FI vs. Carbs

richcarl32 · Post by **richcarl32** » Sun Jul 23, 2006 4:37 pm

i am having a night mare of a time getting my 78 bay going. i have had it for 3 months now and have checked all of the Fi components and they all check out and still no fire. i am thinking of pulling the Fi system for a dual carb setup. i just dont know what else to do. any places to get a good dual carb setup. i want to sell what i have here but dont even know how much to ask for it. guys what should i do.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Mon Jul 24, 2006 5:29 am

Will the engine run at all with the FI fitted?

I sell dual weber carb kits in my store that are ready to bolt on..

Stay far, far away from the single progressive carbs!

raygreenwood · Post by **raygreenwood** » Mon Jul 24, 2006 7:38 am

I have the same question. Does it run at all? Here are some things that are important.

Is it timed correctly, what is your fuel pressure, does the fuel pump buzz when the key is turned to the first position an then does the pump start again after the engien is turning over? There is a microswitch in the AFM that completes this transition. If you disconnect the power to the ignition , have somene turn the engine over while you move teh flap with your finger.....you should hear the fuel pump run.

Also...check all of your grounds. They must be perfect. You are not allowed a single vacuum leak anywhere in sthe system. Most especially in the boot between the TB and the AFM.

Also...what is the resistance on your cylinder head temp sensor....and is teh connection perfect. Tell us what the car is doing and we can probably help. Ray

Bug-a-natic · Post by **Bug-a-natic** » Mon Jul 24, 2006 8:18 am

Hi Jake,
I noticed that u mentioned to stay away from the pregoressive. Why? Are'nt they great for economy engines?

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Mon Jul 24, 2006 8:25 am

The progressive sucks. Period.

I never had any luck with them on TIV engines, all they do is cause rich running, tuning problems and ice up in the winter...

richcarl32 · Post by **richcarl32** » Mon Jul 24, 2006 7:35 pm

like i said before, i have checked and rechecked everything on this system. i have my books, read every page, checked all components, replaced all compinents that didnt check out, and rechecked everything again. i have taken this bus to "doster brothers garage here in athens, ga and they are confused too. i am giving up on FI all together. i went to look at the type 4 store, but the site is down, to price the kits for dual carbs to replace the Fi system. can some one recommend the best dual carb kit for me. i need to know what i am looking for too, like what size, brand, and anything else i need to make sure i geta good deal. i am gonna sell my Fi system too so anyone interested give me a message and i will take offers.

Clatter · Post by **Clatter** » Mon Jul 24, 2006 7:59 pm

Boy, you'll feel dumb if it ends up being an ignition problem...

Carbs get crappier mileage, make less low-end power, and are much less drivable than the factory EFI (especially with a bus).
Plus they have their own set of issues.
You'll spend more time in the long run messing with carbs because they need so much "babysitting".

Your EFI has something SO easy wrong with it. A loose wire somewhere or something basic.
Once you get it right, it stays happy for a long time.

You're obviously taking it to the wrong shop, too.

Give it a rest, sleep on it for a day or two, read and re-read stuff from the FI forum, and try to find a different shop.

When I hear people making this mistake, it makes me cringe!

raygreenwood · Post by **raygreenwood** » Tue Jul 25, 2006 5:14 am

90% of all EFI problems....are wiring harness related. This is a simple system. It has 36 wires or less 3 or 4 sensors....one fuel pump and one trigger....the distributor. Please....not trying to be ugly or pointy at all....but it appears you are "trying" to talk yourself into carbs.

At what point are you going to describe what the engine is ...or is not....doing. Also...what were your fuel pressures? By that I mean....have you checked the pump output for volume? You measure that by running the pump into a graduated jar for one minute...without the fuel pressure regulator attached. Then...check the volume with it attached. You will need to wire the pump directly to the battery. It must have very little reduction in the required volume AT teh required wide open throttle pressure.
Also....have you checked to see if the switch in the AFM....is allowing the pump to run during the starting cycle?

Have you checked the main ground bundle under the plenum?
Have you checked the resistance of the resistor bundles?

Have you checked each and every wire with the VOM...back to the ECU end? That is generally the first thing to do. It is common to have a broken or high resistance wire in the harness after so many years.

It is also most common to have a weak regulator. Have you done a leak down test on the regulator? That is also an immediate requirement on systems that have not run in a while.

