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admvw78
Samba Member
Joined: December 11, 2022
Posts: 40
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 Posted: Tue Dec 13, 2022 8:36 pm Post subject: Re: Official Fuel injection questions thread |
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| Looking at the tin in the back of the engine bay, I have the two heater channels that come up to go to the fan shroud with flexible tin tubing, but on the right (passenger) side, there's also another hole cut through the tin, about the same size, right next to the heater tube. What's that for? There's nothing obvious above or below. Should I cap it for airflow reasons? |
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busdaddy
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Joined: February 12, 2004
Posts: 51121
Location: Surrey B.C. Canada, but thinking of Ukraine
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admvw78
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Joined: December 11, 2022
Posts: 40
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| Posted: Thu Dec 15, 2022 4:24 pm Post subject: Re: Official Fuel injection questions thread |
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I didn't even know that was a thing! I restored the car 15 years ago and that's never been there....
In the course of all of this, I broke a rubber fuel pump bushing by accident (and another on purpose when I thought I was replacing both of them with something else. Now I'm either ordering new ones or mounting the pump differently. So, two questions:
1. Anywhere you recommend I buy fuel pump bushings other than Germansuppy (https://germansupply.com/mount-bushing-fuel-pump-bus-76-79-vanagon-80-92-autostick-control-valve.html)? I'm in the US and haven't found it elsewhere (but perhaps I'm just not looking in the right corners of the internet).
2. What alternatives have people used to mount their pumps if these bushings are unavailable? |
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busdaddy
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Joined: February 12, 2004
Posts: 51121
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Thu Dec 15, 2022 4:32 pm Post subject: Re: Official Fuel injection questions thread |
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Search Amazon for "rubber isolator mounts M6", there's a bazillion of them in various configurations.
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admvw78
Samba Member
Joined: December 11, 2022
Posts: 40
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| Posted: Thu Dec 15, 2022 5:25 pm Post subject: Re: Official Fuel injection questions thread |
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| busdaddy wrote: |
| Search Amazon for "rubber isolator mounts M6", there's a bazillion of them in various configurations. |
Thank you. Sometimes it's just knowing what name people use. |
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Gr0unded
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Joined: October 02, 2018
Posts: 256
Location: North Carolina
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| Posted: Wed Dec 28, 2022 4:56 pm Post subject: Re: Official Fuel injection questions thread |
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I was driving the beetle on the way back home today, around 60 mph. It subtly to slow some like it was losing power, I let off the gas and press it again and a puff of smoke came out the rear looking at my rear view mirror.
So I slowed down to a stop to investigate, there was this loud clicking in the cabin with engine running at idel. When I blipped the throttle for some rpms, the clicking momentarily ceased. I narrowed down the noise to the double relay, also felt with my hand it was clicking. Engine seemingly is running fine.
I have it in my mind to check the wiring connections at the double relay this weekend hopefully it is something simple as a loose connection.
Has anyone experienced anything like this?
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B r i a n
1976 VW Type 1 Beetle - Standard
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busdaddy
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Joined: February 12, 2004
Posts: 51121
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Dec 28, 2022 5:18 pm Post subject: Re: Official Fuel injection questions thread |
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Aside from a sudden split in the S boot causing a big enough vacuum leak to cause the AFM flap to well... flap between the pump on and pump off position a good look at the terminals and plugs would be where I'd start too, they do get wet and corrode on the beetle system.
Also put a test light on the Black wire from the ignition switch (circuit #15), if the ignition switch is failing after being on for a while it could cause similar issues if it's getting intermittant. It may require a long drive to expose that problem.
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L51C_75
Samba Member
Joined: December 29, 2004
Posts: 54
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| Posted: Thu Dec 29, 2022 9:42 pm Post subject: Re: Official Fuel injection questions thread |
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| Gr0unded wrote: |
I was driving the beetle on the way back home today, around 60 mph. It subtly to slow some like it was losing power, I let off the gas and press it again and a puff of smoke came out the rear looking at my rear view mirror.
So I slowed down to a stop to investigate, there was this loud clicking in the cabin with engine running at idel. When I blipped the throttle for some rpms, the clicking momentarily ceased. I narrowed down the noise to the double relay, also felt with my hand it was clicking. Engine seemingly is running fine.
