Problems with idle and hot starting

Couple of small problems that could be connected. When at idle the engine hunts between 800 and 1200 rpm. Also, the engine is reluctant to start when hot and when it does start it is only on a couple of cylinders. The rest fire up after a couple of seconds.

I'm guessing this may be fuel related.

Any ideas chaps?

Can you please tell us what engine you have and is it injection or carb. If carb what are you running?

We need much more detail then that please. 👍

Oops! Sorry about that. Engine is 1.8 gti running unleaded.

Golf Cabrio said

Can you please tell us what engine you have and is it injection or carb. If carb what are you running?

We need much more detail then that please. 👍

As well as the engine type of fuel system
Carbed, CIS, (which CIS -e-k) or Digifant.
Then Automatic or manual.

1.8GTI is a Plethora of things.

Manual gearbox, fuel injection
Not sure what you mean by CIS or Digifant, sorry

Usual suspects I would start with for these would the warm up regulator for the idle issues and fuel accumulator for the hot start.

However, the root cause of these issues could be the overall condition of your fuel system. If you haven't already checked inside your fuel tank for debris this is the first thing I would do, otherwise you could end up going round in circles (been there, done that!)

Quick check on the accumulator is to check if there is any fuel leaking from the small screw on the end (if so it needs replacing)

Malcs_cc said

Manual gearbox, fuel injection
Not sure what you mean by CIS or Digifant, sorry

CIS e-K have metal Jacketed Fuel Lines to the back of head SS wire braid over Rubber hoses.

Digifant there is a Plastic Fuel Rail holding Electrical (usually blue) injectors.
Digi
Vacuum leaks, you need to replace all cloth covered hoses and check the idle bypass Screw on the back of the throttle body. You need to clean the ISV and Validate that you have good grounds from Battery to frame and frame to engine/tranny.

CIS hates vacuum leaks as well and it to has the throttle body Idle bypass screw that can be a vacuum leak.

VW's hate leaky vacuums.

Thanks for the input guys. If it's dry tomorrow I'll have a look under the bonnet and try to identify the injection system. I know the fuel tank was refurbished during the renovation. I'll let you know what I find.
Cheers

See here for difference between k-jet and digifant injection systems, yours should be a k-jet if it's the original engine.
I've posted pictures towards the bottom of this thread.

View topic: Looking for a Mk1 1.6gti engine - The Mk1 Golf Owners Club


for the idle going up and down I expect your car is ticking over on the idle stability valve (ISV) if the revs get to low it kicks in and increases the idle speed it's meant to work when you turn on the headlights, heater, rear heated window etc when there is extra strain on the engine to stop it stalling. Try increasing the idle speed there is a screw at the back of the throttle body which can work it self lose or the rubber O ring is past its best. Adjusting the idle screw will not upset any thing so it's worth a try, after you adjust the screw blip the throttle a couple of times to settle the engine, idle speed should be about 950-1000 rpm but I find mine happier at 1000rpm.
Ive posted pictures in at her thread about the idle screw and the print here.

View topic: 1800 DX idle low (Update Now Sorted) - The Mk1 Golf Owners Club

I should mention that once the engine is running, it is very smooth right through the rev range when driving

Think I had vacuum issue…the hose at back of throttle the clutch cable /5th injector  area the hose had become worn.  So could check there also.

As before check inside tank for rubbish. Via back seat pump cover. Give everything a tap with small hammer when warm or add some wd40.. may free up some sticky parts.

Idle issue fixed with a small tweak of the idle screw. Nicely settled at 1000 rpm. I'll start looking around the vacuum hoses next!

Hot start problem could be the accumulator as already mentioned eairler, remove the small bolt at the back of it and if petrol pours out the accumulator is shot. The accumulator job is to hold the pressure in the fuel system.
It does not matter so much when the car is cold as extra petrol is sprayed in by the 5th injector to help start the car.

Have you checked see what your co. Running at on smoke machine.  Could be running week
I had nightmare with my old 8 valve non start when hot changed everything.   In end put down bein f::ked ( broken )    Spanners came out 2,0 abf  fitted now