1.8JH running problems

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1.8JH running problems

Post by Milan » Tue Sep 08, 2020 8:45 pm


I'm having some engine running problems with my '90 Scirocco mk2 GT2, with 1.8jh engine.

The problem: car tends to stutter when shifting up or going above 5000rpm; really short stuttering (a second or so), then after the stuttering it pulls pretty decently again. Sometimes it runs perfectly fine without any trouble, then an other time it stutters again. Sometimes it even runs fine for a couple of weeks, then the problem shows up again.

What has been done to the car:
-new fuel pump
-fuel filter
-head has had a rebuild
-garage has checked everything from ignition down to fuel, set CO mixture etc.
-checked filler neck and seems fine at first sight

Has anyone had a similar problem?
Thanks already!

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Re: 1.8JH running problems

Post by kidcrewbob » Tue Sep 08, 2020 11:40 pm

Check for crap in the tank via sender port under back seat - take great care removing the plastic bayonet fitting as I managed to trash mine. I thought my filler was ok but the amount of rust flakes surprised me and seemed most likely the cause of a stutter when said bits block the uptake tube randomly, especially after going up / down hills and round bends which slosh the fuel around......gonna flush tank and swap the neck this weekend all being well.

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james butler
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Re: 1.8JH running problems

Post by james butler » Sat Sep 12, 2020 12:18 pm

have to be honest i dont rev mine much past 4500rpm as it enevitably causes a problem and 8vs generally dont pull better past that point.
does sound like fueling issue at first glance though.

I dont mind project cars but I HATE SANDING!!!

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Re: 1.8JH running problems

Post by Kdc169 » Mon Sep 14, 2020 8:12 pm

Are you sure its not the limiter cutting in.. my cabby is jh and only judder on start up..like misfire until warm. Then when high revs its got a limit built in small shudder..

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Re: 1.8JH running problems

Post by RussGLAuto » Wed Oct 14, 2020 8:38 pm

Check your fuel filter, I agree with the previous comments here, I am having the same issues.
My filter was full of rust particles after some vigorous driving on some back roads. Nothing for it but to replace the tank and completely flush everything upstream including the mechanical fuel pump, fuel vapour trap and of course the carb jets.
The filter won't stop everything.

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Re: 1.8JH running problems

Post by Eagle1 » Thu Oct 15, 2020 9:34 pm

I've had a similar problem on my Mk1 Cabby. Now I've replaced all the hard fuel lines and "gone fishin" in the tank with one of those extendable magnets it's a lot better. When the fuel sender is out check the condition of the in tank fuel hose if it has one and the little filter. I changed the fuel pipe and left the old fuel pipe out in the open once I'd changed it and within a couple of days drying time it literally crumbled away.

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Re: 1.8JH running problems

Post by EDDIE-F » Sat Oct 17, 2020 8:21 pm

In my experience. With my carb 1.8 mk2. what works for me is the following. take out the fuel sender/pickup remove or drill big holes in the plastic filter on the end of the pickup. After fitting a cleanable gauze filter in line with the existing paper plastic filter. this way all the on going rust gets pumped up to a cleanable filter which you can monitor and clean out. I also replace the cheap inline filter every 1000 miles or so. you do need to keep the plastic in line filter as the gauze one only catches the bigger stuff. you will know if the fuels being sucked easily out of the tank, as the clear return hose will have no bubbles in it. I found the mechanical pump is so powerful. If the pickup is blocking it sucks air in through the jubilee clip joints, causing bubbles in the return tube. i have used this system for two years no problem.