16 replies to this topic

[Traut]

Hi.

I have a swifttune 1275* engine in my shiny new* mini, done about 2000 miles. I just got the car and done maybe 300 miles with no issues.  After sitting in a bit of traffic on the Mway I found I could not accelerate without misfiring, it got worse. Any attempt to give it throttle and it way seriously frogging like a first time driver in the wrong gear. Idle was fine. After stalling out, it would not restart. Experienced RAC checkd the sparks, fuel supply, tapped the float chambers (dual SUHS4), checked the dizzy and rotor and plugs. 2 wet plugs, 2 dry 1&3 2&4 go figure. Engine will not start.

Later inspection revealed one if the float chambers has a lot of play and needs tightening back on to the body of the carb - but would that be an issue ?

 

I've got new plugs, leads,coil and some Carb gaskets on order, but if anyone has any ideas on this, please chirp in.

I should also mention a minor coolant leak somewhere around the radiator which I could not see the source, so put some rad weld type in. New radiator is on order too.

Thanks.

Edited by Traut, 20 February 2024 - 08:27 AM.

[bpirie1000]

Are there any air leaks in the manifold .

Seams like your issue is fuel related as 2 plugs appear not to be getting fuel. Is there a filter on the tank to carbs? Are the jets both clear and needles match?

Would also get the carbs balance checked.


Your order for new plugs, leads,coil may be for nothing but always good to have spares.

The Carb gaskets may be of use. But always best to rule things out methodically not just throw replacement parts at it.

May also suggest getting in touch with some clubs locally to you to see if you can find someone locally who can assist

[Traut]

I don't know if there is a fuel filter, the fuel tank is new however, and I can't see any inline filter before the carbs. The carbs were balanced on a rolling road before I bought the car and I think are also new with the engine as part of the swiftune kit.

[Traut]

Jets or stuck float were my thoughts, but can you check the jets with the carbs in place? I thought maybe not, hence the gaskets on order before I remove the whole assembly.

[timmy850]

If the fuel bowl is empty, take off the dashpot and damper and see if you can pass air or brake clean from the bottom of the fuel bowl, through the hose and into the jet. It should come through without issue 

 

Although if your issue is 1/3 the same and 2/4 the same then I would think it's more likely to be a spark issue on the wet plugs. Remove all the plugs, buy a new set, gap them properly, check the leads for resistance, check the cap and rotor

 

Check the plug leads are on in the right order 

https://www.theminif...ence/?p=1423374

[slidehammer]

Did the engine get hot whilst you were stuck in traffic? Could it be fuel evaporation due high under bonnet heat. Maybe be it is an electrical component breaking down under heat.

If it was either of the above, I would expect the car to run ok once everything had cooled down. Good luck trying to sort it out. 

[Traut]

I wondered about overheating too, but 3 hrs wait for the RAC gave it plenty time to cool down !

 

I should also have mentioned, electronic ignition, not points, but like I said, all plugs had a spark.

 

Thanks for the thoughts everyone. I'll post back anything I fnd out.

[bpirie1000]

If the float body was really loose the jet pipe may have been compromised and kinked/damaged, therefore restricting flow to that carb.

[Traut]

I'll check if it ever stops raining !

Thx

[timmy850]

A carb issue still doesn’t explain to me why 1/3 plugs were wet and 2/4 were dry (or vice versa)

Surely if it was a carb issue or manifold sealing on a twin carb it’d affect 1/2 and 3/4

I’d probably also do a compression check while you had all the plugs out. It’d at least confirm it’s not a compression issue

[coopertaz]

A carb issue still doesn’t explain to me why 1/3 plugs were wet and 2/4 were dry (or vice versa)

Surely if it was a carb issue or manifold sealing on a twin carb it’d affect 1/2 and 3/4

I’d probably also do a compression check while you had all the plugs out. It’d at least confirm it’s not a compression issue

agree if 2 plugs were wet then that indicates they were not burning the fuel, do not rule out an ignition issue

[Traut]

Just to say, I got it going again, but the jury is out on the cause.

 

I checked & moved the carb oil dampers, piston movement, jet movement ( choke linkage is a bit sticky still). Tightened the float chamber. Checked ignition cables, rotor dizzy cap. Replaced the coil with a new one. Took quite a long while to start, but eventually did. All seems fine for the moment.

 

Thx for all your comments.

Edited by Traut, 01 March 2024 - 12:54 PM.

[Spider]

I'd say here, the fuel pump is on the way out.

[cal844]

Sounds fuel related

[bpirie1000]

How old was the fuel?