Looking for advice - engine dies under heavy load

Reverb · Post by **Reverb** » Sat Jan 21, 2006 5:21 pm

Here`s a short coarse on how to tune a Weber Carb. Step-1: If you are having a problem with how the engine runs...Poor idle quality, stalling, etc then this is the first thing to do. CHECK FOR VACUUM LEAKS ! This is particulary true of new installations where you just purchased and installed a conversion kit and you are having problems. Click the link and follow the steps. http://www.racetep.com/webjettune.html

fubar · Post by **fubar** » Sat Jan 21, 2006 5:22 pm

The "made in China" tag makes me wonder a bit about the float level being set correctly out of the box. The high and variable idle sounds like the thing they use for a "choke" may not be fuctioning right. I don't see much harm in taking it a part and learning about it. Sounds like you know about as much as the guy that worked on it. Just take some tools and a cell phone on your first ride.. The iceing thing I mention because of a 1600 dual port type 3 we had in a baja bug when living in San Diego. The only thing that really cured the ice problem was a set of 36 dcnf webers. I don't know if the solution is easier on an upright style fan motor??????????

joemama · Post by **joemama** » Sat Jan 21, 2006 6:19 pm

BrianK, I dont know where you are in L.A., but there is a good v.w. guy in Tujunga, T.C."s Old V dub Home, 818 353-0011. Tim is a no nonsense kind of guy, and lots of people trust him with their cars, including restorations. If you cant figure things out, I am confident he would be able to help you. He doesnt seem to mind handing out advice, and he also carries a pretty good supply of new and used parts.

BrianK · Post by **BrianK** » Sat Jan 21, 2006 8:56 pm

in answer to some questions: Why is the idle set so high? I have no idea. I'm not sure it is set to be that high, I think something is wrong that's causing it to be that high because it's not that high when it's cold or after it's been idling for a few minutes. This isn't a weber carb, it's an Empi. Maybe one is a clone of the other. (edit: hmm... I see Empi sells weber carbs... Well, I'm not sure if it's a webber or an HPMX... or if that matters) In any event, that bit of reading about tuning will come in handy as a general learning tool. Thanks. Re: Float level - honestly, I don't even know what that is... will start researching.

I certainly hope it doesn't require new carbs... I've invested too much in this thing already. Re: Filter base - good question. I'll have to check if it's still that way (this picture was taken by the previous owner during install) joemama - I'm actually not too far from Tujunga - about 13 miles to his shop... a distance I may or may not be able to actually drive ::sigh:: as it turns out I'm not going to have much time this weekend so he'll probably be getting a call from me on Monday. Thanks for the referal. Thanks again everyone... I'm learning alot here.

5150bossman · Post by **5150bossman** » Sat Jan 21, 2006 10:17 pm

Looks like an Empi HPMX. Pretty much identical to the Weber IDF style. Is it a 40, 44 or 48? I wouldn't worry about having to buy another just yet. These carbs take alot to get running well, but once it gets dialed in, it should run pretty good. Use Reverb's link above, as it has LOTS of good info. I tend to believe that the float level is the first place to look at for your problem. They are notorious for being way out of adjustment out of the box. Unless your mechanic knows how to work on VW's AND Weber carbs, it would be very easy to miss this. Here is another shop in the valley that might help. Top-End Performance 7452 Varna Ave N.Hollywood CA 91605 (818)764-1901 (818)764-0155 fax

1856 · Post by **1856** » Sun Jan 22, 2006 3:49 am

Filter ?

BrianK · Post by **BrianK** » Sun Jan 22, 2006 10:24 pm

The filter has been replaced twice in the last three weeks, so I'd say it's not the ilter.

5150bossman - it's a 40mm. Reading about the float level right now.

newmanx59 · Post by **newmanx59** » Mon Jan 23, 2006 2:56 am

[QUOTE="BrianK"]The filter has been replaced twice in the last three weeks, so I'd say it's not the ilter.

5150bossman - it's a 40mm. Reading about the float level right now.[/QUOTE] There is also a fuel filter in the carb. Remove the large brass nut under the fuel inlet of the carb.

Reverb · Post by **Reverb** » Mon Jan 23, 2006 3:24 am

How old is the gas tank? If it`s an old tank, it could be scaley rust inside, and sure to clog even a new fuel filter in a hurry. I shined a flashlight inside my tank, and didn`t like what I saw, and opted to replace it. New original equipment VW tanks are only about 50 bucks. It costs about the same to have the inside sealed. I`m not saying thats your problem, but it`s certainly worth checking.

Gene-C · Post by **Gene-C** » Mon Jan 23, 2006 4:11 am

My tank was very rusty (I made the mistake of removing the fuel when I got the buggy, then let it sit dry for 5 years...). I cleaned it the best I could but still ran brown fuel for days. filter never clogged. I dont think thats the problem hes having.

