HELP - Fuel Problem !!
Discussion
Chaps,
Can't believe it.....after fault free ownership for 3 years I went to fire up my car on Friday morning ready for a prospective buyer to view it on Friday afternoon and the revs shot around to about 7-8k revs. I shut it off immediately and tried again, same problem. Spoke to Radical and they said it is likely to be the throttle pressure sensor so they sent me a new one,,,,,,hasn't made a difference.
I thought it could be the regulator but they said if that had stuck open the TPS would still not allow too much fuel in without an open throttle. The butterflies are in idle position so the throttle is not stuck open. I am amazed it allows enough air in to let it rev so high. So it seems that however you look at it, too much fuel is getting in. Could it be an ECU problem or could it be the regulator - I am very tempted to try a new regulator ? Any ideas ?
Cheers
Ali
Can't believe it.....after fault free ownership for 3 years I went to fire up my car on Friday morning ready for a prospective buyer to view it on Friday afternoon and the revs shot around to about 7-8k revs. I shut it off immediately and tried again, same problem. Spoke to Radical and they said it is likely to be the throttle pressure sensor so they sent me a new one,,,,,,hasn't made a difference.
I thought it could be the regulator but they said if that had stuck open the TPS would still not allow too much fuel in without an open throttle. The butterflies are in idle position so the throttle is not stuck open. I am amazed it allows enough air in to let it rev so high. So it seems that however you look at it, too much fuel is getting in. Could it be an ECU problem or could it be the regulator - I am very tempted to try a new regulator ? Any ideas ?
Cheers
Ali
Are you completely throttle pedal off when doing this? Without you touching the throttle pedal at all, it just catches and stone cold, flies straight up to 7/8K? 
If so, certainly sounds like the TPS. Very much doubt it's the Regulator; if that was playing up, I'd have thought no start rather than instantly revving it's whatnots off.
Don't take this the wrong way, but are you 100% sure the butterflies are shut i.e. the throttle is 'closed'? I mean you've had the air box off and confirmed same rather than just 'believing' the linkage? You've checked the throttle cable from pedal to linkage? Likewise the linkage itself?
Reason for asking is that I once had an interesting experience on the road (not in a Rad) when something detached itself from the linkage and stopped it returning to closed i.e. foot off the accelerator, pedal came back up as usual, but engine still under full throttle (fast approaching a roundabout.) No alternative but to slip it in neutral and simultaneously turn off the ignition. All ended well except for blowing apart all four boxes of a V engine twin exhaust pipe system.
Have you watched/can you watch what happens to the butterflies when you start up? They certainly can't be closed when the engine doing those sort of revs.
If so, certainly sounds like the TPS. Very much doubt it's the Regulator; if that was playing up, I'd have thought no start rather than instantly revving it's whatnots off.
Don't take this the wrong way, but are you 100% sure the butterflies are shut i.e. the throttle is 'closed'? I mean you've had the air box off and confirmed same rather than just 'believing' the linkage? You've checked the throttle cable from pedal to linkage? Likewise the linkage itself?
Reason for asking is that I once had an interesting experience on the road (not in a Rad) when something detached itself from the linkage and stopped it returning to closed i.e. foot off the accelerator, pedal came back up as usual, but engine still under full throttle (fast approaching a roundabout.) No alternative but to slip it in neutral and simultaneously turn off the ignition. All ended well except for blowing apart all four boxes of a V engine twin exhaust pipe system.
Have you watched/can you watch what happens to the butterflies when you start up? They certainly can't be closed when the engine doing those sort of revs.
thanks guys. The first thing I did was take the airbox off and check the throttle cable etc. The butterflies are at idle position, i.e almost shut. I too cannot believe enough air is getting in too allow it to rev that high but if you but if you put your hand over the throttle bodies it sucks like hell, even with about 3mm of opening on the butterflies......
Any other ideas, i jus don't understand it, can't be the TPS as I tried a new one ?
Any other ideas, i jus don't understand it, can't be the TPS as I tried a new one ?
I can't see where else can get in apart from the butterflies, nowhere else it can come from. Will talk to Radical again on Monday but I guess if there is no way it's the regulator then maybe it's an ECU fault. If I sened the ECU to Radical, can they check it or does it have to be on the car ?
