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Tue Sep 06, 2011 6:31 am

Could someone please explain to me why maintaining a 35 year old FI system is better than updating to a simple dual carb system. I have been working for 2 months trying to get this damn FI system to work. It is complex with vacuum controlled fuel pressure regulator, air metering box with old corroded resistance input, 5 injectors susceptible to clogging, electrical problems etc., an expensive control unit 35 years old that depends on input from the ignition system to trigger the injectors accurately, 2 temperature sensors that effect the fuel input rate. The ignition system is dependent on adequate vacuum based on the functioning of other FI components that are regulated by vacuum and any vacuum leak screws the vacuum - timing - fuel injection. :shock: The whole complex system could leave you on the side of the road with little recourse but to hire an expensive tow truck to pull you in to where you will likely get ripped off by some mechanic that doesn't have a clue what to do. Someone posted that the FI was very reliable and all you had to do was maintain the following items and proceeded to list 14 different things that could go wrong. I could go on, but I think you get the point. Now tell me why it is worth all the risk. Anyone seen a Raby T4 engine with FI?? Rant ended :evil: .

Tue Sep 06, 2011 6:37 am

Maybe a nice HonDUH would be more your style. If you think that fuel injection system is complex, you really shouldn't be working on it in the first place. If you honestly think for some reason going to an aftermarket dual carb setup is going to be better for you, please, be my guest. I'd be happy to take all of those worthless, complex fuel injection parts off your hands.

Tue Sep 06, 2011 6:41 am

I see your point. If you have all the FI components installed and it's still not running right then the cheapest, easiest way to make the bus run and be reliable would be to fix what you've got. A set a good dual carbs with linkage and air filters could easiely cost you $800. Then once you have the new carbs you'll have to jet them and that's not easy to get right. Then you'll have to synch them along with all the linkage so they operate together correctly. Now, let's imagine that you've worked all the bugs out and the bus just purrs.... finally. 5,000 miles down the road you'll be back in there re-synching them to keep them running correctly and this cycle will repeat itself. Once you get the FI working it will work and not be a maintenance hog. There are several guys here on the forum who know the FI system very well. Just tap into their knowledge, get yourself a multimeter, and screw the neighborhood garage that doesn't know what to do except charge you a lot of money.

Tue Sep 06, 2011 6:57 am

Here's one Camper Special with Ljet FI and I wouldn't run it anyother way.

I have run dual carbs, single carbs and love the EFI compared to those. The EFI doesn't need constant tinkering, loves the mountain roads, highway or city driving, sub-zero temps etc without a hitch.
The injectors will never clog if you change the fuel filter once and a while. Yes, the fuel lines need changing every few years along with a few of the vac lines. The large stock air cleaner protects your engine nicely too.

The negatives of carbs.....

When the air/fuel mixture goes around a turn in a manifold it has a tendency to separate
Gaskets dry out when it sits
Warm up is problematic
Mixture gets heated in manifold
Big cams , their low vacuum and intake reversion drives you nuts
Don't adjust for altitude
Not accurate across the temperature spectrum
Don't adjust for a hot or cold engine or air temp
Float bowls are vented to atmosphere causing sludge when sitting
Lots of work to adjust for engine changes
Ice up without "preheat" air

A carb is perfect on Fred's Flintstone's car.....Personally, I would leave it there

Tue Sep 06, 2011 7:00 am

No wonder you can’t make the injection work. Not trying to be a dick….but it appears that you have a bit of a lazy attitude toward things. The factory twin carbs were actually more complex to tune by far than the injection.

The injection produces better usable power, more even running in all weather…and uses slightly less fuel than carbs. It’s extremely reliable as long as it’s in good shape and maintained properly.