If you have not....yourself...replaced all of the seals that I am about to list....then you are 100% guaranteed to have vacuum leaks that you do not know about.
Tb to plenum seal
Injector seals
Oil breather cork seal
runner boots at the plenum
head to runner gaskets
auxiliary air regulator check
pushrod tube seals
valve cover gaskets
vacuum advance cannister (check it)
vacuum advance/retard lines
fuel pressure regulator vacuum line
oil breather to plenum vent lines (if present)
There is more. This will get you started. Doing what the book says...is not enough. Ray

richcarl32 · Post by **richcarl32** » Tue Jul 25, 2006 12:32 pm

okay i get it. i will sleep on it for a few days and try to figure this this out. my thought process was that replacing all of the components you listed will cost me a fortune and the truth is that i have never even heard this engine run. To boot it seems that no one in my area has much knowledge of these engines and/or the FI system that goes with it. every one int he vw club of athens are bug guys and none that i have spoken are even willing to try to help me sans one. my expertiece is in body and interior work. this engien ran last about four years ago. one day it just would not crank for the PO and he let it sit. it was runnig strong and then nothing.

i cleaned and/or changed all of the fuel lines, rails, filters, pump and injectors, not the regulator, and did an overhaul on the fueltank cleaning all of the 4 inch deep sludge in the tank as per richard atwells website.

the starter motor is very strong, the engine is timed correctly as far as i can tell, probably not perfect though since i have never put a light on it as it has never cranked for me. as i try and start the engine i hear a whoosh sound as the starter motor turns. never any hint that it is gonna fire. the fuel pump relay is in good shape as per the bently book, all scenarios check out fine, the pump is getting juice when i try to start it.

i am a good learner and will do as i am told to do, so i will not be changing over to carbs. but i do need help bad. will some one now tell me step one to do to get this old girl to fire. What would be the first thing that you checked. after i check that i will post my results and move onto the next thing that i am told to do. or if anyone is in the athens, ga area and is willing to help me, post to me and we can work something out.

thanks to everyone in advance.

raygreenwood · Post by **raygreenwood** » Tue Jul 25, 2006 1:38 pm

If it has not run in a few years there will be a couple of common problems. Always start with fuel supply first. The fuel lines are a start. But...make sure that the system is running in the right direction. You need pressure to come from the pressure side of the pump. I know it sounds simple...but I would check it.

Usually the pressure regulator is suspect due to rust. Its an easy check...but first...wire the pump up directly to the battery. Mind the polarity of the terminals. It is specific. You want to run the pump...minus the regulator...into a jar. 1 liter per minute or better is what you are looking for. Then....put the regulator on teh end of teh line. It should be able to hold about 42 psi at just under 1 liter per minute.

Also...make sure all the ground braids are properly installed. The one from teh tail of the tranny, any that come from the alternator etc. Ray

richcarl32 · Post by **richcarl32** » Tue Jul 25, 2006 2:38 pm

okay i will get on that tomorrow afternoon. i dont have a fuel pressure gauge though. is there another way.

raygreenwood · Post by **raygreenwood** » Tue Jul 25, 2006 5:20 pm

Basic fuel pressure gauge can be had at home depot. Get a water pressure gauge that reads in 1 psi encrements...with at least 40+ but not more than 60 psi range on te hscale. These are accurate enough for proving and setting up the system. For perfect tuning you must have one accurate to 1 psi at full scale and 1/2 psi readings. But for 90% of the work...a basic pressure gauge with a 1/4" brass barb and a couple feet of fuel line with a clamp on each end will work great. Thw whole thing should not set you back more than $20. Ray

Bleyseng · Post by **Bleyseng** » Tue Jul 25, 2006 7:31 pm

To check if you have spark that is working pour a tablespoon of gas into the plenum then start it.
If it fires you have spark and its a fuel problem.

My son rebuilt his 1.7 914 while I was out of the country for 2 months.
I came back to Djet is crap, won't work, no fuel and the pump is working right.

Hmm, test the fuel hose from the pump to the rail, no fuel pump is running.,,,,wires to the pump were on backwards so the pump was spinning backwards!
fixed that and it started right up!

Its something simple

richcarl32 · Post by **richcarl32** » Wed Jul 26, 2006 5:54 pm

too much rain here today to get out there and do any FI troubleshooting today. will let you guys know what happens tomorrow

raygreenwood · Post by **raygreenwood** » Wed Jul 26, 2006 6:07 pm

Jeeez!....You guys got rain??!!.....what type of animals did you have to sacrfice?....were you required to dance...?...virgins involved?...

Ray

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FI vs. Carbs

FI vs. Carbs

No progressive?

giving up on FI.