Quote:
Originally Posted by ChevyTech
Sometimes a photo helps save a lot of time. I have noticed people had plugged the EGR vent port by looking at photos they posted. That is something people don't find even if I ask them about the EGR vent port.
|
Please see 5 attached photos.
Quote:
Originally Posted by ChevyTech
If the IAC does not work it can cause and engine to load up, or flood, when it is started. You should not have to hold the gas pedal down to start a fuel injected engine. If you have to on a TBI engine it is a good indication there is a IAC problem.
|
Before I rebuilt the TBI, I had to crank it longer than normal when cold, and the throttle was sluggish from idle. Sure this was due to it running lean (one injector was not spraying at idle).
After rebuilting the TBI, it would start right up and had great throttle response at all engine RPMs. But the first time I drove it, it died less than a mile down the road. It did this a couple more times. No smell of gas though!
I wanted to drop the tank, inspect/flush the tank and the fuel lines and replace the fuel filter, but when I disconnected the fuel lines, the gas that ran out was clean. So I decided to just replace the fuel filter. Note that in the photos, there is a short rubber line with two clamps on each end between the tank and the fuel filter. It was like that when I got the truck. I checked all of the rubber hoses, and all are in excellent condition.
I disconnected that short rubber line first and plugged it off and let the gas run out of the filter end of the line (only a constant dribble, not a stream). When I loosened the SECOND fuel line fitting to TBI body (the one on the LEFT side), there was a lot of pressure, and gas kept leaking out onto the back of the intake manifold, and down onto the ground. I used rags to soak up the gas, but it kept on coming, so I tightened the fitting again to stop the flow.
I'm starting to wonder if the gas that leaked out of the fitting could have worked its way into the crankcase? The only thing on that end of the intake manifold that I think could have let the gas in is the DISTRIBUTOR, which of course leads to the crankcase. Could this be how the gas got into the crankcase?
Before the gas leaked out at the TBI body/fitting, the engine was acting like it was flooded (would stall, then would not start until I let it sit for a few hours), BUT, there was no smell of gas, and the injectors were not visible SQUIRTING gas. So, maybe it was not flooding, but something else at that time.
Quote:
Originally Posted by ChevyTech
My biggest worry about people working on the TBI unit is that the aluminum is very thin in the area of the bottom of the injectors and can crack if injectors are forced into the housing without putting lubricant on the o-rings. Also the o-rings can get damaged when the injector are installed. This is why I ask people to turn on the key so the fuel pump runs and watch the injectors for dripping fuel.
Injector failure is not all that common. There are rarely the cause if the TBI sprays to much fuel.
|
The injectors did not drip fuel before OR after I rebuilt the TBI. However, before rebuilding the TBI, I took the injectors out, inspected them for dirt and tested them using a D-cell battery, and cleaned the TBI with carb cleaner (left the body mounted to the intake). When I went to put the injectors back in, I found that the two o-rings for the left injector had swollen up in circumference (but not diameter) and would no longer fit, so I bought two new o-rings that were CLOSE to the same size, but that injector dribbled gas (just ran engine long enough to note the dribble), so I bought a rebuild kit and started over. Since rebuilding the TBI properly, there have been NO drips.
Quote:
Originally Posted by ChevyTech
On the TBI trucks there is no fuel pump on the engine to rupture and leak fuel into the oil. There are not fuel lines or a regulator under the plenum that could leak without being seen. Just look at the TBI for fuel leaks.
|
I assume the short rubber line before the fuel filter is a modification. My dad had this truck serviced its whole life (first 20 years, anyway). Last few years, it sat except when I visited him and drove it. Since the fuel pump is low pressure (for FI), and there have been zero drips/issues with the rubber hose, I assume this is not a problem.
Quote:
Originally Posted by ChevyTech
What you have said is not real clear to me.
If the fuel return line, FROM THE TBI TO THE FUEL TANK, gets plugged, the fuel pressure will go to high, unless there is another problem, like a weak pump or split hose in the fuel tank. This problem does happen, but is not common.
Removing the fuel filters that GM put under the vehicle is a messy job. Often fuel will keep running out until the new filter is installed and tightened. Keep trouble lights away from the vehicle for safety reasons.
|
Do you think I should check the return line out? Which side is it on on the TBI, right or left. I thought it was LEFT (read that somewhere), but now I'm not sure. I have a canopy on the bed and no easy way to prop the bed up to get to the top of the gas tank. Have read that it's difficult to drop the tank due to the short fittings on top of it, and that unbolting and raising the bed is the better way to get to the fittings on the top of the tank. But my truck has a canopy that would make lifting the bed very difficult (no way to rig a hoist).