Seems that this year I need to put a little gas into the carb to get the car started initially. I have single Solex carb that no one seems to be able to identify. I'm sure some PO just pulled it off something that was sitting in a junkyard. Once I get car started and it warms up it idles OK but runs rough when you try to drive it. Timing is spot on. Recent (not too many miles ago) tune up with the help of some very knowledgeable 914world brethren. Let’s say it’s a given that there is nothing wrong with the engine. I have an idea of where to go next. I’ve had car for about 7 years. With only what I’ve told you here what’s your opinion?

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If you have to dump gas in it, the throttle pump if not working. Either the gas is boiling out of the carb after you turn the car off or you need to replace the throttle pump assembly.

Agree with Mike. If the carb has never been rebuilt it could very well be that the accelerator pump diaphragm is shot. It will idle on the the gas running through the idle circuits, but when you give it added gas, the additional "shot" of fuel the accel. pump isn't there, or adequate to keep up with the additional air. Might be time for a rebuild? If these symptoms just sort of crept in, that might be a good place to start as the diaphragm slowly decays over time - eventually it just cracks or tears.

Also, FWIW, it might also be a good idea to get rid of that plastic fuel filter. Those things have a notoriously bad reputation for cracking, and in this case, it's going to run fuel down the sides of your engine... right onto the exhaust.

Yes - I agree. Time for a rebuild. I've had it for 7 years as I've said and never rebuilt the carb. It has slowly been getting worse over the last few years. So my dilemma is I can't find a rebuild kit for this carb. I even sent pictures to a place that sells rebuild kits for solex carbs used in manufacturing during the same era. They have a bunch of rebuild kits for ones used in all different makes and models including Volkswagens. They didn't recognize this one. Does anyone recognize it or know what will work?

is the one butterfly activated by the what looks like a seloniod? if you press on the peddle when cold is that when the butterfly closes? i don't know how that style works.

k

Looks like a manual choke setup to me.

Yes - It's a choke. I don't know why they need that big thing on the side for a manual choke. Not a solenoid though because there are no electrical leads going into or out of it. Look close at the side shot - there is a small piece of wire holding it open. Like I said no one seems to have ever seen this carb before. There is a previous post of mine from within the last couple years where I posted pictures here and asked "what kind of carb is this and where can I get a rebuild kit".

My topic from two years ago looking for carb rebuild kit. More pictures of my carb.

I've got a set of dual weber 44's with manifolds and linkage, that need a rebuild, that I am not going to use if you want to upgrade. (carbs "and" motor)

I agree, if you can't pump some gas into the carb with the pedal then your accelerator pump isn't working. On that carb I think you can see the accelerator pump linkage on the outside of the carb, and see if you're getting a stream of gas down in the carb as you work the throttle, so you should be able to diagnose that without taking anything apart.

That's an old "automatic" choke with the spiral spring inside that loses tension and lets the butterfly open when the carb heats up. It looks like there's a cable missing on the choke, or is it there and I can't make it out in the photo? Converted to manual with a cable? You say there's a spring holding it open? You've watched that choke butterfly before you've started the car and after? As it warms? Is the cable working the choke butterfly normally?

The carb number is cast somewhere on the carb body, and you usually have to remove the carb to be able to read it. They should have a tag on one of the studs that gives you the configuration number, but those disappear. To me it looks like a Solex 34 or 32/34 PDSIT (my memnonic was "Police Department! SIT!"), but that's from a long time ago and my memory's not the best any more. See if there's a number on the carb, then send photos to maybe Pelican and Aircooled.net, see if the can tell for sure. I'd suggest the aftermarket 914 and VW people over a carb rebuilder. Rebuilders deal with everything, so a lot of variables. On the other hand the VW/914 aftermarket parts people sell those carb conversion kits every day, so they should be able to narrow it down a little easier.

Hmmm.. a search for Solex 32/34 or Solex progressive didn't return anything that looks like what Jason has. But DB is on the right track. You might need to pull the carb to verify this for sure... but I think it's a Solex C34. ->

http://www.shoptalkforums.com/viewtopic.ph...64&t=139538

What do you guys think? Jason, if you can find a rebuild kit, I can rebuild the carb for you. Or I/we can probably help you through it.

http://www.carbkits.com/catalog/pr/c5/3/solex%20carb

I think this is the kit, but I would verify the numbers on the carb first to make sure it's a C34.

maybe a ll he needs to do is replace the choke spring assem. one won't come in the rebuild kit.

so in theory you would press once fully on the peddle to set the choke, yes? partial winding of the spring?

