...I am a little nervous to put my foot down because last time i did that the muffler blew up. If you could tell me what putting your foot down all the way will be testing I would really appreciate it.
OK,
The following long "novel" relates to the primary fuel circuit in the carburetor being blocked.
About a year ago, my engine was doing the
exact same thing as yours.
Below are the symptoms I had, and the discovered cause of the problem with my FJ60 USA.\
But of course, it is quite likely that the cause of your problem is not related to the one I experienced, but it is worth considering.
Sorry that my explanation ended up being (way the h*ll) too long for other Mud viewers. But in consolation, this information at least can be helpful for others via Search, even if it is found not to be relevant to your engine woes.
My Symptoms:
- The engine was not running properly. No power. No acceleration. At it's worst, I could barely drive it.
- The engine idled perfectly fine.
- The engine did not have any known vacuum leaks and was properly tuned. Spark plugs were fine. Ignition was fine. Valves were adjusted. Air filter clean. New fuel filter.
- The engine felt like it was running out of gas and would sputter and balk when I put my foot on the pedal. No power.
- It was running hot when I could sort of drive it.
- The problem "just happened one day". Car was running fine the day before, the next day, all hell broke loose.
- The problem was much worse when driving up a hill. Sometimes I could not drive up a hill. On flats the problem would sometimes go away for a while, then come back.
- A few times, a very loud (gun shot) exhaust backfire happened.
- If I quickly pressed the accelerator all the way to the floor, the engine would accelerate sort of OK but not normally.
>>>>>>>>>>>>>>
What Was The Problem?
The accelerator pump plunger boot had dissolved only 4 years after it had been replaced and a very small piece of it had fallen down into the accelerator pump chamber. The top of the boot was pretty much gone.
That very small piece of rubber over time then migrated into the float bowl and eventually got sucked up to the 1st main jet in the carb float bowl after a steep hill climb, causing fuel starvation.
Driving up hills made the problem worse because the tilted carburetor allowed the debris to seal off the 1st main jet more easily with the aid of gravity.
Once that little piece of crap was removed with tweezers, after taking off the top of the carb, the engine ran normally. I also replaced the accelerator pump plunger and it's boot.
>>>>>>>>>>>>>>
When the Primary Fuel Circuit is Plugged:
The car will idle fine because it is running off the slow jet, but once the accelerator starts being pressed down and opens up the throttle valve, all the engine sees is a big vacuum leak minus fuel because it can't suck any fuel out through the primary fuel circuit. The engine may even stall. Once you let your foot off the gas, the engine returns to normal idle and idles fine because only the slow jet is used at idle and the throttle plates are essentially closed.
When the primary circuit is just sort of plugged, engine power is diminished, but it still runs, though the engine will run hot because it will be running too lean.
If the accelerator pedal is suddenly (not slowly) floored, the secondary fuel circuit comes into action and now the engine at least has some fuel to burn, although not quite enough since it is still missing the additional fuel required of the primary. The engine will accelerate floored but will eventually run hot because it will be running too lean. Once the accelerator pedal is backed off a bit, the secondary shuts off, with the primary fuel circuit left to take up the slack. But with no fuel available, you get no power.
If a blockage to the 1st main jet in the float bowl is intermittent, fuel can suddenly spurt through the jet but not get burned fully in the cylinders. An after-fire (backfire) in the exhaust pipe will result.
When the choke is pulled to start the car, the throttle plate opens slightly to allow more fuel to be sucked in through the primary fuel circuit. Also the choke valve cuts off most of the air going to the carb…but the vacuum actuated choke breaker (if the carb has one) automatically opens up the choke valve a few degrees within a few seconds after starting the car. When this happens, the engine with a blocked primary won't be getting the fuel it needs, will experience a big vacuum leak, then stumble or stall at start up.
>>>>>>>>
Outback Limp Home Mode: On The Road.
If the primary fuel circuit is just "intermittently plugged" by a piece if crud that is drifting around inside the float bowl, sometimes the offending debris can be sucked through the system or diverted away from the jet by doing a hand slam on top of the carburetor while the engine is revving high.
To do the One Hand Carb Slam, the air cleaner is removed, the carb stud is removed, the engine is revved high (like 3200 RPM), then a rubber gloved hand is quickly slammed on top of the carb while the accelerator rod is then opened fully to create a huge vacuum pulse to try to suck/divert the crap out of there. Just before the engine dies, the accelerator rod is released, your hand is removed to keep the engine from dying, and the process is done several (maybe 10 or more) times again.
That technique got my car going again so I could drive it several hundred miles miles farther… until I could get the carburetor off and clean it out.
There are other methods, which require unbolting things, and I am sure others can offer tips.
But remember, your engine problem may not be related to this at all.
Though it does sound like the carburetor is suspect.
Fred
