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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Wed Aug 08, 2018 7:06 pm Post subject: 1973 VW 412 Fuel Pump |
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Just bought a 1973 412, and the fuel pump is done. Anyone know where I can purchase a new one from a website or something. Don稚 want to buy the wrong one. It痴 fuel injected.
Also if anyone knows the layout of the fuses and the amps that would be great, most are missing and I知 having trouble finding information about the car. |
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Danno5 Samba Member
Joined: March 19, 2016 Posts: 63 Location: Leavenworth, KS
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Posted: Wed Aug 08, 2018 7:45 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Welcome,
I can't help with the fuel pump. I haven't had to address that yet, but I am pretty sure that Ray and the other guys cover it in here:
https://www.thesamba.com/vw/forum/viewtopic.php?t=639978
Check out the owner's manual posted in the tech area for the fuse layout. Page 44 and 45 have the under-dash fuse box and the under-the-back-seat fuses for your wagon. I have a 73 4-door sedan, so I think some of the relays I root around in the engine bay for is under your back seat with the fuses too. Here is the link to page 44:
https://www.thesamba.com/vw/archives/manuals/73_412.php
The tech area also has a nice color wiring diagram. Good place to start with wiring questions.
https://www.thesamba.com/vw/archives/info/wiringt4.php
I use it when I want to figure out what relay does what. |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Wed Aug 08, 2018 8:13 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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There are many you can use that are cheaper, just as good or better, easier to source and take a minor fuel line re-route.
If the link from the other thread does not get you where you need to be let us know. I have a whole list of Bosch pumps that fit. Ray |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Wed Aug 08, 2018 8:18 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Thank you for the fast replies! I値l check out the links tomorrow and let you all know. |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Thu Aug 09, 2018 2:00 am Post subject: Re: 1973 VW 412 Fuel Pump |
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raygreenwood wrote: |
If the link from the other thread does not get you where you need to be let us know. I have a whole list of Bosch pumps that fit. Ray |
If you could name and link some that would be awesome. |
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KTPhil Samba Member
Joined: April 06, 2006 Posts: 33875 Location: Conejo Valley, CA
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Posted: Thu Aug 09, 2018 9:21 am Post subject: Re: 1973 VW 412 Fuel Pump |
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BTW, I would not crawl under a car supported on cinder blocks. |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Thu Aug 09, 2018 10:39 am Post subject: Re: 1973 VW 412 Fuel Pump |
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KTPhil wrote: |
BTW, I would not crawl under a car supported on cinder blocks. |
That's when I first got it. Picture is 7 months old. |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Mon Aug 13, 2018 9:02 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Sorry Im running late. Been on the road. I will drop you a list of pump part #'s in the am.
Ray |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Tue Aug 14, 2018 8:58 am Post subject: Re: 1973 VW 412 Fuel Pump |
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Here is a link to a post with a series of links in it.
Bear in mind that virtually any two port fuel injection pump that physically fits and has the right port diameters and usable electrical connections will work just fine. It its made for at minimum a four cylinder engine or larger with an average pressure of 32 psi or larger...it will work just fine.
You really should avoid excessively large or very high pressure pumps like CIS pumps that in many cases either require a feeder pump or are required to be submerged for both feed and cooling...again like a CIS pump.
Most of what I am saying right here is in the text at this link...but I'm saying it again. Back in the day...my "go to" pump was the Bosch 044 high pressure roller cell pump used with CIS injection systems.
Simply a bad ass pump. But with the issues of counterfeit 044 pumps...the high cost and the fact that in about 50% of applications you may need a feeder pump if the tank outlet to pump position is not ideal..........and the vast improvements in turbine ring type pumps...which used to not last very long or have very uniform pressure/volume...but now have very high pressure and uniform volume, have a smoother pulse pattern and are cheaper and more available.....I tend to go with those.
As long as the pump puts out a minimum of 1 liter per minute of volume....at operating pressure...it will work well.
