Accelerator Pump Removal (DCOE) - Alfa Romeo Bulletin Board & Forums

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Old 05-05-2009, 03:02 PM
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Accelerator Pump Removal (DCOE)

Hi, I was just wondering if anyone could instruct me on how to remove the accelerator pump? I'm cleaning and rebuilding the carb(s) and it's the last piece and I can't figure it out.

The retaining clip is popped free, so it's just the U shape pump with the spring on one side...

Thanks guys
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Old 05-05-2009, 04:50 PM
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Uh-oh. The clip, spring, rod & piston should lift right out as an assembly.
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Old 05-05-2009, 05:07 PM
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Uh-oh. What?

Hopefully that was a communication problem. The clip is still attached to everything, it's just not "clipped" in. So the spring is extended a little though. The rod and piston are still stuck in somehow though.

Which part is the rod, which is the piston? And please tell me it shouldn't just lift out without the retaining clip...
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Old 05-06-2009, 08:06 AM
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Uh-oh as in it sounds like corrosion is holding the assembly in place.

With the top of the carb removed the retaining clip is the only thing holding the assembly in place. The rod is made of steel and goes through the retaining clip. The piston is brass and not visible until the assembly is removed. The spring is not particulary stiff and everything should move freely.

It may be helpful to know how the accel. pump works. One leg of the rod rides on a cam which falls away as throttle is increaded. The spring applies pressure to push the rod and pistion down and supply the enrichment.

Mike R
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Old 05-06-2009, 04:40 PM
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You are correct, thanks for your help. I soaked the guy and then reeeefed on it against my better judgment . Came free and ya, was just covered in this thick, gum like tar corrosion mixture. Seems like it was also hooked inside lightly?

Last edited by Shpoon; 05-06-2009 at 06:43 PM.
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Old 05-06-2009, 06:04 PM
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Hi Shpoon,
I'm glad it all came apart without too much drama - look after these bits as they are no longer available new. BTW, the pump assembly can be further pulled apart for cleaning, though this is usually not necessary. Also, the pump rods and springs come in different lengths and tensions for different DCOE carbies.
What was the PO running through these? It looks like he was trying to burn tar
Considering how filthy these were, before you reassemble them make sure you clean and blow out all of the fuel galleries as well.
Regards,
Chris
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Last edited by Chris1750; 05-06-2009 at 07:56 PM.
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Old 05-06-2009, 07:21 PM
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Oh holy crap. I completely didn't realize that piston part was there. Guess who has two pistons of the accelerator pump stuck in the carbs?

When I pulled on the pump assembly it actually bent the hook enough to slip free rather than pulling the piston with it...both times.

Thanks for the pictures, I'll have to see if I can free those suckers up...and somehow fix the hook.

*Sigh. One problem after another
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Old 05-06-2009, 08:03 PM
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Quote:
Originally Posted by Shpoon View Post
Oh holy crap. I completely didn't realize that piston part was there. Guess who has two pistons of the accelerator pump stuck in the carbs?

When I pulled on the pump assembly it actually bent the hook enough to slip free rather than pulling the piston with it...both times.

Thanks for the pictures, I'll have to see if I can free those suckers up...and somehow fix the hook.

*Sigh. One problem after another
Be very careful bending that hook back - if it snaps off, you're f*cked as the pump rods are only available second hand. The pair in my photo are out of two 40DCOE32s that I'm rebuilding for a mates' 1750.

As to the pump pistons - it looks like it's back to the soak for another day or so.

Out of interest, are these replacement carbies or are you converting from injection to carburettor?

Chris.

PS: Welcome to the list.
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Old 05-06-2009, 09:47 PM
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And, out of interest, this is how it works .....

Push on loud pedal
Butterflies open
Control lever 25 swings down releasing pump control rod 27
Spring 28 pushes piston 26 down
Fuel is injected past one-way valve 21 through fuel galleries 22
Raw fuel emerges under pressure via pump jets 24 and splashes on butterflies
Fuel atomises in air stream
Car goes faster

Excess fuel is returned to float chamber via valve 23.

Simple, elegant, efficient and very effective.
This is the Weber way.

Chris
(Excuse my sense of humour)
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Old 05-07-2009, 04:41 AM
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I really don't mean to sound testy, but please get a some sort of manual before mangling the most sophisticated carburettors ever made. IIRC, you soaked the bodies in carb cleaner, thus killing the shaft seals. More parts that will have to be removed that are not availabe anymore. Jim Ks book has a good write-up on Weber rebuilding and others are available. This kinda falls under the carpenter's maxim of measure twice, cut once.

