Engine judders only in certain situations. Fuel starvation???

Hi All

I've recently developed a judder whilst turning left and going up a hill at about 20-30 mph.
It's really quite harsh and only does it for the bend and the incline, which is only a brief time. I've tried to get it to do it on a flat left hand bend and right hand bend, but it wont. Unfortunately I've not got a similar right hand bend on an incline to try it on locally.

I'm wondering if there is something about the way the fuel tank is orientated that could effect this, or a pick up pipe internal to the tank has dropped off causing fuel to not be sucked into the pump in this situation?

Only doubt in my mind is that it doesn't seem to matter much if the tank is at differing levels, although I have not tested this extensively. Will be topping it up soon, so will try again then.

Just curious if others have experienced anything similar, and if so, do you know what caused the issue?
The car is an 82 GTi with an ABF fitted. Goes really well the rest of the time.

Many thanks

Sounds like a partially plugged filter screen in the tank, or a iffy fuel pump.

Thanks Briano
If i'm honest, I've had my suspicions about the pump for a while as I can now hear it, but it keeps up just fine when I nail it for a while. Might get a facet.

If I remember there is a tank access port under the rear seat so I don't have to drop the tank. Is that right?

As its low on fuel now, it makes sense to do it before I fill it again.

Thanks

Assuming you are still running the original GTI tank setup it is a known issue with a rubber flap in the tank failing and causing fuel starvation as the petrol sloshes to one side of the tank when the tank is less than a 1/3 full.

Fill tank and see if it cures the problem.

I bet it's your swirl pot, - especially if it's happening when your going round a bend or up hill.
This is the swirl pot it's going to be next to your fuel tank drivers side above the main pump - easy to find if you lift the car up , there is a mesh inside you can't get to you just flush it out - IGNORE the writing on this photo - it's WRONG!


There is a screen inside it, make sure it's not blocked - also as Brian says, check your screen on your lift pump - under the back seat - just lifts out but be careful taking it out that the screen does not pop off as you pull it out. If that screen is blocked it might be starving the swirl pot.
This is the mesh you want to check


While you are at it - check your fuel lines are clean and not perishing - my ones turned to a fine crumbly dust when I took them off to inspect swirl pot and made issues further down the line in the WUR and metering head as I accidentally contaminated the braided lines !!

Then again - it could be any list of other problems! But with your description I bet it's fuel tank end - and you don't need to drop the tank unless you need a new tank!

squideatingdough said

I bet it's your swirl pot, - especially if it's happening when your going round a bend or up hill.
This is the swirl pot it's going to be next to your fuel tank drivers side above the main pump - easy to find if you lift the car up , there is a mesh inside you can't get to you just flush it out - IGNORE the writing on this photo - it's WRONG!

There is a screen inside it, make sure it's not blocked - also as Brian says, check your screen on your lift pump - under the back seat - just lifts out but be careful taking it out that the screen does not pop off as you pull it out. If that screen is blocked it might be starving the swirl pot.
This is the mesh you want to check


While you are at it - check your fuel lines are clean and not perishing - my ones turned to a fine crumbly dust when I took them off to inspect swirl pot and made issues further down the line in the WUR and metering head as I accidentally contaminated the braided lines !!

Then again - it could be any list of other problems! But with your description I bet it's fuel tank end - and you don't need to drop the tank unless you need a new tank!

An '82 GTI won't have all those gubbins, they're from a later Cabrio GTI

Right you are! - just ignore me, didn't read what model we were talking about!

Ignore post and carry on as normal!  🤪👍😄

The 82 fuel tank should be a bottom feeder.  If the internal baffles on the tank are clogged, and the filter port is then that is the issue as the fuel can't hold in the pick up area.  

Some one posted great pictures of that filter screen here a while back….  

