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Carb stuck full throttle
Posted: 04 Oct 2019, 21:07
by pan-al
Travelling down the m62 this morning and the accelerator pedal would not return to the idol position pulled into services brakes smoking came to a stop.called AA they managed to get the cable returning to the correct position.but on starting the engine without touching accelerator engine raving it balls off.any ideas what could be wrong.thanks for any advice in advance.
Re: Carb stuck full throttle
Posted: 04 Oct 2019, 21:12
by 937carrera
Return spring broken
Corrosion on the inside of the cable
Bent / twisted mechanical component
Traffic cone stuck in the mechanism (yep,I really have seen that,but not on a T25)
Engine off, move the throttle at the carb end and make sure it returns to the tickover position normally
Re: Carb stuck full throttle
Posted: 04 Oct 2019, 21:53
by Oldiebut goodie
Frayed inner cable used to be the common cause on old bikes. Had to ride home using a piece of string once! Luckily not far.
Re: Carb stuck full throttle
Posted: 12 Oct 2019, 11:25
by pan-al
Disconnected throttle cable still revving full revs.
Re: Carb stuck full throttle
Posted: 12 Oct 2019, 12:18
by Mr Bean
Might be me but I can't see what engine and fueling system you have from your profile or signature. My WBX revs it's balls off if one of the pipes connected with the induction plumbing leaks or pops off. No where near full throttle but still disconcerting.
So does it fly to that full bore situation from a foot off switch on and start or does it seem to get stuck at the full throttle position?
Can you see what's going on in the throttle butterfly? Maybe the connection between the cable and the butterfly is slipping/disconnected.
Could be stacks depending on you setup...
Re: Carb stuck full throttle
Posted: 12 Oct 2019, 17:36
by 937carrera
pan-al wrote:Disconnected throttle cable still revving full revs.
Have you checked for free movement/ free return of the throttle on the carb itself
Can you post a photo?
Re: Carb stuck full throttle
Posted: 14 Oct 2019, 09:54
by Mr Bean
This one has gone all quiet. Wonder if it is fixed?
Re: Carb stuck full throttle
Posted: 14 Oct 2019, 21:31
by jrt
Mr Bean wrote:This one has gone all quiet. Wonder if it is fixed?
The last i heard he was waiting for a carb' refurb kit... come on Allan pull yer finger out and give us an update.
David.
Re: Carb stuck full throttle
Posted: 16 Oct 2019, 20:19
by pan-al
Sorry for the delay took the carb off and took it down to my local garage all he did was blow it out with airline played about with it seemed to think it was ok refitted
no change still full revs as soon as I turn ignition on.any one recommend a refurb 1900 dg pierburg 2e carb.
Re: Carb stuck full throttle
Posted: 16 Oct 2019, 21:24
by 937carrera
Petrol engines are limited by air and fuel.
I am interpreting full revs as being over 4000 rpm, rather than a high fast idle of 1500 rpmish
This can only happen if there is sufficient air and fuel getting into the cylinders. For this reason I don't think it is an air leak on the intake and the engine is giving the high revs based on lean running of the bypass air from the carb.
What happens if you block the intake of the carb with your palm. Does it continue running unchanged or does it slow down.
Re: Carb stuck full throttle
Posted: 16 Oct 2019, 21:27
by jrt
I've heard good revues from everyone that has had there's refurbed by Bromyard. Surely the refurb kit and a methodical strip down and rebuild would help. Maybe it's now't to do with the carb'?
David.
Re: Carb stuck full throttle
Posted: 16 Oct 2019, 21:30
by jrt
937carrera wrote:Petrol engines are limited.
by air and fuel.
I am interpreting full revs as being over 4000 rpm, rather than a high fast idle of 1500 rpmish
This can only happen if there is sufficient air and fuel getting into the cylinders. For this reason I don't think it is an air leak on the intake and the engine is giving the high revs based on lean running of the bypass air from the carb.
What happens if you block the intake of the carb with your palm. Does it continue running unchanged or does it slow down.
It would be helpful if you could confirm the engine / carb you are using
I think he has the same as me, 1. 9 DG Pierburg
David.
Re: Carb stuck full throttle
Posted: 16 Oct 2019, 21:34
by 937carrera
Yeah, I spotted that on a re-read and removed the last para from my reply. Not quick enough for you though
Key here is that the original problem was that the accelerator pedal would not return. With the cable removed there's no reason why the engine would run at full throttle,unless it's something like the return spring was pulling the throttle open instead of closed.
Re: Carb stuck full throttle
Posted: 16 Oct 2019, 22:10
by pan-al
I'll try and post pictures if I can figure out how to.
Re: Carb stuck full throttle
Posted: 17 Oct 2019, 10:11
by jrt
Messaged you Allan.
David.