Paul
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Old 05-07-2009, 09:03 AM
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Quote:
Originally Posted by Chris1750 View Post
Be very careful bending that hook back - if it snaps off, you're f*cked as the pump rods are only available second hand. The pair in my photo are out of two 40DCOE32s that I'm rebuilding for a mates' 1750.

As to the pump pistons - it looks like it's back to the soak for another day or so.

Out of interest, are these replacement carbies or are you converting from injection to carburettor?

Chris.

PS: Welcome to the list.
Thanks for the info, and your second post. I got one out this morning, the second is soaking. The car had already been converted, and these are the carbs that were on it.

Quote:
Originally Posted by ciscotex View Post
I really don't mean to sound testy, but please get a some sort of manual before mangling the most sophisticated carburettors ever made. IIRC, you soaked the bodies in carb cleaner, thus killing the shaft seals. More parts that will have to be removed that are not availabe anymore. Jim Ks book has a good write-up on Weber rebuilding and others are available. This kinda falls under the carpenter's maxim of measure twice, cut once.

Paul
Don't worry, I soaked in stages so that the throttle shaft was never exposed directly to the carb cleaner. After that most of the cleaning was done with a cloth brush(es) and compressed air. I did a lot of reading, but I didn't understand the accelerator pump I guess. Even if I could have I wouldn't have been able to do anything about the stuck piston.

So I'm really hoping that I didn't damage it, but we'll see. (How do you tell?). In all honesty I was planning on just buying two new carbs anyways, so this is an adventure and a half in learning as well. Hopefully this'll work out in the end though.

Last edited by Shpoon; 05-07-2009 at 09:19 AM.
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Old 05-07-2009, 09:57 AM
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Sounds like you're doing good. Sorry to impugn your approach. Patience with the carb cleaner soak will be rewarded. Yep, I think they probably needed a rebuild .

Paul
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Old 05-07-2009, 02:28 PM
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*sigh. Okay. Big issues.

The two rods are bent. However, I did find a place that can get me the rods if I **** them up.

Weber Carburetors. 818 764-1901 Carbs 40 DCOE 45 DCOE 32/36 32/34 Jeep. Top-End Performance 818 764-1901

$17 a piece, so not very nicely priced, but oh well.

The issue is the piston though. They said Weber no longer sells is as a replacement part. I got one out okay...and the second one the rod snapped (I was using a half moon tool to twist the piston and it snapped...worked fine on the first one..) and the piston is currently jammed inside the bore.

First thing's first though before dying a little...removing the piston. Does anyone have any ideas for this? The rod came clearly out (in two pieces) so there's a tiny lip on two sides before the bore. I tried using dentist like tools with rounded tips to go in the slot and turn/pull the piston, but to no avail. I've soaked the top of the piston for a long time hoping some would flow down the sides, but nothing.

I now have the base plate back on, and I poured cleaner into the main bowl above the level where the bottom of the piston would be (I think it's gummed onto the bottom of it's track), but it doesn't seem to be working.

Any good ideas to remove the sucker?
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Old 05-07-2009, 06:03 PM
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Chemistry is your friend. I've never encountered anything as bad as what you're going thru, but a couple of things occur to me: if it is oxidized to the bore, then a good penetrant might dissove the oxide. Don't know if they're effective on aluminum oxide. Probably a better idea is to look up Gordon Raymond's recent post in either this section, engine rebuilding, or GTVs on his favorite recipes for carb cleaners. If the glue is varnish, IIRC one or more of his recipes seemed more like paint remover than some of the carb cleaners I've seen. Test inconspicuously on the aluminum first, though. I am sure that brute force is not the answer.

Hope this helps,
Paul
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Old 05-08-2009, 02:36 AM
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Quote:
Originally Posted by Shpoon View Post
The car had already been converted, and these are the carbs that were on it.
I'm really suprised that the car ran at all. It must have had a hell of a flat spot if the accelerator pumps were glued in so tight that they didn't move.

I must admit that I'd be trying to source a good second hand pair of DCOEs and then use your current ones for spare parts, that is if you still want to run carbies.

As Paul said (and to the tune of Rawhide)

Soakin', soakin', soakin'
Keep them carbies soakin'
Soakin', soakin', soakin' all night ....

Chris
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