engine help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**68350** · 02-09-2013, 03:56 PM

Ok im getting upset with this, heres my problem. 496 with a holley 750 dp. Has fuel all the eay to carb. Filter stays full. Will not start unless you pour gas in the front bowls or starting fluid. Has msd hei set at 36 advanced and no vacuum advance. Its always been kind of a pig to start, but now wont start at all on its own. Suggestions? Engine builder isnt available until monday...
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AirSpeed · 02-09-2013, 04:25 PM

Do you see any fuel when you pull the throttle? You should be able to see or hear it squirting. Maybe your float valve is stuck closed or the float is full of gas?
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**68350** · 02-09-2013, 04:30 PM

Yes i can see the gas squirt. And this is my first holley so i have no idea on adjustments or how to check anything on it. When they dyno'd it, everything was fine. Basically the only difference from the dyno is i used a mechanical fuel pump(holley aftermarket one) and they used an electric one. It starts fine once its warmed up
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GASoline71 · 02-09-2013, 04:32 PM

What is your fuel pressure? Anything over 8 psi on a Holley will push fuel past the needle and seat, flooding the engine.

Gary

**68350** · 02-09-2013, 05:22 PM

Im not sure on the fuel pressure. Why would it start by pouring fuel down carb if there was excess pressure? Maybe I'm thinking of that wrong, but seems it still wouldn't start if it was flooding??

davepl · 02-09-2013, 05:29 PM

Sounds like something has always been amiss and now its just gotten to the point where you're not willing to overlook it.

To me, that means time to check the basics. Fuel pressure, float level, choke adjustment (and if you don't have a choke, you're already done), and so on.

I'm not accusing you of it personally, but I've seen a lot of "I removed all the driveability features of my engine and now its not very driveable".

In my mind everything should cold start perfectly and idle nicely and not overheat, unless you're at least in the 9s.

ole86chebby · 02-09-2013, 05:35 PM

Quote:

Originally Posted by 68350

Ok im getting upset with this, heres my problem. 496 with a holley 750 dp. Has fuel all the eay to carb. Filter stays full. Will not start unless you pour gas in the front bowls or starting fluid. Has msd hei set at 36 advanced and no vacuum advance. Its always been kind of a pig to start, but now wont start at all on its own. Suggestions? Engine builder isnt available until monday...
Posted via Mobile Device

sounds like your fuel levels in the fuel bowls arent adjusted properly.
there should be two sight screws on the passenger side of the carb. undo the screws and gently rock on the truck. if your fuel level is correct, a little bit of fuel will trickle out.

check to make sure your needle and seats arent stuck open. you might also have to check your accelerator pump arm adjustment.

geezer#99 · 02-09-2013, 07:15 PM

Choke working??

**68350** · 02-09-2013, 11:59 PM

I will check floats and whatnot. Choke is a manual unit.
Posted via Mobile Device

**WIDESIDE72** · 02-10-2013, 07:06 PM

Quote:

Originally Posted by ole86chebby

sounds like your fuel levels in the fuel bowls arent adjusted properly.
there should be two sight screws on the passenger side of the carb. undo the screws and gently rock on the truck. if your fuel level is correct, a little bit of fuel will trickle out.

x2

**WIDESIDE72** · 02-10-2013, 07:06 PM

Let us know what you find out

luvbowties · 02-10-2013, 08:08 PM

Quote:

Originally Posted by geezer#99

choke working??

x2!

02-09-2013, 03:56 PM	#1
68350 Senior Member Join Date: Jan 2002 Location: Williston, ND Posts: 2,999	engine help Ok im getting upset with this, heres my problem. 496 with a holley 750 dp. Has fuel all the eay to carb. Filter stays full. Will not start unless you pour gas in the front bowls or starting fluid. Has msd hei set at 36 advanced and no vacuum advance. Its always been kind of a pig to start, but now wont start at all on its own. Suggestions? Engine builder isnt available until monday... Posted via Mobile Device __________________ 68 Chevy CST/10, 50th Anniversary, 327/th400, 373 posi, buckets 68 GMC Shortbox Stepside, 402/th400, Tilt, Tach, Bucket Seats, 3.08 Positraction 69 Chevy Camaro SS, 383, 4 speed, positraction 70 Chevy El Camino SS396, Triple Black, 454/th400, Tach 70 Chevy Shortbox Stepside 4x4, 350/th350, Tilt, Tach, Cab Lights, Bumper Guards, Tow Hooks 70 Chevy 3/4 Longbox, 350/auto, 70k, SURVIVOR 71 Chevy Blazer, CST, 350/auto 71 GMC Sierra K2500, 454, 4 speed, 4.10 posi, 37s 71 Custom/30, Open Road, 350/th400, tilt 72 Chevy Shortbox Fleetside, 496 Stroker/th400, Tilt, Tach, Bucket Seats, 3.42 Posi 72 GMC Sierra Grande 2500. 427/th400, tilt, a/c, tool and stowage, buckets/console, 3.54 posi

