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Oct 20, 2016 16:19:33 GMT
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Hello! I drive a Citroën BX 16 TRS that has had its original Solex carb swapped to a very low-mileage Weber 32/34 DMTR with manual choke. It worked just fine until yesterday when after a hard acceleration all power was suddenly lost. I managed to coast to a fuel station where I found that it would still idle reasonably well and I could rev it without any load on the engine. It wouldn't hold the revs for long though. However, as soon as I tried to move it would lose all power and barely move. At this point I thought it wasn't getting enough fuel or had a weak spark (even though I've changed all things ignition lately, including the wiring loom) but then I realized I could drive it pretty well with the choke fully on. So I did get it home, but it's not exactly ideal to run it with the choke on all the time. Now this is my 2nd car with a carb and I'm not at all that familiar with them, so does anyone have any idea what could be the cause of this? Chances of a vacuum leak are pretty small as the car only has the breather hoses connected to the intake manifold and the only vacuum line goes to the distributor vacuum adjuster thingy. Oh and by the way, the car was MOT'd with perfect emissions around 5 hours before its death. That joy didn't last for too long!
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bortaf
Posted a lot
Posts: 4,549
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Oct 20, 2016 21:50:18 GMT
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I would say it has an air leak if the choke partialy fixes the issue, get it idling then spray the vac line joins, breather hose and gasket areas with wd 40 or similar, if the revs rise there is a leak in the area you just sprayed ?
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R.I.P photobucket
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could take the jets out one by one and carb cleaner /air line them , check the filter isnt full of curse word
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91 golf g60, 89 golf 16v , 88 polo breadvan
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steveg
Posted a lot
Posts: 1,586
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I had one on a car I used to have and as well as blocked jets it used to ice up sometimes. The fitting kit I had wasn't great and the air filter didn't fit back on very well. This was on a Mk2 Cavalier.
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Oct 21, 2016 10:27:28 GMT
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good call on the icing , they will ice up on damp days if all the hot air gear isnt fitted
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91 golf g60, 89 golf 16v , 88 polo breadvan
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andy-v
Part of things
i like cookies :D
Posts: 358
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Oct 21, 2016 10:45:11 GMT
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Oct 21, 2016 11:28:17 GMT
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Thanks for all the tips, guys!
However, blasting the jets with compressed air seemed to do the trick so I'll just leave it be for now. Drove a good 100 faultless kilometers last night and this day and it went just fine. It does need some further adjustment as it does think a while when the 2nd barrel is opened - but I guess you can only change the jets to a different size in these and that's about it.
Andy-v's link seems very useful as the DGV looks somewhat similar in design.
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Oct 21, 2016 13:41:17 GMT
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tell you what mine was doing , might be worth a look
the manifold and heat sheild were well rusted , on a long trip it was getting crumbs of rust up the hot air pipe and into the air cleaner then blocking a jet
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91 golf g60, 89 golf 16v , 88 polo breadvan
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shin2chin
Part of things
Making curse word cars slightly better
Posts: 820
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Oct 21, 2016 15:19:18 GMT
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It's so easy to get a blocked jet, I used to get this all the time on my old Golf. As suggested good strip down and blow out the jets.
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1977 PORSCHE 2.0na 924 1974 VW Beetle 1600
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bortaf
Posted a lot
Posts: 4,549
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Oct 21, 2016 20:12:12 GMT
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tell you what mine was doing , might be worth a look the manifold and heat sheild were well rusted , on a long trip it was getting crumbs of rust up the hot air pipe and into the air cleaner then blocking a jet Surely rust in the jets will have come from the fuel tank, fuel flows through the jets not air, all the air does if flow into the venturi, speeds up and creates a low pressure area to suck the fuel out of the jets and then goes into the head with the fuel ? add to that the filter would surely filter the rust from the hot air pipe, it is a filter and it err,, well it filters stuff
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R.I.P photobucket
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nah not on mine ...new tank , and i took the hot air pipe off it stopped, i think tiny bits were getting past the filter , or just randomly blocked jet anyway and nothing to do with the rust , plus stupid design the crank breather comes in on the carb side of the filter
cleaned it all up now
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91 golf g60, 89 golf 16v , 88 polo breadvan
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Oct 22, 2016 10:50:48 GMT
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Apparently blowing air didn't quite fix it!
I realized that the problem always comes up after a hard acceleration to higher speeds... However, if I accelerate with more modest revs it seems to be okay. Another thing I realized that the stuttering and hesitation after a hard acceleration actually only happens on revolutions under 3500. Full choke still cures it though. After a night of cooling off it works okay again, so it probably isn't something getting stuck?
So apparently it's flooding (or not getting fuel to?) the primary jet?
I won't be driving the BX during the winter so I might as well take the carb apart and rebuild it. Only need to drive it until next thursday so I can go to the local Citroën meet.
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Oct 22, 2016 11:09:40 GMT
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Rust flake in the tank getting sucked over the outlet? Happens on Dollys occasionally. What does the fuel filter look like? Has this problem just suddenly appeared?
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Oct 22, 2016 11:22:12 GMT
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BX has a plastic tank, however the fuel lines are metal.. I've been meaning to change those to CuNi or plastic at some point, but they don't look terrible. The fuel filter is pretty new and it doesn't look dirty at all.
Yeah, the problem appeared on Oct 19th for the first time, but then again it was my 3rd day driving the car with this (supposedly) low-mileage Weber carb that I got from a friend who had had it in his Pug 405 (with the same XU5 engine) without any problems.
Whether or not I had this problem with the Solex I can't really tell as it was acting up in so many other ways. I actually ended up garaging the whole car for 2,5 years because of it.
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bortaf
Posted a lot
Posts: 4,549
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Oct 22, 2016 12:20:45 GMT
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Have you checked the accel pump diaphram ? that would cause it to hold back if you give it full throttle from low revs but it wouldn't cause it to run funny afterwards and then get better overnight? Does the breather have a flame trap valve in it? that could be sticking after a lot of vacume is pulled? but TBH that would cause it to run rich? I know you said you blew through the jets with air but what exactly did you do? just take the top of the carb off and blow through the jets in the float bowl or remove them and blow them through individualy and also the drilling in the carb body ? if you went to the trouble of removing the carb top i would have used carb cleaner through the drillings in case they are restricted with varnish and gum or a combination of rust and gum then do the same with the jets, have you checked the condition of the fuel inlet filter above the float valve? One other area to check is for play in the throttle shafts, check it at rest and full throttle (engine off) any play will allow air in but that would have shown up if you tried the WD check i suggested earlyer ?
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R.I.P photobucket
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