F.I. To Carb Conversion for Vanagon

[Capn Skully]

First thing... I did searches, I went to Tuna's website and read very fine tech articles on Type IV and Carbs.

I have an 81 Aircooled Type IV Vanagon with F.I.
It stranded me in Pennsylvania with a broken computer.
$300 later it is running good.
This morning I get up and again it starts but won't run

I have an 84 Water Cooled Type IV Vanagon with F.I.
It stranded me on a club cruise. Ran fine but would not start when hot.
It is in the shop waiting for diagnosis.

I have had it with these antique FI systems that I can't fix, can't find parts for and are totally unreliable. I love VW but they don't know crap about FI

I just want to drive my bus, I don't want to drag race it, convert to upright cooling or decrease my zero to sixty time.

What is the most reliable and easiest conversion to carbs I can do?
What do I have to buy?
How does the aircleaner and linkage work?

At least with a carb I can fix it instead of hoping the shop won't hurt me too bad.

[MASSIVE TYPE IV]

Aircooled.net, or CB Performance........

Get a complete Weber 40mm IDF kit and bolt it on. Problem solved.

[dstar]

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I have an 84 Water Cooled Type IV Vanagon with F.I.
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I'd like to see one of those!


Folks call them the Type 5....


Don

[Piledriver]

Might want to hit the FI forum first...
Most problems are trivial to fix.

The `84 has what is called a "wasserboxer", `84 has a 1.9. It is the final water cooled evolution on the T1, and is a fine, long lived, reliable motor (the 1.9 is almost bullet proof) as long as you use the right antifreeze, which should be blue or orange, NEVER green.

(VW blue stuff or GM Dexcool rated orange)

The heads will corrode otherwise.
(BTW, almost any GM product made after `95 should NOT have green antifreeze in it either for the same reason)

I currently have 239K miles on my 88 vanagon, but I did replace the heads when I got it from the original owner, as they were toast.
Does not burn or leak a drop of oil...

[Capn Skully]

Might want to hit the FI forum first...
Most problems are trivial to fix.

Trival yes... expensive yes... Problem is there is about a hundred trival parts involved. A carb gets gas, meters it and dumps in the cylinders. I know FI does the same thing but in a more round about convoluted manner, any thing that requires a computer to control it is too complicated.

[MASSIVE TYPE IV]

I'm a carb guy by birth.... I love the simplicity and also the fact that I'm pretty damn good at tuning them.. That makes my job much easier...

Lately I have been doing alot with the Kit Carlson EMS system and I love its simplicity and its ability to make gobs more power than carbs (look at the reasearch and development portion of my site for the proof)

When I took the carbs off my 912E that had been perfect for 59,000 miles in exchange for a test version of the EMS I was astonished. The carbs were set up at 12.8-13:1 AFR and I yielded a head temp of about 325 all the time in fifth gear and it would hit 340-350 up a hill. When I installed the EMS I leaned it clear to 14:1 and my head temps were a solid 275 all the time and 300 hitting a hill! With the FI I cannot get the heads to 350 if I try!!

[raygreenwood]

Actually..there are not about 100 parts. There are less than 5 sensors...and about 40 wires in the system you are dealing with. Its simple. These systems are not complex at all. Also...chances are exceedingly rare that your ECU/Brain died. I mean like a couple million to one against it. Usually its a connectivity problem and just pulling the same ECU in and out fixes it....by jostling the plug....unless it got wet, or you zapped by improper jump starting or a major power system short.
Actually...there are NO fuel injection systems made anywhere at this time...that are more dependable than the original L and digijet/digifant series....yes..that includes what is out on modern american and European cars. The only parts that are more dependable are the wire jacketing and insulation and coolant temp sensors. All the of the other sensors are other than MAP...are unchanged from 1976 on. Have you ever driven 150-200K miles on a brand new properly cared for L-jet or digifant system? There is nothing undependable about them. Just get a new harness. That is 98% of all problems. The E-prom based semi-conductor circuits in modern EFI fail at a rate about 200 times more prevalent than failures in the solid state ECU's of the systems you are dealing with. A bad spark plug wire is what usually causes most of them....or a leaking coil pack. Thats not saying there are not excellent EFI out there now. Just don't throw away something good because you don't understand why it failed or what its benefits are. Ray

[Piledriver]

Isn't hot start issue something common?
(I've never personally had the issue...)

I'm thinking fuel pump foot valve(not sure if this particular setup has one, buy I bet Ray does), or leaky injectors.

The fuel rails are supposed to have some residual pressure on them IIRC.

The seals on the injectors should also likely be replaced, takes like 5 minutes, the CIS ones work GREAT and cost ~ 2 bucks each.(little kit with 2 or 3 parts for Wabbits, you just need the big o-ring)

Also note that if you think your gas mileage sucks on your Vanagon WITH EFI, just wait until the carbs go on... Less average power thru most of the RPM range as well. (Just what you need in a 5000lb van)

Back in the days of yore, I recall seeing the aircraft electricians use this silicone/antioxidant contact protector in a spray can... Kept the corrosion away. Dielectric greases have been used, and I have been using waxy Pennzoil/rustoleum marine corrosion protection spray with sucess on any connector I see. (rated for 2000 hr saltwater protection, seems dielectric. Smells like fish oil...) (OK Ray, opinions?)

[Capn Skully]

Apparently it is a cold start issue. This afternoon when the temp warmed up into the high 70s it started and runs fine.

This morning it was 30-40 degrees F.

Any ideas?

Forty wires compared to one... is not simple. Five sensors compared to none... My Thing with a single carb, one wire runs very fine thank you very much.

[Piledriver]

Cold start injector? Temp sensor ? Weak battery (I'd start there...)?

A carb setup has LOTS of sensors, they just screw out, and cannot compensate for temperature, altitude, engine wear, sucky gas, or anything else.

It's YOUR money, and Webers work great, I get >40MPG as I said, and the car runs great...

I have as set of 44s on my Pile. Will gladly trade for a working Megasquirt computer with harness (will be building my own harness, but required for testing and initial running),

Weber setup includes Hexbar and my "Pile" cable pull linkage, air cleaners, and a Carter (Bugpack) pump and Purolator regulator.

Sadly the 44s would work like ass on a T4 Vanagon, and the manifolds will not clear the engine lid. (I don't think, maybe)

I still maintain the stock EFI will blow away the carbs, ESPECIALLY in your applications.

[raygreenwood]

The hot start problems are easy to solve. Others opinions...may differ...and I have argued long with them...and care not to anymore......mainly because I have never found a single fuel injection system that I cannot solve ALL of the hot start issues with.
You have to understnd what happens with each part in the system...and not just what the VOM says...based upon what the factory says it should say.

Think about these things. And...don't kid yourself, if the engine basic mechanical state and its compression are not well...nothing will help you, because that affects the metering system.
For starting you need correct fule mixture. If your fuel ixture is not correct in the first place, meaning you are either rich or lean, you will have trouble starting because that condition will be magnified.

Hot starting is usually caused by one of several things. One of the primary causes, is a combination of the CHT being maxed out...and staying that way because it banks heat (this causes a lean condition)....AND couple that with a fuel pressure regulator that is leaking down too quickly. Add to that an auxiliary air regulator that may open back up too quickly (It cools off too quick). So you have air bypassing (lean). Fuel pressure may be low or not stable (lean) and CHT is maxed (still around 100 ohms or lower).

This is most prevalent on L-jet and digijet. It is less of a problem with digifant due to the fact that they have re-added the fuel pump "buzz" or pre-load pump-up, into that system...unlike L-jet...which must have air flowing past the flap in order for the fuel pump to start up and pressurize the system.
You need to check your fuel pressure both at idle with vacuum line connected and without. Also, when you rev it...if it drops more than 2 psi...you have a suspect pump (most likely)...or a suspect regulator ...or both. The regulator should maintain 15-18 psi for at least 30 minutes after shutting down...or its defective.
For the CHT...I recommend sending $2.75 at Freyes electronics...or $8 at radio shack and getting a 0-1000 ohm adjustble cermet resistor to plug in line. Give it about an extra 100 ohms to start with. it will run beter in all modes...and not un so lean in hot weather...and have less hot starting problems.

One of the other great causes of hot starting problems...is running rich. Check all of the injectors for leaks. If you have a single vacuum leak anywhere in the engine....it will run rich. "0" vacuum leaks are allowed.
It causes the fuel pressure regulator to run higher pressure. Also, leaks makes the metering unit flap sluggish. Than can make the lean condition listed above worse.
This is not an insult or a jab...please don't take it that way....but if you need to take your car/van to someone to work on the injection...then you have vacuum leaks...trust me....you don't know enough about where to look for them. there are quite a few place to look that are not obvious. As me and I will list them. The best way to check for vacuum leaks...is to take each part loose, chec the flexibility of the rubber part...or replace it. All hoses...period...must be clamped. Once you have gone through teh whole engine, write down the date in a log book..and replace a little bit of everything over a 3 year period (its cheap and easy that way)...and you will never ever have the problem again. Fuel lines must ALL be replaced every two years.
Also, make sure that your auxiliary air regulator does not re-open until ambient temps drop below 100F after its has been heated up, closed and then shut down. All but the original d-jet auxiliary air regs are easily adjustable.
Almost all stock systems have weak ignition. This makes that problem worse. Even the later vanagons wit electronic..though greatly improved had a weak train of ignition. Use a better coil...use teh best wires you can get. Since they have resistor tips..get rid of the resistor plugs. Clean the carbon from teh cap and rotor at each oil change. It makes a difference.

