Motor stuttering going up hill, not getting enough fuel? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Crazy-J · 12-09-2005, 03:20 PM

Hi,

I am having some trouble with my motor when going up hill. It just starts running flat and doesn't give me the power I get on flat roads. You can actually hear and feel it go from full power to a like stuttering state where it seems to come in and out of power.

Giving it more throttle doesn't help at all. It will downshift but still has the same problem. I've found that giving it about 50% throttle helps keep it from screwing up as much but it still has the problem. It's never bad enough to keep from getting up whatever incline I am on but I do slow down a lot.

Flat surfaces and downhills give me all the power I need and running around town it never has a problem. But come to any incline and it starts giving out.

All I can guess is that it's not getting enough fuel. My '72 shortbed has a stock fuel pump on an early 80's Chevy 1500 5.7L 350. It's running a mild cam, headers, 600 CFM Edelbrock carb, and an Edelbrock RPM manifold. I am also running a Summit fuel cell in back under the bed which also leads me to believe it might be the fuel problem given that going up hill that fuell would be shifting all to the back. Do I need a higher performance fuel pump or could it be something else?

I was told that it could also be the floats on my carb are not set correctly so I am going to check that this weekend, however this motor was built by the previous owner and I think he just popped the carb on and didn't mess with it. Otherwise I am lost.

Thanks for any and all help!

cdowns · 12-09-2005, 04:31 PM

first thing i'd check would be the fuel filter//then i check into the wiring for the distributor if it's an HEI and wired with the original resistor circuit it's possible the module is frying itself due to low voltage//also check for vacumme leaks // also if using rubber fuel hose(BAD) it could be kinking or collapsing //you could also pop off your gascap and see if that solves the problem(bad vent) // check condition of plugs also and see how they look and clean/replace and regap them and while your at it set the timing

**John Fabris** · 12-09-2005, 05:14 PM

Change your spark plug wires.

How does it run in neutral? Are you able to rev it up and it sounds good? If so, then put it in gear, foot on the brake and give it gas. If it starts to run bad, it more then likely is the plug wires are bad, and allowing the spark to jump from the wires. When it is dark outside (nighttime) open the hood with the engine running, and see if you see sparks jumping from the wires...

What is happing is that under normal conditions, the spark is getting to the plugs, but under load (going uphill), it takes more voltage to fire the sparkplug, and due to path of least resistance, the spark is jumping out from the wires.

New plug wires should cure this...

724wdcopper · 12-09-2005, 06:04 PM

fuel filter. i did this 3 years ago, swapped 3 carbs, new plugs and wires, 3 fuel Electric pumps. when i pulled off the $50 fuel filter and put a stock one in the quadrajet, runs fine. cheapest and most likely the culprit is the fuel filter.

ratrod67 · 12-09-2005, 06:56 PM

Is your advance on your distributor working?

Longhorn Man · 12-09-2005, 11:41 PM

Fuel filter would show up at high end more likely.
Do the wires, get a cap and rotor and plugs too sine you'r in there.

Crazy-J · 12-10-2005, 02:00 AM

Thanks all, that gives me a lot more to work with. I will check all of that this weekend. It is running an HEI distributor. I replaced the plugs last weekend and while it helped it run better in general, it didn't solve this particular problem.

Russell · 12-10-2005, 11:05 AM

Sounds like timing to me! Does it ever backfire when it is stuttering like that?

Doesn't have to be your plugs, wires, cap or rotor either, if one of the weights is stuck, or if the vac advance is frozen, you'll get that kind of an issue. A carb running out of fuel will stumble, or sometimes die, but timing won't be noticed till you put a heavy load on the engine

jhwkns · 12-10-2005, 11:05 AM

Check your fuel pump pressure too..

**truckdude239** · 12-10-2005, 11:13 AM

sounds like an fuel problem i have an f-150 that when i'd go up hill i'd lose power and the motor would stall out changed me fuel filter and the problem went away changing the filter is the cheapest try fix to do frist just my $.02

