504 cab intermittent missfire

[NBeale]

Can you help with advice regarding a missfire.
My 1974 cab is generally running beautifully, except for an intermittent missfire, which I believe tends to occur after an extended period of driving (perhaps 1/2 hour or more). This will start as a missfire but will actually bring the car to a stand-still as it loses power and eventually dies.

My experience tends to suggest that playing around with the fuel lift pump beneath the fuel tank will usually have her running again without a problem after 10 mins or so.

Or is it perhaps a heat-related problem - but if so what?

I have changed the fuel lift pump and do not believe it is the pump itself. I have even run a separate power cable from the battery to the pump which I can switch over next time it happens, to establish if it is an electrical feed problem.

However, you can tell I am struggling here and would be grateful for any advice.#nosmileys#nosmileys

[504gld]

You don't say which engine you have? or its fuel system?

This could be an electrical fault with the ignition system, try a new coil ?

Mat.

[504V6Ti]

1974 --> 2.0l XN2 engine. All 4cyl 504cc were with KF injection, whether 1.8l (69-70) or 2.0l (71-74 and 78-83).

The only Cab with carb is the V6 of 75->77.

[mikem]

I had similar problems years ago (with a Hillman Superminx, that's given my age away ), and it was the condenser. Try that, they're cheap enough. Good luck, Mike.

[NBeale]

Woops!

Thanks for the responses. Technical details would have helped you, though.

It's the XN2 series 2 litre engine with KF injection. I should also have mentioned that I have been through the replacement of all the electrical components - distributor, rotor and cap, points, leads, coil, condenser, plugs, fuel filter, earth strap etc. back in Aug '03. I've also checked the fuel flow from the tank to the pump.

The condenser suggestion, though, is not a bad idea as it has proved to be the source of problems before and as you say is very cheap and easy, despite it being only 18 month old or so.

Will try that next, but would still be grateful to hear of any other thoughts, in case this doesn't work.

Many thanks once again.