VW Jetronic mechanical fuel injection swap

Build projects, things that guys have come up with to make a Pinz better (or worse?) and aftermarket add-ons.
AudioNW
United States of America
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Joined: Mon Feb 24, 2020 7:07 pm

Re: VW Jetronic mechanical fuel injection swap

Post by AudioNW » Tue Apr 14, 2020 8:17 pm

During the initial run test I discovered two very important issues. Too long of an assembly to waste space with a pretty TB adapter if it is to fit under the engine cover and even if it did fit, that rubber boot is hilariously too weak under full vac! So next idea.. build an ultra short one from steel. Downside is there's zero flex in the joint meaning the entire assembly needs to be hard mounted to the engine assembly and still clear the cover with engine movement under load. I did a test fit today and with the fuel filter relocated everything seems to fit. Heres pics of the flanges.BTW if anybody goes to make one of these the intake housing is rotated 10deg back. Never noticed that before.
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AudioNW
United States of America
Posts: 16
Joined: Mon Feb 24, 2020 7:07 pm

Re: VW Jetronic mechanical fuel injection swap

Post by AudioNW » Fri May 08, 2020 9:42 pm

I was able to score a CNC plasma table a few weekends ago in trade, so yay! Not currently having income and ultra long shipping times is proving to make me think harder about how I go about this for sure! Stupid Covid. This week I made some progress on bracketry. I ordered some longer studs and made up the gaskets to R&R the oil cooler too. One issue I would like some input on is how much the engine twists under full load. I've owned this thing for 8 years and never bothered to watch the engine twist while driving. Now I can't do that until it runs again. If anybody can take a video I would really appreciate it. The airbox needed trimming to clear the body. Its close, like 13mm close to the sheet metal and it makes me nervous. Besides that it fits great and will be easy to plastic weld back together. Anyway, here's progress pics.....
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Derrickbwg
United States of America
Posts: 94
Joined: Sat Dec 16, 2017 8:09 pm
Location: TN

Re: VW Jetronic mechanical fuel injection swap

Post by Derrickbwg » Sat May 09, 2020 6:47 am

Very cool project!

Ive always been interested in the FI setups but have never been willing to trust power converters to run something so critical. To get 12v to power steering...fine...it reverts to manual if a failure occurs, but I cant get over the hump on trusting the engine to one. Thats why yours is so interesting.

I know many will state that power converters are reliable ect. and Id like to think technology is so good now that they are. But Ive lost one brand new "inverter" on an RV in very short order, so Im a little jaded. I guess you could run power off one battery in a pinch, but I like your period correct approach.

Keep up the great work!
1975 710K
1974 710M
2018 G63

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Mr Zero
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Location: Las Vegas, Nevada

Re: VW Jetronic mechanical fuel injection swap

Post by Mr Zero » Sat May 09, 2020 9:45 am

Do you have any intention or willingness to reproduce the custom bits for other forum members once you've sorted all the kinks?

AudioNW
United States of America
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Joined: Mon Feb 24, 2020 7:07 pm

Re: VW Jetronic mechanical fuel injection swap

Post by AudioNW » Sun May 10, 2020 5:12 pm

As I go I’m taking notes and saving templates and artwork so yes. I can recreate most of this if it is successful. Some of the parts are a bit hard to find as they are from late 70’s cars but hard to find parts shouldn’t scare a Pinz owner! New injectors will be here soon and I’m hoping to get the fuel supply situation sorted in a week or three so I can get on the road to test it out.
Wish me luck!

AudioNW
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Re: VW Jetronic mechanical fuel injection swap

Post by AudioNW » Wed May 20, 2020 10:14 pm

I made some changes to the airbox bracket for small allignment fixes and redesigned it as a single piece for easier reproduction. Made a flange for the cold start injector and brazed into the best location I could find. Aux air valve was going to be ported at the throttle body flange but after a test fit I realized it needed to be relocated so there's a task for the morning. The temp/time switch is usually in the radiator. After failing to come up with a good way to integrate with the oil cooler I thought why not use the fuel pump plate? If the goal is to stick the sensor where engine heat can be read then this should work fine? The warm up regulator needs to ne near an engine block so the fuel pump mount is now serving two jobs. Originally I was only going to use the fuel pump plate as a mounting stud. This is better.

