Starting problem
Discussion
Had the Chim out on Saturday and drove straight to the petrol station, about a mile down the road to fill up, before heading for the countryside. Filled the tank, paid and hopped back in. It took three or four turns of the key, splutterd and died again. This continuded about three or four times, eventually restarting but dieing again half way across the forecourt. Finally it spluttered a little then cleared. 75 miles later, no problems.
Had the car out again yesterday for around 40 miles with no issues at all. First re-starting was after about two miles with no problem. Thereafter a couple more re-starts, again no problem.
I don't believe this is a 'hot start' problem as the engine barely had time to warm through in one mile. I also don't believe it was the fuel as this was at start up, so no time for any duff stuff to run through to the injectors. (Esso super unleaded as there was no Shell V Power garage en-route.) Has anyone had this problem before? Any checks I should make to avoid a recurrence? (It's a 450 if that makes any difference.)
Had the car out again yesterday for around 40 miles with no issues at all. First re-starting was after about two miles with no problem. Thereafter a couple more re-starts, again no problem.
I don't believe this is a 'hot start' problem as the engine barely had time to warm through in one mile. I also don't believe it was the fuel as this was at start up, so no time for any duff stuff to run through to the injectors. (Esso super unleaded as there was no Shell V Power garage en-route.) Has anyone had this problem before? Any checks I should make to avoid a recurrence? (It's a 450 if that makes any difference.)
The classic hot start issue is where the starter doesn't even turn, so if it was cranking then that's not what it was.
Is it possible that you over-filled it? Some people report that this can cause problems - fuel getting into the carbon canister I believe. Perhaps it struggled until you'd purged the fuel from the canister, and now it's okay?
Is it possible that you over-filled it? Some people report that this can cause problems - fuel getting into the carbon canister I believe. Perhaps it struggled until you'd purged the fuel from the canister, and now it's okay?
That sounds feasible David but I have no idea if it was the cause. I wasn't aware of over-filling, using the nozzle cut-off facility when full, wait 5 seconds then pull the trigger once more for final cut-off. Perhaps I shouldn't make the final top-up in future.
Where is the carbon canister and what does this do? Assume it's close to the tank outlet in the boot somewhere?
Where is the carbon canister and what does this do? Assume it's close to the tank outlet in the boot somewhere?
It could be your coil or ignition amp is breaking down when hot but to be honest the symptoms sound more like a fuel related issue to me, either a lack of supply or fuel vaporisation.
It's possible the car started and ran briefly on the small amount of petrol held in the fuel rail, then died when that tiny supply quickly got used up by the engine.
It's also possible for the engine to fire momentarily just on the priming pulse fuel that's injected when you disengage the immobiliser and turn the ignition key to the on position, either way if the main supply is interrupted the engine will be certain to die almost immediately.
The Lucas 14CUX system is fitted with a fuel temperature sensor to stimulate the ECU into it's hot start compensation mode.
Modern fuels vaporise at surprisingly low temperatures (a particular issue under a TVR bonnet) so the ECU will momentarily try to help by increasing the injector duration for a few seconds until the hot fuel in the rail has circulated with cool stuff in the tank.
Once the sensor detects the fuel temperature has returned to normal the ECU will return the fuelling to it's standard map settings, if your fuel temp sensor is on the way out it could promote a hot start fuel starvation type fault.
Other more common sources of fuel starvation are a blocked tank pickup gause, a faulty fuel pump, a partially blocked fuel filter or delivery line, a faulty fuel pump relay, the ECU or immobiliser playing silly buggers (both have a part in energising the fuel pump relay) or a simple blockage in the return line.
The fuel system is a continuous circulating circuit, starting at the pickup in the tank with the excess not used by the engine being returned back to the tank.
Follow the circuit in the same order checking each possible area of restriction to find the issue.
Happy hunting.
NB: If you are only getting the problem when you fill the tank fully you may have a marginal tank venting issue.
