sprint woes.

[longboarder]

my good old sprint powered Dutton has recently been playing me up. I know, shocking aint it. Starts and runs fine, never misses a beat. Recently it does not like hot starts, starts OK but only on a couple of cylinders, then three drive it hard and it all comes together again. Weird. I have changed plugs, cleaned carbs out, fuel lines, filters, even the electric fuel pump has been stripped cleaned and tested. Its only when its hot, could the electric ignition being breaking down when hot? then once driven the engine cools off slightly, I did notice it is up around 200f. in the warm weather and climbs a bit more when parked, stopped. The ignition is a cheap Britpart unit and the dizzie cap is an Ambassador right angle cap.

Any help??

[dollyman]

A pal had the same thing on his stag, we eventually found it was running very rich co of 6% It would start though if the throttle was kept flat to the floor untill it had a good cough and cleared it's lungs How do you start yours when hot?

Tony.

[xvivalve]

I had this on my Sprint when a daily driver. I eventually replaced the starter motor to cure it!!! The reconditioner suggested it wasn't reaching cranking speed when hot, although it didn't 'sound' slow...where are you? Is there anyone local who could loan you a known good unit to test?

[longboarder]

it starts easy but judders and shakes. and only fires on two or maybe three cylinders, once i get it moving it slowly recovers back to full health. The wife has noticed it happens on short 15 minute stops, fine when refuelling or longer stops. Running rich? there is a thing, will fiddle. Starter motor recently refurbished I hope its okay. Down in Plymouth, will see if the Triumph lads down here can help out.

[soe8m]

Valveplay?

Jeroen

[Carledo]

This is a problem I associate with fuel vaporisation connected to ethanol added fuel and have had similar symptoms with several customer cars, notably a Rover powered Stag which I took for MOT only a couple of weeks ago on a warm day (not baking hot) but it ran for several minutes during the emission test, then effectively stationary for a few more during the roller brake test after which it was switched off for maybe 7-8 minutes whilst the cert was printed. Was then hard to start, missy and farty when it did fire up and cleared after a mile or two with the (electric) fan on. It's often like this on hot days or in traffic, high underbonnet temps are responsible, i've got into the habit of pulling the bonnet catch when in traffic to help cut the problem down, what it really needs is a couple of rows of louvres in the bonnet to let the hot air out, but the owner is oddly reluctant to do it.

Steve

[cliftyhanger]

I would suggest fuel vaporisation as a strong contender.

An electric fuel pump (decent quality) may help, and I have wondered if a fuel return to the tank may help after the carbs (maybe put a 2mm restrictor so fuel can still bleed back to the tank but will keep the carbs full of fuel)

But ultimately a way of keeping heat off the fuel system is best. I know somebody who has lagged the fuel pipes, but I worry that it will also keep heat in? Heat shields can help, as can improving pipe runs. Maybe bonnet venting?

[GrahamFountain]

I wondered if its using a 6v coil with a ballast resistor, and the link off the starter solenoid fell off. But thinking about it, that wouldn't make a difference once started.
You got access to a Cryptotune or similar system monitor. That'd likely find an electrics problem in a trice, assuming its not fuel.
Graham