Slight loss of power after driving for an hour

[lazy]

I've only had this happen two or three times but it just feels like there's a very slight loss of power after driving for about an hour. Once you park up and come back to it it's back to normal. There's no fault codes so no obvious indication of anything wrong. If anyone can shed some light on this would be great.

[ZoliWorks]

Check fuel pressure on both sides. This is just a hunch but maybe your in-tank fuel pump control module or the pump itself are on their way out

[mjmallia]

Yes.  The pump control module that is under the rear seat, but on top of the LPFP.

The early ones but even more newer ones (part has had a lot of revisions) start to overheat and cut out.......my wifes one got to the point of burning and caught it just in time.

The very new parts have a metal backplate for heat dissipation

It is worth a look.

[mjmallia]

NEW on the left and old style with a lot of revisions inside on the right

[lazy]

I might as well change the pump while I'm in there I suppose. I'll just get the parts from TPS that way I'll get the latest versions of the parts.
You would think low fuel pressure would put an engine light on  wouldn't you.

[ZoliWorks]

Check out my thread for recent pump related stuff. you've got part numbers and stuff there to help

https://www.mk5golfgti.co.uk/forum/index.php/topic,134567.0.html

[lazy]

I priced up a fuel pump and controller from TPS, £270 for fuel pump and £160 for controller. I wasn't too happy with those prices so spoke to our usual parts supplier who's been in the trade for a very long time and is really good. I asked him to get prices on the best available aftermarket parts. He said VDO didn't supply aftermarket pumps. Bosch was £105 Hella was £100, and for controllers Pierburg £95 or Intermotor £90. I was going to go with Bosch and Pierburg but I asked him what he would go for and he said Hella and Intermotor so I went with those.
The Intermotor controller is actually a VW part so that's good but the Hella fuel pump didn't feel as good as the original.
I now hear the fuel pump buzz when I open the driver's door which I'd never heard before, and normal driving at below 3000 rpm seems slightly smoother and more responsive, I'm wondering if that's just in my mind though, no difference at high rpm. I just need to go on a few long runs to see if the drop in power is fixed.















Old parts are the bottom pictures
The new controller had little black stickers over the VW mark and the Keboda mark.

[lazy]

Also a fault code that has been on the car since I got it has gone now. The code was P129F low pressure fuel pressure too high. I'd changed the sensor on the hpfp when I first got the car and it didn't fix it, but I thought it was running ok so didn't bother trying anything else.

[ZoliWorks]

That code was likely the fuel pump control module, but it's a good thing you sorted it out. While at it, I'd also replace the fuel filter. Go for UFI 6.6bar as it's an OEM manufacturer for half the price. Legit got an OEM filter and it came with the exact same text and markings as the UFI filter, except it had a VW part number and logo on it for 3x the price..

[lazy]

Thanks Zoli I've already done it, I got a genuine one, but it does pay to shop around. I'm going to have to shop around and be more careful with my money this car has cost me a fortune and I haven't even had it a year yet.