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kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
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 Posted: Wed Nov 17, 2021 11:21 am Post subject: Fuel pump on the fritz? |
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| My 412 with L-jet fuel injection had its fuel pump replaced 12 years ago with a "Vanagon" pump - mine was obsolete and the shop said it had the same pressure - that has worked flawlessly all these years. However, nowadays I hear an intermittent whining noise coming through the dash when the engine is running. The only thing I can think of is the pump. Does it have a worn out bearing and is on its last legs? Engine still runs fine; just that whine is getting on my nerves! |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Wed Nov 17, 2021 9:01 pm Post subject: Re: Fuel pump on the fritz? |
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Are you sure its not the vent fan running?
Every once in a while a noisey pump can be from either a clogged fuel filter, a clogged sock filter in the tank or from a piece of grit or filter media oming loose and rattling in the pump.
Yes it could be worn out too. Lots of pumps that fit this fine and run well if you need a list. Ray |
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kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
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| Posted: Fri Dec 17, 2021 10:37 pm Post subject: Re: Fuel pump on the fritz - or is it the ignition switch? |
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So the sound I presumes was the fuel pump sounded like a fly buzzing against a window coming from the area of the dashboard. And now I turn the key and - nothing. All wires to the starter are on tight, and the starter itself is ten years old. Battery is excellent.
Could it be the ignition switch? And perhaps on its way out in the last few weeks it was making that buzzing sound when the engine was running?
I think Ray advised me to test the ignition switch on my other 412 by unplugging it on the column and plugging the wires into a spare. Maybe I'll try that on Sparkie. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Sat Dec 18, 2021 8:37 am Post subject: Re: Fuel pump on the fritz - or is it the ignition switch? |
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| kirk knighton wrote: |
So the sound I presumes was the fuel pump sounded like a fly buzzing against a window coming from the area of the dashboard. And now I turn the key and - nothing. All wires to the starter are on tight, and the starter itself is ten years old. Battery is excellent.
Could it be the ignition switch? And perhaps on its way out in the last few weeks it was making that buzzing sound when the engine was running?
I think Ray advised me to test the ignition switch on my other 412 by unplugging it on the column and plugging the wires into a spare. Maybe I'll try that on Sparkie. |
Well....There is nothing in the ignition switch that should be capable of a buzz like a large fly....which is pretty high frequency.
BUT.....   ...always a "but" in these cars......its possible your key buzzer relay is tweaked.
Are you aware that there is a small 1" cube shaped relay plugged into the bottom of the fuse block?
Its "Supposed" to buzz when you have the key in the ignition and you open the door to get out. It only works when the inner ring shaped plug of the ignition barrel is pushed in.
That part is "SUPPOSED" to pop back out when you pull the key out but with wear and age...it sticks in.
And....on the last couple of years of 412....late 1973 and 1974....the models that had the rectangular "fasten seat belt" light on the dash......that buzzer wae also connected to the seat belt wiring. If uou were witting on the seat which compresses the ignition interlock switch inside the seat.....and you did not have your seat belt buckled......that light would stay on and the dqmn buzzer would buzz.
That is a quick fix by reqching under the seat and pulling the plug on the drivers seat. But......if you have aby weight in the passenger seat.....like 20 lbs......same thing. Buzzer will buzz.
That may not be the issue. But worth checking.
Ray |
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kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
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| Posted: Tue Jan 25, 2022 11:59 am Post subject: Re: Fuel pump on the fritz? |
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I went ahead and installed a new fuel pump - and the buzzing noise is still there! Argh!
Again: only when the engine is running; not a peep with the ignition on.
Almost sounds like spark plug static on the AM radio. But the radio is off, and in any case the buzzing is not coming from the speakers in the back seat area.
I though maybe it was the "vibrator" thing for the fuel gauge, so I took out the fuse for the gauge - nope! Still buzzing.
It varies in volume, comes and goes, but mostly always there and it's driving me crazy.
Help?? |
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ClassicCamper
Samba Member
Joined: December 17, 2002
Posts: 679
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| Posted: Tue Jan 25, 2022 4:56 pm Post subject: Re: Fuel pump on the fritz? |
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Hey Kirk,
Perhaps it is the high-beam or turn signal relay. I've had this happen to me in a Beetle. It's just strange that this occurs when the engine is running.
