I have a Holley Ultra HP 850 carb on my big block Chevy motor, it's a year old. I'm not getting fuel from the squirters. There's 8 lbs. of fuel pressure on the gauge that's on the fuel line, and the bowl sight glasses have fuel in them. Had a problem last year with fuel dripping from the carb like the float was stuck; tapped it with a rubber mallet and it quit dripping. The car will start and run (for 20 minutes) when I pour fuel down the vent tubes, but if I turn it off it won't restart. Any help would be greatly appreciated. Thanks, Jim
Try to pump the lever on the accelerator pump....if it is hard to move.... the needle under the squatters is stuck.
how long has it sat since the last time it "worked".....have you changed anything since......when you say it will run with fuel dumped in, i assume you mean only at idle if the shooters aren't working.....are the secondary shooters working? i had this problem recently on the primary side and replaced the accelerator pump......did not fix the problem....found the throttle cable/return spring bracket was interfering (picture) spaced it up and all was well surprised no one has chimed in yet saying holleys suck and replace it with an edelbrock or q-jet
Yeah, I prefer Edelbrocks too and have an extra 750 and would've used it --- but --- the reason I bought this carb was the intake on my motor is for a Dominator carb. This carb has the double bolt pattern baseplate and will fit the 4500 intake. I was told the 1150 Dominator that was on it when I got it was too big for the engine, it was running too rich. The Edelbrock 750 would've worked with an adapter plate, but then the hood wouldn't clear the air cleaner. With the new Holley I only have 3/4" clearance. Now back to the carb. It has not been started in about 8 months. It will start and run if fuel is poured in the bowl vent tubes. I ran it for 20 minutes thinking the problem would sort itself out. After I backed it into the garage, and parked -- killed and it wouldn't restart. Pulled the breather and checked it for fuel, and nothing was coming out of the squirters. Checked all 4 sight glasses, and saw fuel. The accelerator pump wasn't hard to push. The primary and secondary squirters were working last time I started it. Haven't driven the car much -- the carb has less than 10 miles on it.
Sitting for 8 months.... Death to carbs. The fuel we have now evaporates faster than it used to and the additives will get gummy. You probably need to tear it down, clean it and put a kit in it. Sent from my Moto G Play using The H.A.M.B. mobile app
I think your needle and seat are sticking. Can you still see fuel in the bowls through the sight glass when it won't start? Sent from my iPhone using Tapatalk
Older Holley carbs used a metal check ball in the accelerator pump circuit to seal the system. New ones now use a rubber umbrella. These check valves do not like todays fuels and I find I have to change them once a year. My guess is the rubber umbrella check valve came apart and when the pump is operated it just pushes the fuel back in the fuel bowl. Good luck.
Just to clarify... When you say "squirters", are you referring to the accelerator pump nozzles or the main fuel nozzles? At idle or steady cruise you shouldn't see any fuel from the pump nozzles. Inoperative accelerator pumps will make the engine stumble off idle or bog during part-throttle acceleration, or cause difficult cold-starting. 8 pounds sounds like more than enough pressure, but I don't know how much is "too much" for this carb.
There should be two, one-way check valves in the pump circuit, one on the inlet side and one on the outlet side of the pump. Problems with either one can prevent the pump from discharging or refilling properly.
...yes, but ripley's believe it or not i dug out an OLD 750 that sat for ... r u ready ...16 years, plum forgot about it.... (only the 50cc reo gasket was bad...) that was the only leak and it runs VERY nicely on a junk OT farm truck.
I looked at the pressure gauge again, and it's 7 lbs. not 8 which is OK I'm told. Squirters to me meant accelerator pump nozzles. There's no fuel coming out of them when I try to start it and pump the throttle. Obviously, it's getting fuel from somewhere when I pour fuel into the 2 bowl vents -- because it will start and run. I revved it up a little too after it had warmed up some with no bog, miss or engine shut down. I do see fuel in the bowl sight glasses. If there's a problem in the needle and seats, I'll need to pull the carb -- then the bowls to check it, right ? Think I'll do that first, then the accelerator pump umbrella. What do I need to do to check the accelerator pump umbrella ? Then, How do I check the one way valves on the fuel pump? It's a Magna Fuel with a Magna Fuel filter --- 1/2" stainless fuel line. Here's the deal why I have got to get this done quickly. My 30 year old 16' garage door drum cable came off on one side, it jumped the track and bent the top panel and guide rails. I was able to get the cable back on, and straightened things up enough to be able to raise and lower it by hand. My garage door guy had to order a new door which will come in mid-week and I have to get my Econoline pickup and the '69 Nova out of the garage so he'll have room to install the new door. The Econoline with the BBC started today and I think I can drive it out. I have to get the BBC Nova out first, though to clear another car parked in the drive. I may have to bottle feed the Nova to get it out then bottle feed it to get it back in if there's no trash in the needle & seat, or if the accelerator pump umbrella is OK, and if the fuel pump check valves are OK. Thanks, Jim
If the pumps work then the check valves are OK. And of course there has to be sufficient fuel in the bowls to supply the accelerator pumps. When you compress the pump the discharge valve should open to pass fuel to the nozzles and the inlet valve should close to prevent the fuel from just being pumped back into the bowl. When you release the pump the inlet valve should open to allow more fuel to refill the pump chamber and the outlet valve should seat so it doesn't just draw in air thru the pump nozzles. Some carbs will use a light spring to assist the check ball or valve. If it gets assembled with the spring on the wrong side of the check valve it won't seat properly.
