Fuel pump upgrade

natt · 10-04-18, 08:26 PM

Hi guys. So I'm in the midst of replacing the engine on my 80. One of many jobs is to replace a rusty fuel line and u got to thinking about replacing the fuel pump as it looks like the original. I thinking of fitting an uprated pump and was wondering what, if any, my options are? As far as I'm aware it's an external pump (haven't had a proper look) so I'm hoping I have a wide range of options.

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msh · 10-04-18, 09:00 PM

Changing fuel pump solely because "it looks original", but leaks no fuel and makes no loud noises [although loud pump still could work nicely] is simply waste of time and money. As for "uprated pump" - yeah, if you have an engine with at least 200 bhp and you're going to hit 300 bhp mark, uprated pump will be necessary, but in case you still have stock engine, again, waste of time and money.

quattrodave · 11-04-18, 10:03 AM

Leave it alone, the quality of new parts is nothing like ones made 25 years ago, by all means buy a new replacement just in case in breaks at later date but if it in't broke don't fix it.
Be thankful its not a coupe B3/4 we went through 3 pumps during our ownership of a 2.2 quattro before the car was 16 years old and sold, they used to last 2 to 3 years max.

Replace the lines I'm surprised they are still original, on all the B3/B4's I've owned the fuel lines were totally goosed by the time the cars were 20 years old so you're definitely on borrowed time.

Colin Aitchison · 11-04-18, 10:14 AM

If the pump is old yes replace it, but only with a standard pump, price range you will see from under £20 to £100, you may not realize this but the fuel pump runs at over 100% of what the engine needs at full throttle all the time, www.onlinecarparts.co.uk do many fuel pumps that fit your car depending on the model, pumps are normally rated by fuel pressure and flow rate
( 6 bar at 130 Lt/Hr ) make sure you get the correct pump with the correct inlet and outlet pipe/thread size.

msh · 11-04-18, 08:25 PM

Quote:

Originally Posted by quattrodave

Leave it alone, the quality of new parts is nothing like ones made 25 years ago, by all means buy a new replacement just in case in breaks at later date but if it in't broke don't fix it.
Be thankful its not a coupe B3/4 we went through 3 pumps during our ownership of a 2.2 quattro before the car was 16 years old and sold, they used to last 2 to 3 years max.

The main problem here should be fuel pressure required - new good manufacturer pump that is going to run @ 3-4 bar likely will last long time, but when it comes to K/KE jet, the durable solution will likely be bosch motorsport 044 fuel pump, solely because it has been made for powerful engines with high boost pressures...

Hanuman · 12-04-18, 05:58 AM

Another consideration before uprating, is ensuring that the pump is getting a good electrical supply. It's old wiring, and old fuse box, expected to supply a fuel pump which is quite a distance from the supply.

There are many URs with a relay modification for this reason. It's amazing what the loss of 1-2volts can cause.

msh · 12-04-18, 09:55 AM

Age of the fusebox and wiring should make no difference, but gauge of original wires aren't very thick. But then again - it's not a turbo engine and therefore not important and also probably pump which is spinning slightly slower will have slightly longer life.

Hanuman · 12-04-18, 10:56 AM

Quote:

Originally Posted by msh

Age of the fusebox and wiring should make no difference,

In an ideal world. But the ideal world doesn't exist, and what we have is aged wiring, tarnishing, loose contacts, and a myriad other little niggles. It's not just cars that suffer from aging wiring.
It may be that a pump running slower will last longer. But one that intermittently doesn't run can be a problem.

msh · 12-04-18, 07:37 PM

Well, that's special case, situation when there is some problem

Unless that has happened, there is just one "problem" - some rather long distance with wires of average gauge - but that won't be problem for cars with moderate power NA engines, unlike, let's say, the same thing with headlights - because of that I even didn't bothered to upgrade something for pump wiring of my 2.0 8v mk2 golf, which in VW is even worse than in audi, as it uses main fusebox ground - while headlights have thick wires integrated in loom and pair of relays on top of fusebox, giving "oncoming truck" effect....

