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Help needed on a Gunked carb?

New User
Posts: 1
Joined: 07/13
Posted: 07/06/13 08:37 PM

Hi GUys

I need a little more help in under standing this. I'm relying on work I did on another Mustang when I was 18. So Maybe I'm missing something.

I have since corrected the empty fuel filter problem but the engine still preforms as in the video.

I'm trying to restart my engine after taking off the bowls and cleaning the bowls only on my Holley 4150 vac second heat choke carb.  I did the fuel pump test on my 66 fastback. This time I put the Clear in line 3 dollar filter on the line going to an 18 oz beer bottle. Ran the engine for approx. 4 seconds at high idle.(its own run away operation) Found the beer bottle to be almost full ! 18 ounces!

When going thru my work I fill the front and rear bowls with fuel manually, with a syringe. I hook the line back up to the carb and go thru my cycle again. Get the car running for about 3 seconds at a high idle( I still cant get run time to troubleshoot, ) then she chokes off/stop.

I removed the rubber fuel line to the carb and blew into the carb primary hose and I have some level of resistance and I hear bubbling. I have no idea if that resistance is a problem or regular operation.

Here' my big confusion. This is a Holley 4150 not an Autolite. The old autolite would squirt on a throttle pump. This holley will not. Is that a problem?

I mean it runs ... has to be getting fuel from some where even thought I prime it with Starting fluid aerosol.

If you have a Holley running on your car, Please be clear to inform me of this fact and if you squirt?

Much Thanks


Post Reply
Posts: 223
Joined: 04/13
Posted: 07/06/13 09:41 PM


disconnect IGNITION system.. so no sparks can be created..

disconnect the fuel line at the carb...   extend it again into a bottle...   have somebody or use a remote starter switch to CRANK THE ENGINE.. NOT run the engine.. for 15 seconds..  while you watch the pulses from the end of the hose..

you should have nice even pulses... starting instantly...  and continuing until you stop cranking...

almost half a quart is what you should have for this test...

i looked at your video...

the fuel filter you have installed is in the wrong place from where i would like it...

i like it before the fuel pump....  and try to use a fuel injection type of fuel filter..

this is a filter that you should be able to push the 5/16 hoses over the ridges and get clamps on it.. between the frame rail and the inlet on the fuel pump... i normally get extra fuel line and install it in a LOOP that hangs down.. yes.. butt ugly.. but this works..

if during the cranking test.. the engine cranks for 10 seconds before you get fuel into the bottle. .. you fuel pump check valves are dirty.. install the fuel injection type of fuel filter before the pump as i described.. run the full flow test several times... as the full flow test will since there is only clean fuel coming in to the pump now may clean the check valves..

if you have a fuel pressure tester.. one of those.. that read from 30 inches of vacuum to 15 pounds of pressure..

you can check the fuel pump with that..

will the fuel pump build 4 pounds of fuel pressure and HOLD It for a while when you have it hooked up to the hose from the pump to the carb..  

will the fuel pump create 20 inches of vacuum when you have the fuel pump gauge hooked to the inlet side???

i have run across what you are experiencing so many times .. i cannot count them..

i had a friend who's 67 fairlane 500 that he could not fast idle the car.. or drive the car above about 15 miles an hour for any distance over about 100 yards..   his fuel pump went squirt about 5 times then become just a trickle..

when i hooked up my brake bleeder hand vacuum pump to the line coming up from the tank...  i was able to create 22 inches of vacuum .. in a line that should free flow.. the fuel tubing was not just full of sediment.. it was smashed almost flat..  

Post Reply
Posts: 223
Joined: 04/13
Posted: 07/06/13 09:44 PM

so... lets do a full flow test out of the fuel line right from the inner fender..

put on a long hose...   have a pair of vice grip needle nose pliers ready to stop the flow by pinching off the hose..

a fuel can...   with the hose in the fuel can and not pinched off.. have a friend blow into the fuel tank opening.???  just an easy push of pressure.. do you get a nice full flow on the fuel hose into the gas can???  tell your friend not to inhale..  

Post Reply
Posts: 223
Joined: 04/13
Posted: 07/06/13 09:49 PM

oh... and with the fuel line removed at the CARB...    don't blow into the fuel line into the carb...

blow into the fuel line from the pump...

you should NOT be able to blow bubbles in the gas tank...  you should not be able to blow at all..

one check valve in from the tank....

one check valve out to the carb...


Post Reply
Posts: 343
Joined: 11/09
Posted: 07/07/13 07:42 AM

well that carb is know as a double pumper, it has one accel. pump on each float bowl, it should squirt, unless you have dirt in the passage ways or the accel. pumps are not working or both, have you checked the needle seats, and the float setting, and drop set  on the floats, cleaned out the accel. pumps too.  

Post Reply
Posts: 86
Joined: 07/13
Posted: 07/07/13 07:00 PM


"This is a Holley 4150 not an Autolite. The old autolite would squirt on a throttle pump. This holley will not. Is that a problem?"

Yes it is a problem as 54packman suggests.

The most common cause of no fuel on pump is the check ball bearing under the nozzle in the the throttle body.

The second most is the check ball inside the pump chamber being stuck in the closed position.

The third most common is the nozzle being plugged up, run a single wire from a wire wheel thru them.

Remove carb, remove nozzle, turn carb upside down over towel, if bearing is free it will fall out if it does then check the ball in the pump chamber. Spray cleaner into nozzle area using the long tube. See if it comes out thru the check ball. If the pump diaphragm is dried up replace it.

Do not touch the tiny bar holding the ball in place inside the pump chamber.  

Post Reply