Just had to call the RAC, advice please (relay?)

[finestjammy]

Hi All

I was enjoying a lunch time drive after bringing her out of hibernation last night. I pulled over, turned the engine off to check all was ok under the bonnet. I went to start her up and the relays in the footwell went mental, dials flicking all over the place and no sign of her even attempting to start. I had read about the hot start problem so wondered if she would be better after 30 mins or so. Tried her again, fuel pump primed all appeared normal but just a click (solenoid?) and nothing else.

I gave up in the end and called the RAC, he jumped started it and it was fine. The alternator was putting out 14v so it can't be that at fault. The RAC man thought it was one of the relays (or housing/sicket) that dangles from the loom that was stopping charge getting to the battery. The engine died when he poked one of them.

I managed to get home with him escorting me. I've plugged in the accumate and it is telling me the battery is fully charged, which it definitely isn't.

Any ideas what the most likely cause is? I know the 'dangley' relays are to do with the fuel pump and ignition...but not sure exactly what they do and which one is which.

Any help appreciated.

Thanks

James

[ChimpanLucky]

Iffy wiring?...on a TVR?.......How very dare you!

I find the quality of the wiring beyond any form of criticism

The two metal relays that dangle like testicles are:

1) Fuel Pump

2) ECU

The fuel pump is fitted to the blue connector block.

Hope this helps?

May god (& a decent multimeter) be with you.

[finestjammy]

Thanks. From just having a quick play in the passenger footwell it seems by twisting the fuel pump relay, and hearing it click, allows the battery to be charged. By this I mean that the accumate goes into charging mode, this only happens with the ignition on though, no joy with the ignition off. The relay socket has also become totally perished/brittle/fallen to pieces. I'll need to find a new socket from somewhere before getting a new relay.

Edit: I think it's the relay on the black connector that's merrily clicking away when twisted. Hard to tell though a the whole connector block has disintegrated.

Edited by finestjammy on Thursday 24th May 18:35

Edit 2:
Seems both relays start clicking when prodded, so I assume it's the wiring that's a little deeper that's the problem.

Edited by finestjammy on Thursday 24th May 19:08

[Quietlybonkers]

I have the hot start problem - and what you get randomly on trying to restart within a few minutes, when hot, is.......nothing. You turn the key, press the immobiliser button on the keyring, and total silence follows. No clicking, no whirring, no attempting to start, just a whole load of nothing. You lock and unlock, try various immobiliser things, twiddle the odd footwell connecter, still nothing. 15 minutes later, or when the mechanic arrives, it just starts normally and makes you look a complete idiot for calling them out.

[haircutmike]

Quietlybonkers said:

I have the hot start problem - and what you get randomly on trying to restart within a few minutes, when hot, is.......nothing. You turn the key, press the immobiliser button on the keyring, and total silence follows. No clicking, no whirring, no attempting to start, just a whole load of nothing. You lock and unlock, try various immobiliser things, twiddle the odd footwell connecter, still nothing. 15 minutes later, or when the mechanic arrives, it just starts normally and makes you look a complete idiot for calling them out.

The hot start problem in a lot of cases is down to a bad earth.

Rthem, clean up the contact points and rebolt.

Try the chassis to engine one by the offside wheelarch and the chassis to gearbox one by the box!

[SILICONEKID340HP]

haircutmike said:

Quietlybonkers said:

I have the hot start problem - and what you get randomly on trying to restart within a few minutes, when hot, is.......nothing. You turn the key, press the immobiliser button on the keyring, and total silence follows. No clicking, no whirring, no attempting to start, just a whole load of nothing. You lock and unlock, try various immobiliser things, twiddle the odd footwell connecter, still nothing. 15 minutes later, or when the mechanic arrives, it just starts normally and makes you look a complete idiot for calling them out.

The hot start problem in a lot of cases is down to a bad earth.

Rthem, clean up the contact points and rebolt.

Try the chassis to engine one by the offside wheelarch and the chassis to gearbox one by the box!

Mine does not have an earth strap from the chassis to the gearbox !

[haircutmike]

Daz, it bolts to the chassis cross brace under the box.

[ChimpofDarkness]

haircutmike said:

Quietlybonkers said:

I have the hot start problem - and what you get randomly on trying to restart within a few minutes, when hot, is.......nothing. You turn the key, press the immobiliser button on the keyring, and total silence follows. No clicking, no whirring, no attempting to start, just a whole load of nothing. You lock and unlock, try various immobiliser things, twiddle the odd footwell connecter, still nothing. 15 minutes later, or when the mechanic arrives, it just starts normally and makes you look a complete idiot for calling them out.

The hot start problem in a lot of cases is down to a bad earth.

Rthem, clean up the contact points and rebolt.

Try the chassis to engine one by the offside wheelarch and the chassis to gearbox one by the box!

There are two main issues with the starter wiring on these cars and they seem to get confused.

ISSUE 1 IMMOBILISER RELAY:

This gives the following symptom - Disengage the immobiliser, turn the key to the start position and nothing, not even the faintest click from the solenoid

This is an immobiliser fault or more specifically the failure of a relay inside the Meta unit.

You can prove this (like I did) by putting a test meter on the starter solenoid feed wire with the immobiliser disengaged and the key in the start position.

In my case there was a solid feed from the ignition switch to the Meta immobiliser unit, but zero current exiting it on the starter solenoid side.

The problem had to be inside the problematic Meta immobiliser unit.

The hot start kit is just a relay that masks the fact that the immobiliser relay inside the Meta unit used to energise the starter motor solenoid is inadequate.

This immobiliser relay often starts to show it's on the way out when the car gets hot, that's because the resistance in the entire system goes up dramatically when it gets hot.

To solve my problem permanently I bypassed Meta immobiliser on the starter solenoid circuit only and added a relay back in to protect the ignition switch, this completely solved my immobiliser related starting issues.


ISSUE 2 STARTER CABLE & EARTH:

This gives the following symptom - Disengage the immobiliser and turn the key to the start position, the car fails to start but you hear a faint click from the starter solenoid

This typically happens on a hot restart, say after filling up with fuel on a hot day.

If the starter motor & solenoid itself checks out Ok then the solution in my opinion is to upgrade the feeble and very long starter cable with better quality higher amperage battery cable.

Further improvements can be obtained by upgrading the earth path, a short lead from the battery negative terminal direct to the engine block should be all it needs.


Two different issues, requiring two different solutions.

Both could be described hot start issues.

Edited by ChimpofDarkness on Saturday 2nd June 11:06