egp320i

<center><img src="http://pictureposter.audiworld.com/30890/fuelregulator.jpg"></center><p>this is the fuel regulator thats on my 8V. The small metal lead on the left is a air duct/inlet that goes into the airbox. question is, does anybody know how this functions inside and could 17 years of dirt making its way into this cause it to not seal or work properly? It only took 3 cranks today to get it started after sitting for a week which is getting better but still not as it was.
would hosing carb cleaner inside the air inlet be a good choice? this pup goes for $273 new so to damage anything internal is not my intention. It has a gas inlet and outlet and its under pressure, so how or what the air inlet has to do with its function could somebody explain to me?

MikTip

Bosch fuel pressure regulator

here-<ul><li><a href="http://www.google.com">http://www.google.com</a</li></ul>

dragon-ryder

And in that case, there is probably an internal vacuum solenoid that adjusts the fuel rate or pressure according to how much vacuum is applied

YucatanAudi

Obviously, a completely dead pump will keep the engine from starting. But how will a pump that's on its last legs affect performance? Any fuel injected engine that's difficult to start, idles rough, hesitates, lacks power under load or runs lean probably isn't getting enough fuel, and a weak pump may be to blame.

Install a fuel pressure gauge. Some systems provide a convenient pressure tap; it may be necessary to tee into the supply line on others. Start the engine to determine whether the regulated and unregulated fuel pressures are up to specs. Remove the vacuum hose leading to the pressure regulator. This unregulated fuel pressure indicates how much pressure the pump will deliver while the engine is under full-load, low-manifold-vacuum conditions.

Reinstall the pressure regulator vacuum hose. The fuel pressure should return to the manufacturer's idle specification. The regulator adjusts fuel pressure in response to changes in intake manifold vacuum and engine load. If the regulated fuel pressure is too high, the likely causes are a damaged pressure regulator or an obstructed return line. Low pressure can be caused by a clogged fuel filter or in-tank filter sock, a defective pressure regulator, a restricted fuel supply line or a weak pump. Eliminate all other possible causes of low pressure before installing a new fuel pump.

A deadhead fuel pressure test is similar to the stress test a cardiologist may one day ask you to take. It determines the fuel pump's reserve capacity by briefly asking it to deliver as much pressure as it can. To perform a deadhead fuel pressure test, pinch off the fuel return line while observing the rise in fuel pressure. This test should be brief.

A healthy pump may manage to jump from 60 to 90 psi. But if the pressure rise is minimal, either the fuel pump is weak or something is keeping it from delivering its all.

To prevent tuel percolation and aid hot- and cold-engine starting, fuel injection systems must maintain residual, or "rest," pressure when the engine is off. All systems lose residual pressure over time. Its just a question of how fast and how much before its a problem.

Since the entire supply side of the fuel system is normally pressurized, a loss of residual pressure could be caused by a leaking injector, pressure regulator or fuel pump check valve. Determining which involves isolating various parts of the fuel system, saving you the trouble of visually inspecting each component.

A ruptured regulator diaphragm will pass fuel to the vacuum hose and into the intake manifold. To isolate the regulator, pressurize the fuel system, then pinch off the fuel return line with pliers or clamps designed for this purpose. If the residual pressure continues to drop, the cause lies elsewhere. Repeat the same test to isolate the injector rail.

The fuel pumps internal check valve may be allowing residual pressure to leak into the fuel tank. To test, isolate the pump close to the fuel injector rail, then pressurize the system. No fuel pressure should reach the injectors or the pressure regulator during this test. If the fuel line pressure rapidly drops to zero, the residual fuel pressure is leaking past the fuel pump check valve, or through a fuel line fitting.

An often overlooked, final test is pump volume. The simplest volume test involves opening the fuel supply line at the injector rail, then measuring fuel volume during a timed, power-on fuel purrlp test. This involves pumping gasoline into an open container at a high rate, which poses obvious safety risks. Additionally, this test does not show what the pump will do when its under load. Dedicated equipment is available to safely and conveniently test fuel pressure and volume.

A final word about volume: Some systems use more than one fuel pump. On early Bosch fuel injection systems, one pump is responsible for volume, while another handles pressure. The low-pressure, high-volume pump is located in the tank, and a high-pressure pump is attached to the vehicle frame. The system may work with a worn or inoperative in-tank pump, although not well. This also puts a strain on the external pressure pump, so always check both before replacing either. M

k2bill

This is a CIS car right? If so, it is not a vacuum line. The hose is a "vent" in case the diaphragm ruptures. Furel will then be dumped into the airbox. The CIS cars do not have a vacuum controlled FPR it is purely mechanical.

egp320i

well, the fuel pump is fairly new and so is the check valve so I can disregard that as a cause. the next thing would be the regulator which as I posted about possible dirt causing some troubles. if the line is not a vacuum line but more of a bleed off in case of rupture then it doesnt matter if it has dirt in it or not. The injectors can also be a cause and they have never been checked for flow that I know of. They have about 150k on them which is alot but not enough without a turbo to really be shot. The other thing could be the accumultor that is next to the fuel pump. that item is not even listed for sale through worldpac. it seems to have the same design with a diaphram to keep system pressure up.
the car has power, starts so-so but when running is fairly smooth for its age and flooring it, it doesnt bog or hesitate to suggest the pump is not putting out to spec or the injectors have a weak or blocked outlet. I could just give up and say everything is worn out for its age and this is about as good as its really going to get without replacing everything with brand new parts.

as for miktip, I did a google search already and came up with 118k hits.....I do not have a lifetime to go through all of those to get a simple answer. I am sure one of those hits will be what I am looking for but I certainly do not have the time.