HPE VX Engine cuts out when braking

[gjanssen]

Hi all,

After 29 years of sleeping in a garage box a the Lancia has been inspected and admitted to public roads again !
The garage has spent many hours to make everything technically ready.
The only problem now is that when I press the brake pedal hard, the engine cuts out.
The brake pedal is also not always equally hard. Sometimes I have to pump a bit to be able to put full pressure on the brakes. And as I said, the engine often stops.

I suspect there is something wrong with a vacuum hose. Is this easy to test?



Kind regards,
Gerrit

[gjanssen]

And a nice picture..... :-)

[JohnFol]

Hi Gerrit, I can see you've not had a reply so just giving this a bump.

I'm far from an expert but I had similar on my Spyder. combination of idle set too low and a manifold leak.

The way I found the manifold leak was to spray something flammable around the inlet gasket with engine running. If engine picks up, the spray has been sucked in where it shouldn't.

[Nigel]

Hi Gerrit,
Assuming it's running and pulling normal power, perhaps the
brake servo is leaking air/vacuum?
I say this because applying the brakes is actioning the servo, before that
there is no fault apparent.
There could well be a leak elsewhere as John has suggested, but that type
of leak would not change when the brakes are used.

I suggest you try blanking off the pipe to the servo, and driving it.
Obviously extreme caution needed as you'll have a very heavy brake pedal,
but if it doesn't stall you'll have an answer.

Go carefully
Nigel

[gjanssen]

Thank you both for your answers!

The problem was a vacuum leak between the master brake cylinder and the servo.

Checking cables: no problem.
While the engine was idling, disconnecting the vacuum hose from the carburetor resulted in the engine stalling immediately.
When the pedal was pressed, a small hissing noice was coming from the servo.
Afther that, i noticed one of the 2 bolts, were the master brake sylinder is connected to the servo was not tighten properly and when my son presses the brake, I noticed the master brake cylinder moves one millimeter forward
Just after tighten it, problem is solved.