Complex One · Post by **Complex One** » Mon Jan 23, 2006 5:29 pm

There are a lot of excellent suggestions for you to try that have already been offered so far. Here are a few more for you to check out. I had many carb issues with my new 2007cc after getting it assembled and have been able to resolve just about everything with them from this one site. Lot's of good technical information and parts regarding everything from "Best Lean Idle" adjustments of a Weber carb to "Synchrometers", to "How To". http://www.racetep.com/weber.html Someone suggested closing your "bypass adjustment screws" all the way closed and this is how they should be adjusted. Just make sure not to over tighten them especially when seating the lock down nut. Once seated keep a screw driver in the slot of these screws and then use the wrench to tighten the nut otherwise you will only force these adjustment screws further into the body of the carb causing ring impressions on them and loosing any future fine adjustment if ever needed. I have never found a Weber, EMPI Clone, or any other similar card setup that actually worked to best performance out of the box and you will most likely need to make several adjustments to your existing card in order to get it to function to peak performanced on your particular engine. Just be patient and you will eventually get there. The cost of a new (clean) fuel tank far out ways the expense of clogging up your new carb so I would consider this as a very viable alternative as soon as you can afford it. One BIG thing to check for now and that is...what is the condition of your fuel tanks pre-screen filter. This is the internal tank filter located at the bottm of your tank and is only accessable if you remove the J-Tube where the fuel line attaches to it. If this is clogged from the rust that you referred to earlier in these posts then most likely you are starving this 40IDF for fuel especially once it warms up a bit. These type of carbs like to have a constant PSI fuel pressure applied to them and if they don't get it all kinds of things can go wrong and you just keep chasing problems that don't really exist with the carb at all. If you are running a fuel pump, other than the stock mechanical, then make sure that it is delivering the proper PSI rating for this carb. This can be tested with a simple pressure gauge at the point where it enters the carb. Use of a Synchrometer is almost mandatory. If you do not get both sides of this carb properly balanced then your engine will also run unbalanced and very rough depending upon RPM. Demand for fuel from one side of the engine will be different from the other. If the last owner did not install the heat riser tubes from the exhaust manifolds on either side to the bottom of the carb intake casting then you will need to get these installed. Even if your carb is not getting to the point of you being able to see it freezing on the outside it is most likely still getting too cold inside therefore the more you drive your vehicle the worst it is going to run. Having these heat riser tubes in place is also mandatory for a center mounted carb such as yours. I'm not running them on mine as I have a dual carb setup where the carbs sit on the dual port intake manifolds just above the cylinders. Heat is transferred pretty well to the base of the carbs as it does not have to travel that far. Not true with you single 2-barrel setup in the center and you need to apply heat to the intake manifold for the fuel to stay warm and keep from freezing things up as you drive. As for air filters: Make sure to use the proper oil spray for these filters. After spraying the filter with this oil spray it will turn the filter a slightly darker color from the oil but will help with proper air flow and to help in capturing more dirt than just leaving your filter dry as it came out of the box. One final not here and that is I have not seen anyone post here or make any comments to you about "Velocity Stacks". I spent a lot of time and money on my dual Weber setup last year. Changed out emmulsion tubes, re-jetted several times, installed Zero Bypass valves in each carb. Each and every thng that I did obviously changed the way my carbs reacted and responded, sometime for the better, and sometines for the worse. The one final thing that I did on my Weber carbs, that most people never tell you about, is that Weber carbs and Clones actually work best with Velocity Stacks installed inside the carb filter. They make these stacks in various lengths each making a surprisingly and very noticable differences in how your carbs and engine respond and sound. Weber specifically recommends that you use 2" - 2 3/4" length on the 40/44/48 carbs. I had a couple of sets of 1 1/4" sitting around here and put them on until my actual recommended lengths arrived and what a difference!!! I would have never guessed that installing a set of velocity stacks, let alone going from 1 1/4" to 2" to 2 3/4" alone would make such a difference in the overall performance and sound but they did! Using velocity stacks created a lot more vortex (swirling) of the air as it enters the top of the carbs and then improved the performance of my engine more than anything else that I had done to date with these Weber carbs. Now that I have the correct length stacks on these two carbs everything works great now. Just make sure that what ever length stack you use still leaves enough room above them inside the oval filter for proper air flow. This can be easily calculated by measuring the internal height of your existing filter. Just my :2cents: worth. http://www.redlineweber.com/html/applic ... sories.htm http://www.empius.com/catalog/empi2005_pg79.html

Stewart · Post by **Stewart** » Mon Jan 23, 2006 8:12 pm

My new weber 2 bbl progressive came with the heat tubes , but there no provisions on my tri-mill muffler exuast system to bolt them to.

Are there any adaptors ? ,or is it a build it your self thing ? I dont want to mess up the ceramanic coating trying to rig something !

BrianK · Post by **BrianK** » Mon Jan 23, 2006 8:54 pm

The gas tank is old. It appears to have some rust in the bottom. I actually thought about replacing it - didn't know they were so cheap or readily available. I also didn't think I had a normal VW tank - the fuel filler is up by the driver's side front light and it doesn't seem to hold much gas - maybe 8 gallons (I've only filled it once & don't know how close it was to empty)? maybe it is a VW tank? Wow Complex one, thanks for all the info - that's good stuff!

Gene-C · Post by **Gene-C** » Mon Jan 23, 2006 11:00 pm

Brian, Chances are you do have a stock VW tank. I think any early bug tank will fit.

Reverb · Post by **Reverb** » Mon Jan 23, 2006 11:46 pm

Does your tank look something like this ?

That is the early model tank, and the cap screws directly onto it. The later model is fitted with a rubber filler hose, so the cap can be located elsewhere. Either model can be purchased here, for about $45.00. http://www.chirco.com/cgi-bin/chirco.st ... talog/1367 I`m begining to think your tank could be full of gunk (what becomes of old gas), or rust. Especially if the tank sat empty for a long time, allowing rust to form inside. You might need to have the filler tube re-located for your buggy. Or, if the tank is still in decent shape, you can have it flushed, and the inside coated, but thats likely to cost more than a new tank.