Fuel pump issue

[OldChevys]

I'm still kind of new here, so if this is the wrong spot, feel free to move it around (just tell me where it went )

anywhooo.....I have a 71 chevy with a 350 and it is sputtering at highway speeds and under a load. The local carb 'experts' told me to change all of the fuel filters including the one IN the carb (which I did) and it still ran the same. Next , they tell me to replace the fuel pump (which I did) and it still runs the same. I replaced the inline filter with a see-through model and I can see that very small squirts of fuel are making it into the filter, but it is not filling up. I took the fuel supply line loose from the pump and blew air through the line to make sure that it was not obstructed and gas seems to flow easily - gravity flow? I am now lost, but somehow think that maybe there is a flat lobe on the cam that drives the pump? Anyone have any ideas?

BTW this is a 71 c10 350/350 auto

Thanks in advance

[Littletony]

What about the sock in the fuel tank on the fuel sending unit? It could be causing your fuel flow issues.

[mking]

The tube that goes to the bottum of your tank has a sock like filter on it.
I would check that. If it's stopped up that could be why the fuel isn't getting to the inline filter.

[tex_waco_usmc]

When mine had the same issue it was a partially plugged up sending unit line and sock. soaked the sending unit in carb cleaner over night and replaced the sock and BAMMMMM it ran like it should!!!!

[cdowns]

do u have the original points distributor?? if yes have they been checked cleaned and set for proper specs? ?? what condition r the sparkplugs?

[OldChevys]

Thanks guys
I guess that I will be pulling the sending unit over the weekend.


cdowns - nope is is MSD ignition. the plugs are about a year old, but I don't understand the relationship to the fuel flow? perhaps you could explain? thx

[cdowns]

ignition problems cause sputtering symptoms too not just fuel flo

[ole dollor]

you could also have trash inside the carb, bowl , jets stopped up, things like that, i also have a see in fuel filter and some times its empty and some times its full. you can check your fuel psi. with a gauge to see what psi. you have. lots of things cause this problems...plug wires, plugs, valves..etc. just have to do some checks....that is what make our trucks so much fun....good luck on your truck...

[hayhauler71]

Fuel pump volume test .5 gallons per minute

[So.Cal.Super]

just a few thoughts/questions.

where is the fuel filter, between the carb and pump or pump and tank?

have you changed the gas cap lately? (not sure how long you have had the truck)

you say you changed to a fuel filter you can see. hopefully not glass (fire problem)

have you checked engine vacuum ? I went through a similar problem and the entire fuel system. My valves and springs were shot in my heads. loss of power at highway speed or under a load.

here is what a 40 year old fuel sock looks like.

[OldChevys]

Originally Posted by So.Cal.Super

just a few thoughts/questions.

where is the fuel filter, between the carb and pump or pump and tank?

have you changed the gas cap lately? (not sure how long you have had the truck)

you say you changed to a fuel filter you can see. hopefully not glass (fire problem)

have you checked engine vacuum ? I went through a similar problem and the entire fuel system. My valves and springs were shot in my heads. loss of power at highway speed or under a load.

here is what a 40 year old fuel sock looks like.

Is there a shop selling replacement socks, or do I just re-use the 40+ year old one that is in the tank?

[So.Cal.Super]

Some people remove them completely, I'm not sure if you can buy just the sock.

I know Wes sells the whole unit for around $52.

http://www.classicheartbeat.com/fuel_parts.htm

[cdowns]

Originally Posted by hayhauler71

Fuel pump volume test .5 gallons per minute

dont know where he's gettin his specs

but factory GM service manual calls for 1 pint of gas in 30-45seconds


i have found local autoparts stores have generic fuel socks that can b used

[OldChevys]

Well, I finally got around to pulling the fuel sending unit and the sock was soo brittle that it fell apart in my hands. I shot some carb cleaner into the carb as well....I guess that we will she how she does now...FYI the see-through filter is now full for whatever good that does.

I'll go drive it home and let you guys know how she does later.