HESITATION QUESTION, HELP PLEASE
Safety Car
Joined: Jul 2002
Posts: 4,269
Likes: 3
From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
Re: HESITATION QUESTION, HELP PLEASE (Cali,77,L-82)
Bad accelerator pump causes off idle hesitation. The following is a link to a Lars paper on trouble shooting Quadrajets. There are several other great articles in the http://www.corvettefaq.com site. This is the link to the troubleshooting pages: http://www.corvettefaq.com/redir.asp?site=620
Racer
Joined: Nov 2001
Posts: 478
Likes: 3
From: Huntsville AL
Re: HESITATION QUESTION, HELP PLEASE (Cali,77,L-82)
ok pull your air cleaner cover off and with the engine off look down in the primary ports and see if you have two streams of fuel shooting in there when you work the accelerator by hand. If so the accelerator pump is working. Now with a timing ligh on the timing mark see if it changes when you disconnect the vacuum advance. Also try this just above idle as this will depend it you have the advance hooked up to the ported or unported vacuum port on the carb. If not shut down the engine, hook up a vacuum pump (or mouth) to the to the line going to the vacuum advance on the distrib. to verify it is a bad vacuum advance. If it holds vacuum...look else where, maybe worn timing chain. Hope this helps.
YBNormal...drive a vette
YBNormal...drive a vette
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
Re: HESITATION QUESTION, HELP PLEASE (Ybnormal)
Okay dropped off the Vette at http://www.briansclassics.com/ and the car was acting real bad. here's what they found.
1. #4 plug wire burn't by header, why it didn't show on ohmmeter I don't know and #4 plug fouled.
2. Vacuum advance inoperative, completely.
3. Mechanical advance sloppy.
4. Nuetral safety switch bad, mechanic had to bypass, mechanic couldn't get the car started. I have had to push the clutch in several times to start car but thought it was out of adjustment. I told them to leave it bypassed and I'll order it from Ecklers replace it and avoid 3 hours labor.
So given the labor charge to rebuild the distributor I choose to have them install the http://store.summitracing.com/partdetail.asp?part=9605 and replace the #4 plug and wire. Should be ready tommorow. This car is killing me $$$ I don't understand why the ohmmeter didn't catch the wire and plug, I miked them both. :nonod:
1. #4 plug wire burn't by header, why it didn't show on ohmmeter I don't know and #4 plug fouled.
2. Vacuum advance inoperative, completely.
3. Mechanical advance sloppy.
4. Nuetral safety switch bad, mechanic had to bypass, mechanic couldn't get the car started. I have had to push the clutch in several times to start car but thought it was out of adjustment. I told them to leave it bypassed and I'll order it from Ecklers replace it and avoid 3 hours labor.
So given the labor charge to rebuild the distributor I choose to have them install the http://store.summitracing.com/partdetail.asp?part=9605 and replace the #4 plug and wire. Should be ready tommorow. This car is killing me $$$ I don't understand why the ohmmeter didn't catch the wire and plug, I miked them both. :nonod:
Advanced
Joined: Aug 2002
Posts: 84
Likes: 0
From: Riockwall Texas
Re: HESITATION QUESTION, HELP PLEASE (Cali,77,L-82)
Your base problem was the Vacuum Advance. When you heard the "Pop" the backfire took out the Vacuum Advance diaphram. When uou have a bog" on take off, the first thing to check is accellerator pump, the second is spark advance.
