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viiking
Samba Member
Joined: May 10, 2013
Posts: 3125
Location: Sydney Australia
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 Posted: Fri Jun 13, 2025 6:00 pm Post subject: Re: Fuel Pump not pumping? |
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| thomas. wrote: |
| Have you changed the plastic(bakelite) spacer under your fuel pump in recent years. These are known to swell over time and can prevent the fuel pump push rod from operating correctly. |
This seems only to be a problem when the engine is hot. At cold it won't be an issue.
But you can check by removing the fuel pump and seeing how loose the pushrod is.
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3 |
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 25856
Location: Olympia Wash Rinse & Repeat
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| Posted: Fri Jun 13, 2025 4:45 pm Post subject: Re: Fuel Pump not pumping? |
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| Type One Motors wrote: |
The fuel inlet and outlet and not mixed up.
I have not changed the bakelite under the pump but might be a good idea. Once I can get the pump going the plan is to change all lines from the tank and clear the tank to ensure its working. Wanted to check otherwise before I did that. |
Might try slightly larger drill bit than the push rod to ream it open a tad.
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Type One Motors
Samba Member
Joined: July 18, 2014
Posts: 13
Location: Brisbane, CA
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| Posted: Fri Jun 13, 2025 2:58 pm Post subject: Re: Fuel Pump not pumping? |
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The fuel inlet and outlet and not mixed up.
I have not changed the bakelite under the pump but might be a good idea. Once I can get the pump going the plan is to change all lines from the tank and clear the tank to ensure its working. Wanted to check otherwise before I did that. |
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thomas.
Samba Member
Joined: July 31, 2010
Posts: 1357
Location: South West (Pa.)
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| Posted: Fri Jun 13, 2025 5:00 am Post subject: Re: Fuel Pump not pumping? |
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| Have you changed the plastic(bakelite) spacer under your fuel pump in recent years. These are known to swell over time and can prevent the fuel pump push rod from operating correctly. |
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viiking
Samba Member
Joined: May 10, 2013
Posts: 3125
Location: Sydney Australia
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| Posted: Wed Jun 11, 2025 4:50 pm Post subject: Re: Fuel Pump not pumping? |
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| wcfvw69 wrote: |
You need to ensure the following-
* The rubber fuel lines connecting the steel lines need to be clear. Old rubber fuel lines can collapse internally and prevent flow. |
You need to check this. For every part that has a rubber fuel line.
If you check that fuel comes out from the tank when you disconnect, this may NOT be enough to ensure its integrity.
All pumps will develop some sort of vacuum on the suction side. If the hose is not rated for the vacuum or if it has become weak over the years, you will have no problem seeing liquid flowing through the hose when you disconnect (because it is at a very small pressure and therefore forcing the hose open) but it can internally close or choke when a vacuum is pulled.
Your experiment seems to confirm this. The pump works from a fuel can and I assume a new hose. This eliminates any collapsing hose from the experiment.
Fuel (and hydraulic) hoses can look perfect from the outside but can be internally defective. You don't need too much of any rubber layer to collapse and act just like the rubber diaphragm in the pump to close off.
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3 |
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Bobs67vwagen
Samba Member
Joined: March 27, 2005
Posts: 169
Location: Eastern north carolina
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| Posted: Wed Jun 11, 2025 4:08 pm Post subject: Re: Fuel Pump not pumping? |
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| I had a bug that sat for a few years and I could not get fuel to travel to the pump. I got under the driver side rear of the car and disconnected the braided fuel hose from the metal pipe that runs thru the tin which eventually connects to the fuel pump, and I let It hang down. I then jacked up the front of the car to see if fuel would then flow and it did not. The metal fuel line which exits the tunnel and then sticks up out of the frame horn alongside the transmission was clogged. I had to run some braided cable hooked up to a drill to clear the blockage. I would do this procedure with a pan under the braided hose to catch fuel if it comes out upon jacking up the front of the car. Hope this helps |
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wimkever
Samba Member
Joined: July 16, 2004
Posts: 434
Location: Holland (the Netherlands)
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| Posted: Wed Jun 11, 2025 1:24 pm Post subject: Re: Fuel Pump not pumping? |
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| Type One Motors wrote: |
All,
I did what you mentioned and bench tested it and it works as it should. All is good there. Reinstalled and still did not have the gas tank hooked up but a side line to a full gas can. No obstructions. Primed everything and such. I cannot get it to pump fuel up to the carb. |
This can't be true unless you've switched the input and output lines at the pump.
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a beetle is like a cocker spaniel, always funny but sometimes not listening |
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Type One Motors
Samba Member
Joined: July 18, 2014
Posts: 13
Location: Brisbane, CA
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| Posted: Wed Jun 11, 2025 11:39 am Post subject: Re: Fuel Pump not pumping? |
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Bill,
The pump is working with no issues. I did confirm by trying like you said. It cannot be the pump. This pump replaced another old correct German pump that was in there. No change to the rod and is set up for the generator model. I will take it all apart again and start over and confirm all measurements. It should not be this hard right?