I have it in my mind to check the wiring connections at the double relay this weekend hopefully it is something simple as a loose connection.
Has anyone experienced anything like this? |
I had experienced this exact problem and was able to narrow it down to the PCV valve (or lack thereof). When I originally converted my 74 to l-jetronic, I was using the old "s" shaped hose from the breather to the air cleaner housing. Since the hose was old and hard, it kept slipping off the air cleaner leading to a vacuum leak and poor idle. I thought I would be smart and bypass the air cleaner connection altogether and installed a new hose straight from the breather to the connection to the S-boot. When I did this, I experienced the same clicking of the double relay. I swapped relays, traced all the wires, swapped AFMs but the clicking still persisted. I figured there are only two signals that caused the relay to click on, one from the coil (ignition on) and the other is for the fuel pump, as this is triggered by the afm flap on pins 6 &9 if I remember correctly. My assumption is that the pulses from the crank case breather are causing the AFM flap to close momentarily opening the contacts in the AFM on the fuel pump, but at the same time the engine running is pulling it open, this closing the contacts and making connections at the relay. This oscillations of the AFF is what causes the relay to click. I was able to rig up a proper breather hose with some spare 90 degree connections to simulate the "s" shape back to the air cleaner and the clicking stopped. I think the PCV in the airbox acts as an orifice to smooth out the pulses from the crankcase breather. I will see if I have some pictures to help explain, but my car is currently stored for the winter so I don that's immediate access to it. |
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christyxy
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Joined: October 03, 2022
Posts: 22
Location: England
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| Posted: Fri Dec 30, 2022 11:01 am Post subject: Re: Official Fuel injection questions thread |
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Update on my '79 super running horribly rich! It's not the AFM... I finally got hold of a pressure gauge and plugged it into the cold start injector fuel line... turned the key and fuel pressure stabilised out at 47 PSI!! I believe it should be 35 PSI right? I know the previous owner had the fuel pump changed, it looks rather new and there's new wiring to it. Is the fuel pump adjustable or do I just need a new fuel pressure regulator to get it down to 35 PSI?
| busdaddy wrote: |
Your EGR system has been removed, the 79 would have used the mechanical valve, not easy to find a good one lately, but if you want it for show even a leaker will do if you put a solid gasket between it and the manifold.
Rich running could be related to fuel pressure, or a bad pressure regulator, put a 0-50 PSI water pressure gauge into the cold start valve hose and see what it's doing. Also test for a change when you pull the vacuum hose to the FPR off.
Hopefully you find an issue there, because the next suspect is a messed up AFM from some "expert" trying to compensate for a vacuum leak, that gets more complicated to repair. |
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VW_Jimbo 
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Joined: May 22, 2016
Posts: 9950
Location: Huntington Beach, CA
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| Posted: Fri Dec 30, 2022 11:06 am Post subject: Re: Official Fuel injection questions thread |
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What happens if you apply 21inHg of vacuum to the fuel pressure regulator behind the cooling fan inlet? (On the front tin)
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There is never enough time to do it right the first time, but all the time necessary the second time!
| TDCTDI wrote: |
| Basically, a whole bunch of fuckery to achieve a look. |
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christyxy
Samba Member
Joined: October 03, 2022
Posts: 22
Location: England
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| Posted: Fri Dec 30, 2022 11:15 am Post subject: Re: Official Fuel injection questions thread |
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| VW_Jimbo wrote: |
| What happens if you apply 21inHg of vacuum to the fuel pressure regulator behind the cooling fan inlet? (On the front tin) |
Thanks for comment, I'm just not sure how exactly I would go about doing that? bit of a novice. What's your thinking here?
Thanks again, Christy |
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busdaddy
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Joined: February 12, 2004
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Fri Dec 30, 2022 11:18 am Post subject: Re: Official Fuel injection questions thread |
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 Wow!, there's your problem.
Odds are best the pump isn't suited to the system and makes much flow and pressure than the regulator can handle. See if there's any numbers on the pump to start with.
Other causes could be a kinked or restricted return line, if the tank was out it's not hard to kink the lines when installing it, although the outlet usually gets kinked too. Or possibly a stuck or failed pressure regulator, does the pressure drop if you pull a vacuum on the hose leading to it with a Mightyvac like hand pump?, is the vacuum line wet inside?
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VW_Jimbo
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Joined: May 22, 2016
Posts: 9950
Location: Huntington Beach, CA
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| Posted: Fri Dec 30, 2022 4:07 pm Post subject: Re: Official Fuel injection questions thread |
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Try this manual! Make a copy of it!
http://www.vaglinks.com/Docs/VW/Misc/VW_L-Jetronic_Fuel_Injection_Workshop_Manual.pdf
Go to page 150.
_________________
Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
| TDCTDI wrote: |
| Basically, a whole bunch of fuckery to achieve a look. |
| 67rustavenger wrote: |
| GFY's Xevin and VW_Jimbo! |
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christyxy
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Joined: October 03, 2022
Posts: 22
Location: England
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| Posted: Sun Jan 01, 2023 10:41 am Post subject: Re: Official Fuel injection questions thread |
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I don't have a tool like that to try your suggestion unfortunately, I will look into borrowing or buying one though to try... The pressure regulator seems very difficult to get to! I will try and get a better picture of the pump tomorrow but for now here's a picture from a video I made a while ago. It was installed by the previous owner but I don't think they did anything to remove the tank...
| busdaddy wrote: |
Wow!, there's your problem.
Odds are best the pump isn't suited to the system and makes much flow and pressure than the regulator can handle. See if there's any numbers on the pump to start with.
Other causes could be a kinked or restricted return line, if the tank was out it's not hard to kink the lines when installing it, although the outlet usually gets kinked too. Or possibly a stuck or failed pressure regulator, does the pressure drop if you pull a vacuum on the hose leading to it with a Mightyvac like hand pump?, is the vacuum line wet inside? |
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busdaddy
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Joined: February 12, 2004
Posts: 51121
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sun Jan 01, 2023 10:51 am Post subject: Re: Official Fuel injection questions thread |
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Your FLAPS likely rents or loans them.
Without it you can still watch the fuel pressure as the engine idles when you pull the vacuum signal line off the plenum, and when you reconnect, it should rise when disconnected and drop when vacuum is applied.
That pump looks like the correct one, the numbers on the side will say more.
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Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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busdaddy
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Joined: February 12, 2004
Posts: 51121
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Mon Jan 02, 2023 12:01 pm Post subject: Re: Official Fuel injection questions thread |
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Another ghetto vacuum source for testing a FPR is a large syringe from the pharmacy, pressure should drop when you pull out the plunger, should try to suck itself back in a little as well. You can do that test with the engine off but key on and AFM flap poked open.
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Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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admvw78
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Joined: December 11, 2022
Posts: 40
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| Posted: Fri Jan 06, 2023 1:59 pm Post subject: Re: Official Fuel injection questions thread |
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Sorry if asked and answered. I skimmed but didn't see the specifics.
Had the tank out to replace fuel lines. Using replacements from jbugs (see part: https://www.jbugs.com/product/N202811.html). This works fine from the tank to the fuel filter inlet and the fuel pump outlet and the tunnel tubing, but what is the larger size that's supposed to go between the fuel pump and the fuel filter? It's a good ~2-3mm larger diameter and I can't get the hose to stretch over it. The fuel lines that I'm taking off that I installed ~15 years ago looked like I just figured out a way to stretch the same size. Is that the right method? Is there a larger diameter I should use for that short segment?
Thanks,
Adam |
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Fri Jan 06, 2023 2:33 pm Post subject: Re: Official Fuel injection questions thread |
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You need a short bit of 11mm or 7/16 hose.
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Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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admvw78
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Joined: December 11, 2022
Posts: 40
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| Posted: Fri Jan 06, 2023 3:03 pm Post subject: Re: Official Fuel injection questions thread |
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| Thanks. Anything exciting in terms of pressure (i.e. something I have to order) or can I use a standard hose I find at a local autoparts store? |
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busdaddy
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| Posted: Fri Jan 06, 2023 3:33 pm Post subject: Re: Official Fuel injection questions thread |
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There's no pressure there, just whatever gravity from the tank exerts. Try to get hose rated SAE-J30-R9 or higher anyway, it's usually called fuel injection hose, it resists ethanol.
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