Fuel Pump Not Priming

[kate205gti 4]

can someone point me in the right direction here please i started my 205 tonight for the first time in 18 months (wooooo!), but the fuel pump does not prime on the key

 

Ive hardwired from the back of the tachy relay (wire no: 76) and this then primes so i know its not the pump or the fuse or the any of the wires between the tachy relay and the pump

 

it ran fine when hardwired, ive plugged in 2 other tachy relays and still not priming so dont think its the relay itself - more something from wiring from the tachy into the engine bay?

 

from what I can gather the tachy relay takes a feed from the coil and the rev counter?

 

where can i stick my multimeter and on what setting to find the problem please thankyou

[24seven 104]

If you've access to another try a different crank sensor. I've always been under the impression the fuel pump only primes once the engine is turning over and the CAS is sending a signal.

[kate205gti 4]

its an 8v engine with a loom from pre 88 - dont think ive got a CAS?

[24seven 104]

I'd be surprised if it doesn't have one, but then I'm no expert on 205 history. If it's there it's bolted into the top of the gearbox (beneath the head, easy to get at) with a single bolt and should have a 2 pin plug coming out of it. Looks like this.

 

[edit] just googled and I think you're right, CAS's appeared on the motronic cars.

Edited May 7, 2010 by 24seven

[large 33]

Something in the back of my head is telling me that they only work when you are 27 or less.

[kate205gti 4]

haha aww dont be mean its my birthday it should work for that reason alone

[DamirGTI 342]

Pre 88 Jetronic cars don't have a CAS triggering system triggering signal (for both the fuel and spark) comes from the dizzy , i.e. pick up coil ("pick up" triggering system) ..

 

So , try poking the black signal cable (with 3pin yellow plug on the end..) which goes from the dizzy and plugs on the ignition amp. connector - set the multimeter on the buzzer and pick two terminals of the yellow connector side (tere's 3 terminals , one is positive , one negative and one is just shielding wire so , no signal from that one .. try searching as i've posted some pics regarding this issue "which is which"..)

.. connect the probes , remove all the spark plugs out and turn the engine by hand - if its fine (triggering system/signal) the multimeter will produce intermittent signal (like morse code ) the faster you turn the engine the faster the signal/code will reproduce ..

If there's no signal what so ever , then , the cable might have breakdown somewhere or the pick up coil inside the dizzy is kaputt ..

 

Damir

Edited May 7, 2010 by DamirGTI

[kate205gti 4]

thanks damir i tried poking the black signal wire and sprayed it with wd40 and it then primed for a sec then stopped ive tried replacing the signal wire with another one and also replacing the wires into the back of it but still no go

 

ive added a live switch to the dash now and the car runs fine and idles dead on 1k so thinking it cant be anything seriously wrong with the coil or dizzy? so will just live with a switched pump!

[DamirGTI 342]

Tried with spare (known good ..) fuel pump relay ?

 

Damir

[kate205gti 4]

tried 3 of them 2 came from a good source! all same result - works ok if hardwired but not otherwise

[pug_ham 244 3 Cars]

They don't always prime (its been discusssed before) but no Jetronic 205 GTI has a CAS sensor linked into the ecu.

 

If you're not sure of an answer, please don't post sending people down the wrong route for fault finding!

 

Graham.

[DamirGTI 342]

tried poking the black signal wire and sprayed it with wd40 and it then primed for a sec then stopped

 

So it did made it work/prime then ? though for just short period right ?!

 

Tried replacing all the wiring bit on the side from the dizzy signal cable (yellow 3pin plug end) down i.e. dizzy signal cabe + ignition amp connector with the wiring ?

Also try to wiggle the middle part of this the dizzy signal cable wiring bit (@ and around the yellow plug , and the ignition amp connector) while cranking .. and see if it makes any difference ..

 

 

.. any , check if you've might by any chance miss connected some of the wires around the coil/ignition amp (hardly if it works , let alone with fuel pump relay directly connected .. but worth to check anyway ..) particularly the green wire 112A , this might help a bit :

http://forum.205gtidrivers.com/index.php?s...t=0&start=0

 

.. as this 112A green one switches the fuel pump relay from the coil negative side (IIRC) , and it's cross connected in circuit with fuel pump relay , ignition amp , tachometer and of course coil ..

it's not seen on the pictures above but there's 4 wires , inside this the 112A lets call it cable now -> two thin wires with green insulation (connected together in one terminal which plugs on top on the coil negative side as it can be seen on the pic above) , and two wires without insulation kinda like shielding wires , again , connected together with ring terminal on the end -> which you need to connect on the ally plate near the coil on the coil mount holder screws .. or anywhere as long as they're in contact with the ally plate ..

 

.. one way or another , id suggest detail inspection of the ignition and fuel supply wiring trough the diagram (if you haven't do so already of course ..)

 

.. but obviously , the fuel pump relay , doesn't receive a triggering/circuit opening signal while cranking so it might be this the 112 wire ..

thick brow one No. 20 is direct supply for the relay to the battery positive ..

green M wire is earth for the relay via battery negative ..

red (if i remember) wire No32 is as well some kind of "sense" for the relay as it goes from the relay via fuse box onto the ign. barrel

 

Was i long time a go since i've been messing about with this fuel pump relay/connector/wiring stuff so can't really remember as much details just slipped my mind ..

 

Damir

[kate205gti 4]

i think so! im pretty sure it primed for a second, although im starting to question my own mind now lol

 

ive replaced the signal wire with another one, i cant really replace the ign amp connector wiring as this is all linked into the engine loom i couldnt see any broken wires in here when i pulled the sheild back plus the car runs and revs fine so the other signals are ok

 

cant wiggle while cranking unfortunately as its only me in the workshop and arms arent long enough to do both

 

that link ive printed before to get the coil wiring sorted coil def wired up correctly and green 112a wire seems intact, will print the advice off here though and have another crack later

 

in the meantime does anyone know if I can MOT it with a switch for the pump, or is this an MOT fail?

 

cheers

[kyepan 291]

usually pumps only prime for a second or so, this is just enough to raise the pressure in the rail.

 

If your not sure, get a gauge in line and check what's going on with the pressure, i had a dodgy pump recently that would not hold pressure after switching off, so consequently took forever to start as it had to pump fuel from the tank all the way to the injectors.

 

a new pump sorted it, but i would have been fannying about for ages if it wasn't for the gauge.

[pug_ham 244 3 Cars]

Kate, does it start even when it doesn't prime just takes a bit longer?

 

I'm unsure about the pump switch, I've known of cars with bodged hard wired fuel pumps pass mot's but that just because the tester didn't realise it was done but I suspect it is a saftey issue because with a stand alone switch there isn't a safety cut out in a crash, just wether they'd notice.

 

Its easy to hard wire it through the fusebox with the heated rear window relay out if you need to...

 

Graham.