Mk1 GTI will not start when hot

Helloi have a Golf GTI cabriolet 1987 1.8 k jetit starts from cold perfectly, after half hour or so drive,leave it for 10 mins and it takes ages to start?? Approx 45 seconds once it does start it runs fine
I have replaced the accumulator & in tank fuel pump
would worn/hard injector seals make this happen?please helpthanksSimon 

Help please.

When was the car last serviced with new spark plugs, HT leads, dissy cap and rotor arm?

Do a compression test when cold and hot. Rule out one nasty surprise.

Ensure dizzy and plugs etc are in good shape and check dizzy cap for cracks. Look very close with a bright light.  

It could be running rich and that will help it start when cold but not so when hot. Check plugs for black build up.

5th injector. Is this still firing when hot making it run Rich. Not sure how you can test this but worth a look.

I would say sucking air is not the issue as engines tend to hunt when sucking air and also would be hard to start hot or cold if this was the case.


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Thanks for the advice so far, I will do the suggested and report back.
 Thanks again
 

So the plugs, ht leads, dizzy cap and rotor arm have now been replaced.

should the fuel pump be heard every time the ignition is switched on? Mine doesn’t but it can be heard once the engine is running.

at the minute I cannot get it to fault but am sure it will, I did forget to say that when the fault occurs and the engine eventually starts it misfires - could it be spark or fuel?
could the coil be faulty, could the fuel distributor be faulty?

any advice would be gratefully received

thanks

Simon 

Normal for the fuel pump not to run when you switch the ignition on as you've probably got (I think??? ) No62 relay as the fuel pump relay, other relays or older GTi do prime the fuel pump before starting.

If you are having to press the accelerator pedal to start it when hot the misfire/lumpy running could be to much fuel ?

Sorry can't be much help as I've not had a hot start problem to deal with.

Thanks mark1gls
unsure about the number on the relay as it hasn’t got any numbers on it
 

Your cars only a year older than mine so that's why I recon you have the same relay as mine with no priming before starting.

Another thing you could try to eliminate it is unplug the 5th injector (there's a blue electrical connector on it) when the engines hot to see if it starts any better in case the 5th injector is spraying in more fuel.

I did run with the 5th injector unplugged for about a year as my old fuel injectors leaked when I switched the engine off.

Good idea, I’ll disconnect it and try.
i am wondering if it could be the non return valve on the fuel pump?

I’m thinking of replacing the fuel pump under the car as the one way valve in the end of it could be the issue?
what do you think?

If it was the NRV then the issue would occur hot and cold conditions.  

If only a problem when hot then unlikely to be an issue with fuel delivery (other than too much fuel).

If loss of pressure then simply leaving the ignition on for 30seconds before cranking when hot will give the pump enough time to pressurise the system and therefore rule out a pressure issue.

I would focus on the 5th injector first. Get the engine warm then isolate the 5th and see if it fires up easier.  If it does you found the issue.  

Other issue could be (as I have it with mine) is the low voltage plug on the side of the distributor.  Mine is a dodgy connection and really needs replacing. When it gets hot under the bonnet it tends to lose its grip a little and then won’t start through lack of spark. Just have to give it a gentle press down and off I go again. Will replace next spring but for now it’s manageable as very intermittent. I assume the heat simple allows the plastic to expand a little and it slips free. All but nasty in that area of mine really.

Other issue could be fuel starvation. It may not be heat but just running it for a little. Before I changed my tank and pump etc then the crud in the fuel pump would act like a really slow pass filter. Start fine when cold or sat for a while. Drive it somewhere say 10 miles or so and would be fine but any further would stutter like no fuel. Lift the bonnet have a look a things. Check spark and in the 10-20 minutes of looking around the pump would of cooled down a little, the crud would have let enough fuel pass to recharge the lines and the thing would fire up. Took me about 2 months to diagnose and that was Only because the fuel pump got progressively louder of that time. Like you I originally linked it to being hot but was more about time than heat.  

Hope my ramblings spark some thoughts to help in some way.


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Does your car have a coolant temperature switch (in addition to the gauge sender)? This is a symptom when they go bad. The computer thinks the car is cold and floods it out on hot starts.

Thank you backinblack & nedrager

you both have given me something to go at, I will have a look at the weekend and update you

thank yo so much 👍