Stalling while driving

Hello, I'm Danny.

It sounds like you might be having an intermittent wiring issue like a short in the fuel pump circuit. I've attached a tutorial showing how to test wiring.

https://www.2carpros.com/articles/how-to-check-wiring

There are four wires in the fuel pump circuit. A black-ground, A dark green- black that goes to the power distribution box, A black-light blue that goes to the cruise control and battery temperature sensor, And a light blue-yellow that goes to the PCM- powertrain control module. I've attached the wiring diagram below and circled the wires in red. I would check to see if any of these wires are melted, shorted, rubbing, or in any other way causing this weird condition. Also be sure to check the ground. You might also want to test the fuel pump relay. Here is a tutorial showing how to test a relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

I've also attached a picture of the fuel pump relay which is located in the power distribution box under the hood. Get back to us if you have any further questions on this issue. Hope this helps and thanks for using 2CarPros.

thank you very much for the reply. Certainly i will check all that. The problem is (like i mentioned above) that when the car shuts off it doesn't start up again. there is no hum from the pump when i try to prime the pump (key on-engine off). But it will start immediately if i disconnect one of the quick connects at the fuel filter and connect up again. at that time i can hear the pump hum and it starts right up and runs for hours. It happened 3 times already. It shuts off, unclip the connect at the filter and starts up every time. Also, i forgot to mention before that i have a fuel leak from the top of the tank (possibly bad seal) when i fill up the tank completely. Gross evap leak code.

Hello again.

Having that leak is a big deal as well. The fuel system is supposed to be completely sealed. Having the system unpressurized could be causing this issue as well. After you check all this get back to us with what you find and we'll go from there. Hope this helps and thanks again for using 2CarPros.

Danny-

the vehicle ran for a year with the gross leak code on without a problem.
everything you mentioned is good advise but it does not explain why the vehicle starts only if i disconnect and connect back on one of the quick connect clips in the fuel filter.
It seams to me that you don't read properly what am i saying. Please reply.
Thank you.

Hello again.

Just a few questions while we are trying to figure all this out. When you release the coupler from the fuel filter what happens? Does excess pressure escape? Is there a vacuum and air is let in? Do you notice if any fuel comes out or is it empty-dry of fuel? Get back to us and we'll go from there. Thanks again for using 2CarPros.

Danny-

No pressure escapes, no vacuum as far as i can tell .and some fuel is coming out of the filter. than i connect the coupler and turn the key on, i can hear the pumps hum, crank the car and it starts right up and runs for hours. it happened 3 times already. then i shut the car off and i restart in 1 or 3 or 6 hours and starts right up and stays running for as long as i keep it running. it makes no difference how cold or hot is outside, it will start every time. Now you have to realize that i run the car in the driveway, i don't take it on the road because the 3 times it shut off it was when i was driving. i have no hesitation whatsoever when it runs in the driveway or when i was driving it. perfect idle. no back firing, just shutting off of the blue.
and every time it shuts off it wont start again (just crank) in 1 hour or next morning or 3 days later. It starts only when i do the voodoo thing with the filter. Also it will start when i use starting fluid and will run for 30-40 seconds. it does not make sense. And i know that you are doing your best to figure it out and help me and i really appreciate that.

The 99 is the version with the fuel pressure regulator in the filter if I recall. I think you have a bad fuel pump and disconnecting the line is releasing the small amount of pressure it is creating and lets the pump run again. The pump could be turning just enough to create flow that will let the engine run but not enough to keep it running reliably. That would explain the zero PSI reading and not hearing the pump as well. A way to check that would be to remove the fuel pressure line that comes from the pump to the fuel filter, That would be the one that goes over the fuel line connection on the filter on the side with two ports. The other one that plugs into the filter is the return line. With that line off, connect the pressure gauge to that line, then turn on the key. This should show you the dead head fuel pump pressure so don't let it run very long. Just long enough to get a pressure reading, which should be only a second if the pump is good. You should see a minimum of 50 PSI but it should be higher. The regulator is supposed to allow the pressure at the engine to run at 50 PSI but the pump should put out much more almost instantly. I suspect you will see either very low pressure or it will build very slowly if the pump is bad.
In that event a replacement pump should fix it.

that makes a lot of sense. the only question i have how i will connect the pressure gauge in the fuel pressure line? do i need a special adapter? because the pressure gauge has at its end the fitting that connects to the shrader valve at the fuel rail.

You will need to adapt one or go to one of the parts stores that loans tools and see if they have one of the master kits that has a bunch of adapters to fit it. That or get one of the hose end repair fittings that fit into the line like the end of the filter then you could use hose clamps and a short section of fuel line.

Hello again.

Were you able to test and get a fuel pressure reading? We're just curious as to getting an update. Thanks again for using 2CarPros and Happy Holidays.

Danny-

after numerous attempts to find an adapter for the gauge , i decided to drop the tank and i found that the metal jacket that covers the clip for the high pressure line was completely rusted and the clip was stuck almost half way in. Than using a pair of vise grips i was holding the clip to the pump inlay as in as possible. A friend of mine connected the gauge to the shrader valve and i turn the key on. Pressure jumped to 36-38 psi, i released the grip, pressure down to zero. So now according to your thinking i replaced the weak pump and after an extensive search i found only on e-bay a fuel line set that was a fit for the 1999 Jeep. Started right up ,pressure instantly at 60+ psi.
I'm extremely grateful for your expertise and your instructions, because you were the only ones that tackled the problem. Before i contacted you i did a search for answers on google and i ask a lot of so called "mechanics". Every answers i got were: crank sensor, cam sensor , for sure ECM, bad battery, alternator, plugs, wiring, relays, fuses etc., etc., and i knew that all of that was a bunch of nonsense. Then i remember that years ago i used to watch your TV program that i really enjoyed and i Googled searched you. The rest is history.
Thank you very very much again and i wish you happy holidays. I will keep in touch.

You're welcome!
Glad to hear you solved the problem. Thanks again for using 2CarPros and we hope you will use our site again in the future. Happy Holidays.

Danny-