Hi, not sure if anyone can help me but here goes,
I have a d reg model f 2lt Auto space cruiser fitted with a weber carb, the other week i had a problem where the engine revs wouldn't drop, i dismantled the carb to find one of the jets had come loose i tightened the jet and the engine revs returned to normal operation but now the engine will not hold revs, the engine starts on choke and ticks over nicely at 800rpm without choke (once warm)
as soon as i put my foot on the throttle to raise the revs the engine coughs and the revs drop to nearly nothing and i have to let my foot off before it stalls, i have had the carb apart and fitted a service kit (diaphrams new valves etc) but to no avail, im now thinking pertrol pump can anyone tell me deleivery pressures for the 1986 (d reg) mechanical petrol pump, the unit is a sealed unit so i cannot change any diaphrams inside the pump itself, also any pictures or links to the carb would be nice the only reference i can give is that is a weber carb and has the reference number 32 34 DMTL 7.
On a possibly related issue can anyone tell my a reason why 3 lights would come on and off at will (all together) on my dash, the lights in question are the oil light, water light and the battery light.

- (#1374) yedan, 17 May 05 13:59

have you checked the fan belt tension and alternater
that would cause the lights you mentioned

- (#1374) jon, 17 May 05 14:14

Sounds like fuel starvation, have you checked the fuel filter?
Second the loose belt, but maybe the alternator bush(s) wearing?

- (#1374) Clive (Bristol), 17 May 05 17:53

on the first problem
i have changed in the clear inline fuel filter between the pump and the carb, and i have changed the small filter in hte carb itself,

on the lights issue,
i have had the alternator checked by a garage and they found no faults with the alternator, i haven't checked the fan belt tension but it looks ok(visible check only) once i have sorted my other problem (fingers crossed) i will look at the fam belt in more depth.
- (#1374) yedan, 18 May 05 02:55

And it might be wise to look at the info in Rik vonTrense's thread, a couple of posts down. Carb and charging system are linked on these beasts through the shutoff and autochoke systems.

Check all fuses!


/ hang on, re-read your post... You've got a Weber?

This kind of problem reads like starvation OK. Will the revs rise at all, and are things improved on the choke?

Some weber conversions use a restricted "T" to control flow to the carb and return line. Any chance you've got such an item and have refitted it backwards? Is the second choke linkage or vacuum operated? And if you stroke the accelerator fully, can you see a jet of fuel squirt from the accelerator pump outlet?

I don't think there's a pressure spec for the fuel pump, although Ian or Clive will likely confirm this. Most carb setups run between 1 and 4psi IIRC, and it's flow that's important, not pressure. You could try gravity-feeding the carb to isolate the problem, no?

- (#1374) David Miller, 18 May 05 04:10

the revs will rise if i continually blip the throttle, but to hold the revs at say 2000rpm is next to impossible, the chole does seem to improve the things but althought the revs remain enough to keep the engine running there is a lack of pulling power, i have seen no item like a T the fuel line goes directly to the pump with an inline filter accesable through the floor panel behind the drivers seat, i can only see one choke lever/butterfly assembly and there is a vacum unit attached to the side(which i assume is to do with the second choke chamber), which again is a sealed unit so i cannot change the diaphrams, but through pressure testing etc it seems to be operating ok with no leakage,
- (#1374) yedan, 18 May 05 04:56

Well a 32/34 DMTL is a twin-choke carb. Some versions had a mechanical link that opens the second throttle as you open the first stage. Others use a vacuum capsule to open the second throttle, but you'll not see this opening whilst stationary. the engine would have to be under load to create sufficient vacuum to open the secons choke...

Any chance you've altered the float height when the carb was apart- is the spring in the floatvalve free and are you sure you haven't bent the float assy?

