1500 FWD More Rough Running Problems

[rhisiart]

I'd be grateful for more advice from experienced owners regarding another annoying problem I'm having with my '72 1500.
I won't bore you with the recent problem I had with rough running, which was (I think) sorted by fitting a new ignition coil.
The car performs perfectly very smoothly and quietly around town and on short-ish trips in the surrounding area - surprisingly economical as well - regularly returns around 40mpg.

Basically the problem is this: I had the occasion to travel in the car from Cardiff up to North Wales - a trip of some 200 miles.
For the first 30 miles or so, the car went really well, but after some time along flat-ish roads I started to have problems when trying to climb the hills. The car would loose power quite dramatically, like the power was being 'choked' off, somehow. On a hill, the car would sometimes stall just before coming to a stop, but then, sometimes this wouldn't happen. But every hill and mountain road was a problem - the car would loose power and come to a stop. I then noticed that if I took my foot off the accelerator, or changed gear when the problem started to happen, the car would suddenly have a rush of power and would then travel a little further, but if the accelerator was kept firmly down, the car just wouldn't go. Very strange syndrome. Anyone had a problem like this before?

Since that trip, I've used the car locally in typical stop/start driving and the car runs perfectly well. It seems therefore that the problem occurs after a sustained period of driving without any gear changing and the accelerator pedal being held down without being lifted off, that the car has problems, or so it seems. All very odd. The dials gave no indication of overheating by the way, and the petrol in the filters appeared clean.
The car actually took me all the way up North and then back to Cardiff but the hills were definitely a problem!

If anyone has any ideas, I'd be grateful of advice on how to cure this annoying problem.

[Purplebargeken]

Are you getting a good supply of petrol from the pump?

Ken

[rhisiart]

Haven't checked that specifically. A new pump was fitted some three months ago, and the petrol filter always appears full and clean.

[sprint95m]

An ignition timing problem?
Too far retarded?

[Howard81]

Sounds very similar to the problem I had - turned out to be crap in the fuel tank getting sucked into the outlet pipe at high speed. It would cause the front carb to run dry.

[mbellinger]

When the car starts to lose power, have you tried pulling the choke out to see if it picks up again?

Have you fitted the heat shield yet?

[tinweevil]

I'll third the fuel theory. Here's another couple of similar anecdotes.

Sounds almost as wierd as when Mrs Weevils mini would pull just fine except when going round a right hand bend. We could push it as hard as we liked on the flat & straight, up or down hill or round left handers. New fuel pump fixed that. I don't think in this instance I had to change it twice but I have had an awful lot of new parts that were useless over the years. Just because the pump is new-ish don't discount it.

More straightforward was when my sprint wouldn't pull full bore for more that the shortest spurts. The pump and filter were fine. Turned out the flexi fuel pipe to the front carb was breaking down inside & the bits were collecting inside the metal inlet pipe on the carb top. New fuel pipe rubber sections throughout sorted that. Pipes are more likely than pump imo.

Tin

[rhisiart]

Thanks for the suggestions and anecdotes guys. Glad that It's not only my car that behaves strangely then.

Yes, the timing has been retarted - but would that show up as a problem ONLY after sustained driving then? I'm asking because I don't know the answer.

Yes, carb heat shield fitted after previous problem (which turned out to be a faulty ignition coil)
Choke - as a matter of fact, yes I did try and pull out the choke on a particularly steep hill, and if I remember correctly, it did improve matters very briefly, but didn't make THAT much of a diference in the end.

[Jon Tilson]

I would also check that the coil isnt getting hot....which could mean a condensor breaking down.

I had this on my Sprint recently and like you it cut out after about half an hour. I checked fule delivery was good by lifting the float chamber lid
when the prblem occurred.

But it does sound more like fuel starvation under load....so pump, fuel lines and tank vent all need a check.

You can post this in the general dolomite bit as well and would get more viewers.

Jonners

[rhisiart]

The car has been fitted with Lumination Electronic Ignition. But since everyone seems to be suggesting that the fuel lines/pump etc may be at fault, I'll try and see if that is the main source of this strange malaise!

[Howard81]

Do you have a fuel filter fitted? If not, fit it just before the pump.

[rhisiart]

Yes, in fact there are TWO fuel filters fitted.

[rhisiart]

What I should add, for clarity's sake, is that after many stops and starts whilst struggling UP a hill, the car then runs perfectly well DOWN the other side, and then along flat roads - goes like a dream then. It's only when the next hill looms ahead that the funs starts again. Surely - for a non-technical guy like me - if there was a fuel blockage/dirt in the petrol etc, why does it ONLY appear UP hills, rather than down? That's the intriguing thing for me.

[Purplebargeken]

Still say pump, fuel line issues. However, I have the mechanical abilty of a postage stamp. Hope you sort it!

[1300dolly]

I would look the fuel system
start from the tank,check the breather is breathing, remove the gauge have look inside the tank for bit floating around, check along the fuel line there is a rubber hose which goes over the rear beam, and check teh reast of the line make sure all rubber to metal joins have a clip on them, the filter should be before the pump, having on after the pump can cause problem as they are designed to have fuel sucked through them, take the top of the pump and clean out the filter, clean up the carb linkage with WD40 and ensure the dash pot stays topped up with oil.