hi i have been working on a friends car , and for the life off me its got me . car just stopped suddenly so i changed plugs rotor dizzy cap leads hall semsor . and still no joy its sort of firing but blews back through carb or throttle body its also blew the oil cap off . please help as i am at my wits with it and he has forked out new stuff and no joy .. thanks sean

Saw another thread here which said exhaust problems can lead to back pressure and the oil cap blowing off.

if it's blowing back through the intake i would check to make sure you've connected all the HT leads in the right place

re leads checked re checked firing order 1432 is this right .

it should be 1342

had it 1342 still no joy . thinking timing chain snapped or slipped or its the brain ?////

If it has blown the oil cap off the above running problems could eaisily be caused by clogged oil galleries. Check inside the rocker cover for sludge etc. How often has the oil been changed? Sludge was a common problem in the Ford HCS engine when the oil had been neglected. Use an engine flush and change the oil / filter. Check all engine breather pipes for blockages caused by oil sludging and see how it runs. This could also cause the blow back through the carb due to making the engine over fuel.

Steve

yes but i cant even start it .its baffling me as i am a good mechanic . and its getting to me

It really sounds like a major back pressure issue to me.

Otherwise I've got nothing.

I agree that back pressure is to blame.

I would check the exhaust system fully from the manifold back for problems. It may be a piece of the catalyst breaking up and causing a blockage.

.its baffling me as i am a good mechanic

And a good mechanic thinks the firing order of a four cylinder engine could be 1432 :P

Try disconnecting the exhaust and see if it will go.