A few notes:
(1) This system is dirt simple. It has 36 wires and three main sensors (four if it has a micro switch on the throttle)
(2) While it’s not “complex” it can be complicated because of age and wear
(3) The four main injectors and one cold start injector….are no more or less prone to clogs than any other injector ever built. They are the same technology….so whats your real beef here?
(4) Virtually every fuel injected vehicle built until about 8 years ago….has a vacuum indexed fuel pressure regulator. It’s not an issue….unless you have vacuum leaks
(5) No vacuum leaks allowed …period…in any fuel injection system ever built…by anyone.
(6) What difference does it make that the injection timing is triggered by the coil? Millions of vehicles were built this way and ran fine. What makes yours different?

It’s simply a signal….no more or less reliable than one generated by a crank, cam or flywheel sensor….considering the signal that fires the coil is connected by a GEAR to the crank.

Modern injection also uses a sensor connected to the crank to give the system a basic rpm and timing signal.

You sound like a 16 year old with a lowered Honda sporting a fart can and a $40 reflashed chip....who takes a look under the hood of virtually any car made before 1995 and screams "OMG....this thing gets its ignition signal from a round spinning thing with a crap load of wires coming out of the top...EEEEEEWWWWW.....whats next?...leaches?" :roll:

(7) The same sensors that affect fuel input…are the same type on every fuel injection system ever made….again…whats your complaint? Ever seen how a choke works? Same basic parts as the auxiliary air regulator or a throttle position sensor.

(8) Uh….dewd….a vacuum leak screws with ANY engine…carbed or FI. In fact a vacuum leak on a carbed car runs you LEAN…you know…like pinging and burned valves?....while most vacuum leaks on L-jet injection will cause a rich condition at the fuel pressure regulator.

(9) Yes, Jake Raby occasionally builds engines with programmable fuel injection. Check his website

So you have been playing with a relatively simple fuel injection system for two months….and still can’t get it running right?
You seem pissed off that it has all these worthless (to you it seems) components that get in your way……I’m betting that you are so peeved that you have to put up with this needless complexity that you are trying to make it run by putting as little into it as possible.

There is nothing wrong with the injection. Whats wrong with it is that its 35 years old and needs some new parts and some work. It could probably use a new wiring harness by now.

Have you ever worked on 35 year old carburetors with worn out bushings and corroded jets and rusty and bent linkage? Same issues.

If you need some help, ask. If you want to run carbs…go for it. But don’t act like the machine is requiring you to learn high energy physics. Ray

Tue Sep 06, 2011 7:13 am

FI is actually quite simple, and superior. A little time educating yourself on the system and the role of the individual components could pretty much make you an expert. Simple, simple, simple. This is not rocket science; it's actually very intuitive.

Tue Sep 06, 2011 7:28 am

Video Bob wrote: Could someone please explain to me why maintaining a 35 year old FI system is better than updating to a simple dual carb system. I have been working for 2 months trying to get this damn FI system to work. . . . Anyone seen a Raby T4 engine with FI?? Rant ended :evil: .

Tue Sep 06, 2011 8:00 am

Busboss, yep he stepped right into it didn't he. I can however understand the pain he's going through. There's a learning curve on the FI but once you get over the hump it's pretty simple. He just needs to put in the time learning the system.

Tue Sep 06, 2011 8:19 am

aeromech wrote: Busboss, yep he stepped right into it didn't he. I can however understand the pain he's going through. There's a learning curve on the FI but once you get over the hump it's pretty simple. He just needs to put in the time learning the system.

He's already put some time into it. Just needs to follow through.

OP; you won't get much sympathy here while berating VW fuel injection systems. There are simply too many of us that LOVE IT. Now, if you would like some help getting it working again, just ask. Step by step is the way things are fixed. Do you have a vacuum gauge? A fuel pressure gauge? A multimeter? Patience and respect?

Bentley Manual?

Tue Sep 06, 2011 8:38 am

He's already put some time into it. Just needs to follow through.

No argument there but since he's not getting it yet THEN HE NEEDS TO PUT MORE TIME INTO IT.

