Fuel pump replacement options?

[H8PVMT]

I am suspecting my fuel pump is going to kick the bucket on me. Now looking at the replacement prices I was thinking is it possible to install a different type of one outside of the tank as long as the output psi was correct? And if so what would I have to do to bypass the pump that is in the tank now?:confused:

This would just be alot cheaper to order a high performance one from summit than to get the origional replacement. :wink:

[RangerRick]

If you had a sender unit with pickup from an older Wrangler that had a mechanical fuel pump, you could use one of the GM Hi-Pressure pumps outboard and mount it on your frame rail. Make sure it's high and up outa the way of rocks or well... you'll know what will happen. This may only work if the sender from an early YJ will fit in your tank. Otherwise, you would have to have a pickup tube fabricated in place of where the pump body was in the tank. I am going to do this when my 4cyl dies and I put that V8 in its place.
Rick

[rick]

The problem is that an external pump will almost surely fail before an in-tank pump will. The pump being in the tank helps keep it cool and you will never have to worry about vapor lock. Vapor lock is a huge issue on 4.2L engines with the MPI conversion kit, where the pump is an external type mounted on the frame in front of the tank. Vapor lock can occur any time the fuel lines/pump get hot enough to allow vapor to form in the pump which makes it "lock" up and not pump any fuel. Many people with these kits have gone through the trouble to figure out how to put a pump in the tank. Unfortunately, the only option to keep it in the tank on a late model TJ is to replace it with an OEM part. I would look on ebay, I have seen several TJ pump/sending units complete go for less than $150. If you compare this with the cost of a high quality external pump (I'm not talking about a $45 AutoZone pump), a used might be the way to go.

[H8PVMT]

Thanks for all the info on this one. I had a friend and his car vapor locked alot, not fun. Plus being here in the desert I guess that would be a bad route to go. So it looks like I will stay with the in tank pump afterall.
Before I start hunting for a new one I am gonna get a longer hose so I can watch my pressure when it hesitates on me. I know the pressure is good when I idle but sometimes it hesitates, and when I shut the engine off the system depressurizes to about 5 psi within seconds. Which means a leak.... which I didn't find, or the check valve in the pump module itself went bad. Don't see how that would cause it but maybe. Then there's the whole issue of the blown fuses but I still can't track that one down.

[rick]

If you had a sender unit with pickup from an older Wrangler that had a mechanical fuel pump, you could use one of the GM Hi-Pressure pumps outboard and mount it on your frame rail.

I don't think you can do this on a 96+ 4.0 because the fuel system is a bit different from the older Wranglers. The older Wranglers have the fuel regulator on the fuel rail with a return line to the tank, while the TJs have the regulator at the pump in the tank and no return line. I think this means that if you run an external pump, it would have to be regulated at the pump or you would need an external regulator as well as a return line from the regulator (because there is not return line from the fuel rail). The stock TJ fuel pressure is 49 psi, while I believe the earlier 4.0s are 46 psi. Not sure what a GM hi-pressure pump puts out or if it has an integral regulator, but this all sounds like trouble to me versus an in tank pump.

I think you are on the right track to hunt down the problem before doing anything else. Let me know if you don't have a service manual, I'll check out the diagnostic procedure and see if we can come up with something.

[RangerRick]

I have seen pumps go for 300,000 miles before kicking the bucket. If you suspect the pump check the wiring and connections as well. Also check the filter, some people think these things can go for 50K miles or more...... WRONG! Gotta change them and the more gas you get at wierd places that can have crap in them and the more wheeling you do that's dirty and gritty the sooner you should change it. And in response to my last post, it would take some modifications to make an external pump work. My recommendation is to stick with an in the tank one as well. I have 120K and ive smashed the tank more than once on my rig without a hitch so far. I always carry a spare pump cause I know it's gonna quit in the BIG SLUCE up on the Rubicon when it decides to go.....
Rick

[H8PVMT]

There's only 61,000 on this pump. I started it up and wiggled the wiring that goes from the pump to the engine, plus any wire that had anything to do with it. Doing all this and no fuse popped. So I suspect it is something on the pump, or it was that Jet chip(waste of $$$ but we all know that). The diagnostic procedure was out of my haynes manual, which led me to believe the check valve in the pump module is bad.
As for the filter, they say they are good for 100,000... well I don't believe that. Especially being that this jeeps whole life has been in dusty desert climates.

[rick]

Take it apart and tinker with it... that's what I usually do I'll look at the manual this weekend and we can compare notes. Haynes manuals are notorious for misleading information.

[H8PVMT]

Yeah I was thinking I needed to do that. It the whole dropping the tank thing I'm not looking forward to. I am going to have to wait till next weekend though cause my son is coming down. While you all are on the rubicon I will have my gas tank in pieces. :confused:

[Black & Tan TJ]

I have a factory service manual on CD if that would help. It's for a 2002 but I think in may be for your year too. It's PDF format so I believe I could email what you need.

B&T TJ

Got it on ebay for about $20

[H8PVMT]

That would be a big help. My e-mail is under my profile. Thanks B&T TJ.

[H8PVMT]

Well I got busy this weekend and ended up changing my fuel pump. My old one's pressure started jumping up and down about 10 psi while at idle. Now she purrs like a kitten and didn't even break on the freeway. Oh and it doesn't take me cranking it a while to get it going. Starts up right away. Good stuff!!!!