Q-jet primary question
Thread Starter
Safety Car
Joined: Mar 2000
Posts: 3,544
Likes: 448
From: Central Pennsylvania
Q-jet primary question
I think I know the answer but figured I'd ask anyway.
The passenger side primary jet on my Q-jet hardly pushes any fuel out when the throttle is activated. The drivers side primary appears to be fine. I'm guessing it's a piece of dirt that got thru the filters.
Will spray carb cleaner out of the skinny spray nozzle work, or am I faced with tearing off the top of the carb? Also, mixture adjustment screws couldn't cut down fuel flow THAT much could they? Both are set at the same number of turns and the drivers side sprays great. :confused:
The passenger side primary jet on my Q-jet hardly pushes any fuel out when the throttle is activated. The drivers side primary appears to be fine. I'm guessing it's a piece of dirt that got thru the filters.
Will spray carb cleaner out of the skinny spray nozzle work, or am I faced with tearing off the top of the carb? Also, mixture adjustment screws couldn't cut down fuel flow THAT much could they? Both are set at the same number of turns and the drivers side sprays great. :confused:
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Q-jet primary question (ettev)
ettev -
Spray carb cleaners are ineffective for any clogs or problems. If tyou have a clogging problem, the carb must be disassembled, soaked in cleaner, and each passage must be blown through with compressed air. This is the only method that will actually clean out passages.
The main jets do not control fuel flow from the accel pump, and accel pump discharge is independent of idle mixture screw adjustment. The accel pump has two independent passages up through the float bowl, with a transfer slot and small plenum in the air horn just inside of the discharge nozzles. The discharge nozzle is the smallest and most restrictive part of the circuit. It can only be effectively cleaned out by removing the airhorn and blowing it out from the inside.
If your car is not stumbling off idle, don't worry about the accel pump discharge flow difference from side to side.
Spray carb cleaners are ineffective for any clogs or problems. If tyou have a clogging problem, the carb must be disassembled, soaked in cleaner, and each passage must be blown through with compressed air. This is the only method that will actually clean out passages.
The main jets do not control fuel flow from the accel pump, and accel pump discharge is independent of idle mixture screw adjustment. The accel pump has two independent passages up through the float bowl, with a transfer slot and small plenum in the air horn just inside of the discharge nozzles. The discharge nozzle is the smallest and most restrictive part of the circuit. It can only be effectively cleaned out by removing the airhorn and blowing it out from the inside.
If your car is not stumbling off idle, don't worry about the accel pump discharge flow difference from side to side.
Thread Starter
Safety Car
Joined: Mar 2000
Posts: 3,544
Likes: 448
From: Central Pennsylvania
Re: Q-jet primary question (lars)
If your car is not stumbling off idle, don't worry about the accel pump discharge flow difference from side to side.
I do notice a "leak" for the sake of words around the top of the accelerator pump, and the car does have a slight hesitation or "bog" on a heavy pedal depression off idle. Bad accelerator pump/rubber cup/spring? :confused:
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Q-jet primary question (ettev)
Bad accel pump or restricted discharge nozzles will give you a hesitation upon part-throttle acceleration off idle. If you're getting a bog when you go to wide open throttle (WOT) off idle, you most likely have an airvalve adjustment problem or a bad choke pulloff.
It's not uncommon to have some fuel seapage around the accel pump shaft: there is no seal at this location, so you can get fuel slosh from the bowl up and around the pump shaft hole.
It's not uncommon to have some fuel seapage around the accel pump shaft: there is no seal at this location, so you can get fuel slosh from the bowl up and around the pump shaft hole.
