strange issues with mk2 tdi swap ,

[wisconsinjohnson]

just swapped ahu into 87 golf, had it running temporarily in a b4 passat, put it in mk2 and now have strange issues

suddenly I have no power to fuel shut off solenoid, if i jumper solenoid, car starts and runs, can remove jumper and car continues to run, hooked up electric pedal, engine responds to input, disconnect t3 connector, (dynamic advance and fuel shut off) and engine continues to run.  If  disconnect ecu and sensor power g1 4 and 10, car quits running, like it should

I have to assume that i just have a dead short between pin 53 on ecu, and fuel cut off, no power at pin 12 of connector 24, I dont think its likely that the ecu is bad, cuz it responds to pedal input

but why does engine continue to run with solenoid unpowered, weak solenoid spring... the question mark isnt working on keyboard, sorry.

I am not using the ce2 fuse box , just providing 12v direct to g1 4 and g1 10, ecu ground signal for 109 relay unhooked, not using 109, dont have any grounds hooked up except for big eyelet on tdi engine harness, i guess ill back probe ecu at pin 53 next... , rebooting computer so i can get my punctuation back... thanks for any input

[wisconsinjohnson]

Ok, I have power at ecu pin 53 once its running, but not with start/run power, and not with starter cranking, not too concerned about fuel cut off valve at the moment, because car shuts off when I kill ecu power.  I guess next I look to see if ecu is supposed to be looking for a cranking signal to initiate fuel valve?  I'm thinking ecu ground for relay control could be involved?  I won't give up before I get it sorted, but I'm starting to think I'll be sending a couple of pumps to Ontario soon...

[wisconsinjohnson]

Just trying to make sure I have pertinent info, I had engine running (and starting properly) in b4 with a bare ce2 fuse box, with connectors f, g1, g2, and h1 plugged in, with h1 jumpered to run position on ignition switch, and I was using a jumper from 109 relay socket 1 fuse box ground, to socket 5 ecu switched ground, to ensure relay popped.  When I moved harness to mk2, I lost power to fuel cut off, I unplugged from the fuse box, and wired power to ecu and sensors, g1 4 and 10, directly to 12v, got same result, jumped fuel cut off and it started

So I am thinking that maybe pin 42 on ecu, switched ground, connected to relay 109 socket 5 was seeing voltage before and not now, and ecu "thinks" that relay 109 is faulty?  I am pretty sure I should apply 12v, but I'm going to work on pedal switches, cel and k line for now.

[wisconsinjohnson]

looks like low voltage/ poor conections?  I had a brand new battery in car, hooked in parallel with welding cables to a yellow top, with an automatic charger hooked up,  it appears that the charger has crapped out, my voltage tester is analog and 10v or 50v scale, cant tell diff between 11.5 and 12.5v, looks like maybe  I was getting 11.5 volts or so to ecu, engine would easily start with fuel solenoid jumped, but was only seeing 5-8v for a second or two at pin 53, if I hook charger to cables in car, I now get 12v at pin 53 when ignition circuit is first closed, and it stays for10-15 sec, still no 12v to t3 1 where it plugs in closest to fuel shut off, so that wire is broken somewhere.  Unfortunately all three of my batteries are dead, so I don't know what it does when cranking...

Still kind of surprised that no one has chimed in about car running with fuel cut off disconnected, but needing it hooked up to start...

[theman53]

The only time I have seen it run with no power connected to the cut off *and the pieces were still in the cutoff* was when there was junk in the pump to keep it from cutting fuel.

[wisconsinjohnson]

thanks for input theman53, once I got it started again I couldn't make it run without power to solenoid,
also it did a weird hesitate at 2000 rpms when cold thing,
 when in donor car, still doing it, and I know people have "fixed" by removing and replacing (same) solenoid,  so maybe deteriorated o-ring, or junk in pump, I  will pull solenoid, gravity feed pump to flush junk out, then replace it with new, donor car did spend some time upside down recently, so any thing in bottom of pump may have found its way to top.
probably unrelated, but this solenoid has the quietest click I've heard, my idi solenoids were much louder.

thanks for input

as for low/ no voltage at pin 53, that was just an under 12v thing, was just hard to believe, because engine ran normally once started with jumper to cut off,  so it turns out I just had low voltage,and intermittent short in fuel cut off circuit and battery charger, got new charger, viola! back in business, I should have checked for low voltage when I saw r109 symtoms, just assumed I had enough voltage cuz it would run and start, and I trusted a ***ty charger