Engine will not start after rebuild - suspect electrickery.

Looking at the wiring diagram on vintage bus, it should be a red / white wire so sounds original. The diagram shows:

Black/red from ignition to starter
Red/white one goes from starter to DR
There is also a red/white one that goes from starter to fuse box in the cab - stupid question, but did you check you didn't blow the fuse?

 

not checked no fuses no didn't see how a fuse could have blown as the battery was disconnected all the time until 1st fire up when everything had been connected

 

That's what should happen, ignition on first notch should get voltage to left side of DR, that bit seems to be working fine. It's the cranking circuit you've got problems with.

 

but that left side one feeds the fuel pump which isn't running?

 

Could you get someone to take a few photos of the starter wires? Might be able to get to the bottom of the hanging wire. However, if it worked before the engine rebuild with it dangling then I think it might be a bit of a red herring...

 

No, left side is injectors, ECU and prepping the AFM
Right side does fuel pump and cold start.



Image this image split down the centre. The two boxes in the middle are the relays - ignore the rest if it makes no sense to you except the bits at the bottom. Look at the left side as the 'power' part of the relay and the right as the 'fuel' side of the relay.

Left side 'power' energizes when you get to the first notch of the ignition switch and the right side 'fuel' at the second

 

the starter wires i'm upto speed on as i've been under there loads and tided them up and removed the crappy hot start relay and loads of extra wiring that ran to the ammeter, (check my poo bus thread) i'm fairly certain the wire (although SHOULD be connected isn't the problem as i say it's 100% NEVER been on since i've had the van, i have 3 year old pictures on my pc showing it hanging...... i think you're right - in the past someones bodged it and i've disturbed it, i went through a stage of every start up having to waggle the relay wires to get it to run, these symptoms are exactly the same - i solved the waggle by basically wd40 and making sure the wiring was tidy and never got knocked - unplugging has done some wizardry....

 

so the one with the plug on with a bunch of white wires?
from memory (dodgy) there are 3 connections 2 on the double relay left one coloured wires - clicking then right one white bunch of wires - then another box with black wires going into it next to that.

 

From left to right, the relay with the white wires coming out of it is the 'power' relay, (injectors, ECU, AFM prep), the relay with coloured wires coming out of it is the 'fuel' system, (fuel pump, cold start), and the spare one dangling away to the right of them will have wires coming into the top of if from the rectangular metal box just above the DR and then a bunch of white wires coming out of it is the fuel injector resisters, (they are originally white, depends if the injector resisters have been replaced or not).

You can ignore the random 3rd box as, as far as I can see, it's simply a pass through box so once it's plugged in, that's all there is to it.

 

i might pop up tonight and take some close up pic's as it's bugging me now but more than likely i won't as i'm tired.... maybe tuesday..... shame you're a million miles away you're convincing me you know science.

 

I'd happily help if you weren't from op Norf... Happy to help on here, pm etc where I can.

I'm not a mechanical person but over the years with my van I have got to know the FI system inside out. After an initial bit of trepidation about this mystical system that has the best VW mechanics quaking in their boots I started to read up on it and when you break it down to a basic process flow, step by step, it's as simple as the rest of the bus...Just takes a bit more time to 'get' and to diagnose, than carbs.

That VW mechanic book is a God send, put your trust in it, get someone competent with a multimeter and you'll find the problem.

Then it's a simple, (or very tricky depending on the part), job of replacing it.

 

i'm not sure a part has failed other than disturbing wires have re found a fault i'd "cured" by tidying, i suspect a dodgy relay and will fart around there 1st... @Greenwesty has all the spares (untested though) bar an afm and is going to meet me there on friday to have a looksee.

 

mine looks similar however a lot of my wires are covered in spray paint from someone painting the engine bay white.... the double relay box on mine is sprayed white - yours is black and that ally round shape thing above the relay on yours is to the side on mine - my coil set up looks about the same - the white wire in the sheath comes from the ecu loom by the battery

 

in that plastic sheath to the coil positive is the other wire your oil pressure switch that goes off towards the dissy @MorkC68 ?

 

And here's mine!



That reminds me, must clean the engine bay a bit...

 

no it was just a memory from years ago basically the feed to the coil live from mine comes from up around the fan relay area and used to go in a sheath like that with another wire - this other wire is now hanging (cut short) i think it was from when my original oil pressure wire failed so i ran a new one.

 

your relays look way neater than mine and a different type

 

mines like morks relays sit in a plastic housing yours looks metal and i guess my top one is moved to the side - deffo someone fiddled? my earth wires? can't even recall seeing them like yours. need to investigate more - damn this being an hour drive away!