TVR S1 won't run on after firing up

[Trefhead]

Hi
Ive just (well over the last 18 months) stripped and rebuilt my S1 (chassis failure). I'm nearly finished BUT now she will fire up on the starter circuit but fails to run on when the key goes back to ignition.
Ive replaced the Kalt start module (rusted), fuses (two 15amp & the 25 fuel), tried to clean up terminals, re-made suspicious looking electrical connections etc. My Steve Heath is covered with coloured pen.
I do have fuel, The 'new' pink relay clicks in and off and the new pump buzzes to a stop ok.

Has anyone got any ideas?. Is there something obvious I am missing? What should I test ? (I do own, but am not a wiz at, a multimeter)

I've owned S1's since 1990 and have pushed and towed them for miles, the AA used to know me by my christian name,https://www.pistonheads.com/gassing/imgs/4.gif but this one has beaten me.

Any help would be appreciated Cheers Guys

[Penelope Stopit]

There is a very good chance that there is a supply from a ballast resistor to the coil missing
Turn the ignition on and measure for voltage at the coil positive terminal
When in the starting position the starter motor supplies the coil by bypassing the resistor, this is achieved with a contact in the starter motor solenoid cap

The fault could be as simple as a wire left off somewhere

[GreenV8S]

Is there a voltage to the coil positive when you have ignition on but not cranking?

[Trefhead]

I'il get out there and look Thanks both

[Trefhead]

I'il get out there and look Thanks both Yes there 12.6 volts at the battery 11.3 volts at the coil

[glenrobbo]

Have you checked the 10 amp fuse for [Warning lights, instruments, and indicators]?

Does your ignition warning light come on?

[Trefhead]

Thanks. Yes, just checked again & ignition lights do come on and that 10amp fuse is fine. I have now double checked all fuses A OK

[pequod]

Faulty ignition switch??

Maybe try bypassing the switch (hot wiring the ignition electrics) to see if that works. Where you get a replacement if it is faulty may be a challenge but I suspect it will be a Ford switch so could be obtainable from a classic Ford parts supplier!

[glenrobbo]

You say it's getting fuel through ok and the ign warning light is behaving normally.

Is the convoluted wire spring wound main air inlet hose to the plenum in good condition? Tight connections and no splits?
Is the rubber boot around the air metering valve split anywhere?
Is the 16mm id vacuum hose across the top of the engine old and porous?

Any of these could cause stalling.

[GreenV8S]

Trefhead said:

I'il get out there and look Thanks both Yes there 12.6 volts at the battery 11.3 volts at the coil

That doesn't point to a ballast circuit problem. The voltage drop looks a little high to me. Do you still have the dreaded yellow connection in the circuit to the ignition switch?

[Trefhead]

Thanks PEDQUAD Ive tried that but I am getting voltage to the coil. Where were you suggesting i do the hot wiring . A live from the battery to what point? (back to the morris minor days eh?!)

Glenrobbo the air intake etc is all new. Though I haven't checked the vac hose and will do.

If I keep the starter motor switched 'on' a second or two after it fires (at risk of damage to flywheel etc) it will continue to fire and stops immediately I go back to ignition, so its not that it "stalls" as such, it's that there seems to be no 'firing' . Dead (i will double check)

I don't understand what 'happens' in the ignition module.
I know it received a message from the dizzy to trigger the circuit to the coil but is there something in there that can fail. Is the ignition/run side any different from the start circuit
I have seen one can get replacement module units for 2.8 Capris and it may be worth the money if there is doubt

[GreenV8S]

Trefhead said:

If I keep the starter motor switched 'on' a second or two after it fires (at risk of damage to flywheel etc) it will continue to fire and stops immediately I go back to ignition

THat's strange, because a ballast circuit problem would exactly fit those symptoms but your voltage measurements seem to have ruled that out. Can you connect a test lamp from coil +ve to ground and double check the coil +ve is receiving power throughout the whole process?

