Hi all. I've got an intermittent running problem. Extremely rough running then cuts out then all of a sudden will be fine for a couple of minutes then back to the rough running. It's a 1380 on twin hs4s. I've gone through the ignition system and it's fine. A couple of questions, 1. when primed before starting. How much fuel should there be in the float bowls? What should the fuel flow look like if I were to take the feed off into a plastic container?
Thanks in advance
Fuelling Problem
Started by
speedwell1
, May 11 2025 03:05 PM
4 replies to this topic
#2
speedwell1
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- 107 posts
Mini Mad
- Local Club: m4 minis
Posted 11 May 2025 - 03:06 PM
Hi all. I've got an intermittent running problem. Extremely rough running then cuts out then all of a sudden will be fine for a couple of minutes then back to the rough running. It's a 1380 on twin hs4s. I've gone through the ignition system and it's fine. A couple of questions, 1. when primed before starting. How much fuel should there be in the float bowls? What should the fuel flow look like if I were to take the feed off into a plastic container?
Thanks in advance
#3
speedwell1
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- Noobies
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- 107 posts
Mini Mad
- Local Club: m4 minis
#4
Ratters
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- 7 posts
Just On Tickover
- Location: Sutton Coldfield
Posted 11 May 2025 - 03:39 PM
Hi I had pretty much the same symptoms as you have, went through all the ignition system and took off and stripped my carbs, rebuilt all good same problems. Confirmed fuel reaching the carbs from SU elec pump.
I was out of ideas, but by a stroke of good fortune a petrol leak developed from the rubber pipe from the tank to the SU pump. It was badly swollen and blown, but interestingly it had swollen inside too and was restricting fuel from the tank to the pump, just allowing enough to run for a bit at lower speeds and then cutting out. Then after a short while it would start again as the petrol slowly reached the carbs through the swollen rubber pipe.
The rubber problem seems to be caused by incompatible modern fuel with ethanol attacking old pipes.
After repacing the hose the car was ran perfectly
Good luck
Edited by Ratters, 11 May 2025 - 03:41 PM.
#5
speedwell1
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- Noobies
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- 107 posts
Mini Mad
- Local Club: m4 minis
Posted Today, 11:30 AM
So this problem keeps going. I've checked fuel flow and it looks good. I've checked when it's running rough and running ok and it's the same. It ran well for about 10 mins, then started to die and had a bit of backfire through the exhaust. I'm at a loss
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