Thanks guys. Going to run it to work a couple more days to use some fuel then open it up and have a look.
Thanks for the info  

So the filter screen is clear. There were some filings in the bottom which I took out with a magnet, but generally all looks good in the tank.
Fuel filler pipe is good, and was replaced about 10 years ago.
It looks like the pick up pipe comes in through drivers side of tank and into the filter housing under the inspection port/sender hole. Any one able to point me to an exploded view? But it all looks OK to me.

I guess in just going to have to fill it right up and see. Seems odd that is only happens on the same corner.

Thanks

I had that same thing happen on a dodge that I used to own, and it started to occur prior to the fuel pump going out.....

have a closer look at the plastic swirl pot inside, as mentioned it has a bunch of rubber seals & flaps which degrade. once that happens the pot is nowhere near as effective and can cause starvation while cornering. brim tank and try again, if no better look elsewhere

Thank Rubjonny

I did notice that the rubber star at the bottom of the swirl pot was not in the best of shapes. i may not have helped the situation by digging around in there…

However, this used to do it when full (ish) of fuel, and did it quite bad Tuesday morning on my way into work when fuel was low and after I had fiddled with it at the weekend.

I then topped it right up and it hasn't done it for the last couple of mornings despite pushing it hard around that bend.
I shall keep an eye on it and report back, but for now I can't make it do it.

If I need to change that swirl pot, then I assume there is no option but to drop, drain and split the tank? It is not coming out of that inspection port…

Anyone know of a cost effective, easy to read fuel pressure indicator I can put inline just to keep an eye on pressure? Maybe one I could output to a gauge I could mount in dash?

Many thanks

if the pot has gone then you're stuffed basically, it wont come out without destroying the tank

aftermarket tanks have a crude pot design, some have found them ok some not. an alterntive is mount an external pot and use a lifter or pre-supply pump. but trouble with that is finding the room

if you can poke your head out the window sometimes you can hear the pump gettign loud as it starts to strain

if you didnt check it already some main pumps have a wee mesh basket on the inlet side which can clock, even if not worth a look to see if any crud in there:
https://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=how-to_2%2Ffuel-tank-cleaning_3&kfs103=30

Thank Rubjonny
I'll check if I have the little mesh on the pump inlet.
I'm still pushing it hard around that bend and after my fiddle and the top up, it is yet to show the same starvation issue.
Got a wet weekend ahead and the family are away, so i can check that pump inlet.

What is all the rubber gubbins for in the fuel tank? Is it just about protecting the pump from crud? What other issues might I cause if I just tried to pull the rubber all out??

the main job of the rubber bits is to seal up the pot so it keeps the fuel inside when levels are lower. if seals are gone the fuel drains out the pot and it wont work as well

Thanks Rubjonny
Sounds just like whats happening. I've not got a mesh basket on the pump inlet and all seems clear. I'm thinking it would probably exhibit the same juddering under heavy acceleration and different conditions if this was my problem.

74 miles out of the full tank and it started to show the same issues on the same corner. Hard to judge it correctly as it will depend on the exact speed i'm doing and the relative amount of 'slosh'.

I've concluded my swirl pot is not swirling correctly any more.  
Now to consider correction options, or just fill it up every 70 miles…..

Hi Lads, Trying to fix the same fuel starvation issue, mine gets to about 100 miles which I reckon is around 2/3 empty and it happens around right hand corners.  Did you solve the issue? or does anyone have any other suggestions other than filling the tank every hundred miles.   

as above take out lift pump under back seat.. check tank is clear of debris, 1 of my cars i have to open petrol cap to let breathe on long journeys, and swapped anti gravity pot, clean hoses.. but just for piece of mind i open and close cap prior to driving.

Intank pump i guess depends on model of car..  i have new peirburg spares
 and new vented hella fuel cap
check website below.

Thanks Ken,  Its a Tin Top GTI, so no lift pump.  Have checked for vacuum at the cap and its fine.  Suspect VW  recognised this fuel issue and that why Cab's have the lift pump and the fancy white filter unit.  Going to put a 5lt drum out the window with a pipe to the fuel pump and see once and for all is it the tank or something else.  That should be fun