Hi All, I hope everybody is well? Just looking for some advice if possible please.... again haha. So my mk2 is nearly ready for mot but I seem to have an intermittent problem with the high pressure fuel pump. It appears to stop working after the car has warmed up and obviously then the car won't start. If I smack it with a hammer it will work again but normally only after it has cooled down as well. Does anybody have the capability of being able to rebuild and refirbish it at all? Or if not is there any still available to buy new? Thanks in advance Kind Regards Calvin
power steering or fuel pump? if fuel pump, check lift pump in the fuel tank if this is dead it'll cause main pump to struggle and eventually die.
Hi RJ Good to hear from you hope all is well? Don't want to sound cheeky but I did say high pressure fuel pump lol. After doing some research I think it may be the fuel accumulator that is the problem. As it only seems to be a problem when the car is hot. This I believe is a symptom of a bad accumulator? Do you think I am best just to replace the lift pump in the tank as well? And is there a way I can test the existing lift pump? Thanks for your help Kind Regards Calvin
yeah, but check the title of your thread for the lift pump unplug the main under the car and see if you can hear the lifter pump prime with ignition. if you swap the 18 relay to the fuel relay socket the fuel pumps will run with ignition, once you do that pop the feed line off the lifter and run a pipe from it to a measuring jug. you should see at least 300cc of fuel after 10 seconds
Sorry about that RJ I don't realise I made that mistake on the title woops, if I had brains I would be dangerous . You advice is very much appreciated bud you are some guy. I will run the checks to diagnose the issue fully before spending 150 on a new bosh fuel accumulator. Can't thank you enough. Kind Regards Calvin
if you're having bad hot starts this can be the accumulator or the non-return valve in the fuel pump allowing residual pressure to drop too fast which then allows fuel to evaporate in the lines. does the car run and start otherwise fine, just hot start giving you problems?
In the past before I completed the 2.0ltr 6a conversion it hated a cold start but I just ran it 5 10 mins in the morning and it was fine, never let it bother me as I know its a common fault. After completing the conversion it ran better than ever and started fine cold or hot. It was only the past couple of times where I ran it up to temperature to fine tune the idle. I would then switch it off and then when I try to start it again (hot) there is no noise coming from the fuel pump as it normally does when you switch the ignition on so it doesn't start. On one occasion I gave the accumulator a gentle tap with a hammer and it worked again. The second time it happened I did the same thing but to no avail. Once it cooled down it made the priming noise and started again but ran quite lumpy and was drifting between 700rpm and 1100rpm on its own before dropping below 500rpm and died. Do you think I may be better off just changing the lifter pump and accumulator seeing as they have probably never been changed anyway? Or is this a waste of time and money? Thanks Again RJ
I am beginning to think about just changing all 3? Accumulator, pressure pump and lift? Anything to look out for and any additional things I should buy before starting? You don't happen to know the part numbers at all? Best person to ask seeing as you are the VW wizard, you should seriously consider creating your very own RJ Haynes. I would buy one .
ok so no fuel pump noise isnt a mechanical issue on the injection system then, so n-r valve and accumulator are both ruled out. what you have is an electrical fault either with ecu, relay or wiring, or the fuel pump itself is dead/damaged. since you mention tapping the assembly can help I'd suspect main pump, but do the lifter pump checks as I mentioned first to make sure that is working properly you might want to do a complete fuel pump refresh while you're there thats your call based on the condition of everything underneath, the accumulator is generally pretty reliable plus as I say in this case your symptoms are electrical rather than mechanical. the ecu should trigger the fuel pump regardless, you could have everything after the fuel pump missing entirely and a pipe from pump into a bucket it should still prime it up
OK thanks for that. I will give the lifter a once over to ensure it is working correctly as you have advised. I will also inspect the wiring to ensure there is no damage etc. In the meantime I think I will order a new relay as well just to rule that out. It's definitely a head scratcher as it only seems to play up when the engine is hot. Is there anything I can do to check the ecu is operating correctly? Or is it a case of sending it off to someone who can check for faults? If so is there anybody on here that would have the capability to do so? Thank you Kind Regards Calvin
if you swap the 67/80/167 fuel relay with the 17/18 relay then the fuel pump should come on with ignition regardless of the ecu, so thats something you can try. if the pumps run and engine starts liek this but wont with the proper fuel relay that tells you either the relay is bad or the ecu trigger for some reason. if the pumps run but engine doesnt start that points you to the ecu being at fault either not powering up properly or going bad when hot
Thanks RJ I have said it once and I will say it again. You are some guy, cannot thank you enough. I will let you know how I get on, fingers crossed it is just the relay Kind Regards Calvin
Hi RJ, hope you have had a good week. Just thought I would give you a wee update on my golf. I was back at it today and the fuel pump relay number 67 had some corrosion on it. Cleaned it up a bit and it worked well. Car starts hit or cold now so going to just buy a new one and replace it. I also swapped over the 18 relay and the 67 relay and the fuel pumps worked no bother and the car started no bother as well. So I think it was just the relay after all which is great news, it saved me alot of money. You are a life saver and cannot thank you enough for all of your help. You have helped me so much from start to finish with my build. Just have a couple of wee things to do now and it's going for the mot.
Hi RJ I hope all is well with you? Just as I thought everything was working OK on the mk2 it started playing silly buggers again today. The fuel stopped priming again. I have cleaned the connection and I swapped the 67 relay with the 18 relay and it still didn't prime. I am beginning to think it is an issue with the ecu. Is it just a case of purchasing a new ecu and fitting it or does it need to be coded to my car and swap out the ignition barrel etc? Also if you can point me in the right direction for a new ecu that would be great. Any help is much appreciated. Kind Regards Calvin
if the relay was corroded its likely the fusebox is internally as well, the fact 18 relay didnt get the fuel pumps running rules out the ECU anyway as it should power the fuel pump ignition on even if the ecu was removed
