Electical nightmare anyone good with bug electrics?

[Phil West]

Car no go!  Here's what's happening:

Battery fully charged and good (tested) new 110amp hour leisure battery.  Will run a 5 amp portable fridge.
12v tested ok at generator, ignition switch, fuse box.  All fuses new and good connections.
Turn on lights - work perfectly.  Fuel pump works fine.  Basically everything good.
Then - turn ignition key to far right and get a large pop/spark sound from the general area of the battery/starter motor.
Starter motor does not kick in any way.  After the pop, nothing will work in the car, it's like the whole system has gone dead.  No warning lights in speedo, no fuel pump, no nothing.

Yet - the battery still will power a 5amp fridge and I still get 12v at the generator, ignition key, fusebox.

Any help much appreciated....tearing my hair out with electrics, I'm very crap with them.
Cheers
Phil

[andy M.]

have you got your battery clamps nice and tight?, if you've just pushed them on the current draw will arc out the battery terminals and then nothing will work until you wiggle the terminals again,

regards

andy

[Phil West]

Battery clamps all good.  In addition I've checked the (few) connections in the main wiring circuit - battery earth, start motor, generator, fuses, igntion etc. and all solid.  Starter motor was new a year ago and always worked perfectly.  Haven't tried to start the car since last November.

[Neil Davies]

Phil, how near are you to Bernard Newbury? He's pretty hot on electrics. Richard Morena I think is supposed to be good too. I'll ask my brother what he thinks - he always sorts out my electrical problems. Sounds like a short within the ignition switch to me though.

[benssp]

Phil that fridge is going to cost you tenths , disconnect the fridge and try it

[Phil West]

never mind the fridge - that battery weighs 67 pounds!  Of course I have a 10lb battery for normal use.  Anyway I've had a couple of people who reckon it's the earth, which is weird as it's a new cable last year and it's only 6 inches long and I've not touched it since November and was always perfect before.  Plus I have power before trygni to start the thing (earth good) then try to start and lose all power afterwards (which would indicate no earth exists after trying to start the thing).  So I never even considered it.  Anyway when I get home tonight it's all hands on the earth issue, I'll run new one(s) all the over the place to make sure the earth is great then try again.

In the mean time I realised yesterday that Autometer guages come with solid steel mounts that would allow you to fix a house on a a car, they are mega heavy grade steel so time to fabricate some paper thin ally ones.  Can't believe I've been carting them deadweights up the strip all these years.

[Bernard Newbury]

Phil, it sounds like a bad earth. Low amp current draws are fine but as soon as you try a heavy amperage such as the starter I would think the earth cannot handle it.  Try putting a earth direct to the starter housing. Also those Porsche starters do have a problem with earthing as I have had issues with mine so I fitted an extra earth. Sorry about the extra weight!!! Bernie.

[j-f]

Do you have the cable between body and gearbox? A friend forget it and the car never start because of that.
Same symptoms as you.

[Phil West]

got it sorted last night - added two extra earth cables  - 1 to gearbox and 1 to body - and cleaned the threads of the original earth cable bolt.  So with 3 big earths I had no problems getting correct electrical power.  Starter fired straight away, and indeed for the next 20 minutes on and off as I tried to get the thing running.

Now all I need to do is figure out why the car won't start......

[Neil Davies]

Do you have the cable between body and gearbox? A friend forget it and the car never start because of that.
Same symptoms as you.

Did that with my old T25 - blew the gearbox on the way to a show (with trailer and racecar on the back too!), limped in with first and fourth gears only, changed the gearbox in the camping field and got everything sorted, but it just wouldn't run properly - put the earth cable on and didn't have another problem!

[j-f]

I'm glad to be able help you