02-09-2013, 04:25 PM	#2
AirSpeed Registered User Join Date: Jul 2007 Location: Fall River California Posts: 2,026	Re: engine help Do you see any fuel when you pull the throttle? You should be able to see or hear it squirting. Maybe your float valve is stuck closed or the float is full of gas? Posted via Mobile Device __________________ http://smg.photobucket.com/albums/v655/aaronhero/

02-09-2013, 04:30 PM	#3
68350 Senior Member Join Date: Jan 2002 Location: Williston, ND Posts: 2,999	Re: engine help Yes i can see the gas squirt. And this is my first holley so i have no idea on adjustments or how to check anything on it. When they dyno'd it, everything was fine. Basically the only difference from the dyno is i used a mechanical fuel pump(holley aftermarket one) and they used an electric one. It starts fine once its warmed up Posted via Mobile Device __________________ 68 Chevy CST/10, 50th Anniversary, 327/th400, 373 posi, buckets 68 GMC Shortbox Stepside, 402/th400, Tilt, Tach, Bucket Seats, 3.08 Positraction 69 Chevy Camaro SS, 383, 4 speed, positraction 70 Chevy El Camino SS396, Triple Black, 454/th400, Tach 70 Chevy Shortbox Stepside 4x4, 350/th350, Tilt, Tach, Cab Lights, Bumper Guards, Tow Hooks 70 Chevy 3/4 Longbox, 350/auto, 70k, SURVIVOR 71 Chevy Blazer, CST, 350/auto 71 GMC Sierra K2500, 454, 4 speed, 4.10 posi, 37s 71 Custom/30, Open Road, 350/th400, tilt 72 Chevy Shortbox Fleetside, 496 Stroker/th400, Tilt, Tach, Bucket Seats, 3.42 Posi 72 GMC Sierra Grande 2500. 427/th400, tilt, a/c, tool and stowage, buckets/console, 3.54 posi

02-09-2013, 05:22 PM	#5
68350 Senior Member Join Date: Jan 2002 Location: Williston, ND Posts: 2,999	Re: engine help Im not sure on the fuel pressure. Why would it start by pouring fuel down carb if there was excess pressure? Maybe I'm thinking of that wrong, but seems it still wouldn't start if it was flooding?? __________________ 68 Chevy CST/10, 50th Anniversary, 327/th400, 373 posi, buckets 68 GMC Shortbox Stepside, 402/th400, Tilt, Tach, Bucket Seats, 3.08 Positraction 69 Chevy Camaro SS, 383, 4 speed, positraction 70 Chevy El Camino SS396, Triple Black, 454/th400, Tach 70 Chevy Shortbox Stepside 4x4, 350/th350, Tilt, Tach, Cab Lights, Bumper Guards, Tow Hooks 70 Chevy 3/4 Longbox, 350/auto, 70k, SURVIVOR 71 Chevy Blazer, CST, 350/auto 71 GMC Sierra K2500, 454, 4 speed, 4.10 posi, 37s 71 Custom/30, Open Road, 350/th400, tilt 72 Chevy Shortbox Fleetside, 496 Stroker/th400, Tilt, Tach, Bucket Seats, 3.42 Posi 72 GMC Sierra Grande 2500. 427/th400, tilt, a/c, tool and stowage, buckets/console, 3.54 posi

02-09-2013, 05:29 PM	#6
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: engine help Sounds like something has always been amiss and now its just gotten to the point where you're not willing to overlook it. To me, that means time to check the basics. Fuel pressure, float level, choke adjustment (and if you don't have a choke, you're already done), and so on. I'm not accusing you of it personally, but I've seen a lot of "I removed all the driveability features of my engine and now its not very driveable". In my mind everything should cold start perfectly and idle nicely and not overheat, unless you're at least in the 9s. __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

02-09-2013, 07:15 PM	#8
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,736	Re: engine help Choke working??

02-09-2013, 11:59 PM	#9
68350 Senior Member Join Date: Jan 2002 Location: Williston, ND Posts: 2,999	Re: engine help I will check floats and whatnot. Choke is a manual unit. Posted via Mobile Device __________________ 68 Chevy CST/10, 50th Anniversary, 327/th400, 373 posi, buckets 68 GMC Shortbox Stepside, 402/th400, Tilt, Tach, Bucket Seats, 3.08 Positraction 69 Chevy Camaro SS, 383, 4 speed, positraction 70 Chevy El Camino SS396, Triple Black, 454/th400, Tach 70 Chevy Shortbox Stepside 4x4, 350/th350, Tilt, Tach, Cab Lights, Bumper Guards, Tow Hooks 70 Chevy 3/4 Longbox, 350/auto, 70k, SURVIVOR 71 Chevy Blazer, CST, 350/auto 71 GMC Sierra K2500, 454, 4 speed, 4.10 posi, 37s 71 Custom/30, Open Road, 350/th400, tilt 72 Chevy Shortbox Fleetside, 496 Stroker/th400, Tilt, Tach, Bucket Seats, 3.42 Posi 72 GMC Sierra Grande 2500. 427/th400, tilt, a/c, tool and stowage, buckets/console, 3.54 posi

02-10-2013, 07:06 PM	#11
WIDESIDE72 Senior Member Join Date: Aug 2008 Location: Cedar Park, Texas Posts: 7,500	Re: engine help Let us know what you find out



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