How about taking out the plugs, disconnecting the LTs, getting a mate to turn it over and you watching what happens to the butterflies?
Be interested to hear what Mr T thinks of this i.e. the problem / my thoughts above for investigating further etc.
I would have thought RPE/whoever made yours can check out the ECU off the car.
PS Probably a seriously daft thought (as it's a long time since I fiddled with one) but the vacuum hose to the regulator is nice and sound, not split or blocked?
Be interested to hear what Mr T thinks of this i.e. the problem / my thoughts above for investigating further etc.
I would have thought RPE/whoever made yours can check out the ECU off the car.
PS Probably a seriously daft thought (as it's a long time since I fiddled with one) but the vacuum hose to the regulator is nice and sound, not split or blocked?
Edited by splitpin on Saturday 5th March 20:21
It clearly sounds like a "stuck throttle" on no load even a crack open would cause the high revs.
In a previous car I got a very small stone under the pedal and it caused the engine to rev away, it happened whilst driving and felt like the throttle was stuck wide open. Whilst trying to stop for a hairpin! In reality the amount of opening was minute.
My guess would be the cable or pedal assy followed by the linkage.
In a previous car I got a very small stone under the pedal and it caused the engine to rev away, it happened whilst driving and felt like the throttle was stuck wide open. Whilst trying to stop for a hairpin! In reality the amount of opening was minute.
My guess would be the cable or pedal assy followed by the linkage.
Edited by SportsLibre on Saturday 5th March 21:03
You've got to be right Darcy.
'Foreign body' somewhere in the linkage (like my brown trousers experience) or broken/knackered throttle return spring?
Or as Angus has just said, something at the pedal end whereby the cable appears to have fully returned but hasn't.
Like I said earlier, the whole throttle assembly from one end to the other needs fully checking for proper full functioning.
'Foreign body' somewhere in the linkage (like my brown trousers experience) or broken/knackered throttle return spring?
Or as Angus has just said, something at the pedal end whereby the cable appears to have fully returned but hasn't.
Like I said earlier, the whole throttle assembly from one end to the other needs fully checking for proper full functioning.
Edited by splitpin on Saturday 5th March 20:40
Guys, really appreciate everyone's input. Just to clarify, the throttle pedal, cable, butterfly's are all in a normal position so this is not the issue, the butterfly's are alomost shut (i.e. at idle position). Splitpin: you mention the vaccum hose connected to the regulator, the only thing I have going into the regulator in the side-pod is the fuel line which connects to the right hand side of the fuel rail. I see no vacuum hose ?? There is an opening at the front of thge regulator with no hose coming from it, should there be something connecting to that ? I haven't remove anything there so can't see what could have changed ?
Guys, really appreciate everyone's input. Just to clarify, the throttle pedal, cable, butterfly's are all in a normal position so this is not the issue, the butterfly's are alomost shut (i.e. at idle position). Splitpin: you mention the vaccum hose connected to the regulator, the only thing I have going into the regulator in the side-pod is the fuel line which connects to the right hand side of the fuel rail. I see no vacuum hose ?? There is an opening at the front of thge regulator with no hose coming from it, should there be something connecting to that ? I haven't remove anything there so can't see what could have changed ?
I'm not familiar with the regulator in a pre RS SR3, but presumably it's this in your sidepod? >
http://secure2.cyberware.co.uk/~rad-shop/acatalog/...
Unless Radical do things differently, I'd expect to see the nipple on that receiving a vacuum hose from the rail; a fuel pressure regulator uses a diaphragm and spring combination with a vacuum source on the top side of the diaphragm to counteract the spring pressure when high demand dictates that higher fuel pressure is required; under heavy acceleration, the injectors are obviously open longer and this increased duration lowers the fuel pressure; the vacuum therefore drops off and the fuel pressure regulator reacts to this message by momentarily closing the fuel return line to give the required split second boost in fuel pressure.
All that said, I still find it hard to believe the regulator is the problem; it's a very simple device and if it was playing up, I'd expect 'can't start' or 'rough running' rather than 'screaming it's whatnots off'
http://secure2.cyberware.co.uk/~rad-shop/acatalog/...
