The Stovebolt Site Forums The Shop Area Engine Shop Engine is sputtering/dying at idle

This issue started 2 days ago, a day after I lowered the rearend. My guess is that there is an issue the Rochester carburetor.

The truck runs w the choke on, if turn the choke off it sputters and dies. When I hit the gas, it jerks like it is getting speratic fuel off and on. Once I am up to speed in any gear there is no issue.

Any suggestions?

"day after I lowered the rear end"
might investigate how much that changed the float level

Bill

Park it facing uphill and see if it runs right. I had a similar issue with a Carter YF after a rebuild. Turns out a check ball came out of the accelerator pump assembly and ended up in the bottom of the bowl. I was able to drive it home with the throttle cable pulled out to about 1000 rpms. Will yours run with the throttle cable pulled out some? If not, you may have a vacuum leak. I fart every morning before the sun rises, but I don't think that is what causes the sun to rise. It might be a coincidence.

Where is the accelerator pump located and how do I check it.

I replaced the fuel filter w no positive results. I'm strongly leaning towards a carb issue.

have you leaned far enough to check the float level?

Bill

How do I check the float level?

well, it sounds like maybe you take the truck to a mechanic, but you might try digging out the shop manual and study the section about carburetors - you could even buy a rebuild kit and get some hands on learning experience

Bill

It limped in to work today, finally dies 1 block from the office. It wont fire up any more.

Does sound like a fuel issue. When you lowered the rear end not only did you change the angle of the carb you also moved fuel away or closer to the pickup point in the tank. Take the fuel line off the carb and point it down toward the ground while someone cranks the engine. If fuel flows freely it is probably the carb. If fuel doesn't flow it is a pump or line issue.

I just talked to Tom Langdon, he said its probably dirt in the carb, which makes sense. I will have to take the idler screw out and check for any fuel or dirt.

Well that didnt work. :\

Remove the fuel line from the fuel pump on the inlet side to check for free flow coming from the tank.
If you have flow from the tank, reattach the fuel line and remove the line at the carburetor and turn over the engine with the starter (ignition off) catching the fuel in a bottle.
If you have good flow, teach yourself how to rebuild a carburetor. They are not very complicated. When you are done and it runs like new, you can brag to folks you don't even know.

If you had a fuel filter installed, why would it be dirt in the carburetor?

Those who frequent these forums know the Rochester B is certainly not my favorite carburetor; carburetors (even Rochester B's) fail over 1000's of miles or a couple of years.

On the other hand, ignition systems fail from instantaneously to over a period of days.

Yes, it MAY be the carburetor, but I would investigate the ignition system first. A perfect carburetor will not run an engine with a defective ignition.

And as Carl is suggesting, you may have a fuel delivery issue (fuel pump diaphragms don't care for ethanol fuel).

Try filling the carburetor with fuel through the bowl vent. Then try to start the engine. If it fires, check the fuel pump. If it doesn't fire, try pouring a tablespoon of fuel into the throat of the carburetor; then close the choke and try to start.

If it fires with the fuel down the throat, but not with filling the carb, then its time to rebuild the carb.

If it doesn't fire either time, its time to overhaul the ignition system.

Jon.

I was way off. Ends up it was the points in the rotor. I get Thunderbolt in Houston didn't check them when they rebuilt the engine. Disappointing.