Still Struggling...

[bloodyank]

Hi!
I'm still having trouble with my Moggie.
Symptoms:
Starts and runs fine for about 1/4 mile, then a loss of power, but it doesn't stall. Still idles fine, just won't respond to accelerator. I can get it to go haltingly after that, enough to limp back home, cutting out and dying all the way, but never losing idle.

I have been told it's an HIF SU carb, and a 1275 engine, possibly out of a Marina. (whatever that is!). Does that look right?

You'll see a bodged heat shield installed under the carb, assuming it's because it's so close the the exhaust manifold, but I have never had this problem until recently.

I did check the damper oil and it seems fine.

[kennatt]

sound like fuel supply problem,You need to check the petrol flow from pump to carb,not sure if the marina engine had a mechanical ,or eletrical pump. where does the pipe from carb to pump go,photo would help before further advice comes along .

[oliver90owner]

From the symptoms you have provided, it might appear that there is only sufficient fuel supply for idling. If that is the case you will need to check the fuel system in a systematic manner to find the restriction and rectify the problem.

Question: if the engine is left idling for several minutes, does it respond to the accelerator - at least for a short period of time? This is in addition to telling us the fuel pump type.

[geoberni]

sound like fuel supply problem,You need to check the petrol flow from pump to carb,not sure if the marina engine had a mechanical ,or eletrical pump. where does the pipe from carb to pump go,photo would help before further advice comes along .

See the top photo.

Clearly shows an SU type pump nestling down under the Wiper Motor.

bloodyyank - Worth taking a minute or two checking the filter in the Pump. if you haven't done already.
I do agree it sound like lack of fuel to me, as the first thing to investigate.

As to a Marina, I'm not surprised you haven't heard of it, it was the replacement for the Minor on the production line but only exported to North America for a couple of years.
https://en.wikipedia.org/wiki/Morris_Marina

[panky]

Looks like an odd vac line arrangement, why is the carb line attached to the inlet manifold instead of the dizzy?

[geoberni]

Looks like an odd vac line arrangement, why is the carb line attached to the inlet manifold instead of the dizzy?

Good point, I hadn't spotted that..... a Vacuum going to .... the same vacuum.

i don't actually see a Vacuum Advance unit on the Dizzy..., but perhaps it's just the angle.

vac line.JPG (64.72 KiB) Viewed 1470 times

[philthehill]

If I remember correctly some early Marinas did not have the vacuum advance but it was soon fitted as not having the vacuum advance was causing the engine to knock and damage the crankshaft/engine.
I also had noticed the vacuum advance arrangement but as is would not effect the current engine fault. The OP has stated that the engine ran well before the current fault so the vacuum advance pipe arrangement can be discounted as the cause of the fault.
If there is no vacuum advance fitted to the distributer a distributer with the vacuum advance should be fitted and the vacuum advance pipe connected to the vacuum advance and carb as normal.

[Monty-4]

Sounds exactly like the symptoms I had when the fuel pump points needed a clean-up. Perhaps worth checking the internal filter for gunge too.

[simmitc]

When the problem starts, remove the cap from the fuel tank and see if it improves - if the air vent is blocked, then a vacuum forms and the pump can't lift the petrol. Replace the cap before driving to avoid spillage, but it will prove the point.

With engine cold, remove fuel supply pipe from carb and place in a container suitable for petrol. Switch on ignition for two minutes, then switch off. Measure how much fuel was pumped and report back. The fuel can be returned to the tank and the pipe refitted to the carb.

[svenedin]

If it's the SU fuel pump I posted this some years ago which may help.

viewtopic.php?f=4&t=57395

Could be carburettor or float/float needle valve as well. Sounds like the carburettor piston is sticking. You say you open the throttle but nothing happens so clearly no extra fuel is getting through and the car stays idling. Either the fuel pump is not delivering the extra fuel or the piston in the carb is not rising to allow the needle to deliver more fuel or the float or float valve needle is sticking so the car goes fine for 1/4 mile but when the fuel in the float chamber is exhausted it starts cutting out. Try eliminating each fault one by one.

[sirrom918]

If you're not familiar with the internals of the SU Fuel Pump - for example the filter, an exploded diagram can be found on Burlen's website including a list of the many new parts available from them. The filter can be found at the base of the unit - hover your curser over the diagram to enlarge.

http://sucarb.co.uk/su-fuel-pumps-spare ... arity.html

[oliver90owner]

‘“Starts and runs fine for about a 1/4 mile”

That statement does not indicate anything wrong with the carburettor internals - with the possible exception of the float needle area, which would amount to a blockage,or partial blockage.

[svenedin]

‘“Starts and runs fine for about a 1/4 mile”

That statement does not indicate anything wrong with the carburettor internals - with the possible exception of the float needle area, which would amount to a blockage,or partial blockage.

But what if things only start to stick when they warm up?

[oliver90owner]

‘“Starts and runs fine for about a 1/4 mile”

That statement does not indicate anything wrong with the carburettor internals - with the possible exception of the float needle area, which would amount to a blockage,or partial blockage.

But what if things only start to stick when they warm up?

After only a quarter mile? I very much doubt the carburettor has warmed at in that distance. What do you think?

[svenedin]

‘“Starts and runs fine for about a 1/4 mile”

That statement does not indicate anything wrong with the carburettor internals - with the possible exception of the float needle area, which would amount to a blockage,or partial blockage.

But what if things only start to stick when they warm up?

After only a quarter mile? I very much doubt the carburettor has warmed at in that distance. What do you think?

I think in a 1/4 mile the car has probably used what's in the float chamber and it's not re-filling properly.

[oliver90owner]

That settles that apparent difference of opinion, then?

So we can discount your suggestion of warmed-up items, in this particular situation.

[myoldjalopy]

I'm not sure you would even get 1/4 of a mile on the contents of the float alone, probably more like a few hundred yards.......
Question - could a 'warmed-up' faulty condensor give the symptoms described by the OP after 1/4 mile?

[liammonty]

I'm not sure you would even get 1/4 of a mile on the contents of the float alone, probably more like a few hundred yards.......
Question - could a 'warmed-up' faulty condensor give the symptoms described by the OP after 1/4 mile?

Totally agree on both counts. I'd be looking into condensor, coil, rotor arm etc. I suspect you'll find it's an electrical problem rather than fuel (this is the case 99% of the time in my experience) and that would explain why it becomes an issue only as the engine begins to warm up.

[simmitc]

This needs to be approached methodically. It could be fuel or electrical - a faulty condenser could produce the same symptoms, as could a coil (less likely). Don't change everything at once, concentrate on one system until proved to be OK. As we've started on the fuel system, try removing the fuel cap and run the flow test as I suggested above. Depending on the results, we might need to look at the pump, the carb and the tank/pipe - there might be debris causing a restriction. OR, if there's no sign of a problem, then change the condenser and report back. One step at a time.

[oliver90owner]

I'm not sure you would even get 1/4 of a mile on the contents of the float alone, probably more like a few hundred yards.......
Question - could a 'warmed-up' faulty condensor give the symptoms described by the OP after 1/4 mile?

I like your witticism. In my book, they are identical, the same, not different, very similar, alike and likely indistinguishable!

I personally define ‘few’ as more than two, but the dictionary does state it must be more than one. I go with the majority who consider it to be ‘three or more’.

That it will still idle does not particularly indicate an ignition problem to me. Maybe some are not thinking very deeply, with the details supplied by the OP?