Thread: My motor wont stay running? (383stroker)

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I recently aquired a 72 c10 that I plan to restore over the next few years. I got it in Kansas and made the drive down to Texas (some 500miles). After about 200miles it died on me, we found out that the rubber O-ring inside the fuel cap was starting to rot into the fuel tank causing the fuel lines and filter to clog. After changing the filter it would run as long as I kept pumping the gas, so I drove the other 300 miles with a heavy-foot, made it home where the truck died in the drive-way. Now I cant get it to run?, I prime it and it starts right up, however, it dies in just a few seconds as the gas i poured into the carb runs out. It seems like although the filter is full of gas (and is not clogged) the gas does not seem to be reaching my carb. (A 3310, 750 CFM 4bbl Holley).
What are my next steps here?

Appreciate all inputs!

You'll need to verify or replace all the fuel hoses for deterioration / rot from the tank to the fuel pump to the carb., then every screen / filter will need to be checked or replaced, even the one on the pickup inside the tank. And also test / inspect / replace the fuel pump.

If the filter at the carb has debris or contamination you may consider going inside the carb if you think it's dirty inside.

Oh, and welcome to the club!

Maybe some got through to the carb filter before the external filter was added and the carb is clogging? If it is getting gas to the carb and it wont run unless its primed then Id guess an obstruction is in the carb? Might pull off the cover and take a look see.

Sounds to me like it needs a Carb. Kit

Originally Posted by sg4356

Sounds to me like it needs a Carb. Kit

Yeah, I agree with Denny, but I also think Mike's on target with you needing to change out anything and everything with rubber touching fuel. Sounds like that truck sat a long time and the ethanol got aggressive with the whole system. I'd be dropping the tank to check the in-tank filter, looking at all the lines, changing the in-line filter (paper gets attacked, too), and buying a new fuel pump along with that carb kit.

Carb Kit was my thought also - - - - if you want to know if gas is getting to the carb just unhook the fuel line at the carb and turn the engine over.
Of course, put a can, funnel or something at the open end of the fuel line to catch the gas 'cause I'm pretty sure you're gonna have some there.

Put a pressure guage on the fuel line. Until then, your'e just guessing.

One thing to could do, - this just in... Crank it five seconds, then crack the line at the carb. If you get a squirt of fuel ( the pump should have a check valve ) then the problem is in the carb.

Originally Posted by firebird77clone

Put a pressure guage on the fuel line. Until then, your'e just guessing.

One thing to could do, - this just in... Crank it five seconds, then crack the line at the carb. If you get a squirt of fuel ( the pump should have a check valve ) then the problem is in the carb.

Sorry, but I cannot agree. If you have so much deterioration of an o-ring on the cap that it's coming apart enough to block the fuel filter it's a pretty good indicator that you've got some severe erosion of rubber components from the ethanol, very likely through the system where ever there's rubber. On a 1972 that's extensive as they were not built to be ethanol resistant. If you want to go on the cheap then after you do like Em (MelloYello) says and pump a pint or so of fuel from the carb inlet into a clear plastic/glass container (be careful, have a fire extinguisher present, normal fire safety precautions), see what you get in the container besides gas. You MIGHT get by with a new in-line filter and a carb kit, but if it pumps black particles from the line I'd be changing everything but the steel lines from back to front or you'll likely get stranded again when your new filter plugs. If you just rebuild the carb it'll very likely plug again, you just don't know when.

who you calling cheap???

Originally Posted by MelloYello

who you calling cheap???

Now Emmett, I was very careful with that wording to NOT call names!! I gave you credit for the idea of pumping some gas into a container to see what comes out of the line. The "Cheap" part is trying to get by with just replacing the fuel filter and cleaning out the carb, and not addressing the probable root of the problem. I really think that he's got rubber components shedding throughout the system, and getting all that crap out of the lines may be fun. I'd probably unhook and blow them back with a good flow of compressed air.

Ok spears, ya got me. Kind of. If you have pressure on the carb inlet, then the carb is plugged. That is the immediate problem. You'll have to determine the origin of the crud, and take steps to eliminate that.

It looks like a general consensus that it's the fuel lines deteriorating, and replacement is warranted even if they are not. ( because they will ). Could also be the sock in the tank, on the pick up of the sending unit, or the fuel pump, or a break in the fuel line, causing the pump to suck air.

Originally Posted by firebird77clone

Ok spears, ya got me. Kind of....

Not trying to "get" anyone, firebird, other than trying to "get" VikingRed in better shape on his truck. There's a big difference in "..gettin' it runnin'" and "...gettin' it fixed". No argument that the carb is likely plugged, but I'm advising for the "fix". Mike gave about all the advice needed back in Post #2, and so far Viking hasn't been back to even read any of this, unless he's lurking without logging into the forum. I'm more interested in him reporting back than anything else at this point.

All motor trouble shooting starts with the basics;
1). FUEL
2). AIR
3). SPARK

2 & 3 seem to be covered as the motor runs when primed with fuel. Going back to the original post, he states that there was deterioration at the rubber seal to the cap, the truck ran for several hundred miles then started giving trouble requiring the foot to be held firmly into the pedal and this got him home.

At this point logic brings us to the carburetor (72 pre-fuel injection), one would assume the carb is plugged up with debris from methanol fuel blend we our now using (a likely suspect to the original rubber components deterioration).

Pressure at the carb only tells us the fuel is arriving, not how much is getting into the motor as the motor is not running long enough to see a pressure drop (you can have pressure without volume).

With the knowledge above we would assume the rubber components are likely causing debris to enter the filters and carb, but the deterioration causing the debris may not be limited to just the rubber hoses, as the fuel pump and carb itself have internal rubber components.

I agree with the advice given that all components need to be examined for a long term fix, otherwise you will be further frustrated down the road with continuing problems.

One thing for certain is that a new fuel pump, lines and carb kit doesn't cost that much and, as suggested above, they probably ALL need replacing anyhow. Another certain thing is that Ethanol is a thorn in the b-u-t-t for all Car Owners, regardless of the vehicle.

The truck has been sitting for awhile, but i still managed to drive it some 500miles. I planned on replacing all the rubber hoses and clean out the tank, Ill do the test on the fuel pump, although I think shes working fine. My next step will definitely be a carb kit, and to re-adjust the idle screws (as Im pretty sure it has a vacuum leak).

Thanks for the info guys!