Tue Sep 06, 2011 8:48 am

aeromech wrote: HE NEEDS TO PUT MORE TIME INTO IT.

Competence comes with this:

1) Learn the various FI parts
2) Understand the role of the various parts
3) Understand the effect of each part as it works in concert with the others
4) Learn the common part failures
5) Learn how a specific part failure impacts the engine

Fix it. Drive on. Be happy. Simple.

Tue Sep 06, 2011 10:42 am

Video Bob:

I was in the same place with my FI system a year ago. I had already received a lot of help from the gurus here. I had tried everything, or so I thought, and each time I found a problem and fixed it, a new one popped up that had been masked by the previous issue.

I spent a lot of hours working through everything. Frustrating? Hell ya! I thought about carbs at one time. But progress was made and the bus ran just a little bit better each time.

With all that time spent on the forums here, sometimes getting help, sometimes getting s**t for something I did, or should have done, and all the hours with my head in the engine bay, it finally came together.

The three big things that I gained from all this?

1. I have enough knowledge to at least have a good go at any future problems, and there will undoubtedly be more.
2. When I get in the bus, all I do is turn the key, and it starts right now, and it idles smooth and it pulls smooth.
3. I did it myself, with help from the experienced, selfless people that dedicate many hours on this forum to help me and you because they want to save another bay.

Bottom line - put in the time on the FI - it will be worth it!

Ok, that was bordering on philosophical! :D

Tue Sep 06, 2011 10:44 am

raygreenwood wrote: No wonder you can’t make the injection work. Not trying to be a dick….but it appears that you have a bit of a lazy attitude toward things. The factory twin carbs were actually more complex to tune by far than the injection.

The injection produces better usable power, more even running in all weather…and uses slightly less fuel than carbs. It’s extremely reliable as long as it’s in good shape and maintained properly.

A few notes:
(1) This system is dirt simple. It has 36 wires and three main sensors (four if it has a micro switch on the throttle)
(2) While it’s not “complex” it can be complicated because of age and wear
(3) The four main injectors and one cold start injector….are no more or less prone to clogs than any other injector ever built. They are the same technology….so whats your real beef here?
(4) Virtually every fuel injected vehicle built until about 8 years ago….has a vacuum indexed fuel pressure regulator. It’s not an issue….unless you have vacuum leaks
(5) No vacuum leaks allowed …period…in any fuel injection system ever built…by anyone.
(6) What difference does it make that the injection timing is triggered by the coil? Millions of vehicles were built this way and ran fine. What makes yours different?

It’s simply a signal….no more or less reliable than one generated by a crank, cam or flywheel sensor….considering the signal that fires the coil is connected by a GEAR to the crank.

Modern injection also uses a sensor connected to the crank to give the system a basic rpm and timing signal.

You sound like a 16 year old with a lowered Honda sporting a fart can and a $40 reflashed chip....who takes a look under the hood of virtually any car made before 1995 and screams "OMG....this thing gets its ignition signal from a round spinning thing with a crap load of wires coming out of the top...EEEEEEWWWWW.....whats next?...leaches?" :roll:

(7) The same sensors that affect fuel input…are the same type on every fuel injection system ever made….again…whats your complaint? Ever seen how a choke works? Same basic parts as the auxiliary air regulator or a throttle position sensor.

(8) Uh….dewd….a vacuum leak screws with ANY engine…carbed or FI. In fact a vacuum leak on a carbed car runs you LEAN…you know…like pinging and burned valves?....while most vacuum leaks on L-jet injection will cause a rich condition at the fuel pressure regulator.

(9) Yes, Jake Raby occasionally builds engines with programmable fuel injection. Check his website

So you have been playing with a relatively simple fuel injection system for two months….and still can’t get it running right?
You seem pissed off that it has all these worthless (to you it seems) components that get in your way……I’m betting that you are so peeved that you have to put up with this needless complexity that you are trying to make it run by putting as little into it as possible.

