Engine will not start after rebuild - suspect electrickery.

Phone breakdown and get it relayed home, surely then you can work on it at your leisure?

Sorry you've not managed to sort it yet!

 

Yeah but don't forget they are two different problems. As you've shown you aren't getting power to the fuel pump so it won't work regardless of an airlock.

You have proved the pump works if you bypass the DR so air block or no air block you have proved that if you give it power it will whirr.

Once you've got this you can then deal with an airlock.

 

I would take the petrol cap off then pull the input to the pump until you see fuel fill the filter, but you still need to sort the power out to the pump as well

 

pull input to pump? you mean gravity itt to the pump yes?

 

Yep gravity feeds the pump it pushes fuel it doesnt pull fuel from the tank

 

The starter is latching the relay, we were getting 12v to the air aux so it's triggering the solenoid in the relay.

The question is should the starter latch the relay on cranking or does it hold the relay whilst the ignition is on, and old stop the trigger voltage when ignition is off?

If its the latter hen I suspect that the relay is shot...

I think it's might be easier to bench test the relay, wish we'd brought it back now!

 

Did you try the test with moving the AFM flap with the ignition on, this will make the fuel pump go if everything is OK, if not then you can test for 12volts on the dual relay plug(can't remember terminal number on plug its earlier in the thread though)

 

forgot was that the one take off filter and push summat?

 

Yep

 

That was numero uno thing to try!

 

sorry my brain is fried and i'm over tired

 

But the AFM isn't fully energised until the ignition is cranked so won't do anything to the fuel pump. Remember it is an air flow meter so it works to adjust the air / fuel mix ONLY once there is air flowing across the sensor - ie the engine is running. It does then keep power going to the fuel pump but again it only does this is it senses air moving. No air, no power to pump - VW's very own clever safety switch.

Moons, the ignition passes the voltage to the starter when ignition is cranked, and only when cranked, the starter then passes that voltage onto the DR which energises the fuel pump and cold start. This voltage through is lost when the ignition is returned to on, ie when the engine fires up and you let go of the key, As soon as the AFM notices air flowing through it, it takes over the duty of energising the fuel pump and keeps it running. The cold start value then has no power and stops, it's done its job.

I'd guess it's something between starter and DR, be it wire, dodgy connection, poor DR terminals or a combination. Get that running and the rest should follow.

There may be an airlock as mentioned but you can't tackle it until the fuel pump gets power from the DR.

 

Ok, but I was hearing the click when ignition was on, which did not un click until ignition was off...

 

I swapped my pump for a new one ran a bypass live to it as well but it seamed the fuel one way regulator in the bulk head would not let the air pass through.
With the pipe pulled off the back of it lots of fuel every where connected the pipe back up and it worked.
With the pipe off on cranking you will certainly see if you have fuel which will mean dual relay pump side is working and fuel pump is working which will mean that side of the wiring YES is working...

 

Hi Rick. Sorry i haven't had time to read all posts but this may help. Once my van would not start when it still had FI. Good spark, but no live to the pump!
Turned out to be poor earths at the cluster that bolts to the centre case bolt on top of engine under throttle body. It was a pig to get at.
Try not to get too p'ed off. It will get sorted. Not easy when you've got all these different ideas to look at.
It ran ok before the strip down so may just be a silly connection problem.
Good luck mate.

 

ok i'll try that too for sure.

 

so unless anyone thinks of anything else my plan of attack seems to be this for friday.
manually get fuel to the filter by undoing the filler cap and letting it flow by gravity @pkrboo
undo the pipe on the rear of the regulator and pump the air out after bypassing the pump feed @stevebay
check earths in the centre of engine @vinnyboy
see if the flap thing does power the pump - although @MadFrankie seems to say it shouldn't....
connect the wire that's never been connected in my ownership to the starter solenoid
test continuity through injector loom to ecu plug swap double relay with a different one to see if it's failed.

was there anything else for now?

 

You missed, sit down and have a cuppa' to stop your head spinning.

 

mrs roo is being driven mental by my obsession with the van, she seems to think it's the only thing i care about! i said don't be daft i quite like the dogs as well.

 

At least you still have a sense of humour