When the tank is full there is no air space so a partial venting issue will be exasperated.
If it happens again when you fill the tank right up, just remove the filler cap and see if the problem goes away.
My money is on fuel vaporisation though, when my Chim was very hot it used to do a few hiccups when I refilled until the cool fuel from the tank circulated around the fuel rail.
This condition was completely eliminated when I removed my catalytic converters which had the effect of vastly reducing under bonnet temperatures, oh & it gave me another 10 horse power too
It's possible the car started and ran briefly on the small amount of petrol held in the fuel rail, then died when that tiny supply quickly got used up by the engine.
It's also possible for the engine to fire momentarily just on the priming pulse fuel that's injected when you disengage the immobiliser and turn the ignition key to the on position, either way if the main supply is interrupted the engine will be certain to die almost immediately.
The Lucas 14CUX system is fitted with a fuel temperature sensor to stimulate the ECU into it's hot start compensation mode.
Modern fuels vaporise at surprisingly low temperatures (a particular issue under a TVR bonnet) so the ECU will momentarily try to help by increasing the injector duration for a few seconds until the hot fuel in the rail has circulated with cool stuff in the tank.
Once the sensor detects the fuel temperature has returned to normal the ECU will return the fuelling to it's standard map settings, if your fuel temp sensor is on the way out it could promote a hot start fuel starvation type fault.
Other more common sources of fuel starvation are a blocked tank pickup gause, a faulty fuel pump, a partially blocked fuel filter or delivery line, a faulty fuel pump relay, the ECU or immobiliser playing silly buggers (both have a part in energising the fuel pump relay) or a simple blockage in the return line.
The fuel system is a continuous circulating circuit, starting at the pickup in the tank with the excess not used by the engine being returned back to the tank.
Follow the circuit in the same order checking each possible area of restriction to find the issue.
Happy hunting.
NB: If you are only getting the problem when you fill the tank fully you may have a marginal tank venting issue.
When the tank is full there is no air space so a partial venting issue will be exasperated.
If it happens again when you fill the tank right up, just remove the filler cap and see if the problem goes away.
My money is on fuel vaporisation though, when my Chim was very hot it used to do a few hiccups when I refilled until the cool fuel from the tank circulated around the fuel rail.
This condition was completely eliminated when I removed my catalytic converters which had the effect of vastly reducing under bonnet temperatures, oh & it gave me another 10 horse power too
Edited by ChimpofDarkness on Monday 3rd September 15:28
OK, thanks very much for all this Dave.
Hmmm.... sounds like a LOT of possible options. Right now everything is fine again. Since the event the engine has been re-started around half a dozen times and driven over 100 miles so I could be looking for a fault which isn't there now. I don't have oodles of spare time and am not that familiar with the car yet, having owned it for only 4 months. My spannering days are largely (but not completeley) behind me these days too. No other problems so far. Like you, my money is on some form of fuel vaporisation or short term starvation as the symptoms felt like this. I guess I will have to wait to see if the the problem reoccurs - then remove the filler cap!
One other point; when I turn the ignition on the tank primes contiuously, also after the engine fires I can hear it priming. I assume this is normal if the fuel system is a continuous circulating circuit. Again, I'm a newbie here and very much finding my way around all TVR quirks, having owned a classic MG to date. This is a whole new world to me!
Hmmm.... sounds like a LOT of possible options. Right now everything is fine again. Since the event the engine has been re-started around half a dozen times and driven over 100 miles so I could be looking for a fault which isn't there now. I don't have oodles of spare time and am not that familiar with the car yet, having owned it for only 4 months. My spannering days are largely (but not completeley) behind me these days too. No other problems so far. Like you, my money is on some form of fuel vaporisation or short term starvation as the symptoms felt like this. I guess I will have to wait to see if the the problem reoccurs - then remove the filler cap!
