Last post on Sep 14, 2007 at 4:23 PM
You are in the Speed Shop Tuning and Modification
What is this discussion about?
Chevrolet S-10, Performance Mods
#23 of 26 Re: BLACK OIL [zaken1]
Sep 13, 2007 (6:11 pm)
THERE IS A MECHANICAL PUMP ON THE TRUCK NOW. THIS WASN'T THE CASE A YEAR AGO. YOU ARE SO RIGHT ABOUT THE PUMP IN THE GAS TANK WHICH WAS REMOVED AFTER BLOWING A CARB.THE PUMP RUNS AROUND 4# PRESSURE. THANKS FOR ALL THE KNOWLEDGE COME ON DOWN TO LAKE OKEECHOBEE AND GO FISHING.
THANKS TO ALL
#24 of 26 Re: BLACK OIL [drcarp]
Sep 14, 2007 (10:36 am)
Sounds like we both have been on the same trail, but something still is going on to turn your oil black and suck all that fuel. If the mechanical fuel pump has a leak in the diaphragm, it can pump gasoline into the crankcase. This will make it look like the oil level is not going down, but the oil is gradually being replaced by gasoline. In that kind of situation, I've seen an engine blow the valve covers off when the gas in the oil exploded. If you unbolt the pump from the block, it may be possible to spot a leak; if you can see or smell any gas on the engine side of the mounting flange. Or, you can substitute a low pressure electric fuel pump for the mechanical one, and see if the problem goes away.
One other possibility is that someone left out the check ball, and/or the weight in the accelerator pump discharge nozzle. This would make the pump nozzle act as a siphon, and pour fuel into the engine when it was running. If you take off the air cleaner and look into the carb with the engine speed held steady at about 2500 RPM, there should be no fuel coming from the pump nozzle, unless you speed the engine up.
And, of course, it there is a sound insulating blanket on the underside of the hood, and it is too close to the air cleaner or it is loose; it can be pulled against the air cleaner by the force of the incoming air; which makes it act like a choke that is on all the time.
When I used to live in Kissimmee, I would have been happy to drive down there and go fishing, but since I moved back to California after the hurricanes began, it's now too long a drive.
#25 of 26 Re: BLACK OIL [drcarp]
Sep 14, 2007 (1:17 pm)
Along with the points I raised in the preceding post, there is one other test that's worth doing. With the engine off, take off the covers over the metering rod assemblies, and note the height of the top of the rods. Then start the engine, and see if the rods move to a lower position when the engine idles.
If the metering rod assemblies are always in the up position when the engine is running, then the carb will supply the richest possible mixture at all times; and this will grossly overfeed the engine with fuel.
If the rods did not move down, then they are either stuck, or the rod control pistons are not getting any vacuum. If you can press down on the top of the rods, and they move down easily against their spring, then they are not stuck. In that case, the vacuum passage to the piston well is blocked; either by gasket cement, or by an incorrect or improperly positioned carb mounting flange gasket.
#26 of 26 Re: BLACK OIL [zaken1]
by Mr_Shiftright HOST
Sep 14, 2007 (4:23 pm)
Whatever he does he'd better do it quickly. Having gasoline washing your cylinder walls and bearings is NOT GOOD! This could end up being a relatively low mileage engine.