converting a fuel injected into a carbureted system

Here's the place to start. Introduce yourself and your ride.

Moderator: david58

Post Reply
superbeetle
Posts: 3
Joined: Mon Dec 13, 2004 7:26 pm

converting a fuel injected into a carbureted system

Post by superbeetle » Thu Dec 16, 2004 5:54 pm

ok my 75 super beetle is having fuel injection problems... im thinking about converting it to be carbureted but im not sure how that all works... some tips and advice would awesome.

User avatar
flybayb
Posts: 98
Joined: Wed Jul 07, 2004 11:42 pm

Post by flybayb » Thu Dec 16, 2004 8:29 pm

well,

IMHO: a conversion from FI to carb is a step backwards. Yr gain is nothing.

.02 cents:

1. post yr question in the 'fuel injection' section
2. fix yr FI. Its easier than y think and the benefits will pay off more than having a conversion.

cheerio :arrow:

User avatar
general_lee_jr
Posts: 1811
Joined: Wed Feb 06, 2002 3:01 am

Post by general_lee_jr » Sat Dec 18, 2004 9:29 pm

flybayb wrote:well,

IMHO: a conversion from FI to carb is a step backwards. Yr gain is nothing.

.02 cents:
It all depends on what kind of carb setup you go with and what you want to achieve. The fuel injection is great when it works! If you redo your FI get new parts. Dont waste your money on "good used" parts. I have known too many people with FI who have had to pull over on the side of the road to put a fire out.

User avatar
BeetleBugger
Posts: 388
Joined: Sun Dec 01, 2002 3:01 am

Post by BeetleBugger » Sun Dec 19, 2004 9:05 am

general_lee_jr wrote:
I have known too many people with FI who have had to pull over on the side of the road to put a fire out.
Yeah, that experiance sucks...(Never in a VW) :lol:

User avatar
Marc
Moderator
Posts: 23723
Joined: Thu May 23, 2002 2:01 am
Contact:

Post by Marc » Sun Dec 19, 2004 11:12 am

This was discussed in great detail a couple of years ago but you can't search back that far, so looks like it's time to cover it again. It's not the simple bolt-on swap that it's sometimes made out to be (by people who've apparently never done it).
The fuel-injected Type I engine has smaller valves (33x30 vs 35.5x32mm) than a carbureted engine - it'll never give equal performance with those heads, but they don't have to be changed. The engine block has no provision for a mechanical fuel pump so you'll need to plumb in an electric one - best place is under the tank up front, you'll also need to make some minor alterations like blocking off the return line that'll no longer be needed and adapting from the 7mm FI hose size to the 5.5mm "carb" hose size. The electric pump should have a safety circuit so that it will quit when the engine does even if the key's still on.
The entire exhaust system/heater boxes are different - if you retain the FI stuff you'll have no manifold preheat so you'll have continual problems with driveability if you use a single carburetor. Dual one-barrels, like 34ICT Webers, will work better.
If you choose to retrofit "carbureted" exhaust & heater boxes on so you can have some preheat, you'll also need to replace the sheetmetal between case & heaterboxes and the rearmost engine tin (the freshair hose holes are in different locations); the "carbureted" sheetmetal isn't quite the same width or contour but it comes very close....or you could modify the existing tin. The warmair pickup elbow is also different...and of course you're going to need an aircleaner - one from a `73/`74 will have the fewest issues for the conversion. Either install 1974 heater cables or plan to fabricate extensions for at least one side if you keep the `75 cables; the relay lever mechanisms need to be removed from the heater boxes and the actuating levers bent 180° so they point up for the cables to attach to (they'll be on the inboard side rather than the outboard side like the "FI" boxes' levers are, but they'll work). On #2 & #4 exhaust flanges, one stud is extra-long and needs to be replaced with a shorter one. And of course if you use a stock muffler the rear apron won't have the correct cutouts for the tailpipes and no stock apron which fits that body properly does, although it's possible to "stretch" a `68-`74 apron enough at the ends to get it to fit. Using a header instead sidesteps that issue, but you don't get as good of preheat flow from a header as you do from a stock muffler.
The throttle guide tube that passes through the shroud will need to be relocated (it's also slightly longer than the "carb'ed" part and rather rare - please change it rather than cut it off) which means drilling a couple of new holes very close to the oil cooler - careful! The cable will be too short for a stock carb so a 1974 part may be needed (the `75 cable may be just right for dual carbs, depending upon the linkage you get with them).
You'll need an alternator pedestal from a `73/`74 Type I, or a counterfeit part, and a 12V generator/alternator strap. You'll need to transfer the oil filler/breather over from the FI stand which'll take a special tool (I use a 1" internal pipe wrench). One of the pedestal studs is extra-long, you'll need to either change it to a short one or put spacers under the nut.
To support the intake manifold center section one of the 8mm case studs on top needs to be removed and replaced with a longer one.
If you go with a stock `71-`74 carburetor the FI distributor is close enough. With dual carbs you'll either have to modify them for a vacuum advance line or switch to a mechanical-advance-only distributor.

