Sputtering and Surging?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

muddpile · 08-29-2005, 12:39 AM

Last night I was coming home from a parts run, and when I got up to about 70mph, the truck started bogging, sputtering, etc. It kinda revved down like it was going to stall, but never did. The closer I got to home, the lower speed the truck had to be going for it to do it. 50mph was my average speed for the last hour (nearing 40mph as I got about 15 minutes away). It sounded like a lack of fuel, but I'm not sure. What would cause this? I was thinking fuel filter, but haven't checked yet. Before I look, where is the fuel filter located? The truck is a 72 with an HEI 350 4 barrel out of an 80s burban. Thanks!

jlmtrout · 08-29-2005, 02:31 AM

If you have a carb and manual fuel pump, look for the filter to be between the fuel pump and the carb. Also, look at the filter on the carb. Remove fuel line from carb and remove large nut where the fuel line screws in, and the filter will be under this nut. Another place to look is the rubber fuel line from the tank that connects to the hard line going into the fuel pump. As they age, they can become too pliable and can collapse. One more place to check is the fuel pickup in the tank. Good luck and keep on truckin'.......Jerry

A.P. · 08-29-2005, 06:12 AM

The fuel filter on my Q-jet carb. is located in the front of the carb. Check the pic, the green arrow points to where its located.

vtblazer · 08-29-2005, 11:08 AM

If it's a late model engine, check the EGR valve sticking open or just not operating correctly.
If the EGR valve is still there in will be on the passengers side of the intake toward the rear.

Frizzle Fry · 08-29-2005, 01:42 PM

I've got the same problem on the Burb right now. I have an inline fuel pressure regulator, and when I cranked it up the problem went away for a while. It came back this morning so I think the fuel pump might be going (it's electric). I'll have to check the in-line and carb filters too.

cdowns · 08-29-2005, 02:08 PM

first would be fuel filter/ second would be to check the hei wiring if they used the original wiring(resistor wire) it could be that running on lo voltage has fried the module

muddpile · 08-30-2005, 12:18 AM

Thanks for the help everyone! I'll have to check all that stuff out and let you know how I make out.

classicchev · 08-30-2005, 12:18 AM

If you have already changed your filters, I doubt it would be that though because it would die, believe me I have been there. I had the same problem last week, looked at everything from the plugs to the wires, then MSD and finally the distributer cap. There was a little buildup on the contact points of the HEI cap that would not allow the complete circuit. My truck drove like it only had 5 cylinders, popping and farting, running like crap and since I changed the cap it has been running like a dream for the last week.
It has been really humid in Alberta this summer, I think that is what made the problem show up.
Change the cap and rotor, will probably fix it.

muddpile · 08-30-2005, 12:19 AM

I'll add a cap and rotor to the list of improvements. Thanks!

08-29-2005, 12:39 AM	#1
muddpile Registered User Join Date: Dec 2004 Location: Saskatchewan, Canada Posts: 1,371	Sputtering and Surging?? Last night I was coming home from a parts run, and when I got up to about 70mph, the truck started bogging, sputtering, etc. It kinda revved down like it was going to stall, but never did. The closer I got to home, the lower speed the truck had to be going for it to do it. 50mph was my average speed for the last hour (nearing 40mph as I got about 15 minutes away). It sounded like a lack of fuel, but I'm not sure. What would cause this? I was thinking fuel filter, but haven't checked yet. Before I look, where is the fuel filter located? The truck is a 72 with an HEI 350 4 barrel out of an 80s burban. Thanks! __________________ 1964 Chevy Short Fleet: Tornado 1972 Chevy C10: Fast Orange Secondaries Wide Open

08-29-2005, 02:31 AM	#2
jlmtrout Registered User Join Date: Jul 2002 Location: Memphis, Tn Posts: 194	If you have a carb and manual fuel pump, look for the filter to be between the fuel pump and the carb. Also, look at the filter on the carb. Remove fuel line from carb and remove large nut where the fuel line screws in, and the filter will be under this nut. Another place to look is the rubber fuel line from the tank that connects to the hard line going into the fuel pump. As they age, they can become too pliable and can collapse. One more place to check is the fuel pickup in the tank. Good luck and keep on truckin'.......Jerry __________________ '68 c-10 long wheelbase fleetside, been in family since new, originally 250 3 speed Now (389) 350 .060 over 3.75 stroke,Edelbrock Performer RPM 70cc heads and Intake 600 cfm Edelbrock,Small Comp Cams retro-roller cam and roller rockers,9:1 cr, headers, HEI,Old Air a/c, 72 power disc brakes w/stainless lines, 3.42 gear,T-56 6-speed, original paint(what's left of it). Dakota Digital Dash

08-29-2005, 06:12 AM	#3
A.P. Black 72 Chevy Join Date: May 2002 Location: Los Angeles, California Posts: 662	The fuel filter on my Q-jet carb. is located in the front of the carb. Check the pic, the green arrow points to where its located. Attached Images

08-29-2005, 11:08 AM	#4
vtblazer Registered User Join Date: Oct 2003 Location: Central Vermont Posts: 8,538	If it's a late model engine, check the EGR valve sticking open or just not operating correctly. If the EGR valve is still there in will be on the passengers side of the intake toward the rear. Last edited by vtblazer; 08-29-2005 at 05:37 PM.

08-29-2005, 02:08 PM	#6
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	first would be fuel filter/ second would be to check the hei wiring if they used the original wiring(resistor wire) it could be that running on lo voltage has fried the module __________________ 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

08-29-2005, 01:42 PM	#5
Frizzle Fry Registered User Join Date: Aug 2005 Location: Hillsboro Oregon Posts: 6,449	I've got the same problem on the Burb right now. I have an inline fuel pressure regulator, and when I cranked it up the problem went away for a while. It came back this morning so I think the fuel pump might be going (it's electric). I'll have to check the in-line and carb filters too.

08-30-2005, 12:18 AM	#7
muddpile Registered User Join Date: Dec 2004 Location: Saskatchewan, Canada Posts: 1,371	Thanks for the help everyone! I'll have to check all that stuff out and let you know how I make out. __________________ 1964 Chevy Short Fleet: Tornado 1972 Chevy C10: Fast Orange Secondaries Wide Open

08-30-2005, 12:18 AM	#8
classicchev Senior Member Join Date: Nov 2003 Location: Calgary Alberta Posts: 1,936	If you have already changed your filters, I doubt it would be that though because it would die, believe me I have been there. I had the same problem last week, looked at everything from the plugs to the wires, then MSD and finally the distributer cap. There was a little buildup on the contact points of the HEI cap that would not allow the complete circuit. My truck drove like it only had 5 cylinders, popping and farting, running like crap and since I changed the cap it has been running like a dream for the last week. It has been really humid in Alberta this summer, I think that is what made the problem show up. Change the cap and rotor, will probably fix it. __________________ 67- 72 Parts collecter

08-30-2005, 12:19 AM	#9
muddpile Registered User Join Date: Dec 2004 Location: Saskatchewan, Canada Posts: 1,371	I'll add a cap and rotor to the list of improvements. Thanks! __________________ 1964 Chevy Short Fleet: Tornado 1972 Chevy C10: Fast Orange Secondaries Wide Open



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