Mystery engine cut-out..Please help!!

[Lucy]

My friend has a similar early bay to mine - 1970,
Engine mysteriously cuts out after about 5-7 miles, but will often start again later.
Standard 1600 engine- original

These are the things he has renewed or checked, so it is not any of the following:

The coil
leads- rotar arm and distributor cap
fuel lines and fuel filter
carb has been checked over
distributor has elec ignition
new petrol pump about 4 years ago

It has been suggested that it might be a fuel vacuum - has anyone experienced this??????

Thanks in advance everyone!

 

[easy]

Hmmm i would change the fuel pump, its not much and it may be that the diaphram is split.

 

[Lucy]

Cheers for that - that'll be the next step then!

 

[lard]

Does it cut out on idle or cut out whilst the engine is under load?

If on idle then I would check for air leaks in the intake system - the gasket between the carb and the inlet manifold, the rubber boots on the inlet manifold and also if it has a brake servo, the vacuum pipes leading to this,

There are a number of posts on how to do this on the forum - if I recall correctly you need to run the engine up to warm and then, using something like WD40, spray onto the rubber boots/gasket and note if the engine RPM increases as the WD40 is drawn into the engine (via the vacuum leak)

I too went and replaced a lot of components for engine cut out when it came down to a £3 rubber boot (though not detectable via the test method!)

Best of luck looking into it - let us know how you get on!

If by any chance you are near Cambridge - I have a spare fuel pump that you can borrow to test with if that helps, along with a spare 34pict3 carb

 

[noddy]

Check the electrics to the fuel cut off solinoid on the carb, could be just a bad electrical conection

 

[Lucy]

Hi lard- it cuts out when the engine is under load. Cheers for the offer of fuel pump loan - I'll get my mate to become a member of this forum then he can contact you too

noddy - thanks, we'll try that too

 

[71Westy]

Can still be an air leak even when under load. When mine backfired and blew out the plug on the side of the carb, the engine idled ok. but just died when under load. Air was bing sucked into the side of the carb, weakening the mixture....

 

[cyberdyne systems]

I've had a similar problem though I have to be running for over an hour before it develops! I believe its fuel starvation. Have you tried removing the pipe from the bottom of the tank to check the screen? When I checked mine I found that most of it was missing allowing anything in the tank through. Or it might be in tact but clogged up.

I would run it until it cuts out and then check for fuel at the carb, if there is none then you need to trace back to the point you find some again. There is also a screen in most original fuel pumps that might need a clean. Other than that if you have fuel check you have a good 12v thats not intermitant.