User avatar
sideshow
Posts: 3206
Joined: Mon Oct 27, 2003 2:00 pm
Location: suth'ern oraygun yusa
Contact:

Post by sideshow » Sun Dec 19, 2004 1:36 pm

Geez Marc, you left out a simple step. There is no provision in a FI beetle for the ?VW? or ?Volkswagen? script only the?Fuel Injection? script. Obviously this must be addressed before a proper conversion can be considered done.

And while I haven't done this, but couldn't you use the factory fuel pump relay (High pressure pump) to wire up the low pressure pump? Seems to me that the loom would be ok for reuse, but the dual relay bank would require some thought.

Most of the former FI beetles I have seen have also had the case replaced so they ran a normal fuel pump.

User avatar
Marc
Moderator
Posts: 23723
Joined: Thu May 23, 2002 2:01 am
Contact:

Post by Marc » Mon Dec 20, 2004 10:31 am

sideshow wrote:...couldn't you use the factory fuel pump relay (High pressure pump) to wire up the low pressure pump?
Yes, although the double relay is a high failure rate item (often it's one of the reasons people give up too early on the FI) and quite expensive compared to a standard load reduction relay that's available for a few dollars. Simpler and cleaner to yank out the whole FI harness and put a simple relay in the trunk (you can tie into the stock pump wiring there if you want) controlled by the alternator warning light signal.

Eric3501
Posts: 9
Joined: Fri May 12, 2017 4:15 pm
Location: Crestview, Florida, USA
Contact:

Re: converting a fuel injected into a carbureted system

Post by Eric3501 » Sun Sep 24, 2017 6:03 am

I realize this is a really old thread, hopefully someone can help me or point where I can find the help I need. I am building a 1977 std beetle to a baja bug for street use and mild trail riding. The f/i motor took a major dump prior to me getting it. I will be installing an upright aircooled type 4 carburated engine. What wiring, etc must be removed so this can happen. Not sure of type 4 year but has a single carb now. With the DTM cooling system it will be changed to dual carbs. I know I need a low pressure pump and pressure regulator but don't know what wiring needs to come out. Any help is greatly appreciated. Thank you in advance for the help.

User avatar
sideshow
Posts: 3206
Joined: Mon Oct 27, 2003 2:00 pm
Location: suth'ern oraygun yusa
Contact:

Re: converting a fuel injected into a carbureted system

Post by sideshow » Sun Sep 24, 2017 9:51 am

Since the beetle L-Jet harness is stand alone, it is pretty safe to remove all of it. The chassis harness has what you need for a carburetor type 4.
Add a fuel pump viewtopic.php?f=64&t=149853 (this covers the “hard” part of the wiring the safety shut off) and select the best looking of the two fuel lines to reuse.
Yeah some may call it overkill, but you can't have too much overkill.

Eric3501
Posts: 9
Joined: Fri May 12, 2017 4:15 pm
Location: Crestview, Florida, USA
Contact:

Re: converting a fuel injected into a carbureted system

Post by Eric3501 » Sun Sep 24, 2017 1:40 pm

Thank you or the info sideshow. I have another question you might can answer for me. Can the (I'm assuming it's a charcoal type canister), in the right rear wheel well be removed as Well? I don't want to sound stupid but this is my first bug build. Always played with water cooled before. Thank you again. Eric.

User avatar
Marc
Moderator
Posts: 23723
Joined: Thu May 23, 2002 2:01 am
Contact:

Re: converting a fuel injected into a carbureted system

Post by Marc » Sun Sep 24, 2017 3:56 pm

The charcoal canister is a part of the evaporative emission control system which has been around since 1970. Fumes from the carburetor and the fuel tank are collected there, and blown back into the aircleaner by pressure furnished by the cooling fan upon startup.
Technically it's a violation of federal law to remove/tamper with any emissions control device, including the EEC system, but unless you're in a state that does regular inspections who's to know? If you're going to use this off-road, it'd probably be best to pull the fuel tank ventline which runs under the body out and just run a simple vent/overflow line like the older cars had.

Eric3501
Posts: 9
Joined: Fri May 12, 2017 4:15 pm
Location: Crestview, Florida, USA
Contact:

Re: converting a fuel injected into a carbureted system

Post by Eric3501 » Sun Sep 24, 2017 4:01 pm

Thanks Mark, greatly appreciate the info. This is going to be used on the street, and light trail riding. Have to see what missouri does as will be moving there shortly after first of year. Here in florida, no inspections.

Post Reply