One other point; when I turn the ignition on the tank primes contiuously, also after the engine fires I can hear it priming. I assume this is normal if the fuel system is a continuous circulating circuit. Again, I'm a newbie here and very much finding my way around all TVR quirks, having owned a classic MG to date. This is a whole new world to me!
pb450 said:
One other point; when I turn the ignition on the tank primes contiuously
Peter this is not normal.When you turn the key to the on position and disengage the immobiliser you should hear the pump run for about 5 seconds only.
This is the system pressurising the fuel rail in preparation for the imminent start.
During this 5 second period the injectors are also opened to wet the inlet manifold, this is known as the priming pulse.
After the 5 second period it should be all silence until you crank the engine.
As soon as the engine fires the ECU will detect the engine is running & reinstate the live feed to the fuel pump, all the time the engine is running the fuel pump will run & circulate the fuel.
As soon as the ECU detects the engine is not running the fuel pump live will be cut, this is partly a safety feature.
In summary you should only ever hear the fuel pump run as it primes the rail for 5 seconds, personally (after starting) I can never hear the fuel pump over general engine noise.
If the fuel pump runs continuously when you turn the key to the on position & disengage the immobiliser (before starting) then something is not as it should be, it really should just be the 5 seconds then the pump should go silent.
If there's been starting issues in the past relating to the fuel pump 12v circuit someone may have wired it to get a direct feed from the ignition switch, this would bypass the ECU controlled 5 second fuel rail pressurisation & priming pulse.
It's not right, but I doubt any of this would have any effect on your original issue.
My money is still on fuel vaporisation or tank venting, like I say mine did it but it was so infrequent that I filled the car full when it was very hot that it wasn't exactly a big deal.
Removing my cats removed the heat which eliminated the issue anyway.
OK, thanks again Dave,
I did wonder about this although to be fair, I haven't left the ignition on idefinaitely prior to starting to check it thoroughly. The previous owner may indeed have had the ECU bypassed to solve a problem - perhaps even without his knowledge as he wasn't a DIY man.
The car runs well at start-up and was inspected before purchase. Since my ownership it's been serviced by a TVR specialist and the rubber fuel hoses replaced under the bonnet as a precautionary measure. At no time has anyone picked up a priming fault.
That said, I will have it checked out at the next oportunity, probably mid October when the MOT is due - unless you believe it is a safety issue the way it is now.
I did wonder about this although to be fair, I haven't left the ignition on idefinaitely prior to starting to check it thoroughly. The previous owner may indeed have had the ECU bypassed to solve a problem - perhaps even without his knowledge as he wasn't a DIY man.
The car runs well at start-up and was inspected before purchase. Since my ownership it's been serviced by a TVR specialist and the rubber fuel hoses replaced under the bonnet as a precautionary measure. At no time has anyone picked up a priming fault.
That said, I will have it checked out at the next oportunity, probably mid October when the MOT is due - unless you believe it is a safety issue the way it is now.
Not experienced it myself, but ever since reading on PH about overfilling the tank I have stopped at the first cut off of the petrol pump and then prayed it would start....good luck.
I would suggest you just don't fill it as full and see if the problem recurs......before you try anything else. You can make as many trips as you like to the pumps with 30-50 miles in between. No need to empty the tank each time (to state the cataclysmically, blindingly obvious).
I would suggest you just don't fill it as full and see if the problem recurs......before you try anything else. You can make as many trips as you like to the pumps with 30-50 miles in between. No need to empty the tank each time (to state the cataclysmically, blindingly obvious).
ChimpofDarkness said:
It sounds like the original issue is an intermittent one Peter, my advise is to just drive & enjoy it.
If the issue returns, reactivate this post with some more detail and people will help you.
Happy motoring
This sounds like the most sensible advice! If the issue returns, reactivate this post with some more detail and people will help you.
Happy motoring
Plus, not overfilling which is also a bit of a no-brainer! Thanks guys. I need to rein in my paranoia if I don't actually have a problem! 
I will continue
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