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What can it be?

Cili

Enthusiast
Messages
11
Hello everyone.
First of all it’s a pleasure to see how many people still care about this beautiful cars.
Here’s the problem. I’ve got a R4 TL 1990 with a C1C engine (956 cm3) and a Zenith 28 IF carburator and together with a heavy gas smell coming from the cockpit fan when the engine is not warm yet and a general issue of considerable fuel consumption (only 50-60 kilometres with 4 liters out of town at 80 km/h), if I lightly touch the gas pedal when the engine is warm and the second or the third gear in the motor badly shakes (I can ear a pesky thump). All its anchorage points seems ok. I thought it was due to the carburator and I tried to adjust the screw for the mixture setting as Clementine suggested, but nothing happened. Only if I screw it more (3/4 of turn starting from the all in position) the smell of fuel seems to recede, but not the engine problem (even if it reveals later).
I’m tempted to screw the mixture setting in a little more but I don’t want to make a mess. Any suggestion?
BTW The oil consumption is regular.
Sorry for my poor english!
 
Hi Cili, welcome to the forum.

It sounds like your Renault isn't well. I'm not sure what the problem could be. The engine shake on part throttle sounds like a symptom of weak fuel mixture. Perhaps the fuel is escaping before it reaches the carburettor?

Try removing a spark plug (after driving for at least 5km - you can let the engine cool down again afterwards). If the electrode on the end of the spark plug is white the engine is running too lean (not enough fuel) and if the electrode is black then it is too rich (too much fuel). Light or medium brown is the corect colour.

If the spark plus is white I'd start by checking the fuel pipes for leaks. The metal pipe that runs from the rear of the car can rust causing leaks. Also the rubber pipe on top of the engine can crack.

It the spark plug is black or normal then perhaps the fuel smell could be coming from the carburettor. There is a float chamber that holds fuel. When the fuel level is high enough the float will rise and shut off a valve. If this valve has dirt inside then it might not be sealing correctly. If you remove the air filter and unscrew the screws on the top of the carburettor you can remove the top and clean out the valve.

If the spark plus is black then you could check that the choke flap in the carburettor opens fully when you push in the choke. Often the cable can slip causing a rich mixture.

Do let us know what you find.

I drove through part of Italy in my Renault 4 last year (going from Austria to France). People at the boarder and road tolls were very interested in the car, and especially the "umbrella handle" gear stick on the dashboard. It was good fun. Your car must get a lot of attention over there.

:clementi:
 
Hi Cili,
several things come to mind, there is a breather pipe from the carburettor just under the air cleaner that runs to just under where the carburettor joins the inlet manifold, you can see this between the carb and rocker cover.
If the breather pipe has come off this will alter the mixture badly and cause similar problems,and can cause gases to enter the engine bay and onward to the heater etc, if this pipe is connected you might like to pull it off at the manifold end and inside the pipe you will find a plastic restrictor, this can sometimes become blocked causing the carburettor to run too rich.
Also, if you are not running an in-line fuel filter it is possible that dirt has found its way into the jets inside the carb which if it has happened will need to be cleaned out.
It is possible of course that the ignition system has gone out of adjustment causing a loss of power and increase in fuel consumption
 
In the end, I find out it could be the gas pomp.
I've decided to change it and I'm going to take back my R4 from the mechanic this afternoon, so I can soon say and with no doubt if the diagnosis was right.
 
Oh well... the good news is the fuel pump needed to be changed: it was the very reason of fuel smell, but the main problem was still there :(
As last resource, I've tried to substitute the air filter with a new one this morning (I previously changed it 78 km ago) and... my R4 seems another car!
Only one thing: if I push hard the gas pedal, from the back pipe (exhaust, escape, escapement etc. - I'm not sure about the name in english) comes out black smoke. Perhaps the fuel mixture is too rich?
Thanks again.

BTW for Clementine: in my region the R4 is a well know car and it's not hard to still see a lot of them on the road. But I can tell you a singular episode happened to me last year, in the summer. The car was parked and I was sitting into waiting for my girlfriend to come when I realized there was a woman on the other side of the road steady looking in my direction. I thought she was attract by me :lol: , but - once crossed the road and come near to me - she exclaimed: "Beautiful car! I got one many years ago!" She was from Holland. :D
Again, sorry for my crude english!
 
your English is very good.

Exhaust is the term.

When you press the gas pedal then you will get a puff of black smoke, it should be a small puff, if its a lot of smoke then yes, it is running rich.

Cleaning the carburettor out may help to improve this situation.
 
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