cylinders didnt make much of a difference.

tried an electronic fuel pump, I think it pumped too much gas into the engine.

Basicaly I think the car is not getting the right fuel and air mixture. Should I rebuild the carbs?

Symptoms:

Louder then normal engine noise, non smooth idle.

smell of gas when i get into the car.(not exhaust, GAS)

another bizzar thing is I covered the opening completely to the air filter houseing and the engine didnt change.

The oil dip on the top of my front carb is broken, (compression?)

any ways, its a 1971 240z all stock with the early 71 carbs.

any one have similar symptoms ever and or know what might fix it?

I and a friend pulled the valve cover and the front 6 valves were too tight... last time it got tuned up, they were properly set. after that, and a little carb tunning work, the engine ran great for about 60 miles, and then it sat and cooled, the next morning (this morning) it ran like caca agian....

any thought?

[e_racer1999]

wow, you've got your work cut out for you. so the front carb isn't sucking ANY air? that can't be good... bent valves, maybe?

[Walter Moore]

The oil dip on the top of my front carb is broken, (compression?)

When it runs, does the piston on the front carb move at all? Could it be that the vacuum chamber on the front carb is leaking air? That would certainly cause the car to run very badly.

[JimmyZ]

Look under the car and under the hood for any fuel leaks before proceeding. Make sure that you're doing this outdoors if you smell gas. Hopefully it's just raw fuel in the exhaust. That's not good but better than a leak from your installation.

Replace the plugs and see if #1&2 start working. Check the condition of the plugs against a manual. (Prob running rich or oil fouled)

You've tried taking the tops off the carbs and cleaning/verifying free movement I assume. This sounds like one carb's piston is stuck. Raise one piston at a time to see which carb it is. The carb whose piston when raised kills the engine is the good carb. Brake parts cleaner or laquer thinner are excellent cleaning solvents for the pistons and bodies.

Running an electric pump to SU's can be complicated if the pressure is too high. The needles weren't made to stave off much more than the trickle coming from the stock pump. Many guys I know use a regulator when doing what you've done. A clogged restrictor outlet on the end of the fuel rail can also raise pressure too high.

The louder than normal noise could just be an exhaust flange gasket. One time I forgot to tighten my ignition adjustment and the dizzy turned a bit. The car was louder... Seems odd but true.

[beandip]

you said the valves were set to tight? What were they set at? the dip stick on the top of the carbs is to control the rise and fall of the vacuum piston , which controls the mixture of fuel to air. Because this part is not operating properly. Start there and remedy this problem. The information given so far is vary sketchy and not of much help. the Air Pump has no effect on the running of the engine pro or con. Unless you know what you are doing , do not attempt to adjust the valves. If the front carb is damaged this will account for the first three cylinders not working properly. I don't understand ''the engine is louder than normal" ? are you speaking of clattering of the valves , crank shaft , exhaust ? Since you know that one carb is damaged , this is a starting point. If you start getting into several things first you will not have a clue which direction to look. You said you tried a electric pump. What pressure did this pump put out? if over 5psi then this will overwhelm the shut offs in the carbs and flood the engine. When you pulled the plug wires off do you get any spark from the wire when grounded? Pulling the plug wire off a cylinder that is not receiving any incoming air mixture will till you nothing. Gary

[Arne]

I'm leaning towards a valve adjustment problem. If the valves are not opening, that would account for the lack of vacuum at the front carb.