- (#1374) David Miller, 18 May 05 05:20

I was wondering about float hieght too...as it does sound like fuel starvation. Also about spraying carb cleaner through the jets/secondary orifices in the carb.
'Haynes' do a good carburettor manual which may be worth checking out to see if it lists your carb.....
Is it a newish carb?...wondering about split diaphrams? May be worth checking the diaphrams with a vac guage. Also check any vac tubes going to the carb....some have a small restrictor at the carb end (may be on the end of carb or come off and be in the vac tube) which can easily become blocked on older vehicles.
Do things improve any when the engine gets hot?....

- (#1374) chris turner, 18 May 05 06:24

i have indeed got two throttle butterflies and one choke (manually operated)when the carb was off the car both throttle butterflies operated as expected when full throttle was simulated, as far as i can see the float spring was not bent and the floats are operating with no stickyness or restriction when off the car, i have changed all the diaphrams i could find using a carb service kit, it looks an old carb which was why i used the service kit, as for do things improve when hot no not really if anything it makes it worse,

- (#1374) yedan, 18 May 05 09:32

One slightly out-of-the-box thought. Any chance there's less than 12v going to the ignitor? I've seen iffy points and condensers cause this kind of problem on points-and-magneto motorcycle ignitions...

- (#1374) David Miller, 18 May 05 09:53

Well I would have to throw my hat into the ring and agree with fuel starvation. Have you actually tried what David suggested in his first post about seeing if fuel is pumping into the carb? Disconnect the fuel feed line to the carb and point it at a jar or something to catch the fuel and turn the engine over Is there a constant flow of fuel? If a problem with the integrity of the pump (gasket or seal) then pressure can drop with a reduced or no fuel feed.

If feed is ok then look for blockages in the carb. Does the airfilter sit on top such that if removed you can see into the carb? Is fuel being dispensed through the jets? Any blockages?

- (#1374) Ian Dunse (Derbs), 18 May 05 10:02

i haven't check the voltage through the ignition system but i have now other reasons to think that there is anyting wrong with the battery or charging system but i will check to make sure. as far as the fuel pump pumping i have taken the fuel feed to the barc off and put the loose end in a 500ml coke bottle and it can fill the bottle in a matter of seconds so as far as i can see the pump is pump well enough to feed the carb, i am going to try taking the feul pump out of the equation next by gravity feeding the carb and see what happens. i have put a pressure guage on the fuel line from the pump and to me it reads low i cant rememberthe exact pressures but i have a gauge that shows the recommended general pump pressures and mine didnt even make it into the green. :( which was why i was wondering about pressures.

- (#1374) yedan, 19 May 05 03:56

Pump seems ok then. If it was revving high before you touched the carb and now it isn't, the obvious assumption is that the problem is with the carb. Do you have a colour tune? These usually come with a flow diagram for diagnosing mixture faults and may help steer you to the problem.

Presumably you've checked the obvious like timing and that the distributor advance works when revving?

- (#1374) Ian Dunse (Derbs), 19 May 05 04:42

I would check out the haynes carb manual...get the 'float hieght' measurments and check these are correct on yours.
A possible problem is that the bushes that hold the needle valve in place have dropped.
I had a car with weber and this happened. The brass bush in the inner body of the carb can work loose and drop a few mill...if this has happened it will mean the floats are too low....though it will not be obvious unless you are checking for it as the tabs will appear straight. The bush/es will need pressing back in with a small drift. The cause of the bush drop is the constant hot and cold cycle over the years.
What model weber is it?

- (#1374) chris turner, 19 May 05 05:50

the only info i have on the carb is what i posted in an earlier post it say on the casing 32 34 DMTL 7 then has a long number after it that i cant read all of but starts 101 i believe,
- (#1374) yedan, 19 May 05 10:33

ok update in the problem, i have no tried gravity feeding the carb with no success, and have double checked the pump is indeed pumping, which it is. Can anyone tell if the varb book mentioned actually covers my my carb or will i ahve to get a weber book, or would anyone have the book and could post the heights for the float here for me. ?

- (#1374) yedan, 19 May 05 14:20

Yedan...the Haynes Carburettor manual does cover it.

