Vakis

Ok I did a little searching about this and still was unsure so I figured I would ask. And my apologies if this was already addressed and I missed it.
I have a 98 4.0L with the famous fuel pressure drop off. After sitting you have to prime the lines with anywhere from 2-3 key cycles, obviously a sticking check valve. Common amongst Cherokees and other similar vehicles. I was thinking I had to replace the pump assembly like I used to do often back in the day when I was a Ford line tech.
So, I read on here that the cheap alternative was to install an inline 1 way check valve for about $15 and a few minutes of labor. Sounded great to me until I read that it did not work on the newer cherokees after 98-99. IS this true? Why not, what is the difference and will this fix work on my 98? Just wanted to check before I put the check valve in. If any of you guys could clarify this for me I would greatly appreciate it.
Its quite possible I missed it when I was reading the thread but I didnt understand why it would not work on mine.

SeriousOffroad

The regulator/check valve is a replaceable item. You do not need to replace the entire pump assembly.

tjwalker

The check valve fix will not work on your 98, where the fuel system has no return line.

Some have had success with using the check valve on earlier (95 and earlier where you have a fuel pressure regulator under the hood and a return line), but don't try it on your 98.

As mentioned, you can replace the regulator if you want, but as long as you have the gas tank down, I usually replace the entire fuel pump assembly as when one component on that assembly is failing, the filter or pump may not be far behind.

Do NOT use an Airtex pump! IMHO, their reliability issues are off the charts. I specifically seek out BOSCH fuel pump products; best in the business.

SeriousOffroad

Thats incorrect. The checkvalve keeps the fuel in the line from draining back into the tank.

tjwalker

Not disagreeing with that, but we're not talking about the check valve on the regulator, he is talking about an external check valve installed in the fuel line, so as not to have to drop the tank to repair the check valve on the regulator on the fuel pump assembly.

It is really NOT a good idea to use an external check valve on a 98, which I believe is what he is proposing doing.

Read this thread from NAXJA to find out why.

http://208.101.10.250/~naxjaor1/foru....php?t=1012432

SeriousOffroad

http://www.autopartsnetwork.com/cata...:Cherokee_part name:Fuel+Injection+Pressure+Regulator_brand:OES+G enuine_

Vakis

Thanks guys for the info.
Thank you TJWalker for the link, that was what I needed. Putting a one way check valve will not work on a 97+ because of the returnless style onle line fuel system. It will in fact cause more damage leading to blown regulator diaphrams and the need to replace the entire fuel rail...
So it looks like I will continue to cycle the key a few times before starting to build line pressure until I get the time, money and motivation to drop the tank in my driveway. At which time I will replace the entire pump assembly because like tjwalker said, its likely not far behind(the pump) and its simply not worth it labor wise to do it all over again.
I also agree Bosch is the way to go, Thanks for the heads up on that too.
I sure do miss having access to a lift, trans jack and shop air...that would make this a quick in and out as opposed to an afternoon on my back in my driveway...oh that sounds bad in more ways than one.

tjwalker

Glad I could help. Now you have a plan.

Oftentimes the check valve fails way before the pump and regulator fail, and I know guys that have performed the "poor mans prime" with key-on, key-off for a very long time before they actually had problems with fuel delivery because of the pump/regulator.

96XJ4me

So I have a 96 XJ with about 200k on it and I'm having the same problem (having to cycle the key a few times before cranking over the engine). A few months ago I replaced the fuel filter in hopes it was that so I didn't have to get into the tank, but I ended up replacing the fuel pump and pressure regulator when I dropped the tank. I put in a bosch pump, but the issue started again and I have to prime the line before cranking over the engine every time I start the car. I read that in my '96 jeep there's actually a check valve in the pump, but I'm not sure. I'd rather not have to get back into the fuel tank, but I'm worried I may be left stranded someday. I checked the fuel rail, barely a drip of gas flows out after I leave it overnight but when I prime it the pressure increases drastically. I'm not going to go with an external check valve after reading other posts since my XJ doesn't have a separate return line, but I am wondering what may be the issue. I just replaced the pump, regulator, and filter!

freegdr

Where did you find a pump for a 96 anyway ?

96XJ4me

I should've mentioned I also replaced the MAP sensor.

I ordered the parts online...see the links below
fuel pump:

regulator:

CCKen

I put an access port in my cargo bay so I can change the fuel pump module or regulator without dropping the tank. '99 XJ.

Eat your hearts out.

Don't ask how to do it. If I told you, I'd have to kill ya.

Nanner Nanner Nanner





Cover shown.

freegdr

If everthings new sounds like leaking injector causing over night pressue loss. When it starts after sitting does it run ruff at first ?

DFlintstone

^That's what my 90 did.^ Slow start and stumble a second, till the new injectors.

tjwalker

[QUOTE=CCKen;2830855]I put an access port in my cargo bay so I can change the fuel pump module or regulator without dropping the tank. '99 XJ.

Eat your hearts out.

Don't ask how to do it. If I told you, I'd have to kill ya.

Nanner Nanner Nanner
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Isn't that mod mandatory if you choose to use Airtex fuel pumps?

Great mod by the way! I would expect nothing less from you Ken!

I just spent the day making "mods" on my Snapper mower. Not quite as exciting as XJ mods, but hey....the grass is starting to grow!