Need some help boys...

[TheHammerC10]

I acquired this truck almost a year ago. At 31 I've owned 4 bowties, plus this c10, aka my dream truck.. w/ this said, I'm not the most mechanically inclined. Trying not to ramble so if you want more info please reply. My issue: she surges and dies on occasion. idles fine for about 20 minutes, then surges. If put in reverse or drive and given gas she dies. i can pedal it and alls good but once in gear idling, she passes out. Timing was set recently. My Dad seems to think the gas tank isn't vented properly. I think it may be a carb issue..? Help Fellas..

-Donny

[randy500]

Did it run right when you got it a year ago?

[engineer_gregh]

I would first change the fuel filter that's next to your carb, and then look under the truck to see if someone has put a second filter in line some where that may be clogged. Next I would check the float level on the carb, looks like an Edelbrock. If it is an Edelbrock its fairly easy to build. Is the fuel pump an electric pump or the stock mechanical? The fuel pump could be struggling with the tank re-located to the rear of the truck.

[dmjlambert]

To tell if it is a gas tank vent problem, remove the gas cap and see if the problem goes away.

[LockDoc]

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You don't say what engine/trans you have but also check the trans modulator to make sure it is good, and check the vacuum lines going to it for leaks. If there is a leak in the vacuum line to the modulator or vacuum is low it will kill the engine when you put it in gear. Mine only did it in reverse.

Where is the vacuum line to the modulator connected on the manifold?

LockDoc

[custom10nut]

Sound like your dad may be right. Is your system vented? If yes, is it venting properly? With a half full tank, take It for a ride with the gas cap off. If the the issue stops, venting is the cause. If it continues, filter and pump are the next thing to look at.

[OBS454]

If you did not install it then you have no idea what the previous owner did. Check the entire system from point of origin up to the carburetor. Wrong/improper nipple size on tank outlet... the sock/strainer in on the pickup tube could be restricted... a rubber hose somewhere down the line could be cracked (if mechanical pump is in use)... the metal pickup tube inside the tank could be cracked (2010 /cheap-ass Chinese part installed on 84 Z28 I had to remove gas tank twice) ... weak electric in-tank pump will make enough pressure to run at low speeds but not enough to accelerate... filter at carb ... trash in carb bowl... faulty/improperly adjusted pressure regulator ... fuel tank not vented ... vehicle sat up too long and frigging spider crawled into line, died when gas was added and mummified said spider but did not dissolve said spider thereby restricting fuel flow - true story ... quick tip: on carb side either remove rubber line or install rubber line that will allow you to blow lung air into the line and you should hear/feel bubbling in the tank - that should give some idea of any restriction.

[KQQL IT]

Mine was running crappy.
Pulled the cap off and found this

[TheHammerC10]

Originally Posted by randy500

Did it run right when you got it a year ago?

No. It was having the same problem plus some. Had to replace the starter which led me to milky oil.. the heads were cheap Japanese aluminum trash so i had them replaced w/ OEM.

[TheHammerC10]

Originally Posted by engineer_gregh

I would first change the fuel filter that's next to your carb, and then look under the truck to see if someone has put a second filter in line some where that may be clogged. Next I would check the float level on the carb, looks like an Edelbrock. If it is an Edelbrock its fairly easy to build. Is the fuel pump an electric pump or the stock mechanical? The fuel pump could be struggling with the tank re-located to the rear of the truck.

Iv'e replaced the filter w/ no resolve. I believe the pump is mechanical..? it looks factory. I'll post a pic.

DMJLAMBERT: Started her up today w/ no issues. Got confidant and moved my Silverado to take the C10 for a spin. As I returned it was dipping in RPMs, my perennial problem. Popped the gas cap off. Made no difference. Popped the hood to see the fuel filter semi struggling to pump fuel. My Dad said that might not be a big deal as our tractors look like they're barely pumping fuel all the time.

LocDoc: It's a 350, not sure about the trans. My mechanic said it had a shift kit when i asked about its abrupt shift to 2nd gear. Not sure about modulator but ill be looking into it tomorrow.

OBS454: I wouldn't be surprised about the chinese parts. Seems like the previous owner blew his wad on body work and paint, went cheap on the mechanical side.

I want to give all you guys a big thank you. y'all are badass for giving me this advice. I'm super grateful.

-Donny

[davischevy]

An extremely abrupt shift could indicate a vacuum leak in the line going to the modulator.

[randy500]

Because the truck has been sitting and runs fine sometimes, or sort of fine...this suggests the carburetor is clogged internally, do you know somebody that would let you borrow a known good carb?

[demian5]

That filter and line look like they run fairly close to the headers...

[engineer_gregh]

The previous owner(s) of my 71 had put an inline filter under the truck (under the cab where there is rubber between the metal lines). It took me looking under the truck several times to find it. Once I found the filter and removed it, no more fuel issues. Well, no more issues after removing the filter and installing a new gas tank:-) My tank was full of sludge at the bottom and the filter was almost completely clogged. The symptoms I experienced were about the same you are having.

[HO455]

Since you still seem to have no ideas as to what is causing the problem and you stated it surges and dies which indicates it is running out of fuel. I would let it run it and get it to die. Then without doing anything but turning the key off remove the top of the carb and see how much fuel is in the bowls. If they are empty then you have a supply issue. Possible stuck needle valves, one of those rubber supply hoses could have failed internally or a bad fuel pump. You can check the fuel pump by disconnecting the fuel hose at the carburetor and directing it to a bucket and cranking the engine over and see how much fuel is being pumped.

BE VERY CAREFULL AS THIS IS AN FLAMMABLE LIQUID AND YOU WILL BE SPRAYING IT. I would not attempt this on a hot engine. If you want to add extra hose to get to the bucket that is a good idea but use as much of your existing hose as possible. If you have poor flow then replace the existing hose from the pump to see if it improves. ONCE AGAIN BE SAFE!!! DON'T DO THIS INDOORS OR NEAR IGNITION SOURCES. WE WANT YOU BACK TO HEAR THE RESULTS!

If you have fuel in the bowls then look for dirt/sediment in the bottom of the bowls and check your float settings. If you see dirt or sediment in the bottom its time for the carb to be gone through as that dirt will plug or restrict the calibrated passages in the carburetor.

One more thing and I don't know if it is true on pickups but my Burban there is a little six inch hose under the truck on the passenger side near the tranny cross member and if that is old the fuel pump will suck air and not fuel. It is easy to replace.
Good luck.

[demian5]

Originally Posted by engineer_gregh

My tank was full of sludge at the bottom and the filter was almost completely clogged.

Not the first time I have seen that.

With the aluminum aftermarket tank he has, I wonder if its a fuel pickup issue...

[Metaldoc]

Is the vacuum line to the distributor on the right port on your carb ? It could be vacuum advance problem.