HOME FORUM RULES CONTACT
     
   
   

Go Back   CLASS RACER FORUM > Class Racer Forums > Stock and Super Stock Tech


Reply
 
Thread Tools Display Modes
Old 07-30-2007, 05:25 PM   #1
Ben Kallies
Member
 
Join Date: Jan 2005
Location: Milwaukee, WI
Posts: 105
Likes: 2
Liked 0 Times in 0 Posts
Default Q-jet starting issue

I have a Q-jet on my '71 Corvette Stocker (454/365). Whenever it sits for an extended period of time, the carb will not squirt any fuel. It doesn't matter wether or not the fuel pump is running. So I remove and disassemble the carb, find nothing, reassemble and reinstall the carb and it works fine. This has happened the last 3 times I've let it sit for an extended period. Any ideas? Remedies? Common problem?
Ben Kallies C/S 3869
Ben Kallies is offline   Reply With Quote
Old 07-30-2007, 08:34 PM   #2
Mike Hedger
Junior Member
 
Join Date: Jul 2007
Location: Kemah TX
Posts: 93
Likes: 0
Liked 1 Time in 1 Post
Default Re: Q-jet starting issue

More times than not when you have this problem on a Q Jet the "main well plugs" in the bottom of the carb are leaking letting all of the fuel seap out of the carb and into the intake where it evaorates. To solve this pull the carb flip it over and take the baseplate off (dont forget to pull the back top long screws out first as they hold the rear of the baseplate) where you will find the plugs,(5 total but the 2 rear/bigger ones leak the most) clean them good with carb cleaner and a tooth brush. Take some JB weld or JB quick and seal them back up. I leave them upside down overnight to let it dry before I put fuel back in it. Hope this helps, Mike
__________________
Mike Hedger S/C 4646
MPH Racing and Fabrication
Mike Hedger is offline   Reply With Quote
Old 07-30-2007, 09:40 PM   #3
Ben Kallies
Member
 
Join Date: Jan 2005
Location: Milwaukee, WI
Posts: 105
Likes: 2
Liked 0 Times in 0 Posts
Default Re: Q-jet starting issue

Thank you Mike. I'll try that. If this is occuring, does it make sense that it still doesn't squirt once the fuel pump has pumped fuel back into the carb? Is it possible that the needle is sticking in the seat due to being dry? - Ben
Ben Kallies is offline   Reply With Quote
Old 07-30-2007, 10:16 PM   #4
Alan Roehrich
VIP Member
 
Alan Roehrich's Avatar
 
Join Date: May 2006
Location: Murfreesboro TN
Posts: 4,904
Likes: 984
Liked 1,016 Times in 264 Posts
Default Re: Q-jet starting issue

Quote:
Originally Posted by Ben Kallies View Post
Thank you Mike. I'll try that. If this is occuring, does it make sense that it still doesn't squirt once the fuel pump has pumped fuel back into the carb? Is it possible that the needle is sticking in the seat due to being dry? - Ben
Yes, it is possible that it is sticking. In the other thread, I asked if you had tried pushing the float down. I usually use the plastic straw from a can of carb cleaner, and push on the float through the bowl vent tube. Push down lightly, and release, the float SHOULD push the straw back up. If it does not, turn on the fuel pump, push down again, count to 3 fairly quick, and release. See if it pushes the straw back up.

When dealing with the well plugs, I take a small hammer and tap the plugs to fold the lead edges over. I use JB Weld, it's an old habit from when I used to work at a carb shop, I do all of my Q-Jets that way.

Are you using a nitrophyl float? If not, get one, and set it at 5/16".
__________________
Alan Roehrich
212A G/S
Alan Roehrich is offline   Reply With Quote
Old 07-31-2007, 12:59 AM   #5
Mike Hedger
Junior Member
 
Join Date: Jul 2007
Location: Kemah TX
Posts: 93
Likes: 0
Liked 1 Time in 1 Post
Default Re: Q-jet starting issue

One last thought, I wonder if the accl. pump check ball is sticking after the car sits? This could happen if the float bowl is dry from the main well plugs leaking also.
Give it a look the next time you have the top off. Hope this gets you going, Mike
__________________
Mike Hedger S/C 4646
MPH Racing and Fabrication
Mike Hedger is offline   Reply With Quote
Old 07-31-2007, 11:54 AM   #6
Ben Kallies
Member
 
