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R4 850cc cutting out when driving

Niels Svane

Niels Svane

Renault 4TL '83, 1B1 845cc engine, Ducellier diz
Messages
382
Location
Denmark
Hi everybody
My beloved R4tl 1983 has been standing for two months during winter, and yesterday I took it out for the first run.
Last year it ran fine, but sometimes it cut out (in damp weather). Now it can really only be kept alive by using the choke when approaching a halt. When fiddling around at the parking place, it keeps running but runs pretty roughly (jumps up and down in revolutions).

Am I right to suspect some fuel system problem; either blocked tank ventilation or blocked jets etc in the carburettor?

I dont have the time to go through every bit of the ignition system for a while, so I really dont hope its buried inthere.

If you have any ideas please write :)

Niels
 
Hi Niels,
Before you start pulling the carb to pieces, you might want to check all the breather pipes that run from the carb to the manifold and the rockercover.
To me it sounds like it's pulling in false air.
 
Hi harbourseal, thanks for the reply
I'll look into that then. But should that condition suddenly appear that way? I would thing a worn pipe would show in a gradual way.
The tank breather looks clean btw.
 
Might be worth checking to see the carb flange mounting bolts aren't loose. That will let air in on idle but not be noticable during normal running.
 
If you spray WD40 (other similar products are available) over the joint between the carb and the inlet manifold while the engine is running and you notice the engine then runs more smoothly, then there's an air leak there, which is being temporarily blocked by the WD40. At least you've narrowed down the area of investigation....
 
It doesn't seem to be a air leak problem. So what should be the next thing to look into? I am going to check the points tomorrow, and buy a sparkplug top that can actually reach the plugs ;)
I really think its dirt in the carburetor
 
Is the car fitted with an in-line fuel filter? If it is, it ought to stop too much crud getting into the carb. If not, fit one once all this is sorted out! In the meantime, If you're CERTAIN it's the carb, there are numerous ways of cleaning it out, but whatever you do don't damage any of the jets with a metal probe or anything like that. I know an effective but drastic method of cleaning a carb, which involves the use of a pressure cooker, but I'll save that until all other methods have failed.....
 
Hi again
First of all I will go out on a looong run with the poor thing one of the days, and really get it warm. Secondly I have bought some more of a wondermixture made here in Denmark, which generally sorts out 2/3 of all dirtrelated issues (a mechanics claim). Plus it cleans deposits in the combustion chamber :) I have nothing but good experiences with it on all my motorcycles in the past. Its called BellAdd
I have no filter between fuelpump and carb. but will source one right away.
The airfilter is pretty mucked up, so that will be exchanged too. The points look really tidy, so I dont suspect that it is a distributor-related issue.
 
Capacitors spontaneously fail and you can't see that anything's wrong with them. A failure there might produce these symptoms.
 
Okay, good thing ive ordered one of those then :) Trial and error from now on
 
Hmm, from a 40km's ride today it seems to get worse with the cutting out, and now it is also juddering a wee bit at constant velocity.
I think i'll keep it at a stand-still until the different parts arrive. It's going to be a nice overhaul even though the whole car has only gone 108000km sofar (with service in France until 97000km). The distributor internals and top, condensor, HT leads, plugs, coil, contact breakers, airfilter, and a carb rebuild kit.
Plus new wiperblades ;)

Then i'll measure the different electrical parts to see if the circuit is lacking somewhere (maybe a faulty ground), along with resetting the ignition etc etc etc


Its also strange that it has a Zenith 32 if7 carb i think. Its not even mentioned in the Haynes
 
Last edited:
So now everythings exchanged, and it wont start ;) So i'll begin resetting points etc tomorrow. I think the coil has been one of the things that made it run badly. It was very corroded at the HT output cable.
 
Points gap set, static timing set, aaand no spark or life at all.
I have checked everything, so now I have no idea of what more to do and a car that doesn't run.
It seems like the coil is totally dead, but its the same with both the new and old coil. Ive tried to use the old distributor top too, to see if anything was wrong with the new one (wrong dimensions etc).
 
Hi Niels, when you set the timing the mark on the flywheel has to line up with the mark on the engine block.
At this point, the rotor on the distributor should be pointing at No 1 lead on the cap, which is pretty much facing the right hand side of the car. Be careful because the flywheel turns twice for one revolution of the distributor so you might be 180 degrees out. If this is the case, turn the flywheel around again.
When you set the points, they should be set on one of the 4 lugs(bumps) on the distributor shaft. 0,4mm which you've done.

Now turn the distributor anti-clockwise so that the points close and then very slowly turn it clockwise again until the points open. At this moment, when the points open, you should hear the click of the spark. (if your ignition is turned on, of course!)
If it's dark, you will be able to see the spark.

If there is no spark at all then you know that no power is coming through. So, do you have a spark or not? If not then someone can advise you what to look for
 
Hi mojobaby
There is no spark but current at the + pole on the coil. Therefore it must be something between the coil + pole and the output from the distributor. The condensor, coil leads etc are put in the exact same way as the old ones. And mounting the old coil does not change things either. Thus something is happening between the lead from - pole to points, and I just cant figure out what.
 
Hi Niels, how exactly did you check that current is arriving to the + terminal of the coil? With a multimeter or voltmeter or a wire with a lightbulb in the middle?

If you have current there, then the next step is to check that the current is arriving through the HT lead to the centre of the distributor cap. To do that, take the lead out of the cap, pull back the rubber cover and hold it close to the engine block while someone cranks the engine for you. There should be a spark. Let us know what happens
No spark is faulty HT cable, or faulty coil
 
Not necessarily true mo jobaby as the coil will not generate a spark if there is no make or break action going on at the points either grounded permanently or open circuit or faulty condenser
 
Thank you for your correction! I was thinking that it might be the condenser although that has been newly replaced. Of course it's entirely possible that the new one is a dud.
 
Was not a criticism just as we all have different levels of mechanical knowledge and with possible language barriers as well it can be very hard to diagnose away from car
Maybe a live video web cam broadcast could be arranged lol
 
Sorry for the two nearly identical posts btw :) I hoped to reach more people if I wrote in this 'old' one too. Ill look into the grounding of parts in the distributor, as no spark was generated at the coil HT output yesterday. Neither with the old or the new coil.
I can provide pictures or video if needed ;)
 
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