R16 not idling and running rough since running out of fuel

jsnoble

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Hi all,
I'm still fairly new to owning a Renault 16 since inheriting it from my Dad. After a good stint at Colliers in Sydney, it has been driving like a dream - and it's been great fun! Unfortunately, I hadn't yet learnt how to interpret the fuel gauge, and this afternoon it ran out of petrol.

I got back to it with a jerry can of petrol, and then filled it up not far down the road. But it wasn't driving smoothly - it felt much rougher than before, and it wouldn't idle. I thought it just may have been that the jerry can petrol was perhaps old and that after a bit of drive it'd clear itself and get back to what it was - but it didn't. I needed to basically keep the choke open to keep it from stalling at lights (or try and catch it with the throttle when I clutched as I rolled up) - but when it did stall at a set of lights, it then took a lot of effort to start it (with quite a bit of throttle) - whereas previously it would very happily idle (once it was warm), and starting it would be easy.

So I guess I'm left wondering what I've ended up doing to the carburettor perhaps by letting it run out of fuel? Or any other suggestions? Thanks in advance for any advice!
 

Fireblade

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It sounds like a blocked idle jet. Very common on twin throat webers. Idle jets (2 in total) screw in on each side of the carbs just under the air cleaner. You don't need to dismantle the carby to get to them. I would blow them out and change (or fit) an inline fuel filter between the fuel pump and the carby (<$10 from Repco).
 

Bowie

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Yep!

You are about to learn all about webers. Webers are fun (and straight forward)

Take those jets out and clean :)
 

jsnoble

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Thanks guys! There's definitely already a fuel filter in line, so I'll take the idle jets out and give them a clean.
So is the assumption here that by me letting it get to the dregs of fuel in the tank, it's forced the gunk it the bottom of the tank down the fuel line and that's clogged those jets?
 

geckoeng

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I would suggest a Carb service, as it has been standing the old carb, and in he tank, will be full of deposited shelac which does not desolve again and breaks off in small particles, in particular in the carb. I use a small fuel injection filter, I think a Z400, stops 99% of the tank junk.

Ray
 

jsnoble

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I would suggest a Carb service, as it has been standing the old carb, and in he tank, will be full of deposited shelac which does not desolve again and breaks off in small particles, in particular in the carb. I use a small fuel injection filter, I think a Z400, stops 99% of the tank junk.

Ray
I'm also conscious that it has literally only been 3 weeks since I picked it up from Colliers. And I know David mentioned there was a heap of old fuel in the tank when I got it to him some months ago (the car had been sitting idle for about 3 years at that point). So I'm sure he would've done a full clean of the carby then, and I do know that he installed a new fuel filter (although perhaps not the one you mentioned). So it may not necessarily need a full carb service, and perhaps just the idle jets that the others have mentioned above? Or are you saying if I've let it dredge up crap from the tank then I may very well have undone any work that was done a few weeks back?
 

Frans

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According to me it sounds as if the issue is in the pick-up in the tank and not in the jets, because the dirt cannot really get to the jets because of the filter you have in-line. There is no way to get at it but you could remove the filler cap and disconnect the supply line at the carb and reverse blow compressed air into the tank. That will disperse the dirt into a wide area in the tank and open the pick-up. With normal fuel levels and travelling not enough dirt collects at the pick-up to block it. Then parking the car releases the little bit of dirt back into the fuel and repeat tomorrow and so on.
 

Fireblade

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I wouldn't fret about having "done some damage". The weber is work of art - a very robust and reliable performance carby. When the idle jet is blocked, it seems like its all gone to crap. But it is such a simple fix - I've done it on the roadside. And when I said "common problem" this does not mean it will be a regular problem you'll have to deal with. You should have years of trouble free operation.

Clear the idle jet, replace the filter, don't let the tank run dry!
 

JohnW

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I'm also conscious that it has literally only been 3 weeks since I picked it up from Colliers. And I know David mentioned there was a heap of old fuel in the tank when I got it to him some months ago (the car had been sitting idle for about 3 years at that point). So I'm sure he would've done a full clean of the carby then, and I do know that he installed a new fuel filter (although perhaps not the one you mentioned). So it may not necessarily need a full carb service, and perhaps just the idle jets that the others have mentioned above? Or are you saying if I've let it dredge up crap from the tank then I may very well have undone any work that was done a few weeks back?
I suggest you talk to Colliers as well and find out exactly what was and was not touched. You've got a trip meter in the speedo I guess so get into the habit of zeroing it every time you fill up. You'll soon know how far you can drive.

