Holley carb loses prime to primaries but not secondaries - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**WIDESIDE72** · 01-30-2016, 09:51 AM

Im tying to get one of my trucks going. It has a Holley 750 double pumper. It ran fine about a month ago. I figured the carb would be dry and it would take a while to get it started, but even when priming it, it wont start. I took the air cleaner off and when i work the throttle by hand, gas squirts from the rear secondary nozzles, but not the front primaries.

I had the same issue with another holley 800 double pumper, and i figured it was time for a rebuild when it did the same thing. I ended up swapping it as someone had milled the choke tower off it, and i wanted an electric choke. Now this carb is doing the same thing.

Again, the 750 was running fine the last time i ran it!

Ideas?

Mike C · 01-30-2016, 10:16 AM

Fuel has dried in the accelerator pump circuit plugging the squirter or the metering block or main body is one possibility. Pump diaphragm is torn allowing fuel to run out of accelerator pump circuit. Check ball in accelerator pump is glued shut from sticky dried fuel would be most likely IMO.

Those are a couple of suggestions. You could pull the squirter and use the plastic straw on carb cleaner to blow back down through the pump circuit and see if that would work, that's easiest.

Pull the front bowl off next and remove diaphragm. Visually inspect all then spray carb cleaner from that end to see if it's coming out of the pump circuit and squirter.

Oh, safety glasses step one. You will thank me....

**WIDESIDE72** · 01-30-2016, 11:22 AM

I am running lucas ethanol fuel treatment in the gas, but this is getting old. Like a lot of you, i dont drive my old stuff every day. They need to string up whoever for ethanol on us.

GASoline71 · 01-30-2016, 01:18 PM

Is the accelerator pump lever on the front bowl moving like it should? It should stat to move the instant the throttle moves.

Gary

**WIDESIDE72** · 01-30-2016, 08:50 PM

I found a rotten rubber line between the tank and steel fuel line under the cab. For some reason there was fuel in the secondary bowl but not in the primary bowl. I thought i had a clogged fuel line, so i unhooked the line from the tank to the fuel pump, wrapped a rag around my blow nozzle to blow it out. After a couple of time of gettin fuel to th pump, then not getting fuel, i heard fuel trickling out underneath. I replaced all of th e rubber a few years ago, but im sure th ethanol is doing a number on it.

01-30-2016, 09:51 AM	#1
WIDESIDE72 Senior Member Join Date: Aug 2008 Location: Cedar Park, Texas Posts: 7,500	Holley carb loses prime to primaries but not secondaries Im tying to get one of my trucks going. It has a Holley 750 double pumper. It ran fine about a month ago. I figured the carb would be dry and it would take a while to get it started, but even when priming it, it wont start. I took the air cleaner off and when i work the throttle by hand, gas squirts from the rear secondary nozzles, but not the front primaries. I had the same issue with another holley 800 double pumper, and i figured it was time for a rebuild when it did the same thing. I ended up swapping it as someone had milled the choke tower off it, and i wanted an electric choke. Now this carb is doing the same thing. Again, the 750 was running fine the last time i ran it! Ideas?

01-30-2016, 10:16 AM	#2
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,727	Re: Holley carb loses prime to primaries but not secondaries Fuel has dried in the accelerator pump circuit plugging the squirter or the metering block or main body is one possibility. Pump diaphragm is torn allowing fuel to run out of accelerator pump circuit. Check ball in accelerator pump is glued shut from sticky dried fuel would be most likely IMO. Those are a couple of suggestions. You could pull the squirter and use the plastic straw on carb cleaner to blow back down through the pump circuit and see if that would work, that's easiest. Pull the front bowl off next and remove diaphragm. Visually inspect all then spray carb cleaner from that end to see if it's coming out of the pump circuit and squirter. Oh, safety glasses step one. You will thank me.... __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

01-30-2016, 11:22 AM	#3
WIDESIDE72 Senior Member Join Date: Aug 2008 Location: Cedar Park, Texas Posts: 7,500	Re: Holley carb loses prime to primaries but not secondaries I am running lucas ethanol fuel treatment in the gas, but this is getting old. Like a lot of you, i dont drive my old stuff every day. They need to string up whoever for ethanol on us.

01-30-2016, 08:50 PM	#5
WIDESIDE72 Senior Member Join Date: Aug 2008 Location: Cedar Park, Texas Posts: 7,500	Re: Holley carb loses prime to primaries but not secondaries I found a rotten rubber line between the tank and steel fuel line under the cab. For some reason there was fuel in the secondary bowl but not in the primary bowl. I thought i had a clogged fuel line, so i unhooked the line from the tank to the fuel pump, wrapped a rag around my blow nozzle to blow it out. After a couple of time of gettin fuel to th pump, then not getting fuel, i heard fuel trickling out underneath. I replaced all of th e rubber a few years ago, but im sure th ethanol is doing a number on it.



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