wiring in k-jet

hi newbie here! and complete novice not sure if ive posted this in the right section apologies if i havent

im currently doing up a caddy and everything is in but im having trouble with the k-jet ecu loom,
so many questions ill try not to rabbit on i have a mk1 caddy mk1 cabby loom and fuse box and k-jet ecu and loom which came from the engine which was out of a caddy sport

1) what powers the ecu and how does it connect to the original loom?

2) what does the fuel pump attatch to? …. i have the relay in the fuse box but do i neeed to wire it into there or will there be something on the loom?

3) lastly i have 2 fuel lines in the engine bay one a return and one afeed i presume, obviously thr feed goes into the fuel pump but where does the return come from? ive looked in haynes manual and it seems to come from the air box??? however that all seems pretty made up and i cant see anywhere for it come from

would appreciate some help and much is needed

thanks in advance

Just to make things clear, did your car have a carburettor engine and now you are fitting a fuel injection head/engine?

thats the thing im not sure, i got the caddy as a rolling shell and with it came all the cabby stuff  as a donor car like dash, lights detailing stuff, but the engine seperatly, originally came from a caddy sport with k-jet managemnet system, every plug on the engine has been filled with plugs from the loom, however the ecu loom  came seperate and i cant seem to find anywhere on the engine loom where it would plug into, i do have some plugs that are spare but being the idiot i am i cant figure out from any of the wiring diagrams i have. so im abit of a stuck point  
thanks again

The original Caddy sport had some sort of low compression de-tuned K-Jet 1.8 with @95bhp. There may have been other differences to a regular 112bhp 1.8 DX "GTI" engine.

Also later Cabrio GTI engines had different gubbins for idle stabilisation compared to the tintop >83 engine and also had later MK2 Golf style electrical connectors.

The very late Cabrios (and Caddys???) had the K-Jet replaced with Digifant which was a more modern digital version of the analogue K-jet, complete with ECUs which the K-Jet didn't have.

Are you sure all the bits you have relate to the same version of engine/injection system?

Sorry but I can't be much help with the electric side of things as it confuses me as well…

I'm not 100% sure but I don't think my 1988 Golf cabriolet Gti does not have a ECU to control the fuel injection system just a hall sender which controls the dissy?

It's just fuel injection cars have a different fuel tank and fuel lines compared to a carb car as k-jet fuel injection runs at a high pressure and it will leak fuel if you use the wrong type of fuel lines and connections.

Later fuel injection cars have a fuel pump inside the fuel tank which lifts the fuel out into a swirl pot then the fuel goes into an accumulator which holds the fuel pressure when you switch the car off then fuel goes into the main fuel pump then off to the fuel filter in the engine bay then into the metering head on top of the air box then into the fuel injector lines then finally into the fuel injectors, any left over fuel which is not used by the injectors is then returned into the fuel tank.

Do you have these parts fitted to your car?

Picture of fuel parts.
https://volkswagen.7zap.com/en/rdw/golf+cabriolet/goc/1988-44/2/201-69020/

K-jet fuel injectors injection explained.
Bosch K-Jetronic (CIS) explained - YouTube

Yes, to clarify the GTI engines have many differences depending on;

Version of "Golf" fitted to (Golf, Jetta, Cabrio, Scirocco, Caddy)
Country destined (US cars very different from European)
Year, changes post '83 and throughout Cabrio life span and then '92 at the very end of production

Depending on which combinations of parts you have it could be a simple plug and play exercise or virtually impossible

  

hi thanks for the advice
in reply yes i have all the items listed below (fuel pump-accumulator etc etc) and i know the engine and the bosch ecu work together as i they were out of truck i had seen running, the problem i have is that i dont know where or how the ecu wiring loom attatches to the car/existing cabby loom or the fuse box, i presume it needs power to function but like i said i dont know what colour wires are used to attatch anything with, as i said earlier there are some connections that are spare on both the ecu loom and engine loom,

i have looked at the haynes manual but didnt really tell me much or im just not able to read it properly. i know the engine and the bosch ecu wiring loom  came out og acaddy sport which was on a H plate, but not sure aboiut the engine  loom or interior loom as they were out of a cabby

thanks again

Don't think a H reg Caddy sport will be Digipants so there is no ECU as in the modern sense. Are you meaning the transistor pack for the ignition that's on a big heat sink and lives in the bulkhead tray near to the wiper mechanism??

Stick some pics up of what you have.

thanks ive enclosed the jetronic ecu wires and ive enclosed the vacant wires i have in the engine loom
thanks again for the help
kris

That's what I mean, I thought the ignition control unit was called the hall sender    .

Found this on the web?

Testing ignition coil 1985 scirocco | Volkswagen Owners Club Forum

It looks like this?
https://www.ebay.co.uk/itm/VW-GOLF-MK1-CABRIOLET-MK2-GTI-CORRADO-IGNITION-CONTROL-UNIT-C364/221013501493?hash=item33756e6635:m:mUnCDcpLohfHW1WnHFIdYhw

thanks for this i will have a look into that,
any ideas what connects the jetronic to the wiring loom in the engine
thanks again

some more pics if anyone can identify these that would be great especially the block connections

thanks again

on the bay loom:
1. reverse light switch
2. front fogs
3. mfa wiring for old skool MFA with mpg gauge/shift light. It goes to reverse (5th) switch and vacuum switch
4. ignition amplifier/tci unit/spark module

I've no experience with this random kjetronic module you have there, it looks a bit Heath Robinson as well it doesnt look to be genuine VW? I could only offer semi-educated guesses on the functions of all those plugs I'm afraid

post pics of your metering head and fuel pipes etc, I'd be tempted to forget the ecu and run it with basic mk1 gti management

personally I wouldn't fit the JH engine from the sport, they are detuned for emissions regs that we didnt have in the uk, makes more sense to fit a dx from a gti. the metering head is specific to the sport too so only makes 95 bhp if a dx is fitted to a sport.



if you do keep the JH engine you wont need the jetronic unit, it is only there to control emissions so would need a lamba probe for it to work (sports had a cat from factory), the engine will run without it as it is still has a vacuum dizzy and tci,

 you will need to wire in the fuel pump to the fuse box and make some mountings on the body for it as sports had an extra bracket welded on in the factory, you may have issues with it cutting out if low on fuel as the swirl pot pipe in the tank breaks down (as I did). the tanks are all the same but the injection lines will need to be from a k jet car, the sports had plastic fuel lines

this was when I tried a 16v mk2 pump in mine but didn't work as needs to be fed by a lift pump, but shows pump location and fuel lines,

the return line is from the back of the metering head in between the 5th injector line and wur line

thanks for all your help so far im a little gutted bout the jh engine 95 bhp  
 but hey im so close so will carry on hopefully with all your help!! below are some more pics  of the metering head and ive put some in of the fuse box that were on the laptop anyway

cheers guys

my sport never came with the original engine fitted so cant be much help with the jh, that metering head is different to a normal gti, looks like some sort of fuel valve linking the return and supply ports so ecu might be needed for this.
found this page with the kjetronic parts listed

http://workshop-manuals.com/volkswagen/golf-mk1/power_unit/k-jetronic/ignition_system/mixture_preparation_system_mechanical_injection/k-jetronic_injection_system/fitting_locations_overview_(engine_code_jh)/

thanks for all the help i think im going to get a diferent metering head and see if that any different, but first thing is to put in the fuel pump in,
im still having difficulties locating the fuel return line, maybe its due to tht metering head i have i dint kmow, we will see
cheers