I guess I can't use dual 44s on a stock 1.8 right? That'd be overkill. When the carb was working good, it was adequate and fun enough. I measured it to be 38. Some day I do want to upgrade the engine. I think I'm just looking to get my car dependable again at this point and if I can make it to the Deutschmarque Classic in Vienna, VA on May 5th that would be a plus.

You could go to your local auto parts store and get an electric choke kit to fit that manual assembly. It would replace the black part. Around $10. It would help with the cold start if the cable is not connected.

I didn't ever have anyone push the peddle for me while I watched in the barrel but I pushed it a bunch with the fuel pump running and then got out of the drivers seat and checked the barrel. Wasn't wet and I should have had a stronger gas smell so that would confirm what you and everyone else is saying.

It's always open see attached pic for better explanation of what I was trying to say.
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I'll have to pull it and take it around to some of the local shops. thanks for the advice.

maybe. After I get it rebuilt and it runs great I'll see. I've never really minded having to wait for it to warm up.

Thanks George. I appreciate the offer. I'll have to pull the carb first and look for numbers. It's obvious that that's what I need to do to get it running right again.

I'll probably undertake the rebuild myself. Sounds fun. But I'll be asking for advice here.

And ThePaintedMan wins it! Thanks George...
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Glad I could help and I got something right for once. I've been screwing up a lot lately, but I learn with each step. Good luck Jason.

At what point should this cam bracket actuate the accel pump? This is the at rest position with the butterfly closed. You have to push the peddle a long way before cam shaped bracket even touches the accel pump. By the time this happens both butterflies are wide open. Seems like it should happen before that. Should it be touching the accel pump actuator arm at rest so it sprays extra gas as soon as you touch the peddle at all? Click to view attachment

Assuming it works like every other carb (and physics dictates that it does), you are correct. The accelerator pump should engage with the initial application of the throttle to a mechanically-activated shot of fuel with the in-rush of added air. On some carbs, like the later Webers, this can be adjusted based on how rich the idle circuit already is or how the carb transitions from idles to mains. Every engine "wants" something different. Is there any visible kind of adjustment on that carb, or a reason why it isn't activating with the initial application of throttle?

While you have it out, you might try to carefully remove the accelerator pump cover to inspect the diaphragm. If it's still supple, you could reinstall it and focus on figuring out why the arm isn't actuating the pump itself, and it might be enough to get you to the event you're trying to go to this weekend.

However, since you've had the carb on the car for at least 7 years and with modern fuels, I still betcha it's time for rebuild.

That's a big gap between the cam and pump arm. It almost looks like something is missing. A link maybe? Can you post some more pics of the cam and pump from different angles?

The cam should push the pump as soon as it moves from the idle position.

I see what Mike is saying. I still can't quite figure out how it actuates from the picture, but if that bottom cam is the throttle cam, the two should be tied together somehow.

The accelerator pump actuation is adjustable though. I see the little screw on the end of the arm where it pushes down on the diaphragm itself. Don't mess with that though - follow Mike's thinking - how does the throttle lever push the arm down.

Edit:
http://www.shoptalkforums.com/viewtopic.ph...64&t=139538

I can see it in the diagram down toward the middle of the thread (part #29), but it's hard to tell in the picture if the pump actuating cam is situated with the throttle full open. It should close at some point when the throttle is completely off idle and into the main.

Jason, while you have it out, you might also replace those black vacuum plugs at bottom front side of the carb. If those are cracked or leaking it can wreak havoc with drivability.

Looks like the arm needs to come way down. Where is the adjustment point?

The only adjustment I see is right there in the center of the accel. pump body where it says "Solex."

Ohhhh, I get it now. The end of the arm has a little roller that rides over the cam and as the cam moves up, it levers against the arm, pushing the diaphragm in. Is it possible the diaphragm and/or diaphragm spring has collapsed so far that the arm really doesn't push down at all? I.e. it's never tight up against the plastic nub sticking out of the accel. pump cover Mike?

Without having more info and pics, I agree with you. The spring may have collapsed. Since the arm is cast aluminum, you can't tweak it to seat correctly. The only other variable is the plastic plunger in the pump.

as he stated, the choke looks to be wired in the permanently open position. i think that carb is like a 2 barrel 4 barrel. the venturi with the throttle/choke plate on top is the primary. the other vent has the tp lower and does not crack open until the linkage activates it. consider verifying your fuel pressure. those chrome jobs are not known for their accuracy. the fuel filter should be prior to the pump. not after.

k

So just to confirm... The "at rest" position should be butterfly is closed, accel pump is actuated with the slightest push of the peddle?

