Fred1diver

O.K. so I changed the calipers and the oil today but now the only way to start her up again is to have the gas pedal to the floor, and when I release it, she stalls...what did I miss
FRED

miglia-spyder

Check your vaccum hoses.... Maybe the brake booster line!

Fred1diver

fixed it last night, it was the fuel filter after all...

N20jeep

thats actually a pretty rare fix...lol...

most of the time thats just a BS sales pitch some shops use.

good work

mycherokee

Agreed. But now there is proof that sometimes it really can cause a problem. It never has to me though lol

kbad

good catch! did you happen to check out inside the gas tank? or at least have it flushed out - really well! jeeps are notorious for eroding tanks from the inside = bad QC! the crap from the tank gets into your fuel line and the first thing it takes out is the pump! if the symptoms arise again, down the road, have the inside of the tank inspected thoroughly and flushed - or get a new one ~$100.

cherokeesteve

That is exactly what I did with my cherokee. I was having problems with the gas filter clogging all the time. So I ordered a new tank sender and fuel pump and put them in, no problem from that area anymore.
Got the tank on e-bay for $35, new with warranty and a new sender and pump for $90 at pep boys, works like a charm, just wish everything else on this jeep worked that good!!!
Oh and blow out the lines from the fuel rail up front to the tank in the back to make sure nothing is in the lines also.

kbad

basically, gotta remove it and take a look see inside....here's what i found and asked my mechanic to check it out....it was bad inside the tank he said...

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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.

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cherokeesteve

I beg to differ with you on that no return line to the tank! If it is a pressurized system like fuel injection system than it has to have a return line to the tank. What is the pressure regulator for in a fuel injection system, it is to regulate pressure and return fuel back to the tank that the fuel injectors or injector does not use.
My throttle body injection system has a return line at the throttle body meaning 2 lines at the throttle body, one pressure to the throttle body and one return line to the tank via the pressure regulator.
So I dont know what you mean by a no return line fuel system, there is no such thing in a pressurized fuel injection system!

fishtaconc

97+ XJs have the regulator/return mounted in the tank, there is no return from the fuel rail to the tank on these engines is what this is saying

cherokeesteve

I dont care what the book says, there has to be some kind of return line for the fuel pressure regulator to return un used fuel.
My question to you have you ever worked on fuel injection systems or are you going by what the book says?
There is a build in pressure relese valve in the fuel pump, but there is still a return line from the fuel rail or throttle body and vacuum or electronic controled fuel pressure regulator!
I have been certified ASE fuel injection tech, ASE tune up certified, both electronic and the old point ignition system, ASE engine repair tech, ASE brake system, both hydraulic and air brake system and california smog tech, and I said that just to let you know I am not talking out of my you know what!!!!

offroadnut36

Direct injection doesn't have a return line does it?

kbad

cherokeesteve....you obviously know best, we're all just reading the bulletin and i don't think anyone is arguing that fuel is not returned, it has to be, somehow.....perhaps the bulletin isn't focused on the system as much as the components going bad.....

the fuel is returned, but not via a separate line, "...it is returned through the fuel pump module and back into the tank through the filter and pressure regulator...."

...here is an online jeep manual hosted at Morris 4x4... http://www.jeep4x4center.com/knowled...ex.htm#service

fishtaconc

Any electric fuel pump has to have some sort of return to keep the pump cool by constantly circulating fluid through it via the regulator, as I stated earlier the newer XJs have the regulator mounted on the fuel pump module instead of the fuel rail as is the case in the older XJs. Cherokeesteve to answer your question yes I have worked on fuel injection before, currently Im working on a 99 XJ and I had a 91 previously as well as many other EFI vehicles

A_15

My 96 doesn't have a return line... and I'm looking at the pump/float assembly right now.

Matter of fact my 2000 Mustang doesn't have a return line either.

Steve, you training must be outdated.