Unless Radical do things differently, I'd expect to see the nipple on that receiving a vacuum hose from the rail; a fuel pressure regulator uses a diaphragm and spring combination with a vacuum source on the top side of the diaphragm to counteract the spring pressure when high demand dictates that higher fuel pressure is required; under heavy acceleration, the injectors are obviously open longer and this increased duration lowers the fuel pressure; the vacuum therefore drops off and the fuel pressure regulator reacts to this message by momentarily closing the fuel return line to give the required split second boost in fuel pressure.
All that said, I still find it hard to believe the regulator is the problem; it's a very simple device and if it was playing up, I'd expect 'can't start' or 'rough running' rather than 'screaming it's whatnots off'
splitpin said:
I'm not familiar with the regulator in a pre RS SR3, but presumably it's this in your sidepod? >
http://secure2.cyberware.co.uk/~rad-shop/acatalog/...
Unless Radical do things differently, I'd expect to see the nipple on that receiving a vacuum hose from the rail; a fuel pressure regulator uses a diaphragm and spring combination with a vacuum source on the top side of the diaphragm to counteract the spring pressure when high demand dictates that higher fuel pressure is required; under heavy acceleration, the injectors are obviously open longer and this increased duration lowers the fuel pressure; the vacuum therefore drops off and the fuel pressure regulator reacts to this message by momentarily closing the fuel return line to give the required split second boost in fuel pressure.
All that said, I still find it hard to believe the regulator is the problem; it's a very simple device and if it was playing up, I'd expect 'can't start' or 'rough running' rather than 'screaming it's whatnots off'
My rad has the same regulator as the above link and there is no vacum hose on it. http://secure2.cyberware.co.uk/~rad-shop/acatalog/...
Unless Radical do things differently, I'd expect to see the nipple on that receiving a vacuum hose from the rail; a fuel pressure regulator uses a diaphragm and spring combination with a vacuum source on the top side of the diaphragm to counteract the spring pressure when high demand dictates that higher fuel pressure is required; under heavy acceleration, the injectors are obviously open longer and this increased duration lowers the fuel pressure; the vacuum therefore drops off and the fuel pressure regulator reacts to this message by momentarily closing the fuel return line to give the required split second boost in fuel pressure.
All that said, I still find it hard to believe the regulator is the problem; it's a very simple device and if it was playing up, I'd expect 'can't start' or 'rough running' rather than 'screaming it's whatnots off'
From reading the thread I would be extremely surprised if this is a regulator issue, sounds much more likely that the throttles have jammed ever so slightly (don't need much for it to rev high on idle). Disconnect the throttle cable and then ensure you have free movement in your throttles/butterflies, when idling these should look completely closed. Even better beg, steal or borrow a throttle vacum gauge, depending on exact engine spec should read some where between 8.0 - 9.5 KG/PH.
Alistair,
You can waste your money buying a new regulator if you wish, the spare may come in useful some time. However like most others on here I am convinced that it is far more likely to be a possibly tiny amount of mechanical opening somewhere in the throttle system.
Apart from the incident in my single seater above I have also had the same symptoms on a road car, although it had a simple carb and no electronics so it was obvious what the cause would be mechanical.
The simplest solution is usualy the correct one.
Another check, withpout disconnecting anything would be to put in gear an try to drive off (without touching the pedal). I expect it to effectively stall, as the thottle is only open a crack and will only rev on no load.
Angus
You can waste your money buying a new regulator if you wish, the spare may come in useful some time. However like most others on here I am convinced that it is far more likely to be a possibly tiny amount of mechanical opening somewhere in the throttle system.
Apart from the incident in my single seater above I have also had the same symptoms on a road car, although it had a simple carb and no electronics so it was obvious what the cause would be mechanical.
The simplest solution is usualy the correct one.
Another check, withpout disconnecting anything would be to put in gear an try to drive off (without touching the pedal). I expect it to effectively stall, as the thottle is only open a crack and will only rev on no load.
Angus
Edited by SportsLibre on Sunday 6th March 18:11
Tonto, do you really mean the butterflys should be 100% shut at idle ?? There is about a 3mm gap and yesterday I did slacken the throttle slightly so they closed further to leave about a 1-2mm gap and the revs did drop by about 2k revs. I have not slackened it off to the point that they are completely shut because I presumed there must be some kind of opening otherwise how does it idle ? So they should look completely shut then ?
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