Jump to content
Scottjeffrey

Idle problem suddenly appeared.

17 posts / 384 viewsLast Reply

Recommended Posts

My car has been sitting for most of a year. Its a 1974 with a Weber 32/36 DGAV. It has always started and idled beautifully. I have taken it on several very short runs several times as well as had it idling for long periods, and never had a problem. Today I took it to the bank and waited in line for a lengthy period. All was well but 500 feet or so after exiting the bank and stopping for a stop sign, the idle went vey low and the engine stalled. This would happen at each stop sign and light. The car was at normal operating temperature. The entire cooling system is new.

After I got home I checked the carb’s 4 mounting bolts and three were loose so I tightened them. I noticed in the driveway that closing the choke butterfly increased the idle close to normal speed and it sounded good. I then shut it and turned it on to a normal idle and operation. I took it out and shortly the low idle/stalling condition returned at the next stop. All vacuum lines look good and the carb’s mounting is secure. Any ideas on what may have happened and what the problem may be? Thank you for your input. Much appreciated.

Scott

Share this post


Link to post
Share on other sites

Idle jet maybe clogged.  Screw the idle mixture adjustment screw in until it seats and count the number of turns until it is seated, don't over tighten.  Screw it all the way out, check that the tip of the adjustment screw isn't damaged, check blow out the idle jet hole with compressed air and re-install the adjustment screw till it seats again, then turn it out the same number of turns it took to seat in the beginning.

 

This should put you back in the ballpark.  With the choke off, back the idle speed adjustment screw off the throttle cam until it just touches, then screw it in, 1.5 turns.  Once the car is idling, slowly turn the idle mixture screw in and out until the motor achieves its fastest/smoothest idle.  Adjust the idle speed adjustment screw until your car idles about 900 RPM and you are done.

 

Mark92131

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

The first place to look would be your idle cutoff solenoid and or idle jet. The solenoid if fitted should have a wire to it that provides 12v when the key is on if it's working then pull the idle jet thats located under the solenoid and clean it both problems are fairly common.

  • Thanks 1

Share this post


Link to post
Share on other sites

Loose carb  mounting equals vacuum leak. The Low Speed Circuit   a.k.a. idle circuit might be blocked not allowing gas to flow due to crud and needs to be clean out.

  • Thanks 1

Share this post


Link to post
Share on other sites

If you have a vacuum advance dizzy, try disconnecting the vacuum line at the carb end and sucking on the line.  You should feel resistance.  No resistance = leak in the vacuum advance capsule. which will upset your air/gas mixture at idle. 

 

mike

  • Thanks 1

Share this post


Link to post
Share on other sites
14 minutes ago, coloincaalpine said:

 Idle jet probably has crap in it.

 

I had that problem with my '72 Chevy.

The Quadrajet has much larger jetting, feeding a thirsty big-block V-8; but this chunk was just big enough to get hung up.

Sharing photos for the fun of it.

023.thumb.JPG.d892d513ff236a7436a3b1b60ac8a20e.JPG024.JPG.463d9dbdaf4510b49aaa0ae08e769b3b.JPG

 

I just realized how much it looks like Antarctica  :D 

image.png.3f92d01c40a9a9368ac2e98c4294450c.png

 

 

Tom

  • Like 1
  • Haha 1

Share this post


Link to post
Share on other sites
3 minutes ago, '76mintgrün'02 said:

 

I had that problem with my '72 Chevy.

The Quadrajet has much larger jetting, feeding a thirsty big-block V-8; but this chunk was just big enough to get hung up.

Sharing photos for the fun of it.

023.thumb.JPG.d892d513ff236a7436a3b1b60ac8a20e.JPG024.JPG.463d9dbdaf4510b49aaa0ae08e769b3b.JPG

 

I just realized how much it looks like Antarctica  :D 

image.png.3f92d01c40a9a9368ac2e98c4294450c.png

 

 

Tom

 

You are funny Tom! I haven't rebuilt a quadrate in a million years. I had one on my '70 Caddy. Thanks for the help!

Scott

  • Haha 1

Share this post


Link to post
Share on other sites

I've heard people refer to these carbs as "Quadrapuke" but I have always had good luck with mine.  I like the small primaries for "fuel efficiency" and big fat secondaries for when you get on it.

 

I've done this one twice, in the 23 years I've owned my Suburban.  The second time, I bought a new float and chose brass; but then read that they were originally designed with plastic, so I traded it in for the original style.

038.thumb.JPG.b85c4820a916f7a0b32e8bbb2876bd98.JPG

When it comes to Weber DGV carbs, I prefer brass floats to plastic.

 

Heater valves, I might prefer plastic guts to brass... but now I am really digressing.

 

I just thought you might enjoy one more photo, for old-times sake.

 

( I am trying to be patient, awaiting the simple-solution you find for your problem )

 

Tom

Share this post


Link to post
Share on other sites
11 minutes ago, coloincaalpine said:

Damn. look at the size of that........what's your filter made of,chicken wire?