The fuel tank.. I looked for instructions on removal and was surprised so little came up. I see why now, its easy! 4 bolts and some hose clamps and done. A fuel return line was brazed in to the cap for later. Did my my best to remove loose red death flakes before reassembly.

I would love some input on the fuel pump location. The VW pump has an input much larger than the Pinz 5/16" feed line. The VW also mounts the pump at the bottom of the tank level...Will mounting the pump above the tank cause an issue?
This design puts the pump above the tank and undersizes the feed. The way I think about this is the vehicle was made with a fuel line bigger than what the engines HP requires. I don't expect to make any more power with this swap so wouldn't the OEM fuel line still feed the original engine? I hope so. Reading about other efi conventions, it seems the 5/16" line is sufficient so lets find out. If you've had issues with pump height let me know.

Thats all for now.
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Joeri
Belgium
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Re: VW Jetronic mechanical fuel injection swap

Post by Joeri » Thu May 21, 2020 1:45 am

Hi...dousnt matter where you put the pump but close to the tank Works best, also theres no need for the pre- heating box it runs fine without and it dousnt make much of a difference. Remember that all the sensors and injectors run on 12v :mrgreen:

MTPinz
Germany
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Location: Montana

Re: VW Jetronic mechanical fuel injection swap

Post by MTPinz » Sat May 23, 2020 11:01 pm

This is so cool! I've owned many CIS cars over the years but would never think to adapt the system to a Pinz, nice work! Hopefully you won't run into any hotstart issues...maybe insulate those braided lines a bit? Keep up the excellent work!

AudioNW
United States of America
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Joined: Mon Feb 24, 2020 7:07 pm

Re: VW Jetronic mechanical fuel injection swap

Post by AudioNW » Sun May 24, 2020 9:48 pm

Thank you guys for your kind words.
I stared this thing for what seems like days for a location to mount this big ass filter, pump, and accumulator. The filter fits by the intake and the rest has a home you will see in a couple days! I have some hose ferrules and a crimper the way so I can hopefully make some decent fuel lines that don't leak and catch fire. Also found a home for the aux air valve. That was bothering me due to its weird shape and directional requirements. If I had a way to properly bend ½" tubing I'm sure it would fit elsewhere but I like this solution because its one bracket for two purposes.

I would really love some pictures of the hardware that hold the intake in place too. Mine was lost years ago and I would like to repair it correctly.
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AudioNW
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Re: VW Jetronic mechanical fuel injection swap

Post by AudioNW » Thu May 28, 2020 9:24 pm

I got the fuel system sorted today. There are some threaded mounts on the trans that I was able to use to hold the pump and accumulator bracket. It's low enough to keep the pump happy and higher than the undercarriage so I call it a win. The thread pitch on them looks to be different than what I expected. A M10x1.5 binds up so I ordered some M10x1.25 bolts hoping they fit. Is this a common Pinz thread pitch? A cheap eBay fuel pump bracket and an exhaust clamp hold the parts in place. I was able to get some hoses made today as well and all seems to fit as intended though I really want to do it again in a braided black hose once I know this actually works.. Electrical is all that's left for a test drive and I've got some fun plans for that. New connectors should be here tomorrow, stay tuned for updates.
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AudioNW
United States of America
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Re: VW Jetronic mechanical fuel injection swap

Post by AudioNW » Thu May 28, 2020 9:28 pm

Pass side view
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Last edited by AudioNW on Fri May 29, 2020 9:14 am, edited 1 time in total.

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Mr Zero
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Re: VW Jetronic mechanical fuel injection swap

Post by Mr Zero » Fri May 29, 2020 7:27 am

It all looks excellent so far. Well done! Looking forward to a performance report from your test drive. :)

AudioNW
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Re: VW Jetronic mechanical fuel injection swap

Post by AudioNW » Tue Jun 09, 2020 9:49 pm

I was trying to solve a big flat spot right off idle the other day. It runs great besides acting like a carb without an accelerator pump. I was able to drive it around my yard even but its not steet ready yet. The fuel pressure test results were close to perfect and I was starting to doubt the projects success when I found this. I assumed using parts from 1979 would cause issues. A rebuild kit for the fuel distributor is on order. Till next week,....
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