Engine will not start after rebuild - suspect electrickery.

no he doesn't lol but he knows an ex F1 mclaren mechanic.............

 

No problem, I could start to talk you / text you through the process - pressure in rail - voltage in injectors - voltage at pump etc etc but the book does it in print, with pretty pictures, so you can tick them off as you go. So as long as you know your AFM from your double relay you'll get somewhere.

 

i'll see how it goes - just got to try and get over there but after work it's a bit of a struggle - was wanting to go away for a long weekend for my birthday next sunday but might have to go to ed's friday to tinker as it seems daft to go after work when i'll be tired anyway.

 

Does the pump run if you take the pipe off ?

I am pretty sure it will only run on demand it will not pump if there is air in the system.

My fuel system would not self bleed needing priming up to the regulator by the means of taking the pipe off the back.

White wire from ECU to coil have you got it on the right side of the coil ?

 

can't try anything until i go to the van again mate but thanks for the assistance i'll try these things - the white wire from ecu is on yes - think it was negative off the top of my head but can't remember - whatever it is i labelled all wires just like ed china taught me lol and they went back as took off.

 

@stevebay you mean the regulator that is on the firewall directly behind the starter yes? that feeds (or returns) to the tank?

 

If its in one piece and good to go - why not get it relayed home. (or work) and fettle it there. Im clueless on Fi so cant really help im afraid!

 

'cos whie at ed's i can camp in it lol - worse case i'll be having my birthday at ed's.

 

if any of you clever chaps feel it easier to text me pm me for my number and i'll send it ta.

 

BTW, all the other links work as well on my FI literature thread now, the pictures section at the bottom is very useful to get a 'process flow' of the FI system.

 

Perhaps you should get @Top Banana Racing to take it on a tour round everyone on his trailer until someone spots the problem

 

So, basically explaining the FI system, (while bored at work)

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1) Ignition on - not cranked

Ignition system completes 'on' circuit to get coil and battery to give power to the double relay, (left side is the side that gets voltage here), which in turn energizes the injectors and ECU, it also preps, (but only preps), the AFC.

AAR, fuel pump and cold start have no voltage at this stage. AFC is only prepped so not 'on'

2) Ignition on - cracking

Ignition system completes 'crank' circuit to energize starter which turns over the engine
Voltage continues from starter to the other side of the double relay, (right side this time), which in turn passes voltage to the AAR, Fuel Pump and Cold Start Valve

Everything in the FI system has voltage at this stage

3) Ignition on - engine running

Ignition key is released so starter motor loses the power as it has done it's job.
You might expect the right side of the double relay to drop out as well, (fuel pump etc), but the AFM sees air flowing through itself and decideds that the engine is running, it then energizes the right side of the double relay to keep the fuel pump running.

Starter and cold start valve do not have power, everything else does

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So, looking at you problem we can say that somewhere in point 2 we have a problem, if you are sure that the pump is good outside of the FI electric system and the engine turns over, ie starter motor is doing it's job then you can rule them and the AFM out, (as the AFM only energizes when the engine has started). My guess is that it all points to the double relay - one of the following:

- Starter wire to double relay (slot 86A on relay), isn't passing a voltage
- Slot 88Y on the double relay isn't receiving voltage from battery
- If voltage is getting into the double relay, (right side), then it's not passing it out to the fuel pump, (slot 88D), or cold start valve, (slot 86) - In this case it's not essential for the cold start vale to be working to get the engine running, (it's relatively warm outside at the moment so it should at least try to fire up) so I'd focus on the connection from slot 88D to the fuel pump.

Having said all that, the VW mechanics manual will lead you down that route with diagrams and simple instructions perfectly...

 

See if he'll do you a seasonal pitch you dont have to get it mended

 

@MadFrankie what's your take on my van never having had the wire connected to the starter lucar that feeds something (pump?) and the idea from @stevebay about air lock? also this idea someone mentioned about changing to non specific air hose is bad?

 

Well, the wire goes from the ignition to the starter and then from starter to double relay slot 86A. It passes current through the starter to the double relay...without this connection to the double relay, (DR from this point on), it simply won't work. The DR MUST have some form of voltage.

So, if you are saying that the wires go to the starter and no further either (a) the PO has gerry rigged something else that passes a current to the DR or (b) the wire you see is a different bodge that you shouldn't worry about and there is one going from starter to DR.

If there is no connection from the Starter to DR then the DR must be getting it's voltage from elsewhere, remember without it the FI won't work, period.

It could be that the PO had problems with the FI / double relay and bypassed the voltage circuit to get things working, (bit like what you did to check the fuel pump was working). The options to bypass are infinite really, a couple of more likely ones:

- They could run a wire from ignition direct to DR - (perhaps they had a bad starter in the past and wanted to take it out of the equation).

- They could also have run a cable directly from the ignition to fuel pump - (again, to check fuel pump was working and decided that it worked better than way assuming you would turn the ignition off when stopped so fuel pump would turn off etc), but all bodges are just that, bodges. The FI system works the way VW intended, for a reason.

You 'could' have ignition to starter and no further and then another wire from ignition to DR and it have the same effect as if it was correctly done, however the reason VW had the connection ignition - starter - DR is that it adds the fail safe in if the starter goes, so if your starter motor is dead then who need the rest of the FI system!

As for air locks, yes you should have the same size hoses as original as they produce the correct air flow, but the engine should start or at least fire up first - remember the AFM does not kick in until the van is running. Once it is running the AFM takes over and then you'll know if there is a problem with the pipes. It will splutter, cough, misfire, cut out, run rich / lean etc etc. Regarding different size pipes, the AFM 'should' regulate this and you can supplement this by changing the idle to suit...

Your problem, I think, is before this - you might find it's the next problem in line for you but let's get the engine starting first.

 

Actually, one stupid question, did you clean and remember to earth the DR again?

One stroke of luck, for the first time in about 9 months I drove the van into work so if you need photos of my FI system to compare I can easily get some...

 

cheers guys i have no access to the van to check anything at the moment, may pop up in the week but looking like friday, didn't remove any wire from earth on double relay just pulled the multi plugs off and dropped engine then re fitted

 

wire hanging by starter is not a bodge one is define original white/red wire (thin) with a factory lucar and sleeve on it, was hanging by old starter, when i changed the starter earlier this year i noticed the old starter had 2 lucar connectors and the new one only one but obviously 'cos it was never connected it didn't matter to me, i suspect it's been bodged in the past then.

 

with ignition off but no cranking you can hear the left side relay click (the one with coloured wires on it) the other one is silent (white wires) theres then another connector into a box with loads of black wires to it.