[Penelope Stopit]

As mentioned above, it could be the switch, there is always the possibility that the supply to the coil is being broken as the key travels from the start position to the ignition position

This above fault is sometimes man made in error, many ignition switches have one ignition contact for the coil supply that remains live when in the start position and then they also have a seperate ignition contact for much of the rest of the cars electrics and that contact doesn't stay live when in the start position

If you are sure there is power to the coil when the ignition is switched on then it does sound like the switch wired incorrectly or being faulty

You need to check if that wire powering the coil when in the ignition position is losing its supply when in the start position, to do that you will have to check what wires go where from the coil to the starter and also from the coil to a possible ballast resistor

You are playing with fire by hot-wiring it if there is a ballast resistor in the circuit as you will be bypassing that resistor

[Penelope Stopit]

I have copied the following that I posted for someone the other day, this explains how to properly check the coil voltage to prove that the ballast resistor is in the circuit and working ok

---

There is one little bit of info that I will add as it may help you if you're checking for what supply voltage there is at the coil
Completely disconnect the ignition amplifier from the circuit so that all electronics are safely out of the way, leave the positive supply wire connected to the ignition coil and disconnect any other wires from the coils negative terminal if there happen to be any (there may well not be)

Now you have an ignition coil with only its positive supply wire connected to it. Earth the ignition coils negative terminal, switch the ignition on and measure the voltage at the coils supply terminal

The reason for carrying out the above is that it is not possible to measure the supply voltage at the ignition coil when it's not drawing current if there is a resistor wired into that supply wire.....resistors do nothing until they are in a complete circuit that is drawing current.....what I mean by this is that 12 volt can be found at each end of a resistor until that resistor is drawing current and then 12 volt can be found at one end and whatever the voltage is being dropped to by the resistor at its other end and at the ignition coil

You may think to yourself - " Hold on a minute why have I disconnected the electronic ignition amplifier and created an open circuit"

You have disconnected the ignition amplifier because although it is in the circuit it is not switching a negative to the coil to complete the circuit until the engine is turning and even then the negative from the amplifier is a pulsed negative that prevents a correct voltage measurement from being taken

This is why everything is disconnected from the coil apart from the supply wire and then the coil is earthed at its other terminal to complete the circuit and measure the true supply voltage

The above test is for a coil supply that has a ballast resistor wired somewhere in that supply along the wiring loom before the ignition coil

The same test can be used to check for the true supply voltage present at ignition coils that don't use a ballast resistor....12 volt power to one side of the coil, disconnect amplifier and earth the other side of the coil, switch ignition on and measure the supply voltage

This earthing of the coil before checking the supply voltage at it is guaranteed to show if there are any out of specification volt-drops present between the battery and the coil

[Trefhead]

What great replies. I can see the logic. Ill do both tests and get back to the forum in the next day or two to keep you informed

Great 'S' camaraderie, many thanks

[Trefhead]

Done the two test suggested by both postings
1 Yes The test lamp stayed on through the whole process

2 The coil isolation test gave 5.8 volts. Not enough eh? I have the standard loops of blue wire as the resistor.

Should I replace the resistor?
Is there an alternative option to the blue wire
If not, any ideas where I can get some and what to ask for

Positive stuff!!!

[Trefhead]

contd.......Should the resistor wire provide 1.5 ohms resistance.

Could I replace it with a solid state unit unit on e bay for circa £6.

Would I be better buying a new coil and resistor package

[phillpot]

Trefhead said:

Would I be better buying a new coil and resistor package

I'd go for a "proper" 12 volt coil and ditch the resistor gubins.



Strangely a lot of coils on Ebay are listed as compatible with the 2.8 and 2.9 engine but I'm pretty sure the 2.9 has no ballast resistor set up and uses a 12v coil ?

[Trefhead]

12 v coil is an idea...
I have taken out the resistor wire and put in a temporary short loop on bullet connectors as a tester to try it at 12 v BUT still 'no go' on ignition.

I've given up for today but I will do the voltage to the coil (without resistor wire) on ignition test later in the week when I have got my sense of humour back

Thanks for the input so far everyone... Ill be back!!!!

[Penelope Stopit]

You could disconnect the crank wire from the starter solenoid when carrying out the tests as this will stop the engine from cranking over while working on them