There is nothing wrong with the injection. Whats wrong with it is that its 35 years old and needs some new parts and some work. It could probably use a new wiring harness by now.

Have you ever worked on 35 year old carburetors with worn out bushings and corroded jets and rusty and bent linkage? Same issues.

If you need some help, ask. If you want to run carbs…go for it. But don’t act like the machine is requiring you to learn high energy physics. Ray

Obviously I have stepped on some very sensitive toes here considering the number of replies and personal attacks. A little personal background here: I started doing my own mechanical work over 60 years ago first reworking bicycle clutch and brakes at age 10 and then later pulling the head and replacing ignition parts on my Vespa scooter. As I progressed to my 6 year old '49 Ford I changed out manifolds carbs. did all the maintenance and since then have done nearly all the maintenance on cars, trucks tractors, tillers, mowers and garden tractors. I am not a 16 year old beginner. I was probably working on tractors and farm equipment before most of you were even born.

I have read every article published in Bentley, Chilton, Muir, and Haynes about FI more than once. I have download and studied the 42 page AFC article describing the elements, how to check, and maintain AFC FI multiple times. I have Viewed R Atwells website and many others in effort to find the elusive answer to why I am having problems.
Please don't say that I am lazy and not willing to make an effort.
Yes I have 2 - VOMs, Compressions test gauge, 2 - vacuum gauges, dwell meter, Tach, digital timing light/tach and know how to use them. Up till now I didn't have a need for a fuel pressure gauge. I have spent more than 100 hours working on the interrelated components of this system replacing vacuum lines, crankcase hoses, elbows, Ts and bypassing nonfunctional systems such as the brake booster. I have replaced all ignition components, tested all FI components, measured ohm readings of airflow meter connectors. I may not be the smartest wrench in the tool box, but I have done my best. One time it ran well enough for me to go to the tire dealer and have 5 - 8 ply Yokohama Super van tires installed Two days later it wouldn't run at all. At other time it has run but not well enough to drive on the road. The next day or two nothing. Yes it has a new battery fully charged, fresh gas.

Jake and Beth Raby are members of our local Athens VW Club. Our club was instrumental in the handling of the "Aircooled Assault" show at "Aircooled Heaven" in Cleveland GA a few months ago. This is the URL to the video I made of the show while there. www.vimeo.com/24789585

VDubTech I already have a 2004 HonDUH Element I bought new that has hauled my equipment to location shoots that have generated more than $500,000 income. So far I have replaced 2 odometer bulbs, the battery and a set of tires plus oil and filters. It has never let me down. My wife has a 2002 HonDUH bought new that has had new tires, battery and oil changes. That's it.

Look to the left and see my '74 Thing I resurrected from 12 years of storage under a shelter. The wheels were locked the engine would not run and it was a wreck. I bead blasted the suspension system, brakes system, repainted, rebuilt, re-upholstered seats, replaced top and did all the maintenance work myself. My '56 Oval in my profile has been a challenge if you want to deal with old corroded parts 55 years old and still was a piece of cake compared to my '76 Westy.

I really do WANT this bus to work. I do have respect for ALL my VW's, but my patients is just about gone.

Tue Sep 06, 2011 10:50 am

Westfabulous wrote: aeromech wrote: HE NEEDS TO PUT MORE TIME INTO IT.

Competence comes with this:

1) Learn the various FI parts
2) Understand the role of the various parts
3) Understand the effect of each part as it works in concert with the others
4) Learn the common part failures
5) Learn how a specific part failure impacts the engine

Fix it. Drive on. Be happy. Simple.

A very good asnwer.

#'s 1, 2 and 3 ...could have been done in about a week...either online or with a book for anyone who is serios about fixing their engine.

The OP already has a liking and affinity for simpler carburettors. He already is fuming because simply pouring gas in it will not make it run.

If he has seriously put in time over two months working with the system...he would at least have taken stock of the system and learned a few things.

