WHEN HOT, WONT START GTI!!!!

Howdy. I really would appreciate some input with this problem.
I have just started using my mk1 1.8 1983 (A plate) gti. It starts cold perfectly, and runs perfectly, but once i turn the engine off and leave it 5 mins plus, it just will nort start again for at least an hour till its cold.

Please, if you have an idea what could be the cause then let me know asap as i am now needing the car as my main run about also dropping baby off / picking up so i need it reliable…..it has also had these replaced just recently:

Engine: A timing belt kit and water pump
Transmission: New Clutch Kit, rear crankshaft oil seal, clutch cable, gear change bush kit and new gaitor
Fuel System: New fuel pump, fuel tank sender, new accumulator, new regulator, fuel filter and non return valve
Brakes: Front brake pads, brake hoses and offside rear wheel bearing kit

It has also had a full service where the plugs, plug leads, distributor cap, coil, air filter and oil filter were replaced.

thanks in advance….
DOG   

could be the 5th injector or the wur

possible faulty thermo time switch or maybe leaking injectors. try running it then stopping when hot. disconnect the 5th injector and see if she starts.
also worth taking the plugs out and seeing how they look.

quite a common fault in gtis from what ive seen posted

If you do get it started when it's hot how does it run, is it lumpy for a bit and then smooths out or does it run OK.

If i start it not too long (few minutes) after i stopped it when hot then earlier it did start very lumpy and yes after about 30 seconds it smoothed out and was fine. If i leave it too long then it just wont start. (i managed to jump out - fill her up - then start again (pay at pump) and it started but any longer and not a chance till she is cold again)
cherers
DOG  :dontknow:

Same thing happened to mine.

Change your fuel pump check valve. I think it was about 20 quid and can be changed in about half an hour.

It screws into the fuel pump at the outlet end by the way :wink:

Hi. Do you know where i might get hold of a fuel pump check valve from.
cheers
DOG

Be careful with the "change bits, hope it will fix it approach" it can cost you a lot of money before you get it fixed.
K-Jet is a mechcanical system driven by fuel pressures, so to fault find it you need a fuel pressure gauge to measure and check the pressures.
Check system pressure, control pressures warm and hot, accumulator holding pressure, injector flow and leakage.

Poor hot start could be because of:
Knackered WUR - check hot control pressure
Low system pressure - shot pump or metering head, could be shimmed
Faulty 5th injector or thermotime switch - take it out a see if it operates when the car is hot
Leaky injectors - pull them out to check, manually run the pump to check spray pattern and flow rate
Knackered accumulator/pump check valve - system pressure will not be held long enough

One check you can do is to try some "cold start" fluid during (hot) starting. You'll need a good long squirt, or get someone to do it while you try start it. If it then starts, this indicates the car is lean, which could be due to a worn fuel pump. Basically what's happening is the pump is unable to develop enough pressure to open the mechanical injectors during startup (lower volts to fuel pump). It starts at cold because the 5th injector fires, this is able to open despite much less fuel pressure because its an electrical injector and just needs 12V to open.

You can get one from your local vw dealer.

I think the 'change it and see if it works' strattergy will work in this case. :wink:

The problem i think is thst there is no fuel filter between the tank and the fuel pump. The check valve is (i think) basically a sprung loaded ball bearing. It can get crap from your tank stuck in it, causing it to leak.

It's purpouse is to maintain fuel pressure, especially when hot, to stop your fuel evaporating in the lines.

Good luck!

If it's lumpy when it does start from hot it could be the injectors leaking fuel into the cylinders, the engine has to burn this excess off and that causes the lumpy running or hunting. It could also mean that the longer you leave it the more fuel gets into the cylinders and the flooding reaches a point where the car just won't start. If you start it from cold then stop it immediately and pull the injectors out, you might see them leaking. As in  previous replies you really need to test the fuel delivery, the control pressures hot and cold, and the holding pressure. It sounds complicated but is simple if you've got the gear to do it, ie a pressure gauge and something to collect the fuel when you check the fuel delivery. A manual is essential, so is a fire extinguisher. Cheers

Hi. Thanks for all the replies so far. Youve been very helpfull. I think so far that if i can get a new check valve for the pump for a relatively cheap price then i will replace it first. I am a bit suspicious that this problem has been around with the car before i bought it as the guy has put on a brand new pump, actuator, filter and loads of other parts that could possibly have been replaced in the "hunt" for this fault.
If the valve wont sort it then it will be full pressure checks on the lines to see whats happening. The first other check i thought to do would be to just loosen a fuel feed line  when it doesent start and just make sure that fuel is being sent.

I`m stil open to ideas but the more i have looked into the check valve on the net, the more it seems to be the issue in this case.

I will let you know how i get on.
Many thanks again
DOG

DOG said

 The first other check i thought to do would be to just loosen a fuel feed line  when it doesent start and just make sure that fuel is being sent.

please do not do this. the system runs on such a high pressure that it will spray fuel. it's bad enough when you change a fuel filter, but if you are turning the engine over you'll get petrol spraying in your, by now HOT, engine bay. also you need 47psi to open the injectors. if you have 46psi or less, then you will still get fuel peeing out if you loosen a fuel line, but it may not be at a high enough pressure to actually open the injectors.

Have you fixed it?

my 1982 1.8 gti cab starts 1st time then wont tick over until its warm does any1 have a clue to wot it cud be thanks ant

bigant said

my 1982 1.8 gti cab starts 1st time then wont tick over until its warm does any1 have a clue to wot it cud be thanks ant

Best to start a new thread…..welcome to the club!

Its going to be either WUR, too low idle speed set or faulty AAV.

howdy….still on with this problem..summary is ……it starts perfect cold everytime and runs all day long, but if i turn it off and try to start it again after 5 mins then NOTHING…turns over but wont start.
SO i went to replace the check valve (cheers) but then looked through the paperwork and it had just had 1 prior to me buying it.

I havent really put much time into sorting this problem out yet but i sure am gonna kick its ass now.
last qucik check i did was basically inspect the spark (which it does on every 1 when trying to start so that aint it)….BUT what i have now found is that there is no fuel coming through at all when trying to start…..or at least i think so…………as i removed all the spark plugs and there was not even the slightest sniff off fuel in the cylinders……

I HAVE JUST BOUGHT….the bosch service manuals for k-jetronic and others etc so i will be reading every scrap off spec for the k-jet system tomorrow…..
I Think its most likely an electrical/sensor issue cutting off the fuel when warm as this seems to be the real issue…
ANYWAY thanks for all the input ive had and i will let y`all know how i get on….and if you think i`m barking up the wrong tree than please say….i appreciate and really could do with doing a fuel pressure test but at the mo im kinda in the "dont want to throw good money after bad" type catch.

dog

 :dontknow:

did you ever find out what the problem was. As this is a major problem with mine.  

cheers Alex

Have you tried to start it by connecting the starter to the battery when it's warm? This will rule out lots of possible ignition issues? Also are there any immobilisers fitted or old bits of them wired in?