Intermittent rough running

[Ulf]

Hi guys, about two months ago a new problem developed. The car runs very rough, almost like a student driver having the first driving lesson in a manual car, it most certainly does not fire on all cylinders, it crackles, vibrates and gives the occasional bang from the exhaust. But the weird thing is that all of a sudden - everything is fine, especially if it has been driven at speed for some time. When it runs great, it's better than ever. That would lead to think that it's related to the cold start valve, but it cannot be, as the rough running returns intermittently - also with a warm engine. Since the problem occurred, I've changed the distributor leads, coil, plugs and have had the valves, timing etc. set at a very renowned engine tuner (famous for building classic racing engines). But all to no avail :-(
So my question is - can this be related to fouling of the fuel system? And if yes, what is the easiest way of troubleshooting this? Where are the fuel filters located?

Thanks in advance

Ulf

[Bonnyboy]

I recommend that you check the forum for instructions and inspect your cold start valve.  My problems were intermittent and it was partly the cold start valve - the other half was the auto-advance/retard on my distributor lost a bolt so wasn't running right.   

But make sure the cold start valve is perfect before you go forward - its an easy job but be careful you are dealing with gas and the possibility of a fire is real.   Have a fire extinguisher handy -  I am sure glad I did.

[Ulf]

Thanks, will do that :-)

[kampala]

I have had this occasional rough running a couple of years ago.   After much fiddling, I found that the small wires going to the coil (the ones under the protective boot, were frayed.  I chased all sorts of issues and mine turned out to be the wire. 

You asked where the fuel filters are located?  - There is one fitted at the bottom of the tank (screen), another screen fitted in the line at the fuel pump  (the pump near the tank) and the MAIN fuel filter is in a canister in the engine compartment just under the fuel injection pump closer to the front of the car.  You can reach it from above or below depending on power steering or not.

Good luck. 

[Ulf]

Thanks Kampala, will look into that as well :-)