problem starting when warm

Hi
Who knows?
But i do know that i am no longer going na use supermarket fuel in my MK1
Fill up with shell optimax & see how you get on
baz

maybe supermarket fuel has a lower vapourising point  :dontknow:

I had this exact same problem. Turned out to be the metering head leaking and so not maintaining enough fuel presure to start again. Always started fine from cold but that's the cold start valve doing it's job and adding enough fuel to fire it up. As suggested above, try starting for 10-20 seconds then floor the gas and keep cranking. Not ideal but generally worked in the end for me. Another way (and be careful !) is to try starting it in gear, seemed to suck enough fuel in to start it…sometimes. In the end though, and if you've searched on this you'll read it a thousand times, it seems the only way to get the bottom of it is to test the fuel pressures from top to bottom.

Good luck mate, try not to let it dull your enthusiasm, you'll get there  :wink: .

Another problem could be rust/paint form the filler neck or petrol tank , temporarly jamming the non-return-valve open (its only a 3mmish bore)
cheers

any updates

Daft question, but have you checked the condition of the fuel pump relay ? They often get very hot and melting occurs.

jamiebell said

i am using supermarket fuel

its strange though as when i got it back last week i ran it for a couple of hours stopping and starting at intervals and it was completly fine  :roll:  i have had the car a few months now and done 85 miles in it  8O  i want to get it sorted so i can go to bugjam in it at the end of july

surely i have to be a way down the list of things to try  :dontknow:

Out of interest what RON fuel are you running? i.e normal unleaded (95) or super (97/98/99)

im just using standard unleaded tesco fuel pump jobby but im going to let it run down and try some super duper high octane gear next trip to the garage (i dont even dare go to the petrol station incase it doesnt start again so use a jerry can)  :redfaced:

filler neck doesnt look bad but i will try checking it out

fuel pump relay will now also get a check cheers lhasadreams

metering head leak will also get a mention when i next take it to the garage or mechanic friend thanks granty

the problem is i am not mechanicly minded at all so i cant do these 'simple' checks myself without frustration beating me  :roll: so i just keep having to pass on this info from you guys to the mechanics

thanks again for all the ideas/help keep them coming  

if you metering head has a leak then this might be the cause get that sorted straight away

You are wasting your time and money on higher octane fuel. This will make zero difference. Octane numbers matter only in higher compression situations.
Check your fuel system from front to back. I have been down this road twice. If you have a boost pump in the tank, check that first. They get weak with age and they tend to get even weaker when warm. If your boost pump is worn, it loads the main pump (by right rear wheel) and then it starts to lose pressure. You need something like 70 psi of fuel pressure for the CIS system to work reliably. If you have a Warm Up Regulator - check that as well. It is often overlooked.
If you have a boost pump in the tank (in the trunk in some and under the back seat in the Cabby) then pull it and look in the tank and see how rusty it is. You may have a crud problem plugging your lines. FYI: if you suspect the accumulator all you have to do is check to see if the little rivet is weeping fuel on the back side. If it's dry then 99% of the time it's good.

"LittleBetty" said

You are wasting your time and money on higher octane fuel. This will make zero difference. Octane numbers matter only in higher compression situations.

hi

Disagree
Last year i would of probably agreed  , but not anymore , the mk1s were designed to run on leaded fuel which was 97-98 octane , so the alternative now is super-unleaded.
My mk1 is running/starting like a dream since i changed from 95octane supermarket fuel . it was fingers crossed starting when Hot before

baz

The guy says his metering head is leaking , its got to be first on the list.

LittleBetty said

You are wasting your time and money on higher octane fuel. This will make zero difference. Octane numbers matter only in higher compression situations.
Check your fuel system from front to back. I have been down this road twice. If you have a boost pump in the tank, check that first. They get weak with age and they tend to get even weaker when warm. If your boost pump is worn, it loads the main pump (by right rear wheel) and then it starts to lose pressure. You need something like 70 psi of fuel pressure for the CIS system to work reliably. If you have a Warm Up Regulator - check that as well. It is often overlooked.
If you have a boost pump in the tank (in the trunk in some and under the back seat in the Cabby) then pull it and look in the tank and see how rusty it is. You may have a crud problem plugging your lines. FYI: if you suspect the accumulator all you have to do is check to see if the little rivet is weeping fuel on the back side. If it's dry then 99% of the time it's good.

cheers for the advice,like i said i have a new accumulator on so its not that,il check the wur and the fuel tank check is next on the list,to be honest im not sure if i have a boost pump or not  :redfaced: its a a reg cabby 18 8valve gti

Interesting. Clearly it's experience that counts, however I wouldn't have believed that those sort of starting problems could be octane dependent. I put about 900 to 1,000 kms a week on my '87 cabby (I use it in the summer as a daily driver) and I use only 87 octane in it, and I have no issues whatever with starting, highway / city driving etc. for the last three years. I had two episodes of difficulty keeping it going once it was hot, and both of those were pump related. I would be very concerned about the fire risk if the fuel dizzy is leaking.

jellybelly said

if you metering head has a leak then this might be the cause get that sorted straight away

i didnt mean i have a leaking metering head its just a member mentioned it on this thread so i will ask them to have a look for one,im trying to explore every avenue

i had a quick drive around in it earlier and noticed the fuel pump was making a bit of a noise every now and again so i think im going to stick a new one on see if that helps

does the car run perfect?
is your only issue hot starting?
if its yes to the above two Qs, i doubt its your fuel pump. But maybe its a sign there is rust in your system if the Pump is working hard.
have you tried running it on non-supermarket fuel ? costs nothing to try this.
does the car start first turn of the starter motor when its cold? & then run perfectly straight away?

its starts first time every time from cold but then runs a bit lumpy for a minute or so and then its fine until the above problem starts to occur,im going to stick some better fuel in as soon as i have run this batch down a bit

the problem is it never does it when i have someone to look at it  :dontknow:  soda law eh

jamiebell said

its starts first time every time from cold but then runs a bit lumpy for a minute or so and then its fine until the above problem starts to occur,im going to stick some better fuel in as soon as i have run this batch down a bit

the problem is it never does it when i have someone to look at it  :dontknow:  soda law eh

Injectors are leaking

so a new set of injectors and seals are on the to do list as well now  :roll:  never mind as long as it gets sorted



i realy realy appreciate all the helps you guys are giving me with this   when i get it sorted il be buying a few of you a beer at the meets  8)

jamiebell said

so a new set of injectors and seals are on the to do list as well now  :roll:  never mind as long as it gets sorted



i realy realy appreciate all the helps you guys are giving me with this   when i get it sorted il be buying a few of you a beer at the meets  8)

The reason i now think its injectors is because it sounds like your injectors are flooding the engine when youve left the car over-night , hence the lumpy start-up
You should maybe test them first , how to guide on the left.
good luck
baz

Yip of course back to the Main problem ( hot starts ) leaky injectors will also cause problems starting when hot