This means that to test this...with the pump installed in a fuel loop either on the car or on the workbench....you can either have the car off and hot wire the pump to run constant...or have the car idling.....you put the return line from the fuel pressure regulator to a 2-3 liter graduated jar. Install a fuel pressure gauge....a good one.
Run the pump for about 1.5 minutes. Note the fuel level in the jar at 30 seconds and start the stop watch. Note the fuel pressure gauge. It should be stable with no more than a 1/2 psi +/- oscillation.
That means for example if the pressure reading is 28 psi....the oscillation of the needle should move between about 27.5 psi and 28.5 psi.
Time its output at operating pressure for 1 minute. You should get a solid 1 liter or better. This is with no demand (engine off) or low demand (at idle).
Its better to test while running. So you can see that if you rev it....the pressure should not dip more than about 1-1.5 psi and not for more than about 1/2 second. It should just be a blip then stable fuel pressure.
If the volume at idle pressure is excellent but fuel pressure has poor stability...suspect your pressure gauge first if you are working with a new pump.
And..whatever pump you buy make sure it has a check valve on teh outlet side. If it does not it can cause this problem as well.
https://www.thesamba.com/vw/forum/viewtopic.php?t=640244&highlight
Ray |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Tue Aug 14, 2018 12:21 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Thanks for the reply. I値l check it out after work. Would the two pumps I listed work? |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Tue Aug 14, 2018 12:52 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Najemnikarmy wrote: |
Thanks for the reply. I値l check it out after work. Would the two pumps I listed work? |
Quantum does most of their work on diesels. Not a bad thing. HFP seems to be an automotive subsidiary. I cannot find much about them or specs on that pump....so I would stay away from them.
Stay with Bosch, Airtex, Delphi and other name brands with advertised specs.
That Delphi pump you listed would work fine. Designed to work at constant pressurs of 43 psi....pumps out 2.45 liters per minute at 0 pressure so should be plenty.
Check to make sure what thread is on inlet and outlet and that you buy the proper barbed fittings. Ray |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Thu Aug 16, 2018 5:02 am Post subject: Re: 1973 VW 412 Fuel Pump |
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raygreenwood wrote: |
Najemnikarmy wrote: |
Thanks for the reply. I値l check it out after work. Would the two pumps I listed work? |
Quantum does most of their work on diesels. Not a bad thing. HFP seems to be an automotive subsidiary. I cannot find much about them or specs on that pump....so I would stay away from them.
Stay with Bosch, Airtex, Delphi and other name brands with advertised specs.
That Delphi pump you listed would work fine. Designed to work at constant pressurs of 43 psi....pumps out 2.45 liters per minute at 0 pressure so should be plenty.
Check to make sure what thread is on inlet and outlet and that you buy the proper barbed fittings. Ray |
I知 replacing all the fuel delivery components. Do you happen to have a fuel system diagram showing all the fuel components like the fuel filter and pressure regulator locations?
Sort of like this.
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Thu Aug 16, 2018 11:55 am Post subject: Re: 1973 VW 412 Fuel Pump |
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Najemnikarmy wrote: |
raygreenwood wrote: |
Najemnikarmy wrote: |
Thanks for the reply. I値l check it out after work. Would the two pumps I listed work? |
Quantum does most of their work on diesels. Not a bad thing. HFP seems to be an automotive subsidiary. I cannot find much about them or specs on that pump....so I would stay away from them.
Stay with Bosch, Airtex, Delphi and other name brands with advertised specs.
That Delphi pump you listed would work fine. Designed to work at constant pressurs of 43 psi....pumps out 2.45 liters per minute at 0 pressure so should be plenty.
Check to make sure what thread is on inlet and outlet and that you buy the proper barbed fittings. Ray |
I知 replacing all the fuel delivery components. Do you happen to have a fuel system diagram showing all the fuel components like the fuel filter and pressure regulator locations?
Sort of like this.
