DG overfueling ?

[hal2710]

Hi All,

I've put a recon 1.9 DG in Bertie, but he still doesn't run great. After reading and reading the wiki and the forums I think that I have overfueling problems ?

But advice please..... Here is the scene. Engine starts from cold ok. Under light throttle Bertie is fine, drove gentley from Warrington to Crosby (25 miles?), next day went for a blast to the tip. Under full throttle the power goes, engine coughs and backfires and I pull over. Then under light throttle I go home. Next day go for another blast, this time Bertie dies and wont start again. Local garage tow us back. The sprak plugs are clogged up. Cleaned up and Bertie runs again but gentley.

Is this "Classic Pierburg Carb problems" ??

I have sourced a second hand carb but just want to check before I spend any more, the budget is WELL blown and I'm almost at the point of giving up.


Mick

[Ian Hulley]

What colour are the plugs ? Running too rich they should be black ?

[hal2710]

Hi Ian,

I think thats what the garage said, old fouled spark plugs only running on 3, new set in now but still same problem.

Thanks.

Mick

[hal2710]

Hi,

One other thing, when Bertie won't start up again after stopping, when trying to start up I see white smoke, like burning oil ?

HTH, thanks for looking.

Mick

[Ian Hulley]

Sounds like a compression test may be in order ? White 'smoke' is usually steam or coolant, blue is oil ... what are the emissions like ?

Ian

[hal2710]

Hi,

I don't think it's steam cos I just changed the engine because the old one leaked water and put exhaust into coolant. So not steam. This white smoke stays low to the floor and swirls around not up into the air like steam.

It only smokes when flooded and won't start. Bettie has just passed the MOT. Engine emissions very good. Well below fail.

Thanks again.

[Ian Hulley]

Bettie has just passed the MOT. Engine emissions very good. Well below fail.

If it was over-fuelling surely it would have failed the HC part of the emissions test ?

[kevtherev]

IMHO it's not over fueling but under fueling
When cold the choke richens the mixture, and the engine runs ok..
When the choke comes off 6-8 mins it's a bag of poo

say to me that the mixture leans out too much when the choke is off.
backfiring, no power and stalling are classic symptoms.

many causes..
air leaking into the inlet side after the carb, has many contributors.
vac pips
choke pull down
brake servo hose
distributor diaphragm
and so on

Or it could be fuel delivery...
Filter blocked (inc. the carb filter)
fuel pump weak or ineffective (worn pushrod)
Main jet partially blocked

[bigherb]

White smoke oily plugs, have you topped it up with diesel by any chance?

[hal2710]

IMHO it's not over fueling but under fueling
When cold the choke richens the mixture, and the engine runs ok..
When the choke comes off 6-8 mins it's a bag of poo

say to me that the mixture leans out too much when the choke is off.
backfiring, no power and stalling are classic symptoms.

many causes..
air leaking into the inlet side after the carb, has many contributors.
vac pips
choke pull down
brake servo hose
distributor diaphragm
and so on

Or it could be fuel delivery...
Filter blocked (inc. the carb filter)
fuel pump weak or ineffective (worn pushrod)
Main jet partially blocked

Wow kev. Food for thought.

Hi bigherb. No not diesel. Thanks for suggesting though.

Mick.

[kevtherev]

Proper diagnosis is almost impossible remotely
However one should not jump to conclusion on one piece of evidence..plug colour

Plug colour is meaningless if the engine has not been ran at high speed for a few miles.
Main jet comes in at around 1500 rpm and a transfer jet helps this happen.
If crud gets sucked into the jet from the floatbowl, the mixture is affected
To complicate matters the pierburg has a second throttle that opens with vacuum
So the more you stamp on the gas the faster you get on the second throttle, and the secondary jet.

Discovery of the problem should be a process of elimination

Fuel is clearly the problem, so remove any doubts that the carb is getting what it needs, don't assume..find out.
Then we can move on to the carb itself
very litte can go wrong here...unless a human being starts tatting with the settings or filling it with debris from perishing rubber from petrol pipes.

[hal2710]

Ok, I've managed to borrow a carb from a friend. Went for a run in his then took the carb off. Just dropped it off at the garage now. They said to ring in the morning. Fingers crossed we can start figuring this out soon .

Thanks for all your help. I'll keep you all posted

Mick

[hal2710]

Oh well. Swapped the carbs. Bertie is still the same. Ticks over ok. Goes if you use the throttle gently but if you boot it he dies.

Mick.

Ps Going to beer garden to drown me sorrows.

[kevtherev]

I can't believe you fitted a carb without checking the fuel supply
Tell me you did?
...and did you find out whether you have any manifold air leaks?
like the servo hose?

remember don't assume.

[hal2710]

I can't believe you fitted a carb without checking the fuel supply
Tell me you did?
...and did you find out whether you have any manifold air leaks?
like the servo hose?

remember don't assume.

I disconnected the fuel line to the carb after the pump and turned the engine over and over and over nothing came out.

I have taken the pump off and manually pumped it and after 4 or 5 pumps fuel comes out.

I pulled out the push rod and bakelite flange. The flange is cracked at the bottom and about 3/4 of an inch of the side opposite the dizzy is missing.

The push rod "Looks" worn on the bottom.

Seems the pump isn't doing its job properly.


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Thanks Kev.