Try feeling the relays while it's running and let us know if you feel any vibration. Also, it may be helpful if you could post a link youtube or the like with a recording of the sound.
_________________
1973 412 Wagon
1976 Westy
1978 SB Vert |
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Pepperbilly
Samba Member
Joined: April 08, 2017
Posts: 977
Location: Seattle, Wa
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| Posted: Tue Jan 25, 2022 5:34 pm Post subject: Re: Fuel pump on the fritz? |
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Kirk,
Good advice. Feel all the relays by hand…one by one. Also sounds like ignition interference through the radio. Do you still have a front in dash speaker? If the static from the ignition is not properly suppressed it will buzz with varying intensity. Disconnect your radio and see what happens.
Bill |
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kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
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| Posted: Tue Jan 25, 2022 6:01 pm Post subject: Re: Fuel pump on the fritz? |
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| Pepperbilly wrote: |
Kirk,
Good advice. Feel all the relays by hand…one by one. Also sounds like ignition interference through the radio. Do you still have a front in dash speaker? If the static from the ignition is not properly suppressed it will buzz with varying intensity. Disconnect your radio and see what happens.
Bill |
In fact the front speaker is still there though I'm pretty sure it isn't connected to the aftermarket radio, which goes to speakers in the back seat area. |
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ClassicCamper
Samba Member
Joined: December 17, 2002
Posts: 679
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| Posted: Tue Jan 25, 2022 8:03 pm Post subject: Re: Fuel pump on the fritz? |
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| Quote: |
| Feel all the relays by hand…one by one |
That's a real good idea - double check that speaker. Based on your symptoms, I'd be surprised if it wasn't one of those relays. My '78 Super Beetle had the same issue you described. It ended up being a wiring issue (short) with the hazard switch. It would cause the relay to make a buzzing noise and for whatever reason, it only buzzed when the engine was running.
Good luck!
_________________
1973 412 Wagon
1976 Westy
1978 SB Vert |
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kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
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| Posted: Wed Jan 26, 2022 3:14 pm Post subject: Re: Fuel pump on the fritz? |
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| ClassicCamper wrote: |
| Quote: |
| Feel all the relays by hand…one by one |
That's a real good idea - double check that speaker. Based on your symptoms, I'd be surprised if it wasn't one of those relays. My '78 Super Beetle had the same issue you described. It ended up being a wiring issue (short) with the hazard switch. It would cause the relay to make a buzzing noise and for whatever reason, it only buzzed when the engine was running.
Good luck! |
Okay, I just pulled out every single fuse while the engine was running ( except the fuel pump ) and NOTHING changed.
It sounds like a low arthritic whine/buzz; does not change with accelerating the engine, and SEEMS to be coming through the firewall down low. Like where the fuel pump is on the other side.
But it can't be the fuel pump because I just changed it!
Is there anything associated with the pump that might be causing the noise? |
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Pepperbilly
Samba Member
Joined: April 08, 2017
Posts: 977
Location: Seattle, Wa
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| Posted: Wed Jan 26, 2022 7:14 pm Post subject: Re: Fuel pump on the fritz? |
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Now you need to get under the front end while the engine is running. Things to look for…
Are the rubber mounts (vibration isolators) all there and in good shape?
Is the fuel pump making unusual noises? If it is could be a faulty pump OR there is a restriction in the fuel tank at the outlet or return pipes. Bad sock filter possibly dirty and causing a restriction in the tank.
Restriction in the round inline fuel damper…
Is the fuel filter in good shape?
Your fuel tank is old and could have an accumulation of dirt/rust etc. Lots of things to consider here. Process of elimination now.
Bill |
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KTPhil 
Samba Member
Joined: April 06, 2006
Posts: 33986
Location: Conejo Valley, CA
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| Posted: Thu Jan 27, 2022 10:17 am Post subject: Re: Fuel pump on the fritz? |
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| Pepperbilly wrote: |
Restriction in the round inline fuel damper…
Bill |
...or it's missing or gutted/rusted. |
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ClassicCamper
Samba Member
Joined: December 17, 2002
Posts: 679
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| Posted: Thu Jan 27, 2022 11:33 am Post subject: Re: Fuel pump on the fritz? |
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It looks like you can eleiminate this being an electrical sound, seems to be noise in the fuel system up front. Try a mechanics stethoscope or ear to the back of a screwdriver in the suspect area.