As for the gas can, I had it at all locations. I had it above the pump, below the pump and at level. Also had the line primed with fluid.
I will take it all apart and confirm the measurements. |
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kreemoweet
Samba Member
Joined: March 13, 2008
Posts: 4084
Location: Seattle, WA
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| Posted: Tue Jun 10, 2025 5:30 pm Post subject: Re: Fuel Pump not pumping? |
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| Type One Motors wrote: |
| Reinstalled and still did not have the gas tank hooked up but a side line to a full gas can. No obstructions. Primed everything and such. I cannot get it to pump fuel up to the carb. |
Just where exactly is this gas can sitting? On the floor? How on earth can you "prime" a gas line from the pump to a can on the floor?
"Priming" means to have the line and pump cavities FULL of gas, so the pump diaphragm will not be trying to suck air instead of
liquid fuel. There is no way a VW mechanical pump can suck gas up from a can sitting on the floor. The VW tanks were situated at
just about the pump inlet level, so the pump would never have to suck fuel up against gravity more than a few inches.
You could get a gas can to work, provided it was located ABOVE the fuel pump and the feed line was FULL of gas.
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wcfvw69
Samba Purist
Joined: June 10, 2004
Posts: 13679
Location: Arizona
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| Posted: Tue Jun 10, 2025 3:51 pm Post subject: Re: Fuel Pump not pumping? |
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| Type One Motors wrote: |
All,
Thanks for all this information. Bill, I believe you actually built this pump for me and I have had it sitting on my shelf in the garage for a number of years. Just never got around to it.
I did what you mentioned and bench tested it and it works as it should. All is good there. Reinstalled and still did not have the gas tank hooked up but a side line to a full gas can. No obstructions. Primed everything and such. I cannot get it to pump fuel up to the carb. I really do give up. I am out of patience right now.
I am coming off a major injury and need to get this car fixed so I can sell it. This pump is what is holding it up. I just can't figure out what the hell is going on. Everything is as it should and pump is working. |
So this pump works on the bench but not on the engine. Did you measure your pushrod? Is it 108mm in length or no shorter than say 107.7mm? How much does the pushrod stick up above the fuel pump stand at its highest travel point with the fuel pump off? It should stick up 13mm.
If those measurements are right and you have the inlet fuel line connected to the lower tube inlet side of the pump and the outlet at the top tube of the pump, it should work as long as the pump is feed a strong flow of gas.
Again, if those measurements are correct, you can prime the fuel pump by filling up the inlet side of the pump.
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Contact me at [email protected]
Follow me on instagram @sparxwerksllc
40+ years of VW repair, and VW parts and vehicle restoration experience.
The Samba member since 2004.
**Now rebuilding throttle bodies for VW's and Porsche's**
**Restored German Bosch distributors for sale or I can restore yours**
**Restored German Pierburg fuel pumps for sale or I can restore yours**
**Restored Porsche fuel pumps or I can restore yours**
**Restored Porsche distributors or I can restore yours** |
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Type One Motors
Samba Member
Joined: July 18, 2014
Posts: 13
Location: Brisbane, CA
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| Posted: Tue Jun 10, 2025 2:32 pm Post subject: Re: Fuel Pump not pumping? |
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All,
Thanks for all this information. Bill, I believe you actually built this pump for me and I have had it sitting on my shelf in the garage for a number of years. Just never got around to it.
I did what you mentioned and bench tested it and it works as it should. All is good there. Reinstalled and still did not have the gas tank hooked up but a side line to a full gas can. No obstructions. Primed everything and such. I cannot get it to pump fuel up to the carb. I really do give up. I am out of patience right now.
I am coming off a major injury and need to get this car fixed so I can sell it. This pump is what is holding it up. I just can't figure out what the hell is going on. Everything is as it should and pump is working. |
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wcfvw69
Samba Purist
Joined: June 10, 2004
Posts: 13679
Location: Arizona
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| Posted: Mon Jun 02, 2025 6:31 pm Post subject: Re: Fuel Pump not pumping? |
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The biggest measurement that's important on these fuel pumps is how much the pushrod sticks up above the plastic bakelite fuel pump stand. With one gasket under the fuel pump stand, you want the pushrod to stick up 13mm at its highest travel point with a non alternator pump using a 108mm pushrod.
The square tops really need a full flow of fuel to the pump to prime and pump. VW's that sit for a while can have obstructions from the fuel tank to the pump.
These obstructions can reduce the flow to 1/2 or 1/4 of what it should be and the pump will never prime and pump.
You need to ensure the following-
* The fuel tank is clean and the fuel tank sock is clean and clear.
* The rubber fuel lines connecting the steel lines need to be clear. Old rubber fuel lines can collapse internally and prevent flow.
