wtnxj1991

How are you guys checking fuel pressure on 99-04 gc’s that have no shraeder valve?

I have one with the good old “starts but runs like garbage” problem they are plagued with and all the normal problems check out so I’m on to the fuel system.

dave1123

A fuel pressure test kit has a fitting that goes on the fuel supply hose and snaps onto the fuel rail. It has a shraeder in it. You must have a 4.7 because every 4.0 I've seen has a shraeder valve on the rail.

wtnxj1991

quite the opposite.

the consensus on every thread I have found is that the 2004 4.0 grand Cherokee did not come with a shraeder valve on the fuel rail and this one does not have it either (I’m working on one for a friend)

trust me I’ve searched and was amazed that Chrysler did that.

Although I guess I should not be, anyone that makes trash this many years in a row definitely would take the shraeder valve off lol.

love the Jeep 4.0 but hate the electronics with a passion.but anyway!

so the reason I posted the question is to see what everyone has used to work around this.

dave1123

I bought a kit with a gauge, hose, and 3 T fittings of different sizes that fit fuel line quick disconnects and in effect adds a shreader valve for the gauge. I bought it on Amazon. It's a cheap set and it doesn't have a pressure relief port, but it works perfectly for what you need it for.

On the WJ 4.0, all I know for sure is my 2000 has one, so I assumed they all had one. Excuse my ignorance. My 2000 XJ also has one. I really didn't need the kit, but the Harbor Freight one I bought leaked like a sieve and the gauge filled up with fuel. Returned the same day.

The reason I've spent so much to maintain my 2000 WJ is because the electronics are simple enough that I can still work on it. That being said, I won't buy a newer one because all they did from then on was make them more complex to the point where they became unmanageable for a simple guy like me. For instance, who needs a completely electronically controlled 4wd system? Especially for people who wouldn't even think about taking them off-road.

wtnxj1991

agreed on the harbor freight kit I have what’s left of one also, it’s junk.

agreed on the electric 4wd as well, especially knowing that electronics are not jeeps strong suit in any fashion.

in fact that is what most problems in my experience end up being lol. Pcm or wiring.

this one is no different but I’m running through the motions anyway but I too assumed it would have a shraeder valve but according to the interweb google search it never had one.

crazy

in other words “bring it to the dealer to check fuel pressure” is what they were trying to tell us. Lol

dave1123

According to wjjeeps.com in 2002 they made the oil pressure sensor just a slide switch the sends a 40 psi signal to the PCM so the gauge reads 40 psi anytime there is oil pressure of any kind. I found this out when I went to NAPA for a new sensor for my WJ. All it read was 40. I took it back and bought one from the dealer that worked properly. SO, if you need one, buy one for a 99-01. It actually reads pressure! This is backed up by the fact that my WJ always showed 50 on cold startup, but with the NAPA one, it only read 40.

I spoke to my dealer parts manager who has been a jeep fanatic ever since owning a CJ years ago. I asked him why they didn't just install an idiot light instead. He seems to think people buy Chrysler products because they've always had a full set of gauges and using idiot lights might detract from sales. It's a fairly logical assessment.

One other thing about dealers. Once upon a time, I needed a serpentine belt pulley urgently because I was about to go out of town that night and needed the jeep, so I took it to the dealer to get it done. I got charged a $100 electrical diagnostic fee! I asked the service manager why this was charged because all I needed was that pulley. He said they do that to every vehicle that comes in as a safety check. WTF? Seems like a scam to me! I wonder if they ever did it because it didn't take very long to fix my jeep. They didn't even replace the belt!

Ralph77

When I did my 4 hole injector upgrade in my '00 XJ I poked around for a new fuel rail.
Reason being that an '00 has that fuel dampner disc on it. Sometimes referred to has the flame thrower.
It is a non serviceable part according to Jeep but guys have refreshed it with a new O-Ring.
Which apparently can deteriorates over time and leaks fuel. Hence the flame thrower part.
Anyway did not want to do the injector upgrade and have the dampner start leaking later on.
I also was not comfortable with doing the O-Ring replacement that guys did.
Figure with my luck I would screw it up and it would leak like all hell.
Found a really good deal on a Mopar one and purchased it. After getting it and taking a look at it noticed that there was no schrader valve on it.
I was torn between reusing the old one or putting on the new one. Ended up going with the new one.
If the fuel rail did not have that dampner on it would not have even wasted my time.
I always figure something like this is what they would use to check fuel pressure in a line without a schrader valve.

https://www.toolsource.com/misc-c-31...-p-101306.html

But also that a bigger/better fuel pressure testing kit would have all the adapters and whatnot to duplicate something like that.

dave1123

Mine are just the brass T with the male and female snap-ons screwed to each end of it and a schrader valve in the center. It's got 1/4", 5/16", and 3/8" snap-on sizes in the kit.

I'm not sure about my XJ, but my WJ fuel rail has a schrader valve and no dampner on it, but it's actually a 99 because it was made in July of 99 and sold as a 2000. You'll find all that dampner does is steady the gauge needle when you test pressure, so I guess it takes the injector pulses out of the fuel delivery. Not having a dampner doesn't seem to bother my 4.0 at all.

I'm sorry. I went out to the garage and looked at my kit. The T fittings have the schrader valve in one end, the male fitting in the center section, and the female end on a 3" piece of hose on the other end. The female ends are soft plastic that squeeze easily to release them. Also, there are no cores in the schrader fittings, just an open hole.

My kit is BETOOLL HW9116 but I just looked on Amazon and it's not available anymore. Probably because it's only a 100 lb gauge.

Ralph77

Thinking your XJ should have a shrader valve and the dampner. It is an '00 right?
Your WJ made in 7/99. Does it have a 2 piece exhaust manifold, dual front cat, and 0331 head?
See I always wondered if that dampner was really necessary on my '00 XJ.

dave1123

As I said, they don't really do much but smooth out the fuel pulses in the rail. They cause about a 2 to 3 lb drop each time an injector opens. My WJ could care less!