Won't start...idiot check.

[Smosh]

Morning all, hoping for some quick early Sunday morning responses...

I cant get my van's engine to turn over.



I've replaced the alternator with a 90amp one. The previous had a plug connector and new is round terminals.



I have removed the alt to junction box cable and gone straight to starter.



I have a new positive connection from B+ to starter solenoid. the existing start solenoid to battery and solenoid to junction box look ok.



I am getting 12+ volts at the start solenoid, B+ post and junction box.



I havent added nor (I think) removed any earths. There is one from gearbox to chassis and battery to chassis.

Note: It used to start (slow turnover and crap battery) before I made these changes.



Any suggestions?

[MidLifeCrisis]

None of those changes you made should effect the ability to turn over the engine (but they may stop it starting up)
If your starter is not working at all then I'd check that
A) you have 12v at the thick wire going to the starter
B) you have 12v at the thin wire going to the starter when the ignition key is turned to start position
C) the starter external case has continuity to ground

[Smosh]

None of those changes you made should effect the ability to turn over the engine (but they may stop it starting up)
If your starter is not working at all then I'd check that
A) you have 12v at the thick wire going to the starter
B) you have 12v at the thin wire going to the starter when the ignition key is turned to start position
C) the starter external case has continuity to ground

How do I check 'C) the starter external case has continuity to ground' is there a good point to clip a jump lead onto?

[Smosh]

A) Yes
B) Yes
C) Not sure

I have a drop in the power levels at about 0.01v per second when the ignition is on.

I have power going to trigger wire.

[Smosh]

okay. So the problem seems to be with the run from the battery to the starter. I say this because;

With everything hooked up, a multimeter from negative to earth reads 12.5v; positive to earth reads 0.07.

with the battery/starter cable replaced with jump leads the voltage switches; 0.07 negative; 12.5v positive.

This to me suggests a problem with the cable (maybe trapped and earthing on the fuel tank i changed).

However, with the cable temporarily replaced by jump leads, the van still didnt spring to life...

[Smosh]

Okay, so I maybe wrong. It looks like all my new wiring is fine and I have a short on the way to the dash. If I remove that cable from the battery my positive and negative work the right way around.

Any suggestions on how to locate the area at fault?

[BOXY]

With everything hooked up, a multimeter from negative to earth reads 12.5v; positive to earth reads 0.07.

with the battery/starter cable replaced with jump leads the voltage switches; 0.07 negative; 12.5v positive.

How are you checking the voltage? The flow of electricity from the battery can only go from positive to negative (earth). If you had a short from the positive terminal to earth you would either be blowing a fuse or melting the insulation of the wiring.

[Smosh]

Sorry, I must be explaining what I did badly and jumping to conclusions! Is this clearer?

Step one
So with everything connected as I thought it should be on a freshly charged battery:

Probed the multimeter between the +ve of the battery and the bodywork = 0v
probed the multimeter between the -ve of the battery and the bodywork = 12v

Step two
removed the feed to the dash

Probed the multimeter between the +ve of the battery and the bodywork = 12v
probed the multimeter between the -ve of the battery and the bodywork = 0v

Problem
Not a feckin' clue... short somewhere?

Solution
Not a feckin' clue... Beg for help on the forum

[Ralf85]

Knackered ignition switch?

[Smiffo]

Sorry, I must be explaining what I did badly and jumping to conclusions! Is this clearer?

Step one
So with everything connected as I thought it should be on a freshly charged battery:

Probed the multimeter between the +ve of the battery and the bodywork = 0v
probed the multimeter between the -ve of the battery and the bodywork = 12v

Step two
removed the feed to the dash

Probed the multimeter between the +ve of the battery and the bodywork = 12v
probed the multimeter between the -ve of the battery and the bodywork = 0v

Problem
Not a feckin' clue... short somewhere?

Solution
Not a feckin' clue... Beg for help on the forum

Negative side of battery to bodywork = 12v?

Jeepers mate, is that with key in and turned on, or with key out of ignition, or with jey in and trying to start the engine?
I am struggling to picture exactly what is going on there.
What is resistance of -ve of battery to body?

[Smosh]

Yep! -ve of Batt. to bodywork. I believe that was with the ignition off! I didnt check resistance?

As a side note I recently changed the fuel tank (havent ran it since) so could have trapped/ damaged the dash feed at some point?

[CovKid]

With battery disconnected, check EVERYTHING you've done - twice, in turn. Something somewhere isn't right. You'll no doubt kick yourself when you spot it.

[Smiffo]

Yep! -ve of Batt. to bodywork. I believe that was with the ignition off! I didnt check resistance?

As a side note I recently changed the fuel tank (havent ran it since) so could have trapped/ damaged the dash feed at some point?

Tell me to sod off if this sounds stupid, but you have made sure that the neg post on the battery goes to the earth strap the the body?
Sounds like you have battery in the wrong way round to me

[Smosh]

Yep! -ve of Batt. to bodywork. I believe that was with the ignition off! I didnt check resistance?

As a side note I recently changed the fuel tank (havent ran it since) so could have trapped/ damaged the dash feed at some point?

Tell me to sod off if this sounds stupid, but you have made sure that the neg post on the battery goes to the earth strap the the body?
Sounds like you have battery in the wrong way round to me

Not too stupid a thing to ask. I did have to check that!

TOPIC REVIEW: WON'T START...IDIOT CHECK.

I'm sure it is something stupid. But I cannot find it. The thing that is throwing me is that it seems to go to "pooh" when I connect the feed to the dash. something I haven't actually messed with.

[BOXY]

As Covkid said, disconnect the battery & the leisure battery if you've got one.
Put the multimeter set to DC across the battery terminals and see what voltage you've got from the battery or batteries.
I'm struggling to see how you can be getting +12v between the negative on the battery and the earth. Are you sure you've got the probes on the multimeter plugged in to the right sockets?