Join Date: Jan 2005
Location: Milwaukee, WI
Posts: 105
Likes: 2
Liked 0 Times in 0 Posts
Default Re: Q-jet starting issue

Thank you both Mike and Alan. I appreciate you taking the time to respond. That gives me a few areas to work with. If I find something, I'll let you know. - Ben
Ben Kallies is offline   Reply With Quote
Old 07-31-2007, 12:06 PM   #7
Mike Pearson
VIP Member
 
Mike Pearson's Avatar
 
Join Date: Mar 2007
Posts: 2,366
Likes: 553
Liked 1,636 Times in 506 Posts
Default Re: Q-jet starting issue

Ben,

All that is happening is your accelerator pump plunger is drying out when your car sits for a while. When you are ready to use your car fill the carb up with gas by brunning the fuel pump a day prior to starting it and this will swell up the plunger and the accelerator pump will work again. The racing gas is very dry especially C-11. When your car is sitting fill the carb regularly to stop the drying out this will solve your problem. I have the same problem on my super stocker. Dont get to race enough.

Mike
__________________
Mike Pearson 2485 SS
Mike Pearson is offline   Reply With Quote
Old 07-31-2007, 02:47 PM   #8
Dean Oliver
Junior Member
 
Join Date: May 2002
Location: Stuttgart, AR
Posts: 53
Likes: 1
Liked 0 Times in 0 Posts
Default Re: Q-jet starting issue

Ben,

You have received very good advice so far. One question, is the rubber pump cup on your accelerator pump black? If it is, these cups usually have a short life when exposed to racing fuels. Like Mike mentioned, C-11 is the toughest to deal with because it even seems to leave a residual film inside the carb when it dries. If you have the black cup, I'd be happy to send you one of mine to see if it helps.

I would also recommend that you take a look at the check ball and the seat that it sits in to make sure they are clean. If the check ball is not sealing properly, the upstroke of the accelerator pump could be sucking this circuit dry. I can give you some pointers on how to check this if you want me to.

Keep in mind also, the bowl area of a Q-jet is very small, so if the car sits for a couple of weeks most/all of the fuel inside the carb can be lost to evaporation. If this is the case, then the carb is simply "empty". However, this leads to the situation described earlier where the pump cup will now start to dry out.

Dean Oliver
www.deanoscarbs.com
Dean Oliver is offline   Reply With Quote
Old 07-31-2007, 02:47 PM   #9
Dean Oliver
Junior Member
 
Join Date: May 2002
Location: Stuttgart, AR
Posts: 53
Likes: 1
Liked 0 Times in 0 Posts
Default Re: Q-jet starting issue

Ben,

You have received very good advice so far. One question, is the rubber pump cup on your accelerator pump black? If it is, these cups usually have a short life when exposed to racing fuels. Like Mike mentioned, C-11 is the toughest to deal with because it even seems to leave a residual film inside the carb when it dries. If you have the black cup, I'd be happy to send you one of mine to see if it helps.

I would also recommend that you take a look at the check ball and the seat that it sits in to make sure they are clean. If the check ball is not sealing properly, the upstroke of the accelerator pump could be sucking this circuit dry. I can give you some pointers on how to check this if you want me to.

Keep in mind also, the bowl area of a Q-jet is very small, so if the car sits for a couple of weeks most/all of the fuel inside the carb can be lost to evaporation. If this is the case, then the carb is simply "empty". However, this leads to the situation described earlier where the pump cup will now start to dry out.

Dean Oliver
www.deanoscarbs.com
Dean Oliver is offline   Reply With Quote
Old 08-02-2007, 02:50 PM   #10
Ben Kallies
Member
 
Join Date: Jan 2005
Location: Milwaukee, WI
Posts: 105
Likes: 2
Liked 0 Times in 0 Posts
Talking Re: Q-jet starting issue

Thank you Mike and Dean,
It sounds like you've both got the problem figured out. I appreciate your input. Dean, I would love to try one of your pump cups. I'll give you a call soon.

Ben Kallies C/S 3869
Ben Kallies is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump


All times are GMT -4. The time now is 05:39 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright © Class Racer.com. All Rights Reserved. Designated trademarks and brands are the property of their respective owners.