_________________
1973 412 Wagon
1976 Westy
1978 SB Vert |
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ClassicCamper
Samba Member
Joined: December 17, 2002
Posts: 679
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| Posted: Thu Jan 27, 2022 10:30 pm Post subject: Re: Fuel pump on the fritz? |
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| Quote: |
| My grandmother had a brand new '73 Automatic that would quit like that, but with a noise from the dash area that she said sounded like a "rattler". That was, of course, a faulty fuel pump relay. Her dealer replaced it under warranty and I don't think she had another problem with that car until the floors rusted out of it around about 1982. |
I was geeking out by brushing up on my D-Jet skills in the T3 forums and came across the above post. It’s a good possibilty your fuel pump relay just under the brake master cylinder is the culprit. Anxious to see what you find out.
_________________
1973 412 Wagon
1976 Westy
1978 SB Vert |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Fri Jan 28, 2022 7:59 am Post subject: Re: Fuel pump on the fritz? |
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| ClassicCamper wrote: |
| Quote: |
| My grandmother had a brand new '73 Automatic that would quit like that, but with a noise from the dash area that she said sounded like a "rattler". That was, of course, a faulty fuel pump relay. Her dealer replaced it under warranty and I don't think she had another problem with that car until the floors rusted out of it around about 1982. |
I was geeking out by brushing up on my D-Jet skills in the T3 forums and came across the above post. It’s a good possibilty your fuel pump relay just under the brake master cylinder is the culprit. Anxious to see what you find out. |
Yes....and just like the same part number relay that feeds the ECU sysytem in the back....some relays used a small ground pigtail connected to one pin on the relay and usually going to a ring terminal at the screw that holds the relay down.
If the screw is loose ground can be variable and the delay can rattle off and on. It can also be corrosion inside. Ray |
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kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
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| Posted: Thu Feb 24, 2022 10:33 pm Post subject: Re: Fuel pump on the fritz? |
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| raygreenwood wrote: |
| ClassicCamper wrote: |
| Quote: |
| My grandmother had a brand new '73 Automatic that would quit like that, but with a noise from the dash area that she said sounded like a "rattler". That was, of course, a faulty fuel pump relay. Her dealer replaced it under warranty and I don't think she had another problem with that car until the floors rusted out of it around about 1982. |
I was geeking out by brushing up on my D-Jet skills in the T3 forums and came across the above post. It’s a good possibilty your fuel pump relay just under the brake master cylinder is the culprit. Anxious to see what you find out. |
Yes....and just like the same part number relay that feeds the ECU sysytem in the back....some relays used a small ground pigtail connected to one pin on the relay and usually going to a ring terminal at the screw that holds the relay down.
If the screw is loose ground can be variable and the delay can rattle off and on. It can also be corrosion inside. Ray |
I am just now seeing this post!
Hmmm....so if I take the covering off to access the master cylinder what does the relay look like? I will check to see if it is loose. And if it is shot are there replacements available? |
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kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
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| Posted: Fri Feb 25, 2022 4:05 pm Post subject: Re: Fuel pump on the fritz? |
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| ClassicCamper wrote: |
| Quote: |
| My grandmother had a brand new '73 Automatic that would quit like that, but with a noise from the dash area that she said sounded like a "rattler". That was, of course, a faulty fuel pump relay. Her dealer replaced it under warranty and I don't think she had another problem with that car until the floors rusted out of it around about 1982. |
I was geeking out by brushing up on my D-Jet skills in the T3 forums and came across the above post. It’s a good possibilty your fuel pump relay just under the brake master cylinder is the culprit. Anxious to see what you find out. |
Well the relay is NOT under the MC after all. My shop manual says it's in the engine compartment! I looked, not there either.
In any case the noise continues. It doesn't come on right away after starting the engine, maybe 30 seconds later. I had my head up under the dash and looked and listened; the sound just seems to be coming from everywhere - and nowhere. Argh! |
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Pepperbilly
Samba Member
Joined: April 08, 2017
Posts: 977
Location: Seattle, Wa
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| Posted: Fri Feb 25, 2022 4:48 pm Post subject: Re: Fuel pump on the fritz? |
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Hmmm... Sounds like you have eliminated all the electrical relays for noise. I still have a feeling it is in the fuel system. Loose fuel lines rubbing somewhere on the chassis will cause a vibration and cause noises. Check the steel fuel lines running in and out of your undercarriage. At those points there are rubber isolation bushings around the lines. They rot in old cars. Just maybe...
