Posted 06 July 2007 - 08:43 PM
Posted 07 July 2007 - 07:10 PM
Posted 07 July 2007 - 07:45 PM
Leaks are certainly just what you think. Burnt parts usually follow.
If it consistently runs fat, then it generally isn't a pressure problem. Going from low consumption idle to full load will generally change the symptoms if it is a pressure related. A stuck piece of dirt in the needle usually causes the same thing if it makes the needle not seat.
It sure sounds a lot like an internal leak. Does the smoke factor change with load?
1951 M - 1951 MD - 1957 450 - 1953 Super C
1953 TD9 "Ichabod JR" aka "Icky"
1949 TD18 "Brutus" -- 1956 TD18-182 "Yard Dog"
1964 Loadstar 1600 -- 1975 Loadstar 1700 dump truck
1949 Massey 44
Posted 07 July 2007 - 07:58 PM
Posted 07 July 2007 - 08:51 PM
I assume that you have checked for a sinking float. Stampmaint also has a very good suggestion in making sure that your getting good air to the carb inlet and take it a step further and check the that the choke plate is opening correctly.
Have you owned this rig long or is it new to you? Have you ever seen it run correctly or has it been wonky since you've had it. If ran good at one time and then changed, while you've owned it, then we can assume that the jet is correct. If you've never seen it run correctly then you have to figure out what the PO may have done or changed to get it to run rich. It could have been the PO wanted more HP and figured the easy way to get it was to drill the jet.
no neat sig line
Posted 07 July 2007 - 08:53 PM
Check that metering orifice is in solenoid end. Is the plastic venturi distorted\melted?
I hope someone can help me. I have a 674 gas with a Marvel-Schebler model TSX carb on it. It always runs really rich. It operates this way from idle to wide open, looks like a diesel pulling a load! I've had the carb apart twice with a new kit. This model is of the fixed jet style so there is no adjustment needle on the main jet. It just has the idle adjustment needle and can't get it to lean out even on idle, you can screw that one in until engine quits and will smoke til it shuts off. I've adjusted the float so I know that the bowl is not overfilling. If you unplug the the anti-dieseling solenoid the engine will clear up and sound good right before it quits. Any ideas before I say the heck with it and get a different carb?
Posted 08 July 2007 - 10:06 AM
As far as the metering orfice it all matches what the book shows is should look like but everything is brass not plastic?
Oh yea as far as changing underload or at different rpms idle to around 1500 is the worst but pulling a load or running down the road wide open it still smokes quite a bit. Its black smoke too not the blue like if it were burning oil. Been checking that too and have to dump oil often as you can smell gas in it after a while.
Posted 08 July 2007 - 10:29 AM
Posted 08 July 2007 - 10:59 AM
The first two years... was this the first two years since new or since you owned it? And when was the fuel pump put on?
The first 2 years it ran great then it started this running rich thing.
I brought up the fact about the fuel pump because sometime after puting on a new one is when this all seems to of started.
Lets assume that you have properly diagonsed that the fuel pump is the culperit. Can you easily take the pump out of the system and run it on gravity flow? On the few old tractors that I've worked on these all have run on gravity flow from the tank to the carb. If you can rubber hose around the pump as a test it would give you a data point to go with. If that proves good then you can can do what ever is necessary to keep the fuel pump from pushing fuel past the needle valve, which is what I suspect. Or you didn't fail to put a gasket under the needle seat before installing it or have developed a crack in the casting. Lets assume that you've not left the gasket out. Then it comes down to knowing what the fuel pressure is to the carb, what it is supposed to be.
I'm going to leap out here with a wild guess... you didn't get a diesel pump per chance. I think that they are quite a bit higher in pressure than a gas rig. I would guess that the gas rig would be in the 3-5 psi range and diesel in the 20-35 psi range.
I'm basing my opinions on years of hotrodding and some tractor repairs around the farm. I'm not familier with your rig but have been into a few of these carbs in the past.
no neat sig line
Posted 08 July 2007 - 12:35 PM
Make it run without the air cleaner pipe attached. When it runs as it should, then reattach it. This will take that potential air cleaner problem out of the loop. The guys are right, there have been a lot of wierd stuff found in air cleaners.
The diesel lift pumps are generally identical in pressure. All either has to do is get a full flow of fuel to the carb or diesel pump.
Keep us in the loop.