Hot start problem ?
Discussion
It seems I may have the famous “hot start” problem, although I would say it is dependant entierly on battery volts rather than temperature.
The fuel pump primes every time but if the battery volts are below 12.2 the starter solenoid will not pull in, connect a power supply and as soon as it is above 12.2 all is well.
Tomorrow I will get underneath, find the end of the solenoid drive wire and measure the supply, but if somebody who knows reads this please could you clarify how things are connected.
As far as I can work out there are two wires from the battery to the relay / fuse board (which doesn’t look like either of the ones in Steve’s book) on my 98 car, then there is a fused feed to the ignition switch. From here there are separate feeds to the ignition and fuel pump circuits and when selected, to the starter solenoid, probably via the immobiliser. I guess when I measure the solenoid supply it will be well down. Where do the volts go missing ? across the switch or the immobiliser.
As a point of interest the problem has only occurred since the starter was replaced so perhaps the new solenoid is less tolerant of low volts.
Any comments appreciated.
The fuel pump primes every time but if the battery volts are below 12.2 the starter solenoid will not pull in, connect a power supply and as soon as it is above 12.2 all is well.
Tomorrow I will get underneath, find the end of the solenoid drive wire and measure the supply, but if somebody who knows reads this please could you clarify how things are connected.
As far as I can work out there are two wires from the battery to the relay / fuse board (which doesn’t look like either of the ones in Steve’s book) on my 98 car, then there is a fused feed to the ignition switch. From here there are separate feeds to the ignition and fuel pump circuits and when selected, to the starter solenoid, probably via the immobiliser. I guess when I measure the solenoid supply it will be well down. Where do the volts go missing ? across the switch or the immobiliser.
As a point of interest the problem has only occurred since the starter was replaced so perhaps the new solenoid is less tolerant of low volts.
Any comments appreciated.
Hi, can I clarify if I understand this: the electrical supply to the starter will be a damn big cable, routed via a solenoid - the solenoid will be switched by a low current supply via the ignition switch. Where can there be a low voltage / high resistance? Surely not in the large cables which actually do all the work?
Confused, Nic
Confused, Nic
nicbowman said:
Hi, can I clarify if I understand this: the electrical supply to the starter will be a damn big cable, routed via a solenoid - the solenoid will be switched by a low current supply via the ignition switch. Where can there be a low voltage / high resistance? Surely not in the large cables which actually do all the work?
Confused, Nic
The cable supplying the solenoid isn't large enough,so theres a volt drop at the solenoid,hence it struggles,particularly with age.Confused, Nic
Hi Mike
the new relay draws 200 Ma, from the TVR wireing, the solenoid still draws the same 12-15 amps but now from the battery direct or the two brass links on the fusebox, via the relay of course. On my car the wiring was loosing 6 amps, ie only alowing 6 amps to pull in a device that is rated at 12-15 !! A bit like crap lights,slow windows,slow cooling fans,all down to poor wiring spec.
the new relay draws 200 Ma, from the TVR wireing, the solenoid still draws the same 12-15 amps but now from the battery direct or the two brass links on the fusebox, via the relay of course. On my car the wiring was loosing 6 amps, ie only alowing 6 amps to pull in a device that is rated at 12-15 !! A bit like crap lights,slow windows,slow cooling fans,all down to poor wiring spec.
The original starter I had in the car would always engage even at fairly low voltages but cranked very slowly when hot. I had this one replaced under warranty and then had no problems, even when very hot. This motor failed mechanically (due to a fault elsewhere) and was replaced again with one which cranks enthusiastically but the solenoid will not pull in unless the battery volts are very high. As said there is a thick wire for the motor and a thin one for the solenoid. The white / red cable leaving the ignition switch is fine, probably 24/02 but the one that arrives at the solenoid is a lot thinner and black, so somewhere along the way there is at least one connector and I guess a black box.
The problem on my car has only occurred since the recent motor change so I wonder if the more recent motors have solenoids that are less tolerant of lower supply volts, which is why there seems to be popular topic.
One solution, as David says is use the signal from the standard, current challenged cable to operate a relay to switch a more robust supply.
My original post was because the cable run from switch to solenoid was and still is a mystery.
The problem on my car has only occurred since the recent motor change so I wonder if the more recent motors have solenoids that are less tolerant of lower supply volts, which is why there seems to be popular topic.
One solution, as David says is use the signal from the standard, current challenged cable to operate a relay to switch a more robust supply.
My original post was because the cable run from switch to solenoid was and still is a mystery.
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