I noticed that when I had disconnected the fuel line, and took the carb out, I was pressing the actuator arm against the acel pump button and it was spraying a good amount of gas in the barrel... I did it more than a couple of times. Maybe I need to just adjust that cam shaped actuating arm. Possibly it is not tight and got pushed back or I did it a couple years ago without realizing it.

That's my exact symptom that if I hit the throttle hard it would stall out. Accelerate slowly and it worked Ok but what fun is that. I think I'll try to adjust it and put it back in just to see. Anyway, rebuild kit is on the way...

No linkage missing. I think I just need to adjust. It does make contact but in the at rest position it's in now, the peddle has to be all the way to the floor and by then both butterflies are full open. So that's not right. I will try to take more pictures.

I might but remember my week this week and I'm trying to make the show on Sunday. I'll give them a close examination. I could do that with the carb on the engine.

Correct.



That's a good sign. If there is fuel in the bowl and the little plastic nub of the accelerator is depressed, fuel should squirt into the throttle body. So it does look like either the cam or the arm needs some work to actuate the pump.

The problem is, I don't know how the cam could have moved. It looks like from the diagram the way it attaches to the throttle shaft is fixed. I.e. it has a slot in it that the throttle shaft can only pass through in one way. It is possible that either the cam or the throttle shaft has somehow become stripped, but we wouldn't be able to see that until you pull the cam off.

The other scenario is that somehow the accelerator pump arm is somehow bent. But as Mike said, it's cast aluminum and if it is bent, there's probably little you can do to bend it back without breaking something.


Replacing the vaccuum caps is easy - they're just the two rubber black stopper looking things at the bottom of the carb. Autozone/Advance auto sells them in packs of assorted sizes.

You are correct the one with the choke is primary and the after the primary is full open, pushing the peddle more opens the secondary.

Good point! I will eventually move the fuel filter back under the car.

Damn! I didn't look closely enough at the drawing to see that the cam was slotted. I was hoping I could rotate it into position after loosening some nuts or something.

No way the accel pump arm is bent. It's totally straight. Funny that it does look like it reaches down further in the picture.

Just got off the phone with the carb rebuild kit supplier. May have discovered the reason why the cam that actuates the pump arm doesn't touch (is so far offset) the arm when everything is at rest. Kit being sent priority mail in mail today from Cali. More to come...

So everyone is pointing out this distance that just shouldn't be here. Looks like it's been like this for a while. I found two other Accelerator pumps in a bag of old stuff from the PO. Both were used and looked exactly the same as the one that's in the carb.

So we all agree this gap is too big. The only adjustment is the fine adjustment screw you see in the picture and it can't be screwed in anymore than it already is. Obviously the person who last rebuilt the carb turned the screw in as far as it can go. Nothing is broken or bent.

I also took a good look at the carb tonight turning the throttle and watching how the cam interacted with the accelerator pump actuating arm at different points. There's actually two lobes, first lobe sprays more when engaging the primary and the second lobe sprays when the secondary is engaged.

So I can think of only two other logical conclusions.
1. The pump is so torn that the button is pushed in farther than it should be.
or
2. The answer I'm hoping is the silver bullet I've been looking for.

Anyone?
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Take off the screws holding in the accelerator pump diaphram, the housing around where that punger screw sticks out. Should be four screws. Behind it will be the diaphram, peel it off around the edges, carefully so you don't tear it. Below the diaphram will be the spring that it pushes against, that returns it to the pump position. I'm betting it's that spring, only think I can think of to explain that gap in the outside in the linkage, but look to see. And look closely at the diaphram, when they wear out there's a hole in a line that usually looks like it's been abraded. All easy to take apart, easy to put back together, and will be replaced when your carb kit arrives anyway. So no real reason other than curiousity.

The only other thing I can think of to explain that gap is that there was a cap on the plunger, where it sticks out, that's come off. Can't really tell, is that plunger plastic? If so it probalby had a cap where that screw contacted it. Any wear there on the plastic part, if it's plastic? If not that's another inication there was a metal cap that's not there any more.

Pull the accelerator pump cover off so we can see what we're dealing with. If diaphragm has deteriorated, or the spring has collapsed, it isn't functioning at all anyways. As DB said, if you'll be getting the kit in before this weekend, you'll be able to replace the diaphragm and reinstall the carb to get you where you're going.

Then you can pull it back off when you have the time to do the rest of the carb. If the rubber in the diaphragm is gone, it's likely that other o-rings and gaskets are on their way out soon too.