One of my friends just told me that if the fuel pressure gauge drops after the engine is shut off that the fuel pump check valve is bad. Mine drops I also think that the problem with the carb being flooded with fuel last year may be a check valve problem. . If he's correct and the new check valve is only $35.00 -- I might try that first.
Ethanol fuel and storage is the death to any carb. I can't tell you how many small engine carbs I have had to replace because people keep leaving ethanol fuel in them. Take them apart and soak them and they are still plugged up. Get a kit for your Holley and soak it in carb cleaner and blow out all the passages. Holley carbs are not as bad as small engine stuff , but they still plug up. The ethanol also kills electric fuel pumps.
^^ You said it. A big profiteer of ethanol, besides the farmers, is the small engine sales and repair shops. In addition to selling and fixing the stuff, our local shop sells non-ethanol fuel. For 8 bucks. A quart. Mechanic friend of mine just retired. He's picking up discarded lawn mowers, saws etc., replacing the fuel lines and carbs and selling them. Doing pretty well.
If the fuel pump check valve is bad it can allow the float bowl level to drop enough that the acc pump won't pump. However, with 7-8 psi when running, the accelerator pump should pump, when the engine is running.
Thanks, I'm contacting Magnafuel tech support tomorrow and see if they have the check valve without buying the $500.00 fuel pump and filter. Jim
Consider that the needle and seat is also responsible for holding fuel pressure in the line between the pump and the carb. A sunk or stuck float, loose needle and seat or a piece of debris in the needle and seat would allow the pressure to drop after the engine and fuel pump are shut off. This could also cause a flooding condition and give you hot start problems.
I would remove the pump squirters and blow air back thru the passages to make sure you don't have plugged/gummed up passages. Are you sure the accelerator pump arm is adjusted properly? SPark
Pulled the front bowl, pulled the float and squirted carb cleaner thru the needle and seat. Cleaned the inside of the bowl with carb cleaner. There was no evidence of dirt or contamination. I left the float level alone - no changes. Cleaned the inside of the rear bowl, took out the float and squirted carb cleaner thru the other needle and seat. Still no dirt or contamination found. I left the float level alone - no changes. The carb still looks pretty new inside, did see some yellow dust, but that wiped right out. Got the carb back together, and it's flooding again. I did notice the pump was making a funny sound and it didn't shut off when I thought the bowls should've been full. Also, it's not holding pressure in the fuel line, went back to zero right after I shut it down. Thanks
Actually, it has two of them. I didn't pull them, checked and they weren't stuck. I shot carb cleaner thru the holes and saw it come out of the center of the diaphrams.
8 pounds of fuel pressure is too high. At first look, is think that was causing the flooding. But that doesn't add up if it ran before. I've seen fuel pumps that bled off after being shut off many times. That's not causing your problem. Sent from my iPhone using Tapatalk
Turned the pressure down to 3 lbs, still had gas coming out of the vent tubes. Took the carb off again, and tore it apart. This time I found something black in the bowl. Pulled the needles and seats and cleaned them again, and found one of the O rings had come apart. Replaced both O rings on the needles and seats and put the carb back together. (The O rings looked OK yesterday in the late evening, but they weren't). Reinstalled the carb, regulator pressure went up to 5 lbs., then 6 lbs. So, the regulator is acting strangely. BUT -- it runs and restarts and doesn't blow gas out the vent tubes. It also restarted. Lesson learned: check the O rings on the needles and seats when there's plenty of daylight. Holley uses rubber O rings instead of something that will last longer. I only had rubber ones, but will order the alky proof ones. Thanks to all that responded -- you were all right about trash being in the carb. Jim
Glad you stuck with it. You made one repair and cured about three problems! They may not realize it, but many people are actually smarter than a carburetor... Even a Holley double-pumper.
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