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This is the factory standard "3 port" pump diagram. It is for a type 3 so the fuel pressure regulator is on the opposite side of the engine compartment.
It also does not show the cold start valve in teh middle of teh engine compartment.
Here is the same diagram modified for a two port modern fuel pump....with the cold start valve location added...and flipped to look type 4 specific from above.
Ray |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Thu Aug 16, 2018 12:16 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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What痴 the number 3 on the diagram? |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Thu Aug 16, 2018 1:37 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Thats the fuel filter. The filter always goes between the fuel tank and pump on low pressure systems like this.
The first part after the pump is the fuel system harmonic damper. Do not remove ot from the system. It has no movong parts and does not wear out. It dampens harmonic pulses created by the fuel pump check valve opening and closing.....and through thks helps to keep fuel pressure more stable and reduce wear on the fuel pressure regulator metering plate. Ray |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Thu Aug 16, 2018 3:38 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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raygreenwood wrote: |
Thats the fuel filter. The filter always goes between the fuel tank and pump on low pressure systems like this.
The first part after the pump is the fuel system harmonic damper. Do not remove ot from the system. It has no movong parts and does not wear out. It dampens harmonic pulses created by the fuel pump check valve opening and closing.....and through thks helps to keep fuel pressure more stable and reduce wear on the fuel pressure regulator metering plate. Ray |
Ok, I order a new fuel filter and pressure regulator along with the Delphi fuel pump and a fuel pump relay. I also ordered a new high performance oil filter. Is there anything else I should replace while changing the fuel pump? |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Thu Aug 16, 2018 5:31 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Najemnikarmy wrote: |
raygreenwood wrote: |
Thats the fuel filter. The filter always goes between the fuel tank and pump on low pressure systems like this.
The first part after the pump is the fuel system harmonic damper. Do not remove ot from the system. It has no movong parts and does not wear out. It dampens harmonic pulses created by the fuel pump check valve opening and closing.....and through thks helps to keep fuel pressure more stable and reduce wear on the fuel pressure regulator metering plate. Ray |
Ok, I order a new fuel filter and pressure regulator along with the Delphi fuel pump and a fuel pump relay. I also ordered a new high performance oil filter. Is there anything else I should replace while changing the fuel pump? |
What oil filter?....what is supposed to be high performance about it?
The stock filters of good quality are excellent. Be careful to not order something restrictive.
Stock filter brands and part numbers that are known to be good:
Mann- W92017
Wix- 51521
Bosch- 3402
Mahle- OC28
NAPA gold- FIL-1521 (same as Wix)
Purolator (new numbers) PL14670 or PBL14670 or L14670
Or in old filters....Knecht are good. They are Mahle now.
Beck Arnley are good. I think they are Mann or Mahle. New Part # 041-8137
Do NOT use the,Fram filters. Their very top of the line have improved...but the rest like the PH2844 are low grade.
Whatever you use make sure it has an anti drainback valve.
Ray |
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Najemnikarmy Samba Member
Joined: August 08, 2018 Posts: 33
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Posted: Thu Aug 23, 2018 1:41 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Hey so everything came in, the fuel pump says it requires a 20 amp fuse. I just relaxed all the fuses with 8 amp fuses and a 12 amp fuse relay for th fuel pump. Is that fine or should I change anything? |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21474 Location: Oklahoma City
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Posted: Thu Aug 23, 2018 2:50 pm Post subject: Re: 1973 VW 412 Fuel Pump |
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Najemnikarmy wrote: |
Hey so everything came in, the fuel pump says it requires a 20 amp fuse. I just relaxed all the fuses with 8 amp fuses and a 12 amp fuse relay for th fuel pump. Is that fine or should I change anything? |
What do you mean by "relaxed"? Did you mean replace?
The two stock fuse sizes in the car are 8 and 16 amp. Most aftermarket pumps should be fine for no more than about 10-12 amps.....but a lot of this depends on what else is on the circuit. I would put a stock 16 or similar on it.
Which pump did you buy?
Ray |
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