I will get the accel pump out but can't do it tonight. Maybe tomorrow. Soonest I get parts is on Friday.

latest news. I got the carb kit and what I thought was the problem was not. The vendor told me that there were two accelerator pumps for my carb. He said one was longer.I thought that was my problem all along; I had the wrong accelerator pump. But that was not my issue. Turns out my issue was gum. As in my accelerator pump was gummed up. my accelerator pump was in very good condition it was just held in buy dried gummed up gas. I cleaned up, and put everything back together, and now I'm here at the inspection station. I'll let you know how it turns out, pictures to follow when I have time.

The story picks up here...

So last you knew I was using my phone at the inspection station to make the last post. Lets rewind to Tuesday... I got a call from the carb rebuild kit vendor telling me that there were two different accelerator pumps for my carb and asking which one I had so he'd know which to include in my kit. He said one was much longer than the other. I thought to myself this must be my problem all along... I have the wrong one in my carb. I paid the extra $10 to have him include both pumps and a few more dollars for priority mail. Remember I'm trying to make it to a show on Sunday.

In retrospect it didn't make much sense that I had the wrong pump all this time. My car didn't run bad the first several years I had it.

After a really hectic week I was excited to receive the kit in mail on Friday. I ripped open the package only to discover that the longer accelerator pump was the same one I already had. I set it aside to enjoy a pre-arranged, Friday night dinner with the in-laws.

At about 8 this morning I went outside and started giving the carb a gasoline bath. I wanted to put the same accel pump back in because it looked to be in good condition. The spring also looked to be just fine.
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I wanted to just clean out the inside of the accelerator pump reservoir because it looked a little dirty. I was hoping I could find some other adjustment to get the cam closer to the accel pump actuating arm. When I got everything back together it lined up perfectly! It was just some gummed-up grime that was holding the button in and the gasoline bath had cleared it out. I mounted the carb back on the intake and made some small adjustments to the fine adjustment screw in the actuating arm so that the accelerator pump is actuated with the smallest push of the peddle. I also put the tension spring on a little tighter. I had an issue where my carpet was keeping the peddle from fully returning to the neutral position which made the car idle a bit higher when that happened. Now it doesn't do that. Here's what it looks like now.
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Much better right?

Runs much better. Here's my problem now...

My car runs 95% better but I still don't know how to tune this thing. When I got everything back on my car I still had an issue where it was dying out when I hit the throttle. I found that if I tuned the screw for Primary idle jet a tiny bit, it got rid of that. See earlier in my thread the diagram of my carb that kg6dxn posted...
Should I be turning that screw?
What knobs should I be tweaking to tune this carb?
What jets should I be adjusting if any?

The only symptom I have now that I would try to get rid of is that when I'm in the wrong gear, the car bucks and backfires a little bit. For example if I'm in 3rd going slowly up a hill and I nail the throttle, the car bucks instead of slowly accelerates to speed like I would expect a FI car to behave. This is not really a huge problem but I bet with the right adjustments I could get rid of it.

Oh and by the way...
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Now you're at the point where you find the achilles heal of that type of carb setup. The biggest challenge is tau. The effect of the long runners is tau or fuel that falls out of suspension and runs down the walls of the runner. VW solved the problem in the Bug with an exhaust tube running next to the intake runner. The extra heat helps keep the tau from forming.

The bucking could be either too much or too little fuel due to tau. Most likely to little fuel in suspension. As the fuel on the wall makes it to the combustion chamber, it is liquid and not aerated. This can make it run like it's lean while blowing excess fuel out the exhaust. You will not get a good burn with liquid gas.

As far as tuning you will need to find jets for the carb and get a wide band AF meter or use the seat of your pants method.

Bottom line, you will need to play with it but it may never be perfect.

Thanks Mike - makes a lot of sense. There is a strong gas smell when my car is idling. Always been there so I'm probably running rich. What I'm looking to figure out is what dials on my carb are adjustable or should be adjusted. Are jets always something that should be all the way in or should I be able to adjust them?

I agree with what Mike is saying. The longer intake runners on the Type 4 makes a single carb setup far from ideal, regardless of how the carb itself if setup. That being said, people have made them work for a long time, even if it is an imperfect option.

It sounds to me like when you open up the throttle like that, the secondary is providing too much fuel - similar to flooding. As Mike said, without an AFR gauge, you can't know for sure, but in that case, you would need to first identify the size of secondary main ets, then source one a size (or several sizes) smaller.

Adjusting the idle mixture won't make much of a difference, if any on the top end (or when you "punch" it). If the car is running rich at idle, you should be able to dial some of that out though.