My '88 Chevy G20 Van (5.0 liter) was running fine when I stopped using it over 4 years ago. It did suffer from worn valve stem guides, so it would smoke for a few seconds upon starting, and occasionally the O2 sensor would fritz out causing it to run rough until it regained its composure. That was its condition when I parked it in my yard over 4 years ago.
When I first tried to start it I got no combustion, but the spark was good. So I changed the fuel filter and added about 2 gallons of gasoline to the maybe 1 gallon that was left from before. To my amazement, and without too much difficulty I got lots of combustion with the throttle fully opened … and voila, a miracle … it started, and within a minute or two was absolutely humming like I had just driven it yesterday. I put a brick on the gas pedal and let it run for about 45 minutes at about 1800 rpm. The next day when I went to start it, I couldn’t get it started, and haven’t been able to for several months now, though I try several times a week. I tried pulling the new fuel filter to see if maybe it had clogged again, but there was no resistance to my blow test, so the filter was ok and after confirming the fuel pump operation, I re-installed the fuel filter.
When I try to start the engine, I seem to get varying amounts of combustion. I seem to get the most combustion when I leave it untouched for many days. It seems the longer I leave it, the better my chances of getting more combustion. I seem to get more combustion with the throttle fully open … and none if fully closed. I have pulled the engine cover and the air filter and sprayed into the throttle body gasoline, carb cleaner, and WD40.
I have noticed that with the ignition turned on, there is the sound of some kind of small motor (perhaps?) maybe to pump fuel into the throttle body ?? But the operation of whatever is causing that soft motor sound, doesn’t seem to always result in the same amount of fuel getting into the throttle. Sometimes, after cranking, when I turn the key back (though still “on”) I can actually hear fuel swishing into the throttle body. That swishing sound overpowers the “small motor” sound. Other times however, I don’t hear fuel swishing, and can only hear the small hum of the little motor.
My (probably poor) automotive instincts tell me that when I am getting no combustion, it is because it’s not getting fuel. However the fact that relatively good combustion eventually deteriorates and then disappears altogether argues that the engine has flooded. Maybe better luck after waiting many days also argues that flooding is the problem ?? However the best combustion seems to happen when I can actually see fuel fumes and fuel spray hovering above the throttle. And other times when I can’t see hear or smell any fuel … I get nothing.
I’m at a loss as to what to do. All suggestions eagerly welcomed. If somebody could explain to me what what is that little motor sound I hear when the key is turned to “on” and how it is supposed to affect fuel delivery to the throttle, that would be helpful information too. Thanks so much.