12-09-2005, 03:20 PM	#1
Crazy-J Registered User Join Date: Mar 2005 Location: Cool, CA Posts: 34	Motor stuttering going up hill, not getting enough fuel? Hi, I am having some trouble with my motor when going up hill. It just starts running flat and doesn't give me the power I get on flat roads. You can actually hear and feel it go from full power to a like stuttering state where it seems to come in and out of power. Giving it more throttle doesn't help at all. It will downshift but still has the same problem. I've found that giving it about 50% throttle helps keep it from screwing up as much but it still has the problem. It's never bad enough to keep from getting up whatever incline I am on but I do slow down a lot. Flat surfaces and downhills give me all the power I need and running around town it never has a problem. But come to any incline and it starts giving out. All I can guess is that it's not getting enough fuel. My '72 shortbed has a stock fuel pump on an early 80's Chevy 1500 5.7L 350. It's running a mild cam, headers, 600 CFM Edelbrock carb, and an Edelbrock RPM manifold. I am also running a Summit fuel cell in back under the bed which also leads me to believe it might be the fuel problem given that going up hill that fuell would be shifting all to the back. Do I need a higher performance fuel pump or could it be something else? I was told that it could also be the floats on my carb are not set correctly so I am going to check that this weekend, however this motor was built by the previous owner and I think he just popped the carb on and didn't mess with it. Otherwise I am lost. Thanks for any and all help! __________________ 1972 Chevrolet C10 1969 Camaro Now filled with GOLDOLINE!

12-09-2005, 04:31 PM	#2
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Motor stuttering going up hill, not getting enough fuel? first thing i'd check would be the fuel filter//then i check into the wiring for the distributor if it's an HEI and wired with the original resistor circuit it's possible the module is frying itself due to low voltage//also check for vacumme leaks // also if using rubber fuel hose(BAD) it could be kinking or collapsing //you could also pop off your gascap and see if that solves the problem(bad vent) // check condition of plugs also and see how they look and clean/replace and regap them and while your at it set the timing __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

12-09-2005, 05:14 PM	#3
John Fabris TOTY 2006 Join Date: Dec 1999 Location: Magalia CA USA Posts: 2,270	Re: Motor stuttering going up hill, not getting enough fuel? Change your spark plug wires. How does it run in neutral? Are you able to rev it up and it sounds good? If so, then put it in gear, foot on the brake and give it gas. If it starts to run bad, it more then likely is the plug wires are bad, and allowing the spark to jump from the wires. When it is dark outside (nighttime) open the hood with the engine running, and see if you see sparks jumping from the wires... What is happing is that under normal conditions, the spark is getting to the plugs, but under load (going uphill), it takes more voltage to fire the sparkplug, and due to path of least resistance, the spark is jumping out from the wires. New plug wires should cure this... __________________ John Fabris 67 C10 SWB

12-09-2005, 06:04 PM	#4
724wdcopper graphic designer Join Date: May 2004 Location: Spokane, Washington Posts: 841	Re: Motor stuttering going up hill, not getting enough fuel? fuel filter. i did this 3 years ago, swapped 3 carbs, new plugs and wires, 3 fuel Electric pumps. when i pulled off the $50 fuel filter and put a stock one in the quadrajet, runs fine. cheapest and most likely the culprit is the fuel filter.

12-09-2005, 06:56 PM	#5
ratrod67 Registered User Join Date: Sep 2002 Location: DFW Texas Posts: 2,269	Re: Motor stuttering going up hill, not getting enough fuel? Is your advance on your distributor working?

12-09-2005, 11:41 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Motor stuttering going up hill, not getting enough fuel? Fuel filter would show up at high end more likely. Do the wires, get a cap and rotor and plugs too sine you'r in there.

12-10-2005, 02:00 AM	#7
Crazy-J Registered User Join Date: Mar 2005 Location: Cool, CA Posts: 34	Re: Motor stuttering going up hill, not getting enough fuel? Thanks all, that gives me a lot more to work with. I will check all of that this weekend. It is running an HEI distributor. I replaced the plugs last weekend and while it helped it run better in general, it didn't solve this particular problem. __________________ 1972 Chevrolet C10 1969 Camaro Now filled with GOLDOLINE!

12-10-2005, 11:05 AM	#8
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Re: Motor stuttering going up hill, not getting enough fuel? Sounds like timing to me! Does it ever backfire when it is stuttering like that? Doesn't have to be your plugs, wires, cap or rotor either, if one of the weights is stuck, or if the vac advance is frozen, you'll get that kind of an issue. A carb running out of fuel will stumble, or sometimes die, but timing won't be noticed till you put a heavy load on the engine __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) Last edited by Russell; 12-10-2005 at 11:06 AM.

12-10-2005, 11:05 AM	#9
jhwkns Registered Cruiser Join Date: May 2002 Location: Las Vegas NV Posts: 2,230	Re: Motor stuttering going up hill, not getting enough fuel? Check your fuel pump pressure too.. __________________ I intend to live forever. So far, so good.

12-10-2005, 11:13 AM	#10
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,237	Re: Motor stuttering going up hill, not getting enough fuel? sounds like an fuel problem i have an f-150 that when i'd go up hill i'd lose power and the motor would stall out changed me fuel filter and the problem went away changing the filter is the cheapest try fix to do frist just my $.02 __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

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