Yeah a carb has one wire ...but is actually more complex than FI...and less dependable...and has sloppier/slower throttle response...less HP and less torque....gets less gas milage...AND you have to synch the carbs. I have a carb synch tool...I use it as a wheel chock . Oh...if you have solid lifters..adjust your valves...and check them hot to make sure they are symmetrical. This makes a huge difference on injected vehicles. Ray

[Piledriver]

IMHO, one of the "problems" with Bosch based FI systems is that a very small percentage of mechanics know them like carbs. The reason is not obvious, since they have been out for >30 years, but I have a basic theory...

You understand what you have to fix, because you LEARN by fixing.

Theses FI systems very, very seldom "break", and very few people ever get the "opportunity" of becoming proficient without intentionally doing so, and working quite hard at it.

I have worked on many FI issues over the years, although I have never done it for a living... and have fixed quite a few FI issues for freinds and family and the odd stranger..

They were ALL on the order of "trivial/obvious/stupid" like loose/no hose clamps, retained/"fixed" with duct tape (several times), leaky cracked boots, disconnected hoses, and the odd leaky injector.

And many (obviously) cruddy grounds.

And the occasional dead ECU on GM cars. Those units *do* die.

I have never had to actually replace more than a big handfull of hard parts (pumps/regulators/injectors) in >20 years.

I do NOT consider myself "proficient" on FI in any way. I have yet to have to be.

I "fix stuff" for a living, and you only get really GOOD if you are in a firefight, so to speak, and SEE problems, and must come up with solutions/troubleshoot and understand the system, as you MUST.
On must learn by doing...

In the semiconductor industry, to component level electronic troubleshooting experience is almost cherished... And yet fabs almost NEVER fix ANY boards in house... Confused?

People with those skills are "get in" not because they have those particular skills per se, but an prerequisite ability that comes with it: They can TROUBLESHOOT stuff. Any stuff. It's a way of thinking more than anything else. That's all I can really claim to have learned from ~10 years of fixing the odd aircraft and mostly black boxes in the USAF.

Jake for instance just didn't come by his extensive T4 knowledge by only making perfect killer T4 engines from day one, he certainly has personally torn down hundreds and seen how they die... Including some of his own children. I know he learns new stuff every day.

In that way, a good tech will learn, and start to think how to prevent those issues..

FI is NOT complicated. I have worked on complicated, do it every day. The FI forum on this site (Ray in particular) is likely one of the better "shops" on the planet to get your Bosch EFI woes troubleshot, and to learn how it works.

[amskeptic]

unlike L-jet...which must have air flowing past the flap in order for the fuel pump to start up and pressurize the system.

The double relay does allow fuel pump priming during start #50 to d.r.

If you have a single vacuum leak anywhere in the engine....it will run rich. It causes the fuel pressure regulator to run higher pressure.
Also, leaks makes the metering unit flap sluggish. Than can make the lean condition listed above worse.

Only leaks in the control vacuum circuit to the regulator may cause a minor richening noticeable at idle. There are other components that use vacuum also to confabulate your symptoms, decel valve, and advance unit. The lean-out at the AFM can indeed show up right away, as can the big hoses like leaking one-way valve to the booster and the auxilary air regulator. I ran into a few buses this summer that had leaks at the dipstick (and the plastic breather domes on Vanagons). I love these L-jet systems, and find people shy away too vehemently, like a horse from a field mouse
Colin

[j-bro]

I just have to object to the comment that VW doesn't know crap about fuel injection. These are very good systems they are just old. I agree that its usually a connectivity problem. Over the years the systems that used to be practically trouble free are starting to let people down. The problem is finding intermittantly bad wires or connections can be difficult, while finding a replacement wiring harness is difficult and expensive; rebuilding it yourself laborious. I understand if you want to swap from FI to carbs but I would suggest you keep or sell the parts and don't throw them away. They may be desirable to a future buyer of the bus. Good luck.

[raygreenwood]

Thanks amskeptic. I am getting less and less accurate with memory. But..not all L-jet systems that I have found...prime their pumps with the turn of the key. A glitch? a fault? perhaps...I will check that circuit more carefully on all L-jet systems I work on in the future.
One point of difference though...ALL vacuum leaks affect all injection. Even though they are not in the metering circuit...which does affect idle and does affect fuel mixture....downstream leaks may not affect idle but do affect fuel mixtue. A leak anywhere south of the TB can affect the pressure regulator. It also is added unmetered air. Since the volume of this air increases with rpm...depending on where it is...the volume of un-added fuel goes up. It usually shows up as poor powe in the midrange rpms. If your level of tuning s just basic stock...it may not be noticable at all. If its a non stock base motor with some cam changes...it can greatly limit the tunability and output of an otherwise sound system. Ray