guys, I gotta 250 Chevy straight six that's drivin' me nuts

[a.d._510_n_ok]

My son is home from the desert for my mom's funeral......bad, bad, bad nursing home deal....anyway, he's been driving his '81 Chevy short wide since last Friday with no problem.

 

Yesterday, it died on the way home. I've swapped out two fuel filters, the fuel pump and replaced a section of metal fuel line (pinhole leak) with rubber fuel line.

 

The 250 six in this thing will idle in the yard for as long as you want it to and sound like a sewing machine doing it. When you take it out the road it does fine for a while but then acts like it has run out of fuel.

 

When I pop the hood the filter is full of fuel. If I take the line off the filter on the "out" side the fuel shoots out with a lot of force.

 

When I put the line back together the truck fires right up and idles like a champ.......until I get rolling again. The carb is an old Rochester.

 

Any help is greatly appreciated - thanks!

[datzenmike]

It may have a kink in the fuel line somewhere back to the pick up in the tank. The pump will supply pressure but volume is restricted. Remove the hose from the pump and aim into a pail. Crank the motor over... there should be good strong squirts. If weak dribble, then the pump may be bad, fuel line or filter clogged or line pinched.

 

Carb float may be set too low and not allowing enough fuel in fast enough for hi speed running. Needle valve my have obstruction. (dirt)

[Mark_Z28]

Id say the needle is partially blocked, hence the fuel shooting out of the line when you removed it. Check the float level also. Its easy to remove the top of the car, remove the float and needle to see if its dirty.

[Icehouse]

Id say the needle is partially blocked, hence the fuel shooting out of the line when you removed it. Check the float level also. Its easy to remove the top of the car, remove the float and needle to see if its dirty.

 

Damn my guess was going to be the floats... :D I think the float has a whole in it so it's not filling properly, or not adjusted properly.

[koback68]

if yours has 2 tanks theres a tank valve switch under the truck i had the same problem i would pick one up from pull a part and switch it out for some reson they get stuck between

[ggzilla]

Rochesters originally had a brass filter in the carburetor inlet. Sometimes those get plugged.

[Guest DatsuNoob]

Rochesters originally had a brass filter in the carburetor inlet. Sometimes those get plugged.

 

I had one of these in my 77 impala. I was on the freeway, chugging along at a whopping 30 mph. Turned off at a local Schucks and pulled the clogged cylindrical filter out of the inlet. I just put it back together without it in there and ran an inline filter behind it. Worked great, and got me back up to speed on the way home. As for the sewing machine sound, I swear, they all do that. Valves can be adjusted a little to make the ticking go away, all in all, I'd say the GM 250 straight six, is an extremely reliable motor.

[MikeRL411]

I agree that the sintered bronze carb inlet filter is the most likely culprit. I had this engine in my 65 Nova wagon, sweet machine. The only other possible is that the vacuum advance line has a leak. There is a swedged joint between 2 sections of metal line on the drivers side of the engine. Eventually a circumferential crack develops and is nearly invisible, and the line leaks defeating the advance. Locate this joint, cut it off with a tubing cutter and slip on a length of fuel injector fuel hose [it will last forever].

[a.d._510_n_ok]

Hey guys thanks! We got it to run and drive but it still wasn't right. I took it too a bud who is an awesome mechanic. He climbed on top of the running engine, listened and said, "Rocker arm is about to come loose". :o

 

He's fixing it and tweaking a few things as we speak.

[510kevin]

gotta love those 250's thats what powers my land yacht!