might as well drop the tank....empty it and take a look inside! jeep tanks are notorious for erosion from the inside which will cause havoc on your fuel system....like, damage to pump, regulator, filter, injectors, etc....if you see sludge and crap, either get the tank boiled or get a new one to be sure....it's not worth not doing the tank check, too many other expensive problems are caused by it...
......this may not apply to yours, however, fyi....basically, gotta remove tank and take a look see inside....below is what i found and asked my mechanic to check it out....it was bad inside the tank he said...so, had new tank installed as well....NO MORE STALLAGE, CHOKAGE, ETC....
Jeep tech service bulletin 14-06-97 - Fuel Pump & Fuel Tank NEW DESIGN
Jeep tech service bulletin 14-06-97, which indicates that a new fuel pump module design has been released for Wranglers, Cherokees and Grand Cherokees that delivers "improved performance." The new pump module should be used whenever fuel pump failures are encountered.
Fuel pump failures have not been an uncommon occurrence on these vehicles, and part of the blame may be traced to weaknesses in the original design (hence the improved pump). This is a return-less fuel system, which means the fuel makes a one-way trip from the tank to the injectors. There is no fuel return line, as found on conventional fuel systems. The pump, which sits inside a module that also contains the level sensor, contains a small armature with a very weak set of commutator bars. The brushes come in from the sides and the brush-to-commutator speed is very high.
When these pumps fail, they can spread debris throughout the inside of the fuel tank. If the contamination is not removed before a new pump is installed, the new pump will almost certainly self-destruct. It's just a question of when. Some of the pump debris may also find its way to the fuel injector screens. Once there, it has no place to go, since it's a return-less fuel system. Pack enough debris into the screens and the vehicle may develop other symptoms, like stalling or hesitation, regardless of whether or not the fuel pump is any good.
The Jeep bulletin further states:
In rare cases where multiple fuel pump failures have occurred on the same vehicle, a buildup of residue may have accumulated on the inside of the fuel tank. The presence of this residue is not easily identifiable. The residue can pass through the in-tank filter and contaminate the pump rotor. If multiple failures have occurred with no obvious indication of the cause, consideration should be made to replacing the fuel tank to avoid future problems.
The wording of this recommendation is just vague enough to make a lawyer smile, because it doesn't actually identify the source or composition of the residue. Is it failed pump debris, renegade bacterial microbes, space goo or all three? It could be failed pump debris, but it could also be caused by the inside of the fuel tank dissolving. The gas and dissolved plastic mixture is fine enough to get past the fuel pump strainer. After that, the new pump may keep working, for a while. But once it's shut off, the plastic residue attacks the pump rotor and gums up the works. So even if you clean the inside of the tank thoroughly before installing the new pump, the tank lining deterioration may continue as soon as it's refilled with fuel. There's no indication of how widespread this problem may be. The lining on the new fuel tank has apparently been changed to address the deterioration problem.
So what should you do to make sure the sixth fuel pump your customer receives is also his last? Begin by making sure the new pump is the updated design cited in the service bulletin. When the old pump is removed, inspect the inside of the fuel tank thoroughly. Remove any pump (or other) debris you find. To make sure it's squeaky clean, consider having the tank boiled out. The fuel rail and lines should also be cleaned and the injectors may need to be cleaned or replaced. You might want to replace the fuel tank with the updated design.
Last edited by kbad; 06-18-2010 at 09:09 AM.