Sputtering and Surging??

[muddpile]

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]

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.]

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]

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]

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]

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]

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

[classicchev]

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]

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