AdrianH · 14-04-18, 09:55 AM

IMO the basic test for a pump which is otherwise working OK, would now be to measure the current draw. I wish I'd done this on my 30-year old MB, it would have saved me from being stranded side of road while I figured out why it'd suddenly stopped. Not sure what this one is supposed to be but on a urQ it's supposed to be about 8A, I think, and mine was drawing 13.5A+, which eventually blew the fuse.

12-04-18, 05:58 AM	#6
Hanuman Trickster Classic Audi Club Member Join Date: May 2009 Location: Heckling from the cheap seats, Phnom Penh, KoW Posts: 7,006	Another consideration before uprating, is ensuring that the pump is getting a good electrical supply. It's old wiring, and old fuse box, expected to supply a fuel pump which is quite a distance from the supply. There are many URs with a relay modification for this reason. It's amazing what the loss of 1-2volts can cause. __________________ I wish they would keep the damned Chinese away now that I can go home, so that I can enjoy Fish amok and a draught Angkor

10-04-18, 09:00 PM	#2
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	Changing fuel pump solely because "it looks original", but leaks no fuel and makes no loud noises [although loud pump still could work nicely] is simply waste of time and money. As for "uprated pump" - yeah, if you have an engine with at least 200 bhp and you're going to hit 300 bhp mark, uprated pump will be necessary, but in case you still have stock engine, again, waste of time and money.

11-04-18, 10:03 AM	#3
quattrodave Grown up member Classic Audi Club Member Join Date: Dec 2010 Location: Bingley Posts: 634	Leave it alone, the quality of new parts is nothing like ones made 25 years ago, by all means buy a new replacement just in case in breaks at later date but if it in't broke don't fix it. Be thankful its not a coupe B3/4 we went through 3 pumps during our ownership of a 2.2 quattro before the car was 16 years old and sold, they used to last 2 to 3 years max. Replace the lines I'm surprised they are still original, on all the B3/B4's I've owned the fuel lines were totally goosed by the time the cars were 20 years old so you're definitely on borrowed time.

11-04-18, 10:14 AM	#4
Colin Aitchison Senior Member Classic Audi Club Member Join Date: Dec 2013 Location: Back home in Tillicoultry Posts: 1,308	If the pump is old yes replace it, but only with a standard pump, price range you will see from under £20 to £100, you may not realize this but the fuel pump runs at over 100% of what the engine needs at full throttle all the time, www.onlinecarparts.co.uk do many fuel pumps that fit your car depending on the model, pumps are normally rated by fuel pressure and flow rate ( 6 bar at 130 Lt/Hr ) make sure you get the correct pump with the correct inlet and outlet pipe/thread size.

12-04-18, 09:55 AM	#7
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	Age of the fusebox and wiring should make no difference, but gauge of original wires aren't very thick. But then again - it's not a turbo engine and therefore not important and also probably pump which is spinning slightly slower will have slightly longer life.

12-04-18, 07:37 PM	#9
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	Well, that's special case, situation when there is some problem Unless that has happened, there is just one "problem" - some rather long distance with wires of average gauge - but that won't be problem for cars with moderate power NA engines, unlike, let's say, the same thing with headlights - because of that I even didn't bothered to upgrade something for pump wiring of my 2.0 8v mk2 golf, which in VW is even worse than in audi, as it uses main fusebox ground - while headlights have thick wires integrated in loom and pair of relays on top of fusebox, giving "oncoming truck" effect....

14-04-18, 09:55 AM	#10
AdrianH Grown up member Join Date: Jan 2014 Posts: 218	IMO the basic test for a pump which is otherwise working OK, would now be to measure the current draw. I wish I'd done this on my 30-year old MB, it would have saved me from being stranded side of road while I figured out why it'd suddenly stopped. Not sure what this one is supposed to be but on a urQ it's supposed to be about 8A, I think, and mine was drawing 13.5A+, which eventually blew the fuse.