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 Posted: Sep 27, 2020 07:34AM
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CA
There are two (at least) causes of sudden cutting out and loss of power: fuel supply and spark supply.

A sudden complete loss of power suggests loss of spark. This could be as simple as a loose or broken wire, which loses contact intermittently and sometimes reconnects when the action of the car jostles it back into contact.

A partial or full loss of power suggests a fuel related problem.

The first thing to check is that there is a consistent supply of fuel to the carb. Is the gas clean and fresh? Is there a filter anywhere in the fuel line? Is it clogged? Is the fuel pump working adequately? A mechanical pump is pretty consistent - if it fails, it stays failed, but an electric pump can lose electric power (the loose wire problem) or may have dirt in it or may be tired and overheats and stalls.

The next thing to check is that the fuel is actually getting into the carb. Dirt in the float inlet valve may hold it open, resulting in flooding, or block the fuel supply. On A HIF type carb, this requires removal of the carb to get to the fuel bowl, which is on its underside. Another (older, not very common) problem was that some of the inlet valve needles did not have enough tolerance in the jet. If this is the case, when the car runs well from cool but fails to start after a run, heat from the manifold warms the carb body, expanding the jet and needle, and the needle begins to stick. If it sticks closed, the engine starves, If it sticks open, the fuel pump will fill the carb to the point fuel comes out the vent/overflow port. (See my other response.) If the car is running, it may drink all the excess fuel  because it will overflow the main jet before it comes out the vent port. If this happens, the engine eventually may flood on partial throttle but may keep running if given enough air by keeping revs high..

If you get to the point of suspecting the fuel inlet valve and jet, you will see that the needle has a "X" cross section - 4 rectangular fins. The solution to the sticking needle is to take a very fine file and rub down the 8 sharp edges of the fins.  It does not require removal of much - just to round the edges off a bit.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Sep 27, 2020 05:58AM
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CA
Quote:
Originally Posted by Durtbag
Have you been running without a vacuum cap on the copper looking nipple above the fuel supply line?
That is NOT a vacuum port. That is the fuel bowl vent/overflow. It should have a 1/4" tube connected leading away from the exhaust and down toward the bottom of the car, so if the fuel bowl overfills, the spill goes away from the engine.

In the pictures, you can see rubber hoses connected to a Y-connector, then up to the vacuum port on the engine. This is the crankcase ventilation system and should be connected as shown.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Sep 27, 2020 01:57AM
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Quote:
Originally Posted by Marc13
Quote:
Originally Posted by Durtbag
Have you been running without a vacuum cap on the copper looking nipple above the fuel supply line?
Yes it must have been running like that - that is exactly how the car was when i picked it up
Sorry, that wasn't very clear. No it has not been running with a vacuum cap. Would that create the sort of problem that I have been experiencing?
I had heard that you can run the car without one?

 Posted: Sep 27, 2020 01:14AM
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Quote:
Originally Posted by Durtbag
Have you been running without a vacuum cap on the copper looking nipple above the fuel supply line?
Yes it must have been running like that - that is exactly how the car was when i picked it up

 Posted: Sep 26, 2020 09:50AM
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Have you been running without a vacuum cap on the copper looking nipple above the fuel supply line?

 Posted: Sep 26, 2020 07:44AM
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Quote:
Originally Posted by Se7en
What type carburetor(s) is fitted and is there a proper heat shield in place between the carb(s) and the exhaust manifold/header?
its a 1 & 3/4 inch HIF44 su carb

I'm not sure about the heat shield - see the images....does this look suitable?

 Posted: Sep 26, 2020 01:28AM
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Fue

 Posted: Sep 25, 2020 03:54PM
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US
What type carburetor(s) is fitted and is there a proper heat shield in place between the carb(s) and the exhaust manifold/header?

SE7EN

 Posted: Sep 25, 2020 06:40AM
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Does it have a fuel injected motor?

 Posted: Sep 25, 2020 04:52AM
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fuel pump then...maybe?

 Posted: Sep 25, 2020 03:40AM
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Start with fuel delivery.

 Posted: Sep 25, 2020 03:03AM
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Hi picked up my 1971 Morris Mini this week and it kept cutting out on the way back. It was ok for the first 50 minutes and the cut out frequently, eventually I called recovery. I thought it may be something to do with something getting to hot, or failing when the engine got hot, as the first 50 mins were trouble free.

However, I w
ent for short drive yesterday. 10 mins to destination...no problem. Parked up for 30 mins, Got back in the car and on the drive back home the car was repeatedly cutting out, right from the off almost. Losing all power instantly. The first time I coasted to a stop, and it started back up straight away on turning the key. Less than a minute later, cut out again....this time I popped it down in to 3rd gear which had the effect of jump starting it, and it fired back up no problem. It did this a couple more time - and I also got it revving again just by dipping the clutch on one occasion. On another occasion it wouldn't start again by going in to third, still no power, I was losing speed now, so popped it in to 2nd a few seconds later and it started up again.

 

Considering yesterdays short journey - I'm now not sure it has anything to do with getting hot. Any ideas what the problem could be?