Carb stuck full throttle

Big lumps of metals and spanners. Including servicing and fluids.

Moderators: User administrators, Moderators

Carb stuck full throttle

Postby pan-al » 04 Oct 2019, 21:07

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.
User avatar
pan-al
 
Posts: 141
Joined: 05 Mar 2011, 17:40
Location: manchester
80-90 Mem No: 12948

Re: Carb stuck full throttle

Postby 937carrera » 04 Oct 2019, 21:12

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
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
User avatar
937carrera
 
Posts: 3265
Joined: 05 Apr 2015, 19:29
Location: N Yorks.
80-90 Mem No: 16333

Re: Carb stuck full throttle

Postby Oldiebut goodie » 04 Oct 2019, 21:53

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.
1.6D 2019 VW T-Cross
200hp T6
1̶Y̶ ̶1̶9̶8̶7̶ ̶H̶i̶-̶t̶o̶p̶ ̶C̶a̶r̶a̶v̶e̶l̶l̶e̶
5̶0̶8̶d̶ ̶M̶e̶r̶c̶
User avatar
Oldiebut goodie
 
Posts: 6383
Joined: 18 Apr 2008, 01:19
Location: Eastern Angle
80-90 Mem No: 11135

Re: Carb stuck full throttle

Postby pan-al » 12 Oct 2019, 11:25

Disconnected throttle cable still revving full revs.
User avatar
pan-al
 
Posts: 141
Joined: 05 Mar 2011, 17:40
Location: manchester
80-90 Mem No: 12948

Re: Carb stuck full throttle

Postby Mr Bean » 12 Oct 2019, 12:18

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...
Well-timed silence hath more eloquence than speech.
Practice makes better
88 High top 2.1 WBX
User avatar
Mr Bean
 
Posts: 2495
Joined: 11 Jun 2008, 06:49
Location: Hertfordshire
80-90 Mem No: 5485

Re: Carb stuck full throttle

Postby 937carrera » 12 Oct 2019, 17:36

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?
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
User avatar
937carrera
 
Posts: 3265
Joined: 05 Apr 2015, 19:29
Location: N Yorks.
80-90 Mem No: 16333

Re: Carb stuck full throttle

Postby Mr Bean » 14 Oct 2019, 09:54

This one has gone all quiet. Wonder if it is fixed?
Well-timed silence hath more eloquence than speech.
Practice makes better
88 High top 2.1 WBX
User avatar
Mr Bean
 
Posts: 2495
Joined: 11 Jun 2008, 06:49
Location: Hertfordshire
80-90 Mem No: 5485

Re: Carb stuck full throttle

Postby jrt » 14 Oct 2019, 21:31

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. :lol:
David.
the future is unwritten
User avatar
jrt
 
Posts: 2606
Joined: 01 Oct 2011, 15:53
Location: East Cheshire
80-90 Mem No: 10288

Re: Carb stuck full throttle

Postby pan-al » 16 Oct 2019, 20:19

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.
User avatar
pan-al
 
Posts: 141
Joined: 05 Mar 2011, 17:40
Location: manchester
80-90 Mem No: 12948

Re: Carb stuck full throttle

Postby 937carrera » 16 Oct 2019, 21:24

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.
Last edited by 937carrera on 16 Oct 2019, 21:29, edited 1 time in total.
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
User avatar
937carrera
 
Posts: 3265
Joined: 05 Apr 2015, 19:29
Location: N Yorks.
80-90 Mem No: 16333

Re: Carb stuck full throttle

Postby jrt » 16 Oct 2019, 21:27

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.
the future is unwritten
User avatar
jrt
 
Posts: 2606
Joined: 01 Oct 2011, 15:53
Location: East Cheshire
80-90 Mem No: 10288

Re: Carb stuck full throttle

Postby jrt » 16 Oct 2019, 21:30

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.
the future is unwritten
User avatar
jrt
 
Posts: 2606
Joined: 01 Oct 2011, 15:53
Location: East Cheshire
80-90 Mem No: 10288

Re: Carb stuck full throttle

Postby 937carrera » 16 Oct 2019, 21:34

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.
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
User avatar
937carrera
 
Posts: 3265
Joined: 05 Apr 2015, 19:29
Location: N Yorks.
80-90 Mem No: 16333

Re: Carb stuck full throttle

Postby pan-al » 16 Oct 2019, 22:10

I'll try and post pictures if I can figure out how to.
User avatar
pan-al
 
Posts: 141
Joined: 05 Mar 2011, 17:40
Location: manchester
80-90 Mem No: 12948

Re: Carb stuck full throttle

Postby jrt » 17 Oct 2019, 10:11

Messaged you Allan.
David.
the future is unwritten
User avatar
jrt
 
Posts: 2606
Joined: 01 Oct 2011, 15:53
Location: East Cheshire
80-90 Mem No: 10288

Next

Return to Mechanical

Who is online

Users browsing this forum: Stesaw and 26 guests