 

The Suburban spends a lot of time in the pasture these days.  At one time, it was my daily driver.  Eleven miles to the gallon got old though.

003.thumb.JPG.02ec805672b93b8ede268095085a3951.JPG

It is a long run from the gas tank in back (42 gallons) to the fuel pump, with sections of original cloth covered fuel lines along the way.  I am too lazy to crawl under and replace them, since there are several to deal with and it is cRusty under there.  Emissions return lines and crap complicate the situation and dropping that tank to get at the ones on top does not sound like fun.

 

All that to explain that it has fuel starvation issues when it sits and I started priming the carb to fire it up and then the fuel pump could pull fuel from the tank.  I probably primed it with chunky gasoline.  You're right, there's no way that crud got through the filter.

Share this post


Link to post
Share on other sites
28 minutes ago, '76mintgrün'02 said:

I just realized how much it looks like Antarctica  :D 

image.png.3f92d01c40a9a9368ac2e98c4294450c.png

 

 

 

For obvious reasons, smaller idle jet orifices are more prone to collecting smaller land masses, meteorites, flotsam, jetsam, occult rtv, dryer lint, penguin feathers and mineral deposits. 

 

spacer.png    .  spacer.pngspacer.png

 

spacer.pngspacer.png

  • Thanks 1

Share this post


Link to post
Share on other sites
33 minutes ago, '76mintgrün'02 said:

I've heard people refer to these carbs as "Quadrapuke" but I have always had good luck with mine.  I like the small primaries for "fuel efficiency" and big fat secondaries for when you get on it.

 

I've done this one twice, in the 23 years I've owned my Suburban.  The second time, I bought a new float and chose brass; but then read that they were originally designed with plastic, so I traded it in for the original style.

038.thumb.JPG.b85c4820a916f7a0b32e8bbb2876bd98.JPG

When it comes to Weber DGV carbs, I prefer brass floats to plastic.

 

Heater valves, I might prefer plastic guts to brass... but now I am really digressing.

 

I just thought you might enjoy one more photo, for old-times sake.

 

( I am trying to be patient, awaiting the simple-solution you find for your problem )

 

Tom

Nice to see, Tom. My quadrajet once rebuilt ran beautiful really reminding you that there were 472 cubic inches under the hood. I seem to remember there was a linkage that was difficult connect from below to the butterfly valve if I remember correctly. 

I just removed the idle solenoid to clean the jet. The solenoid was loose but is now snug yet Its not running right. If I ope the choke valve full travel it bogs down though not shutting off now. I'm thinking I should just do a full rebuild so I know its right in and out. Also found a cracked hose to the vacuum advance which I cut and reattached. Its just interesting how 'all of a sudden yesterday' it crapped out. I am guessing it was the first time the choke opened up all the way and as I said, three nuts were loose mounting the carb which I did tighten. Ah the challenges of playing with old cars.

Share this post


Link to post
Share on other sites

Removing the carb to open it up, clean and inspect it and check the float height seems like a good idea to me.  I have had mine apart a whole bunch of times and just reuse the gaskets.  The diaphragms can get old and stiff and that is when rebuild kits come in handy.

 

You might as well write down the jets that you have when you have it apart.  The AFR gauge I installed showed me that the infamous c.d.eisel jetting prescription was just a bit rich for my engine, so I bumped the air corrector on the primary side up to 185.  It does seem like a good baseline jetting setup, but there are others out there too.

 

Brass floats are set around 40mm and plastic around 35mm.  I'd confirm those numbers, but am just pointing out that they are different.

Share this post


Link to post
Share on other sites
20 minutes ago, '76mintgrün'02 said:

Removing the carb to open it up, clean and inspect it and check the float height seems like a good idea to me.  I have had mine apart a whole bunch of times and just reuse the gaskets.  The diaphragms can get old and stiff and that is when rebuild kits come in handy.

 

You might as well write down the jets that you have when you have it apart.  The AFR gauge I installed showed me that the infamous c.d.eisel jetting prescription was just a bit rich for my engine, so I bumped the air corrector on the primary side up to 185.  It does seem like a good baseline jetting setup, but there are others out there too.

 

Brass floats are set around 40mm and plastic around 35mm.  I'd confirm those numbers, but am just pointing out that they are different.

Thank, Tom. I am going to rebuild it. What the hell. I have no clue when it was installed and its maintenance history. I just posted some questions on rebuilding it and perhaps you have already answered them in part just now. I take it your motor is stock? Mine is a BMW new or remanufactured engine installed in 84. I believe it has about 90k on it but can't be sure. No less however pricing bills together that came with the car. I bought the car a year ago and have been renewing many systems but haven't driven it beyond a few trips around the block. Almost done mechanically and then off to the paint shop. It will be my daily driver. Sold my last one 24 years ago. I'm having fun though my now 63 year old body hasn't stopped bitching. Have a great weekend and thanks again for everything.

Scott

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.