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Running Rough

Malcolm Brown

Enthusiast
Messages
51
Location
Cellefrouin France
Hi all, My 1981 R4 GTL, (fitted with a 1985 engine) will only run on lots of choke, If I close the choke, the motor dies.

The timing is spot on (7degs b4 TDC) and the points are too (0.4mm)

The carb is a V.0. 5 073A 81.11,,, however the manual shows a V.0. 5 83A.

Any ideas as to what the solution is?

I have dismantled said carb and cleaned the jets, bowl and the inline gauze filter, to no avail.

Stupidly enough, it was fine before it went to the paint shop for respray. Guess I should'nt have had him resprayed!

HELP!!!!
 
Hi Malcolm,

You have part of the diagnosis in your explanation.

Because you need to run on lots of choke, you are probably taking in to much air.

Check all the piping that runs from the engine to the carburetor
The lowest pipe that goes onto the manifold just underneath the carburetor needs to have a restriction of 1,3mm in it.
The T-joint on top of the rocker cover can be cracked.
Or there might be a crack in the plastic joint that acts as a heat absorber underneath the carburetor foot.
So many places to look.
Best thing is to run the car at idle put as much choke on it that it doesn’t cut out. And spray WD 40 or break cleaner all over the visible joints. If it starts to run better you have found the leak.

Lots off luck.
 
Thanks Harbourseal, will check them asap tomorrow. I've already changed the auto advance retard pipe as it looked a tad suspect. Hey ho,, these old buggers certainly get the grey matter going!
 
Well, had the carb fully off, gaskets OK, plastic heat absorber in excellent condition, all pipes in good condition, no splits. 'T' joint on rocker cover clean, free and no cracks. Pipe with restrictions in checked, has the restrictions in and is clear and clean. WD40 sprayed onto all joints, no audible or running improvement. I'M BEATEN (for now).
 
How is your co setting? Because the engine is not getting enough petrol. Somebody might have turned the air screw al the way in and cut of the fuel supply to the engine.
Then we go off the beaten track a bit. Try and advance somewhat more. Until the engine starts pinking and then a tat back. To be honest I don't look at the manuals anymore.
Todays petrol is of such pour quality that you need quite a bit more advance to make the engine run ok.
 
I run at 11 degrees timing advance - runs a bit better than at the book value. Seems quite flexible on the timing front - I had no problems with over 20 degrees at one point!

I agree that air/petrol mixture setting may be a problem - either screw too far out of adjustment or an inner pipe channel blocked. Mixture screw should connect to tickover jet channel (jet in the middle of carb when it's in two pieces) - check with wd40/carb cleaner.
 
Hi Malcolm, you didn't say whether the problem exists when you're driving on the open road or only when you're idling.

If it's an idle problem then have a look at my post below and scroll down to Mar 31st entry. I had the same symptoms as you and found that the idle jet was blocked. I used very thin copper wire that I pulled out of some electrical flex and unblocked the hole/passage. Carb cleaner didn't work, only the wire could clear the blockage.

https://www.renault4.co.uk/forum/threads/zenith-28if-problem-solving.8248/page-2
 
Thanks MOJO, yes, the problem exists when driving. So far, I have removed the manifold and checked it for cracks and for leaks It has been re fitted with a new gasket. I have cleaned the carb to within an inch of its life, and cleared the all of the jets by blowing through. Today I will re-check the jets with some fine nylon fishing line, as wire is not really recommended. The carb is to be refitted with new gaskets and a new upper gasket too. (When the upper gasket kit arrives),The carb has been set up as described in www.la4ldesylvie.fr Here's hoping. Thank you very much to all that have offered help and possible solutions.
 
Excellent! Thanks for letting us know that it's cured. What was wrong, do you think?
 
Well, after fully re-furbishing the carb, inlet maniford and re-assembly with all new gaskets. I recon it was a blocked idle jet. I did not see the very small jet port underneath the idler jet, thinking it was a casting mark. It was obviously blocked. The car now ticks over like a gold watch. Be aware, there are THREE holes in the idler jet!, one each side and one on the underside. Happy days!
 
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