It wont react when I push accelerator pedal

[lazaserb]

I cleaned carburator, change and checked everything about electric and ignition, and when I want to accelerate it is like its choking, I have detonations in engine. When it works on idle it has no problems , but when I press pedal its like choking, it like it cant get any fuel. And after  few minutes it works normaly, and after few kilometers it starts to choke again. Any suggestions? Maybe oil?

[drcdb15]

Three possible causes:

1. Not enough air - check the air filter is CLEAN!! and properly fitted. I have known of cars with air filters so blocked you could not blow through them. Easy check - remove paper air filter and try engine again. If it works fine, then the air filter was the problem.

2. Not enough fuel - check the fuel line is clear and the filter is not blocked. If the carburettor is full of petrol, then that is probably OK unless a jet is blocked. As you have just disturbed the carburettor, there is a strong probability that a small particle of dirt is blocking a jet, so strip the jets out and blow through them.

3. Not enough spark - check that the spark plugs are actually sparking. Hold the plug by the cylinder head and turn the engine, you should be able to see a good strong spark even in daylight. If you get a good spark, check the plug gap.

3a. Good enough spark, but at the wrong time - that is, ignition timing is out. Is the distributor operating the advance mechanism correctly? Your 'kick-down', initial acceleration symptoms are classic for retarded timing.

REMEMBER - you may have more than one fault present, so do not assume that when you find a fault it is the only one!

Good luck 

[lazaserb]

1. , 3. and 4. are not problem, checked. So it is fuel line,I will check line first than tank,  maybe it has dirt inside. Car haven't been driven in past 3 years, until I bought it. And it has never been repaired, just regular maintenance. I hope that the problem is dirt in fuel line and tank. I don't see anything else , I put new parts for ignition, set up timing, cleaned carb, everything.

[1973/126]

 Also check the fuel pump. Could be it`s not delivering enough fuel.

[Rusty's Uncle]

Loose carb or air leak at base maybe?

[Da Londo]

Check the carb float also

[drcdb15]

Check the carb float also

Good point - could be sticking. (wouldn't be a wrong size, taken from a different size carb, could it?) But anyway, this is a flow issue. So not a simple air leak that will be constant, but a starvation issue where the flow is restricted in some way, which then clears only to gradually build up again.

OK, here's a theory, talking of a restriction that clears... It's a wasted spark ignition. There is a ballast resistor, which normally has low/zero resistance when cold but heats up as the engine runs and the resistance goes up. Now in this case, this resistor is faulty. When cold it's fine, the engine starts and idles. But as the engine heats up the ballast resistor resistance stays low. Too high a voltage now reaches the coil, the coil is breaking down internally resulting in erratic feed to the HT leads and spark plugs, and consequent misfiring and loss of power.

Engine stops, cools, the cycle begins again.

Is that feasible ? (assuming this car has wasted spark ignition... now lazerserb will tell us it has a distributor!!    )

[lazaserb]

Yes I have a distributor, but I think I have finally come to solution. I removed gas tank, and cleaned it completely. First , the part on the top of tank, in which goes 2 hoses in and out was dirty so i cleaned it up, and whole tank inside. And one hose was pinched down, becouse somebody before me was removing tank,   so when some dirt come along , it doesn't have a good flow. I hope that I am finally done with this problem

[drcdb15]

... one hose was pinched down, ...

Looks promising 

[lazaserb]

but it isn't.... after a few days of normal driving , the engine won't work properly again. Same problem, it takes long to start, wont work properly, when I want to accelerate it wont , the engine sound like choking, and it has detonations... but when I drive it like that few minutes it begins to work better and better. not good as it should be working , but better. I don't know what to do, I tried everything....

[drcdb15]

Remember I said you may have more than one problem ? Looks like you have!

But as I also said, this is a problem of FLOW. You only have three flows to worry about - fuel, air, and sparks. We considered if flow was too restricted, and you found blockages in the fuel line. Now suppose a flow is too MUCH...

Are any hoses split, letting in too much air? Is the carburettor jet the correct size, letting in too much fuel? Could the carburettor float be bent, and allowing too much fuel through?

What do the spark plugs indicate - are they black and sooty - too much fuel. Or are they light grey/brown - too little fuel? Do they have the correct gap ?

Check again the air filter - or even try running with it removed.

On the electrical side, is the battery OK - are all cells topped up with water? Are the connections good? Does the battery hold its charge OK?

Is the distributor cap clean and dry, no oil or grease that could be tracking the current? Are the HT leads in good condition?  Are they properly secured into the coil and onto the plugs?

Is the vent in the fuel filler cap blocked? try blowing through it, or running with it removed (put a piece of rag into the filler hole as a temporary measure to prevent spillage). Disconnect the large air inlet hose at its top end, and check it has not kinked near the bottom. Try running with the top end disconnected.

I think first priority is to check the spark plugs colour - is the engine running too rich, or too weak, or just fine?

Then I would check the air supply - split hoses, blocked vent, soiled air filter. You've already thoroughly checked the ignition, you found a problem in the fuel supply - there's only the air supply left so I'd check that next, after the plugs. If there is still no solution, then it's time to begin again, as you must have missed something.

I know you said you checked all the ignition system, but I still think the uneven running of the engine, the detonations you mention, sounds to me like retarded timing...

[drcdb15]

A few posts ago 1973/126 suggested the fuel pump may not be delivering enough fuel. A related issue could be excessive heat causing the fuel to vaporise too early. Do you have proper cooling of the engine? Do you have an air-cooled or water-cooled engine (I think that so far you have not told us).

If water-cooled, is the water pump working properly and the coolant level fully topped up? Are the waterways clear so that you are getting full flow of coolant around the engine?

If air-cooled, do you have any obstructions that impede the cooling of the carburettor and/or cylinder head region? Do you have a stainless steel exhaust? This does not dissipate heat as well as cast iron, and heat build up in the head can be transmitted through to the inlet ports and carburettor, causing fuel to vaporise too early in the inlet flow.

If this is the case, then heat shielding may be needed, or an alternative may be to fit an electric fuel pump to feed the fuel at a higher rate when it is called for, under acceleration.

Remember too that cooling air must not only be allowed to get IN to the engine, it must also be allowed to get OUT! So, are there any blockages or constrictions to the hot air escaping to the outside? If air-cooled, is the thermostatic air flap/valve working OK ? Try opening the air vents to the car interior - is there hot air being blown through?