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Help 2.5 Petrol

DOMFISH

DOMFISH

Overdrive!
Ive just about had enough now after changing my 2.5 to run on the proper carb its just not having any of it. when its cold it runs sweet but as soon as it gets warm it farts and bangs like chitty chitty bang bang. i have put a brand new carb on it to solve that problem but no good still the same and when on tick over it seems to rev then drop if you know what i mean thing (hunting is the word but dont quote me) so if anyone out there has any ideas or have had and solved this i would be greatfull for the info.. plus i need a diagram for sed carb as it wasnt in the box
cheers in advance!!! dom
 
When cold, do you mean when the choke is out?

Sounds very much like you have a vacuum leak on the inlet manifold. Not got a split servo pipe have you?

Chris
 
I'm guessing you have the weber 32/34 dmtl carb. If so these files will assist.
 

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Think that is the one but main things i need to know is which pipe goes where and what are the wired conectors for as ive put the engine into my series. know the fuel one and thats about it to be honest...photo with pipes conected would be great..
 
have no leak in manifold and the vacum is working ok as i took it of and the revs dropped. sucked the pipe and they increased.. could it be down to ignition problem'???
 
should the idle shut of valve have a live running to it when ignition is on?? as the series doesnt have the nes wiring to carb???
 
OK,

The two solenoids are linked (in series) to the ignition switched live side of the coil (i.e. not the side with the wire that goes to the dizzy.

On the front (i.e facing it from the radiator) of the carb starting from the topmost connection

a) The topmost (to the lhs of the solenoid) is to the petrol tank (or to a bulkhead mounted swirl pot on mine which means the fuel recirculates and is kept cool).

c) The middle connector goes to an 8" pipe that vents to the atmosphere. the end of the pipe has a small restrictor in it. The topmost solenoid ensures that this vent pipe is only opens the float chamber when the ignition is off .

c) The bottom connector is tee-ed into the breather between the plastic carb inlet cover and the filler cap on the rocker.

On the RHS of the carb next to the solenoid that cuts off the idle circuit is a small connector that goes the vacuum capsule on the dizzy.

On the LHS of the carb is a small pipe that goes to the vacuum pulldown connected to the choke plate (so that at high manifold vacuum with full choke the mixture doesn't go to rich .. I think).
 
so the middle one doesnt go back to the tank ie return for the fuel????
also any idea what the timming is for the 2.5??
 
DOMFISH said:
so the middle one doesnt go back to the tank ie return for the fuel????
also any idea what the timming is for the 2.5??
Click to expand...

Not on mine it doesn't ... there's a swirlpot on the bulkhead that has the feed and return to the tank with a single pipe going to the carb.

According to the manual the timing is:

16deg BTDC at 2000rpm with vacuum pipe disconnected when using 90 octane 2 star fuel, so for unleaded I've been told that you can usually add another 3-5 degrees to the advance. The dwell is 49-59deg.

In an emergency it says it can be set statically at TDC.

On mine my strobe says that I'm about 22BTDC at 200rpm, but there all a bit different and I time it by ear so that it's just backed off from pinking when hot in 4th climbing a hill. I use the strobe just to see where it ended up at.
 
Hi, I had the same problems as you are having, you need to fit a vapour seperator in the fuel line or the pressure from the pump floods the carb and also causes the carb to syphon fuel when the engine isn't running. The vapour seperator goes between fuel pump and carb and a return to the tank which is the important one. I used a vapour seperator from a Skoda as it was only a fiver compared to £66 for the Land Rover one. Hope this helps. Cheers Jon.
 
The only problems I have ever experienced with this carb are that in the four years I have owned the vehicle the jets have become blocked about four times. Each time just needed each jet unscrewed in turn and blown out, an easy job, just don't get them muddled up .. there are four.

The other major problem was a total inability to do more than 50mph. Once I reached that after about 4 seconds the engine would misfire and die unless I backed off the throttle. Turned out to be a blocked fuel filter behind attached to the driver's side outrigger, which meant that the float chamber would empty on full throttle. The retaining bolt was completely rounded so the previous probably hadn't changed it for some time. Of course I only discovered this after reconditioning the carb and replacing all the ignition components.
 
G7TZZ said:
Hi, I had the same problems as you are having, you need to fit a vapour seperator in the fuel line or the pressure from the pump floods the carb and also causes the carb to syphon fuel when the engine isn't running. The vapour seperator goes between fuel pump and carb and a return to the tank which is the important one. I used a vapour seperator from a Skoda as it was only a fiver compared to £66 for the Land Rover one. Hope this helps. Cheers Jon.
Click to expand...

Apologies,

Just seen this post, where i called it a swirl pot I should have said vapour separator (NRC9772). looks like this ...


Looks like these guys have one for a far more reasonable £11

http://www.hobsonindustries.demon.co.uk/VR.html
 

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Think i could do with some photos if poss as im getting confused believe me its not hard to confuse me.. think i have a vaporiser in the garage..
 
Hi, on my vapour seperator the fuel comes in at the bottom from the pump the middle connection goes to the carb and the top connection goes back to the tank. Hope this helps. Jon.
 
My separator is connected is as shown in the attached diagram. It shows the pipes for a 110, but both top connections go to the tank and the bottom is the single connection to the carb.
 

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I think i have a blockage as it seems to run ok on gas, but on petrol it ticks over but as soon as you put the throttle down it seems to strve the carb and it dies.. you say its easy enough to clean the jets can situ??not t good it carbs to be honest so wouldnt know where to start!!!
 
To clean the jets

1) Undo the four nuts holding down the plastic cover on top of carb.

2) Look down on top of carb and see that between the the chokes / venturi openings there is a line of four brass looking bolt heads, these are the jets.

3) They are all different (jet sizes that is, if you look at the endo of each with a magnifying glass you will see numbers like F30 and 112, refer to the manula for more details) , so only remove one at a time. Use a screwdriver to unscrew the first. They are very difficult to lift out because there is no space for fingers plus they're not magnetic. I use long needle nose pliers or tweezers. The one at the back is the hardest because without removing the bonnet you cannot easily look directly down on it. I use tweezers and a mirror.

4) When you have a jet out the blockage may be obvious (it does'nt take much to block the small hole in the end). The jets also pull to pieces (2 - 3 bits). Never use anything metal to clean, I keep a plastic broom bristle handy.

5) I also have a good blow down the hole the jet unscrewed from, easier with an airline, but beware one of them goes directly to the float chamber. It doesn't hurt to use it bit of carb cleaner, but usually the obstrunction is in one of the jet holes.

5) Replace the jet an move on to the next.


An alternative roadside option to all the above is just to remove the plastic cover and then race the engine using the accelaratort linkage. When the engine is gulping tons of air place your hand over both openings (chokes / venturis). Its stings a little .. lift you hand off just before the engin dies and repeat. This technique can often suck the blockage out of the way.

I used to get these sort of blockages but then realised it wasn't the petrol it was tiny flakes of crap from the old hose leading from the air filter, that were coming off and blocking the idle jet, this meant the car would die on idle without the choke on full, but when you put your foot down the other three jets came into play and everything was fine).

Sound like one of you main jets is blocked.
 
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