Fulvia running problems

[Davidb]

My 1st series Fulvia 1.3 has a serious running problem the source of which is eluding me.
Symptoms are:
Engine starts easily and runs well for a while - until hot, then begins to misfire and backfire on acceleration under load. Eventually it will peter out, stop and refuse to re-start. After about an hour when cooled down it will start again and the cycle repeats itself.
Fuel supply is OK and I have rebuilt the carbs with new gaskets and accelerator pump diaphrams.
On the ignition side of things I have renewed the points, condensor, distributor cap, rotor arm, coil and plugs.
Valve timing, ignition timing and compression pressure are OK.
The problem still persists.
I would appreciate any ideas, thoughts and suggestions, at the moment the thing has me beat!

[inthedark]

Best to email  "chris" on the members list for that one

[peterbaker]

It could still be fuel pump, I spent hours playing with points and condensor etc and put myself out of a rally because I was convinced the problem was electrical. Turned out the pump would run long enough to fool you into thinking all was okay. I changed the pump and bingo, problem solved.

[rogerelias]

David. Silly though it may sound, but if you still have the old points,try refiiting them, or were they changed because of the problem? When i bought my 1600 hf, 7 or 8 years ago, that had a misfire which was one of the reasons i got it cheap, turned out it was a dodgy set of points, shorting out. There are some cheap electrical components on the market at the moment that are Cr#p. Hope that helps. Let us know how you get on.But the symptoms point to a coil breaking down. Regards Roger.

[jackois]

David.

Worth checking your fuel tank cap. I've seen in the past where a blockage in the breather system leads to a slight vacuum being pulled in the tank starving the engine of fuel. After the car sits for a while air seeps back into the tank and the cycle starts again.

The other thing that comes to mind is the choke. Is it coming off fully when released.

[Jai Sharma]

Another thought - probably not the most likely but an easy one to check - one of the fuses in the centre console is on the ignition circuit - I wonder if that is making a good contact?

Otherwise, agree with Roger that many of the ignition points available now are very poor, though I note you have changed yours and also the coil. Also agree that Chris is the man most likely to know.

[Davidb]

Hello all,
Thank you all very much for your prompt responses.

Jai/Rogerelias: I'm fairly sure that I have a good enough spark even when its in stop mode and I have tried a couple of different sets of points.
 
Jackois: I did think of that and tried running it with the fuel cap off - no difference!

Peterbaker: I have both an electric and the mechanical pump fitted in series and have tried bypassing each one in turn, to no avail. In view of your comments however I will look again.

Jai/inthedark: I will do as you suggest and contact Chris.


Once again thanks and I will post news of progress as soon as there is any.


Best Regards, David Brown

[peterbaker]

As a rule of thumb, if an engine stops suddenly it is electrics, if it stutters, coughs and slowly dies its lack of fuel.
As you obviously understand this, its difficult. Maybe you are dragging rubbish up through the fuel system, (there is a filter hidden under the tank) and this falls away when left standing. The backfire is more in line with a failing coil or condensor or something loose. Sometimes co-incidence plays a part and a bad connection creates the wrong impression but I still stick with a fuel problem. I assume the battery is healthy, it must be to start the car.

[lancialulu]

I would normally say condensor but youve changed it. Unless your plug leads are copper type this could be the problem - as I experienced recently on an MX5. New leads and bingo - new car.

Tim

[peterbaker]

You may get a mis-fire but you would be very unlucky to stop altogether. Plus it doesnt add up if, when the engine cools down, the car starts normally again. Normally a plug lead will be a constant not intermittent. It has to be heat or wear related.

[stuwilson128]

David,

The symproms you are experiencing sound very similar to those that I experienced a couple of years ago.  My Fulvia would run ok and then after the engine became warm, it would stutter and cut out.  After the engine cooled, it would start ok.  After replacing the spark plugs, leads, points, condensor, carb mount, fuel pump and fuel lines, I eventually found a pin sized hole in the breather pipe between the carbs.  After rectifying this, I have had no more problems!

[nistri]

Engine cutting out when hot:

It might help to check the following points.

1. Fuel is indeed reaching the carbs when the engine is spun on the starter motor. Disconnect the fuel line at the rear carb and see good flow of petrol pouring in a glass jar. If not, work out where the problem is going backwards.

2. Cylinder compression is good and equal in all 4 cylinders. A head/head gasket problem can show up when the engine is hot.

3. Good spark is generated by the plug removed from cylinder head and connected to ground.

Good luck
Andrea

[Nick]

Did this ever get sorted?, interested as I think I am suffering something similar.

[Davidb]

Hello Nick/all,

I think I have traced the problem. The coil was wired in reverse polarity i.e. positive to earth. My current diagnosis is that this was causing it to overheat and break down. Hence the reason that it would happen gradually and then be OK again aftrer some cooling down time.
I have yet to do a thorough road test since it is not currently tested or insured but static running seems to indicate problem solved.
Thanks to all who contributed ideas.

David

[Davidb]

A final update.

After road testing the problem does seem to be solved. I would like particularlty to thank Chris Payne for his time and expertise which undoubtably led to the solution.