Just On Tickover
Posted 26 July 2024 - 01:24 AM
Mine did exactly the same thing. Replaced with a new square Facet electric fuel pump which helped a little. Changed to Fuelmiser which increased flow by heaps but not pressure (did the flow/timing in a 1 litre container test) and never had a problem again, even at 90mph.
Can you provide the model number of Fuelmiser pump you used? Also, did you need to install a fuel regulator with it? Thanks.
Up Into Fourth
Posted 26 July 2024 - 01:57 AM
Edited by timmy850, 26 July 2024 - 01:58 AM.
Just On Tickover
Posted 26 July 2024 - 02:24 AM
I'll try pulling out the choke to see if it picks up speed next time I take it out on the freeway. At least I no longer freak out when it starts to sputter on me. It's starting to feel rather routine! I don't have another needle, but I can probably get one. I have noticed on the SU needle charts that the EB is used for both 850 and 998 engines. Wondering if my wife had it installed as a sort of govenor to keep me off the freeway!
A single HS2 on a 997 with an EB needle doesn’t sound right. My guess is that it’s running quite lean, as that needle was standard for an 850
Preferably you’d measure the air fuel ratio and select a more appropriate needle. Have you got any other needles you can try? Something like an M or AH2 might get it running a little better in the short term. If you pull out the choke at the time when it’s running poorly, does it get any better?
Twin HS2 carbs or a single HS4 would be better long term to unlock at least the performance it had stock
Mini Mad
Posted 26 July 2024 - 02:27 AM
Fuelmiser FPE135: 23 UK GPH @ 2.9PSI
The Facet: 12.5 UK GPH @ 3PSI
Big difference for same fuel pressure, but don’t ask me why because I don’t know. The Fuelmiser was recommended to me by my mini mechanic guru.
I’d definitely agree with Tim’s carb suggestions too.
Edited by Clip, 26 July 2024 - 02:33 AM.
One Carb Or Two?
Posted 26 July 2024 - 09:42 AM
I'll try pulling out the choke to see if it picks up speed next time I take it out on the freeway. At least I no longer freak out when it starts to sputter on me. It's starting to feel rather routine! I don't have another needle, but I can probably get one. I have noticed on the SU needle charts that the EB is used for both 850 and 998 engines. Wondering if my wife had it installed as a sort of govenor to keep me off the freeway!
A single HS2 on a 997 with an EB needle doesn’t sound right. My guess is that it’s running quite lean, as that needle was standard for an 850
Preferably you’d measure the air fuel ratio and select a more appropriate needle. Have you got any other needles you can try? Something like an M or AH2 might get it running a little better in the short term. If you pull out the choke at the time when it’s running poorly, does it get any better?
Twin HS2 carbs or a single HS4 would be better long term to unlock at least the performance it had stock
If the needle was the primary cause you would feel the misfire as soon as you reached 50 mph. The fact it takes time to develop suggests to me that this is a fuel flow problem before the needle and jet. If the float bowl is already nearly empty, I'm not sure pulling out the choke will make a huge difference, but it's worth a try.
Well I'll be buggered if I can find it
Posted 26 July 2024 - 11:34 AM
Super Mini Mad
Posted 26 July 2024 - 12:09 PM
I don't believe it's the needle either.
One Carb Or Two?
Posted 26 July 2024 - 01:47 PM
Further to the carb spec, the 997 cooper had 2 HS2s with GZ needles. The EB was the weak alternative to the GZ. Whilst I don't think this problem is primarily needlle related, I do think a richer needle would be a good idea for Freeway/high power use anyway.
Just On Tickover
Posted 26 July 2024 - 06:43 PM
I drove it WITHOUT a cap at all and the problem was identical, so unlikely it's a venting problem at the filler hole/cap part of the car.
Check the petrol cap is the vented type. My estate had the same problem
Just On Tickover
Posted 27 July 2024 - 05:32 AM
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Speeding Along Now
Posted 30 July 2024 - 12:57 PM
I recall from another type of vehicle that similar symptoms were caused by carb icing where warm air feed to the carb had been deleted "for power". This was on a cross-flow engine though, where the carb was a fairly long way from the warm exhaust, not sure if this is a thing in the mini world.
If I recall correctly, this presented as a problem on long high speed runs as the conditions in the carb were perfect and the air around the inlet wasn't warming like it was on city streets.
Just a thought!
One Carb Or Two?
Posted 30 July 2024 - 02:05 PM
I recall from another type of vehicle that similar symptoms were caused by carb icing where warm air feed to the carb had been deleted "for power". This was on a cross-flow engine though, where the carb was a fairly long way from the warm exhaust, not sure if this is a thing in the mini world.
If I recall correctly, this presented as a problem on long high speed runs as the conditions in the carb were perfect and the air around the inlet wasn't warming like it was on city streets.
Just a thought!
This did also occur to me. With a relatively small carb for the engine, it is a possibility in the UK; but I'm not sure Los Angeles in the summer is somewhere it would occur. (unless the OP is not where they seem to be.)
Speeding Along Now
Posted 31 July 2024 - 11:58 AM
This did also occur to me. With a relatively small carb for the engine, it is a possibility in the UK; but I'm not sure Los Angeles in the summer is somewhere it would occur. (unless the OP is not where they seem to be.)
Doing some online reading on the topic in a brief moment of peace! Apparently can happen up to 28 degC if the humidity is high and the conditions are right. Lots of info seemingly available for pilots where this can be a real show stopper!
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