Carb question, need to dump little gas in carb just to get car started Options

[angerosa]

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?

[ThePaintedMan]

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.

[Mike Bellis]

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.

[ThePaintedMan]

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.

[Mike Bellis]

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

(IMG:http://www.914world.com/bbs2/uploads_offsite/i892.photobucket.com-10496-1367296937.1.jpg)

[ThePaintedMan]

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?

[Mike Bellis]

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.

[rhodyguy]

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

[angerosa]

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.

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...

[angerosa]

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.

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.

[angerosa]

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.

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.

[ThePaintedMan]

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

Correct.

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 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.

[angerosa]

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

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.

[angerosa]

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

Correct.

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 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.

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.

[angerosa]

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...

[angerosa]

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?

[DBCooper]

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.

[ThePaintedMan]

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.

(IMG:style_emoticons/default/agree.gif) 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.

[angerosa]

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

[angerosa]

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.