* Make sure there isn't a hidden fuel filter under the bug by the transmission or under the tank.
With the pump on the bench, if you pump the rocker with your thumb, you should hear the pump making a sucking sound and can feel on the outlet air coming out.
_________________
Contact me at [email protected]
Follow me on instagram @sparxwerksllc
40+ years of VW repair, and VW parts and vehicle restoration experience.
The Samba member since 2004.
**Now rebuilding throttle bodies for VW's and Porsche's**
**Restored German Bosch distributors for sale or I can restore yours**
**Restored German Pierburg fuel pumps for sale or I can restore yours**
**Restored Porsche fuel pumps or I can restore yours**
**Restored Porsche distributors or I can restore yours** |
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Type One Motors
Samba Member
Joined: July 18, 2014
Posts: 13
Location: Brisbane, CA
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| Posted: Mon Jun 02, 2025 2:42 pm Post subject: Re: Fuel Pump not pumping? |
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| Thank you all. I do have the correct pump as you show in the picture. I will try it by hand and also double check the dimensions for rise and fall. |
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Multi69s
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Joined: January 24, 2006
Posts: 5552
Location: Lefty, CA
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Cusser
Samba Member
Joined: October 02, 2006
Posts: 32960
Location: Hot Arizona
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| Posted: Mon Jun 02, 2025 2:18 pm Post subject: Re: Fuel Pump not pumping? |
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| Eric&Barb wrote: |
| Type One Motors wrote: |
| I don't believe I have the inlet and outlet lines mixed. Can you show a photo of how it is supposed to be on a stock German fuel pump? |
The below from the original from factory only 22 mile 1964 beetle:
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A 1968 VW would use a "square top" fuel pump, similar to the one in these photos.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 25856
Location: Olympia Wash Rinse & Repeat
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| Posted: Mon Jun 02, 2025 1:38 pm Post subject: Re: Fuel Pump not pumping? |
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| Type One Motors wrote: |
| Perhaps this is the issue and how to rectify? |
Should only be about 13mm 1/2" at top of travel, with 8mm 5/16" at lowest and between 4-5mm stroke. Should work as long as you have the proper length of fuel pump rod. Not the shorter for only alternator type of rod.
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 25856
Location: Olympia Wash Rinse & Repeat
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| Posted: Mon Jun 02, 2025 1:29 pm Post subject: Re: Fuel Pump not pumping? |
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| bsairhead wrote: |
| I have not seen a crank brass gear fail at the ramp but I guess it's possible. |
Fuel pump rod ramp is on the steel shaft that also drives the distributor.
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bsairhead
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Joined: October 08, 2008
Posts: 4432
Location: viroqua wi.
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| Posted: Mon Jun 02, 2025 1:03 pm Post subject: Re: Fuel Pump not pumping? |
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| Type One Motors wrote: |
| I did not. I did however see that I think I have an issue here. I just took the pump back off and wanted to check travel of the rod. It is correct and for a generator. There is very little up and down travel on the rod. From video's I have watched it is supposed to go all the way down almost and back up to the high point. It comes to the correct high point but the amount of travel does not seem to be that much. Perhaps this is the issue and how to rectify? |
I have not seen a crank brass gear fail at the ramp but I guess it's possible. |
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 25856
Location: Olympia Wash Rinse & Repeat
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| Posted: Mon Jun 02, 2025 12:47 pm Post subject: Re: Fuel Pump not pumping? |
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| Multi69s wrote: |
| It looks like someone changed the spark plug wires. My Dad used to have a VW / Porsche shop, so I have been around VWs for over forty years, and all of the OEM wires were always black. Was this your car? |
That would be the original factory spark plug cables. If you look at the early 1960s owner manuals the B&W images show the spark plug cables as a lighter grey color, that is due to the blue of the cables. Also thru the link previously posted you can see an example of NOS type 3 engine in the original packing with blue cables.
Guess the blue cables did not hold up as well as they should have, and so by time I got into VWs in the late 1970s those cables had been replaced long long before.
Boy do I wish that could be our car, there are places that would be so interesting to photograph for documentation. Last heard the owner was wanting a quarter million for it. Really it should be in a museum behind glass.
Do note the black of the boots on the ends of the cables at the distributor ends in the images below.
From the 1963 model year beetle owner's manual:
From 1960-64 replacement bus OM:
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Type One Motors
Samba Member
Joined: July 18, 2014
Posts: 13
Location: Brisbane, CA
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| Posted: Mon Jun 02, 2025 12:45 pm Post subject: Re: Fuel Pump not pumping? |
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| I did not. I did however see that I think I have an issue here. I just took the pump back off and wanted to check travel of the rod. It is correct and for a generator. There is very little up and down travel on the rod. From video's I have watched it is supposed to go all the way down almost and back up to the high point. It comes to the correct high point but the amount of travel does not seem to be that much. Perhaps this is the issue and how to rectify? |
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