Q-Jet accel pump not pumping fully - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
LinkBack Thread Tools Display Modes
post #1 of 5 (permalink) Old Nov 15th, 01, 04:21 AM Thread Starter
 
Join Date: Feb 2001
Location: Wylie, TX
Posts: 15
Post

I have just built a 383 and am having problems with my carb. When I "blip" my throttle, the engine stalls for a second and then comes on. Under load, it will only run under small throttle changes. I manually opened the throttle and when the accel pump rod is first pushed, no fuel is coming out. Pushing it a little further causes fuel to dribble out and if I push it all the way down, I get a stream of fuel.

The carb is an Edelbrock Q-Jet replacement that I bought about 1 year ago and have been running it on my old engine without this problem. I did pull the air horn due to my float getting stuck and pouring gas everywhere. I also have replaced the accel pump with a new one with the same results.

I am relatively new to carbs, but have read up a bit. What should I check next?

Chris
Amblefinie is offline  
Sponsored Links
Advertisement
 
post #2 of 5 (permalink) Old Nov 15th, 01, 06:38 AM
Super Moderator
Bess-68's rule
 
Everett#2390's Avatar
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 31,620
Garage
Cool

One should adjust the pump linkage to move the same time the throttle moves, a one for one action.

One should also check for two of the following problems,
1. Check to make sure the edge of the new acell pistion is not curled up when installed last time,
2. Check to make sure the power valve and its spring is in place, sometimes, they can become stuck, the piston has a bar acroos the top suspending the metering rods, and a spring in the bottom of the well. Metering rod may have fallen off, or piston stuck in bore, or spring is sprung/damaged.
3. Check timing and readjust idle mixture screws with a vacuum gauge and reset curb idle. Always adjust screws for highest vacuum reading.
4. Make sure the spring on the acellerator pump shaft is not stuck/damaged. Use vaseline on lip of piston to prevent roll-up.

These are just a few items to check, others here may have some real good suggestions....

------------------
Everett 68/350/PG/11.90/115mph
Everett#2390 is offline  
post #3 of 5 (permalink) Old Nov 15th, 01, 09:02 AM Thread Starter
 
Join Date: Feb 2001
Location: Wylie, TX
Posts: 15
Post

<BLOCKQUOTE>quote:</font><HR>Originally posted by Everett#2390:
One should adjust the pump linkage to move the same time the throttle moves, a one for one action. <HR></BLOCKQUOTE>
The linkage is adjusted properly so that the slightest throttle movement depresses the pump.

<BLOCKQUOTE>quote:</font><HR>One should also check for two of the following problems,
1. Check to make sure the edge of the new acell pistion is not curled up when installed last time,
<HR></BLOCKQUOTE>
I'll check this.
<BLOCKQUOTE>quote:</font><HR>2. Check to make sure the power valve and its spring is in place, sometimes, they can become stuck, the piston has a bar acroos the top suspending the metering rods, and a spring in the bottom of the well. Metering rod may have fallen off, or piston stuck in bore, or spring is sprung/damaged. <HR></BLOCKQUOTE>
I've already checked over the power system and it is correct.
<BLOCKQUOTE>quote:</font><HR>3. Check timing and readjust idle mixture screws with a vacuum gauge and reset curb idle. Always adjust screws for highest vacuum reading.<HR></BLOCKQUOTE>
Checked this too.
<BLOCKQUOTE>quote:</font><HR>4. Make sure the spring on the acellerator pump shaft is not stuck/damaged. Use vaseline on lip of piston to prevent roll-up.<HR></BLOCKQUOTE>
Which piston are you referring to? Do you mean the pump plunger?

<BLOCKQUOTE>quote:</font><HR>These are just a few items to check, others here may have some real good suggestions....

<HR></BLOCKQUOTE>

Thanks for the help,

Chris

Amblefinie is offline  
 
post #4 of 5 (permalink) Old Nov 15th, 01, 12:32 PM
Super Moderator
Bess-68's rule
 
Everett#2390's Avatar
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 31,620
Garage
Cool

Yes, the pump plunger, the lip.

You also might check to see if the check ball is still there at the bottm of the accell pump cylinder.

Should be able to move throttle plates open and see a coresponding action at pump linkage, is accell pump passage plugged,gas freezing up, etc.? Try finger on pump rod and with very little pressure, s/b able to pump out fuel.


------------------
Everett 68/350/PG/11.90/115mph
Everett#2390 is offline  
post #5 of 5 (permalink) Old Nov 19th, 01, 04:12 AM Thread Starter
 
Join Date: Feb 2001
Location: Wylie, TX
Posts: 15
Post

OK, I found the problem.

I pulled the new accel pump and compared it to my old one. It is about 1/4" shorter, causing the plunger to be above the fill slot making it inoperable at low throttle. My old plunger was not making a good seal, so I re-installed my old pump assembly with the new plunger and it works great now.

Thanks for the help.

Chris
Amblefinie is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome