Battery in boot problem

hi guys,

just put my battery in the boot of me mk2 but now i have a problem.

so here is the low down......

i'm using 4 gauge power cable for the positive thats going to a 4 way distribution block, this then has the 2 power cables that go to the starter and the alternator.

i was having bad trouble with the earth, but now thats sorted as i have taking the old cable/wire from the earth in the bonnet and taking it to the back and have drilled a hole in the boot and bolted it all down and that alkl works fine, now i go to turn the ignition and all the lights come on.

now, i go to turn it over and nothing, the fuel pump primes etc but nothing no click nothing.

any ideas what it could be please guys?

thanks alot
Ash

 

bump

 

you need a better or 2 earths

 

where else shall i put an earth?

drill another hole and bolt it down?

 

yep

 

If you've moved the earth from the engine bay (normally one cable from battery to body, and an extension piece to the gearbox casing) then your engine isn't earthed. You need to put another one back in the original position.

If it's a digifant car, you may well have blown the ECU, but hopefully not.

 

sorry mike is right if you have removed the earth from the box

 

I did that once, expensive mistake, never done it again though......

 

yea, i have taken the wire/cable from the engine bay

so i take it i am best of putting the cable one back to the 2 earthing points in the bay (one gearbox and the other 10mm one) and using some left over 4 gauge for my earthing point in the boot?!?!

sureley if the fuel pump primes and all my dash, clocks, indicaters etc work then the ECU hasn't gone?

 

You can buy earth straps from Halfords, or just about any motor factor. Just make sure you've got an earth from the engine/box area to the body, as well as one from the battery to the body.

If the fuel pump primes and then stops, you should be ok. If it goes on and on, your ECU is shot.

The ECU only runs the engine and fuelling, on the Mk2s. Not like a modern car, where you have to ask the ECU permission to change channel on the radio

 

A couple of tips for putting the battery in the boot that will help:

As mike says, batt to body, body to engine earths are required and far better than wire from battery to engine bay.
I would run the large power cable straight to the starter, then wire alternator to that.
For the ecu/coil/starter solenoid power it helps to have a separate cable all the way from the battery. Then all this lot won't see the voltage drops along the starter cable during cranking.
For headlights and rad fan its best to run relays in the engine bay, take power off the starter/alternator. This reduces the load through the fusebox.

I have done all this, and my mk1 car uses a small motorbike battery behind the seats, on a 2.0 16v with a tired starter. Not had a problem with starting yet.

Just had a look and i did use 1AWG cable, you used 4AWG which has half the xsectional area, have you tested the voltage at the starter with the switch on crank?

Mike

 

No voltage without an earth, tbh.

 

hi guys, just a update incase anyone else has this problem, as mike said the engine wasn't earthed and now she fires up fine.

thanks alot for everyones help. now on with putting the washer jet bottle in the boot too