Float level is 7mm + -0.25mm so thats a tight tolerance.

These carbs were also fitted to Land rovers,
90 - 83-86, 110 - 83-86, 90+110 85-90.
Also fitted to Citroen CX2400 76-80, Fiat 126 82-83, Fiat unos, Regatas, Stradas, Lancia Y10 turbos...all 1980s.
The float level is the same for all vehicles, but the jets and needle valve size vary slightly from vehicle to vehicle.
A 'quick' look at the manual and I can't tell whether the needle valve bush is press fit or threaded into the body....but I can say that on mine there was a ring (press fit bush) which was not flush with the inner body cast that had dropped 1-2mm....thereby not allowing the fuel level to reach the secondary hole. My symptoms were as yours.
I would recommend the book as its easily available from Halfords and the like. Its helped me out on more than one occasion and also covers general carb theory.
Good luck

- (#1374) chris turner, 19 May 05 16:30

As an aside, if you can get the tel number of Weber UK (ask local carb specialist) I have found them to be very helpful...even to the point of sending me a photocopy of their manual for another carb...it was all in Italian (which I can't read)...but the gesture was there......and the manual had piccies!

- (#1374) chris turner, 19 May 05 16:43

Sorry Yedan...I try to help and confound matters.
I am incorrect....forget the French and Italian vehicles...though the float hieght seems consistent.
You have a suffix of 7, which is not listed as such..
Nearest is 32/34 DTML with suffixes 1, 1/101, 6/101 as fitted to the Landrovers in the 80s.
I would also check the choke butterfly with the engine hot..make sure its fully open just incase its choking itself to death.........
The accelarator pump diaphram on the side should be removable for inspection by 4 screws. By this is the idle cut off valve which may be worth removing to check its operating fully. The mixture screw is below this.
Check your vac tubes too.
If you can see down the barrel, the secondary progression outlet is just above the butterfly. This is the outlet that injects fuel when you put it under load.
May be worth checking yellow pages for carburettor specialists (a dying breed?)....sometimes their work is cheaper than you think and saves a lot of time and hassle....
Sorry for any confusion.......
- (#1374) chris turner, 19 May 05 17:58

god, when will i go away!!...as you have had the carb off, gaskets spring to mind too..........

- (#1374) chris turner, 19 May 05 18:00

i have removed and changed all the diaphrams and gaskets i can find, i have replaced the inlet filter that sits just behind the inlet pipe, i have check athe fuel cut of and all seems to be working, i have had the electric switch things of the sides and they seem to operate as expected (at ignition at least). what else ? oh yeah the butterfly i have check the choke butterfly is fully open, and the throttle butterfly opens and closes as expected when the throttle pedal is depressed, i ahve tried a colour tune on her and she burns a very nice bunsen blue, which to be honest im not sure if unleaded fuel should or not but i cant find anything to say otherwise. compression has been test and everything is within 25psi of each other at around 180, all vacum hoses have been changed, and the fuel pump is pumping, the only things i can see that i havent changed are the vacum switch on the side of the carb (i believe this is something to do with the second choke, and the the vacum switch on the distrubter advance and retard, oh and the needle valvue on mine (if its what your talking about ) is a screw in valve threaded intot he body, i know cos i have change it :), thanks for every ones help on this and i'm still open to suggestions, will any dmtl 7 carb fit or do they vary vehicle to vehicle?

- (#1374) yedan, 20 May 05 04:50

They vary. DMTL is the range, 32/34 are the choke sizes. But it's the big long numer that would tell Mr Weber what size jets, venturis, atomisers etc go into it, plus what settings to use for accel pump plunger stroke etc...

Are you certain all the replaced parts are identical to those taken off?


- (#1374) David Miller, 20 May 05 09:59

If the floats are at the right height and all jets clear and diaphram good..ie: carb fine......wonder about inlet manifold leak??

- (#1374) chris turner, 20 May 05 12:02