MG Turbo running problem

[steve smith]

right after refitting the whole thing back together i am still having the cutting out fault the engine dies but if u dip the clutch she runs ok seems to me electrics any ideas people as to what it could be ?

[G Force]

Hi Steve sorry to hear your probs continue. You say you think the problem is electrical, and not knowing exactly how the engine behaves when it cuts out its difficult to think what electrical fault would cause this. If the engine revs accelerate up to a given speed then lose all power but keeps running if you immediately dip the clutch sounds more like fuel related.

I would try get hold of a fuel pressure gauge and a boost gauge and see what exactly was happening with these pressures as a diagnosis aid.

If you cant do this it might help you to find out if the engine still cuts out when running atmospherically. I know it is not a particularly safe thing to do running an engine with unfiltered air, but if you disconnect the rubber hose from the large feed hose from intercooler to plenum chamber the engine will run without the turbo charger. If the engine runs atmospherically all be it poorly but does not cut out then you certainly have a fuel problem. If it still cuts out the problem could be fuel or electrical.


Gary

[Guest]

Hi, Steve this might sound daft, but have a look at the breather pipes as my maestro was doing this, and it turn out to be the pipes block from the oil filler cap to the air filter. Also check the wire that goes to the side of the oil filter,because if this is broke or not on then the engine will cut out when you rev her. hope this helps Nigel

[steve smith]

i go have a look at it later see what is what i try also to get a boost gauge and fuel pressure gauge to see if it helps me .

[steve smith]

right i disconected the hose from the intercooler to the plenum chamber and she seems to run ok coudl the fault be with the plenum chamber ? i take it apart later see if i can clean it up

[G Force]

right I disconnected the hose from the intercooler to the plenum chamber and she seems to run ok could the fault be with the plenum chamber? i take it apart later see if i can clean it up

Hi Steve, I would say what you have is fuelling issue. You have proved that the ignition is capable of working throughout the full rpm range and the carburettor and fuel pump can supply enough fuel under atmospheric conditions.

What the carburettor and fuel system can’t do is supply enough fuel to the engine to cope with the extra air supplied by the turbo charger.

For the engine to work properly under turbo pressure the fuel pressure must always be 4psi above boost pressure, and pressure inside the float chamber must be the same as the pressure in the plenum chamber. The float chamber must be sealed to atmosphere and the drilling from the float chamber clear and not obstructed by the plenum chamber gasket.

The fuel pressure from the pump is regulated by the fuel pressure regulator. The pipe from the plenum chamber to the regulator must be perfectly sealed and clear to ensure the regulator sees boost pressure, and the regulator must function properly to ensure the fuel pressure stays 4psi above boost pressure.

The carburettor has to be perfectly sealed to atmosphere, all gaskets, the dash pot seal, balance pipe, and throttle spindle, must be perfect. The drillings to the underside of the dash pot piston must not be obscured by the plenum chamber gasket and sealed to atmosphere.

The fuel delivery jet must be perfectly clear, it is not uncommon to find slithers of rubber up there. The needle must be the correct one. The float chamber needle and seat must be the correct size, the turbo one is bigger than the normal one. The pipe to the wastegate must be a perfect seal as well.

Good luck