I would surmise that it is really....over a period of two months...he has spent several days "poking" at it, plugging and unplugging things and fuming that its not as simple as a carb.

I would be surprised if in this process the manual had been bought....or even if he knows his fuel pressure. Ray

Tue Sep 06, 2011 10:55 am

have you tried taking it to someone else to get a second set of eyes checking your work?

and now that you have vented about how you hate FI and listed your credentials - what's the actual problem right now?

list the steps you have taken and their results.

you checked A and it was B, then checked C and saw D. laying it all out is good both as a sanity check for yourself, but so others can review your process and see if there's anything missed or anything that needs to be revisited.

anytime these things drag on forever it seems to come back to something stupid, like bad ground's somewhere. start with the easiest things, don't rule out anything and start making a list.

Tue Sep 06, 2011 11:03 am

Okay Bob, looks like you pass the experience test. Now, the most important tool in any mechanics box is patience. Go find that tool and put it to work.

So you say you've checked everything twice and it still runs like crap? You say you have a fuel pressure gauge but you never needed one before. Have you in fact checked your fuel pressure when you've had a failure? The reason I ask is that lately I've had to deal with two buses that had tank contamination. The first bus had a damn towel inside it. The second, rust. So you can see that a towel in the fuel tank won't be addressed in any of the manuals you own. There's always the unexpected stupid cause out there that just stumps people and you just have to find it. This is why we mechanics need to understand how and why things work the way they do. If you understand that then you can work your way methodically through the problem until you have the answer. Have you removed the S duct and thoroughly inspected it for cracks and holes? Have you rung all the wiring while bending the cables looking for opens? I have a spare 1978 engine harness I can lend you if you want to try that. Just slave it in over the top of the existing one and see what happens.

EDIT: I actually have several FI components available for troubleshooting including an AFM, harness, AAR, set of injectors, etc.

Tue Sep 06, 2011 11:04 am

Have you had your injectors cleaned and replaced your fuel pressure regulator?

Tue Sep 06, 2011 11:05 am

Bob, with all the time, energy, reading up, etc. that you've done, do you have any ideas about what to really point your finger at here? I mean, you must have some hunches. For example, why do you think it's the FI system, and not something else (ignition, etc.)?

Let's take this from rant, to diagnosis, and then success. Most people find that ranting in the forums will only contribute to a recoil effect from fellow members, and then a pile-up. :wink:

Tue Sep 06, 2011 11:07 am

Video Bob wrote: [ I have spent more than 100 hours working on the interrelated components of this system replacing vacuum lines, crankcase hoses, elbows, Ts and bypassing nonfunctional systems such as the brake booster. I have replaced all ignition components, tested all FI components, measured ohm readings of airflow meter connectors. ...

...but my patients is just about gone.

100 hours is whole lot of time. I'd have lost my patience by now too.

Are you looking for advice? or did you just want to vent? Either is fine, just let us know so we can structure our replies appropriately.

Tue Sep 06, 2011 11:07 am

When I bought my bus 3 years ago it had been sitting rotting for the previous 4 years. I had it towed home. Dropped the engine, hammered the frozen clutch plate loose, gave it a hardcore tune up, plugs, hoses, installed electronic ignition, etc. I've been driving it every day since then. Never had a fuel injection problem. Starts up and purrs every day.

Sure, I've done lots of OTHER work to it, did fix a rusty fuel tank and a hundred other things, mostly pro-active upgrades. But I've never messed with the fuel injection AT ALL. Seems like a great system to me.

I'm not trying to taunt you, just to instill a little confidence in the system. Get it running and you shouldn't have to mess with it too much - unless I'm just really really lucky.

I had never tinkered with FI before either. I was a "carb guy" for sure. But after reading the manual, looking at the parts, thinking about it... It's not that complex. If you can learn carbs you can learn FI. It seems new at first, but it's actually not that complex or scary anymore.