Stalling after throttle release

[DoubleOSeven]

‘84 Velle has been stalling whilst driving along and at roundabouts. Sudden cutting out and recovering for very brief periods also.

I thought it was my Pierburg 2E3 (on 2.1MV). Wilbur lent me his Pierburg, but same issue. Changed the fuel filter, same issue, coil checked out ok, 1.5 ohms primary, 4.5k ohms secondary.

So, borrowed this £11 fuel pump and boom - problem solved.



So, the question is; I bought the £77 fuel pump in March 2019 from Brickwerks, it should be ok. I trust Brickwerks kit, we all do.

Q? Is it perhaps delivering too much pressure? Are Pierburgs sensitive to that?

Anyway to test it before I bin it?

Hard to imagine it’s already had it.

p.s. Just remembered. Few weeks back I changed my spark plugs; just regular service stuff. They were black, from running too rich, which suggests too much fuel being delivered.

[bigherb]

‘84 Velle has been stalling whilst driving along and at roundabouts. Sudden cutting out and recovering for very brief periods also.

I thought it was my Pierburg 2E3 (on 2.1MV). Wilbur lent me his Pierburg, but same issue. Changed the fuel filter, same issue, coil checked out ok, 1.5 ohms primary, 4.5k ohms secondary.

So, borrowed this £11 fuel pump and boom - problem solved.



So, the question is; I bought the £77 fuel pump in March 2019 from Brickwerks, it should be ok. I trust Brickwerks kit, we all do.

Q? Is it perhaps delivering too much pressure? Are Pierburgs sensitive to that?

Anyway to test it before I bin it?

Hard to imagine it’s already had it.

p.s. Just remembered. Few weeks back I changed my spark plugs; just regular service stuff. They were black, from running too rich, which suggests too much fuel being delivered.

Did you change the pushrod as well?
 

[Aidan]

carbs are not generally sensitive to excess fuel pressure as the reservoir bowl has a float valve in it and there is a bypass back to the tank so fuel is returned when not needed
rich running is likely a set up issue or engine is breathing badly, dirty air filter, too much oil vapour from crank case, poor spark, wrong plugs, timing, etc...., fuel filter blocked ? or maybe you've had water in the fuel which is blocking the carb when it emulsifies (it's like someone came in the fuel) 
changing the carbs and fuel pump what else got changed or cleaned as a by-product of the work
try swapping back the BW pump see if it brings back THE fault

[DoubleOSeven]

Push rod got changed last year, it measures 100mm exactly

[DoubleOSeven]

Engine breathing badly, yes.

Air Filter is checked regularly, it’s always clean as is the housing.
*Too much oil from crank case, yes there is, it always has the oil residue on the pancake and large pipe to air filter.
Correct new spark plugs.
Timing ok.
New fuel filter.

*So too much oil from crank case breather, WoT to do?

[Cobra88]

Aidan

i really don't want to know how you know this !
Euuwww! 

[Aidan]

breather tower

maybe

many old ones just seem to be open vent to crank case, but obviously pressurised crank case could indicate worn rings with blow by which the breather tower won't fix, what are compression readings like ?

[DoubleOSeven]

The engine doesn’t burn oil, I rarely have to top it up. I’ll check the compression figures though, should do this when it’s warm I guess. Have a new tower on order.

[Cobra88]

I would check the fuel return is not partially blocked or kinked

Rick

[DoubleOSeven]

Fuel Return does need a new fuel pipe from tank, will check that too.

[DoubleOSeven]

In other news: My Mk2 Golf has a Pierburg too - a 2E2, but would you believe it the air/fuel mixture screw works in the opposite direction to a 2E3!

[DoubleOSeven]

Solved.

Process of elimination in the end.

Symptoms: Stalling when coming off the throttle.

What I changed;
- Fuel Return line and checked non-return valve (needed doing)
- Oil Separator (possibly this as well, making it run very rich)
- Vacuum lines (not bad)
- Fuel Pump (ok)
- Air/ Fuel mixture (possibly affected by oil separator)
- Idle (ok)
- Carb. Solenoid (clicked and 12v feed ok)

What it was primarily;
- Choke pull down unit



Injuries etc;

x2 Oh! That’s Hot!
x3 Humph’s, third Phillips screw on back of carb. choke!
- Various groans whilst getting on and off the floor during fuel return change.

B-)

[DoubleOSeven]

Not solved. Stalled again whilst on a drive. Partially warmed up. So my next change has to be the 2nd choke pull down unit.

[DoubleOSeven]

^^ I’ve already swapped this once for a 2nd hard part few months back, must have also been past it, so my question is can you bench test these and how? Thanks.

[DoubleOSeven]

Brickwerks always deliver

Right; see if this fixes the problem.