bubba Posted July 31, 2009 Share Posted July 31, 2009 I just got a 1979 toyota stardust, it had been sitting for awhile, wasn't running right when i got it. When i get it out on the freeway it will run down the road at a nice 60 to 65 for about 5-7 miles. Then i start to lose speed, acts like i am running out of gas. This happened right after i got it up and running. At that time, i replaced the fuel filter. I put on an aftermarket one that is clear. ( i like to see what's going on lol) The first time it happened the filter was plugged up you could see it. I then put 3 bottles of b-12, a bottle of heat and some marvel mystery oil in the gas. Let it sit for a couple of days. Went out replaced the cartrage in the filter, ran it for about 2 hours....ran great....nothing in the filter...looked clean and was full of gas. I thought cool, i have it fixed. Drove it around town all day doing my erands....ran great no probs. Drove it to work.....np...drove it home on the freeway....went 65 all the way (about 12 miles)....seemed to have good power. Put new shocks on it yesterday...thought i would drive it to work again and check out the "new" ride feel. Got on the freeway....it was running great...about 5-7 miles in to the trip...it starts cutting out again....got out quick looked at the filter....looks clean and it's full of fuel. revved up the motor while sitting there with the hood open...filter stayed full but the motor started acting like it wasn't getting gas again. one more note.....if when it starts to cut out...i let off the gas and let it idle (which it does sorta)....wait for about 20 to 40 sec i can get it to run for about another 100 feet. I know this cause this is how i made it the last 3 miles into work this morning...lol Anyone have any ideas of what to look at next??? Quote Link to comment Share on other sites More sharing options...
shandamac Posted July 31, 2009 Share Posted July 31, 2009 Sadie had same issues. Was the carburator. Old bad gas is nasty stuff. Quote Link to comment Share on other sites More sharing options...
bubba Posted July 31, 2009 Author Share Posted July 31, 2009 Carb has been redone.... Quote Link to comment Share on other sites More sharing options...
Iowacamper Posted August 1, 2009 Share Posted August 1, 2009 Gas cap vent plugged?Or vapor locking fuel line,or maybe a weak fuel pump.Just ideas.When you find your problem I bet it will be a simple fix,god luck. Quote Link to comment Share on other sites More sharing options...
Bodybagger Posted August 1, 2009 Share Posted August 1, 2009 I hate to say this but there are many things that could be causing this. *Fuel Delivery Try running a long fuel pressure hose to a gauge in the cab. Install a tee AT THE CARB. Today's fuels will vapor-lock at delivery pressures less than 9psi at 100 degree carb temp. Also, just because the carb has been rebuilt and a new filter installed doesn't mean it can't been the carb. I have seen several times when a dirty fuel system is addressed and rebuilt carb has a fuel filter installed, but it SOMEHOW ends up dirty again. In your particular case, it sounds like the float valve is either sticking, or the seat's orifice is obstructed by foreign matter OR simply by a thick layer of oxidation (hence lack of fuel at only the highest flow rates), which can happen despite perfect filtration. Perhaps the filter, though not clogged, is dropping the delivery pressure enough to cause vaporization as it enters the float bowl. *Oxygenated (10% Ethanol) Fuels Note that float needle valves with the rubber tip can swell and bind in the presence of alcohols (a well documented problem associated with the addition of ethanol to motor fuels - alcohol destroys rubber). If you have 10% ethanol added to your gas locally, you should be sure the carb parts are either 100% metallic or made from alcohol-compatible polymers. *Ignition Weak ignition has a most profound effect with lean mixtures at high speeds, such as encountered on the highway. Make sure you have strong fire. Also, make sure the vacuum advance is operating correctly and the timing is within limits. *Sticking valves or exhaust restrictions Install a vacuum line from the intake manifold to the cab. Connect a vacuum gauge and look for vacuum to drop near zero when this high speed loss of power occurs. If it smoothly drops to zero, you may have an exhaust restriction (ie plugged converter). If it jumps around until it reaches zero and you lose power, your valves might be sticking OR in dire need of having the clearance reset. Summary: check fuel pressure at carb check carb float valve check ignition vacuum diagnosis There are a bunch of tests that could tell us more. Drivability problems are a challenge to troubleshoot. Quote Link to comment Share on other sites More sharing options...
bubba Posted December 26, 2009 Author Share Posted December 26, 2009 Sorry it has taken so long to reply....had some computer probs. I got it figured out. The gas tank was a mess, really dirty. The fuel filter was getting plugged up and so was the little filter built into the carb at the intake connection. Removed the tank, cleaned it and ran dual filters for the rest of the summer. Has worked great every since. Quote Link to comment Share on other sites More sharing options...
Tundrawolf Posted December 28, 2009 Share Posted December 28, 2009 Sorry it has taken so long to reply....had some computer probs. I got it figured out. The gas tank was a mess, really dirty. The fuel filter was getting plugged up and so was the little filter built into the carb at the intake connection. Removed the tank, cleaned it and ran dual filters for the rest of the summer. Has worked great every since. Something that works great for filthy, rusty tanks are a bunch of nuts and bolts. Put them in the tank and shake the tank for a while. Rinse it out with the garden hose and start over until the water comes out clean. It can take a while, but when it is clean, trust me, you won't worry about your filters after that. Quote Link to comment Share on other sites More sharing options...
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