If you are lucky, this might be a very quick fix but if you have some junk now loosened inside the carby (as Mr Geckoeng observed) it might happen again. They are good, simple and reliable carburettors but do need to be clean. I doubt Colliers would have done a full carby service if it ran OK with new fuel and filter. But who knows....

Enjoy your 16. Wonderful cars.
 

jsnoble

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You are all legends and scholars. Thanks so much for the replies and advice!
(Aside, I'm so sad that just as I get into learning and loving my 16, this brilliant forum will be no more!)
 

dacia4x4

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as well as sound advice above regarding fuel contamination,air filter quality can also cause restrictions in Weber carby air correction and emulsion tube jets, just a thought.... jim
 

schlitzaugen

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Just before you go back to Colliers or pull the jets out, I would suggest you try this. Unplug the fuel hose from the carby and put it in a coke bottle. Now fill the carby if you can from a bottle or something with clean fuel and try to start the engine. If it starts and idles nicely, leave the carby alone, there's nothing wrong with it.

While you have the engine running (it will run for a while if you don't open the throttle), look in the coke bottle to check what the pump is doing. Do you have a nice steady flow of fuel or not? If not, check the tank pickup, lines, etc, everything upstream of the carby (including pump).

If the engine doesn't idle, you found your problem.

If you can't fill the carby with clean fuel, just crank the car and look in the bottle. Do you have petrol coming? It will be a rather weak, interrupted stream but should be clear if there's a problem.

If all these tests reveal everything is hunky dory, I would suggest you have an ignition problem. Unrelated to running the tank dry, of course but you may be the lucky one who has a real problem masked by another not so real problem that just happened to happen at the same time.
 
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RINGER

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Thanks guys! There's definitely already a fuel filter in line, so I'll take the idle jets out and give them a clean.
So is the assumption here that by me letting it get to the dregs of fuel in the tank, it's forced the gunk it the bottom of the tank down the fuel line and that's clogged those jets?
I haven't read everything else here but added filters are always recommended before a pump - i.e. before pressure side.
 

Wildebeest

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I haven't read everything else here but added filters are always recommended before a pump - i.e. before pressure side.
As Ringer posted. Put the filter on the tank side of the pump. No pressure at this point, less risk of fire particularly if plastic type filters used.
I would bet all the money in JS Noble's wallet that it is the idle jet/s.
 

jsnoble

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Hey all. So firstly, the fuel filter I have in place before the carby was FULL of crap. Unbelievably gross. So I replaced that, and it now idles and drives a lot better. However, it's definitely not perfect - I tend to think it's a combination of the carb needing re-tuning perhaps, but also as has been suggested, the idle jets.

I did have a play with trying to tune the carb, but a) it's definitely a learned art, and b) it's so damn hard to get to the idle speed screw!! Given there's a couple of other things that I need to get done at Colliers next week, I've asked David if he can have a look at it.

Genuinely appreciate everyone's advice here! I did learn quite a bit about how the carb, fuel flow, filters, etc all work.
 

JohnW

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Hey all. So firstly, the fuel filter I have in place before the carby was FULL of crap. Unbelievably gross. So I replaced that, and it now idles and drives a lot better. However, it's definitely not perfect - I tend to think it's a combination of the carb needing re-tuning perhaps, but also as has been suggested, the idle jets.

I did have a play with trying to tune the carb, but a) it's definitely a learned art, and b) it's so damn hard to get to the idle speed screw!! Given there's a couple of other things that I need to get done at Colliers next week, I've asked David if he can have a look at it.

Genuinely appreciate everyone's advice here! I did learn quite a bit about how the carb, fuel flow, filters, etc all work.
All you can adjust is the idle mixture and it was perhaps OK before? I never needed to touch the carby on either of our 16TS cars. Back to those idle jets........ but Colliers will fix it. All good.
 

sfrawley

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As an aside, crap does not tend to settle in the fuel tank of a moving vehicle as the fuel is continually sloshed around and any crap soon finds its way through to the filter. I once had to replace the fuel sender on a 504 after 25 years and the bottom of the tank was bright and shiny as new.
 

Brad Johnson

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Thanks guys! There's definitely already a fuel filter in line, so I'll take the idle jets out and give them a clean.
So is the assumption here that by me letting it get to the dregs of fuel in the tank, it's forced the gunk it the bottom of the tank down the fuel line and that's clogged those jets?
Something like that was my first thought. Doesn’t take a lot to block or partially block the idle jets. I agree with previous comments. Replacing the inline filter wouldn’t be a bad idea either and they are very inexpensive.
 

driven

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Hey all. So firstly, the fuel filter I have in place before the carby was FULL of crap. Unbelievably gross. So I replaced that, and it now idles and drives a lot better.
Fuel pump will also be probably full of rubbish.
 
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