Bill |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Sat Feb 26, 2022 12:24 am Post subject: Re: Fuel pump on the fritz? |
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| kirk knighton wrote: |
| ClassicCamper wrote: |
| Quote: |
| My grandmother had a brand new '73 Automatic that would quit like that, but with a noise from the dash area that she said sounded like a "rattler". That was, of course, a faulty fuel pump relay. Her dealer replaced it under warranty and I don't think she had another problem with that car until the floors rusted out of it around about 1982. |
I was geeking out by brushing up on my D-Jet skills in the T3 forums and came across the above post. It’s a good possibilty your fuel pump relay just under the brake master cylinder is the culprit. Anxious to see what you find out. |
Well the relay is NOT under the MC after all. My shop manual says it's in the engine compartment! I looked, not there either.
In any case the noise continues. It doesn't come on right away after starting the engine, maybe 30 seconds later. I had my head up under the dash and looked and listened; the sound just seems to be coming from everywhere - and nowhere. Argh! |
The fuel pump relay "should" be mounted to the underside of the brake pedal cluster assembly.
It is NOT in the engine compartment.
However.....the relay in question......is identical to one that IS in the engine compartment of 411 and 412 SEDANS.
So.....in 411 and 412 wagons.....when you remove the right rear armrest.....you see the fuel injection ECU...right? Mounted on top of the ECU....in wagons......is a relay. Tjat is the EFI system power relay. It is the IDENTICAL part number relay as the fuel pump relay. Interchangeable.
This same EFI system relay is mounted in the engine compartment of 411 and 412 SEDANS......on the left side of the engine bay on the far left end of the rack of relays.
That being said...having had two 411 wagons and one 412 wagon....all of my fuel pump relays were mounted under the pedal cluster to the right of the steering column almost directly under the master cylinder.
But....because there is.....in the wagons.....a rack of aystem relays under the back seat on the drivers side....its "possible" in some cars that it is mounted there.
Ray |
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kirk knighton
Samba Member
Joined: January 23, 2005
Posts: 282
Location: Seattle
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| Posted: Fri Mar 04, 2022 6:40 pm Post subject: Re: Fuel pump on the fritz? |
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| raygreenwood wrote: |
| kirk knighton wrote: |
| ClassicCamper wrote: |
| Quote: |
| My grandmother had a brand new '73 Automatic that would quit like that, but with a noise from the dash area that she said sounded like a "rattler". That was, of course, a faulty fuel pump relay. Her dealer replaced it under warranty and I don't think she had another problem with that car until the floors rusted out of it around about 1982. |
I was geeking out by brushing up on my D-Jet skills in the T3 forums and came across the above post. It’s a good possibilty your fuel pump relay just under the brake master cylinder is the culprit. Anxious to see what you find out. |
Well the relay is NOT under the MC after all. My shop manual says it's in the engine compartment! I looked, not there either.
In any case the noise continues. It doesn't come on right away after starting the engine, maybe 30 seconds later. I had my head up under the dash and looked and listened; the sound just seems to be coming from everywhere - and nowhere. Argh! |
The fuel pump relay "should" be mounted to the underside of the brake pedal cluster assembly.
It is NOT in the engine compartment.
However.....the relay in question......is identical to one that IS in the engine compartment of 411 and 412 SEDANS.
So.....in 411 and 412 wagons.....when you remove the right rear armrest.....you see the fuel injection ECU...right? Mounted on top of the ECU....in wagons......is a relay. Tjat is the EFI system power relay. It is the IDENTICAL part number relay as the fuel pump relay. Interchangeable.
This same EFI system relay is mounted in the engine compartment of 411 and 412 SEDANS......on the left side of the engine bay on the far left end of the rack of relays.
That being said...having had two 411 wagons and one 412 wagon....all of my fuel pump relays were mounted under the pedal cluster to the right of the steering column almost directly under the master cylinder.
But....because there is.....in the wagons.....a rack of aystem relays under the back seat on the drivers side....its "possible" in some cars that it is mounted there.
I stopped by my mechanic's shop and had him sit in the passenger seat with the engine running. He heard the buzz and instantly thought - relay!
Now if the relay is in the back seat like you said would it be buzzing under the dash?
Definitely did not see anything resembling a relay anywhere around the MC.
Hmmm....the mystery continues.
Ray |
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