Which fuel pump is which?

[kamiller]

Can someone please tell me which fuel pump is the one on the passenger side of the car. I am getting conflicting stories from dealers and from the Internet. The one on the passenger side of my car is making lots of noise and I want to replace it but don't know which one to buy. One is primary and the other (the jet pump) feeds gas to the primary pump.

One dealer tells me the passenger side pump is primary, another says it is the jet pump. Please help.

[joegr]

The passenger side is the primary for the 2003 to 2006 LS. (You should always give the year of your LS when asking questions, as there are differences from year to year.)

[kamiller]

Okay. Thought that when I registered and entered the vehicle specific information it would appear.

My car is a 2000 LS with the 3.9L V8. Your help is appreciated.

[kamiller]

The wealth of knowledge that exists on this site and yet no one can tell me which fuel pump is which. Maybe this question was too easy for all of you guys (and girls) discussing much more technical matter about much more technical parts with much more tecnical jargon. Somebody once told me that there is no stupid question, but maybe I hit on it!

Perhaps I should rephrase my question with all of the popular jargon I have read here, but alas i don't even know where to start. I do like the one guy who talks about air, fire, and fuel - that I understand. This brings me back to my fuel pump question - WHICH ONE IS WHICH!

I feel like I'm talking to myself now and even worse, rambling to myself. Any help (and no, not psychiatric) would be appreciated.

[danielsatur]

Here's a good thread with a bad jet pump,
see www.automotiveforums.com/vbulletin/showthread.php?t=975424
www.alldata.com , should have a fuel pressure test for both fuel pumps under the rear seat.

If starving for fuel from 700-2000 rpms limit, it's probably a filter, or a bad primary fuel pump.
Theres a rev limiter of 2k rpms in the parked pos, if starving for fuel above 2000 rpms in drive, it's the high flow jet pump.

Primary fuel - passenger side
Jet pump - Drivers side

Don't forget, a plugged catalytic converter can choke your fire out!

[joegr]

Originally Posted by kamiller

The wealth of knowledge that exists on this site and yet no one can tell me which fuel pump is which. ...

What about my post on the 8th?

[kamiller]

Thank you fire, air, and fuel guy! I will let you know how it turns out. The primary pump is making noise, so I will start there. I already read the thread on the jet pump and will replace that if the primary doesn't correct the problem. Car's pushing 200k so I don't mind replacing both.

Hard to tell at what rpm it is cutting out. Starts bucking as soon as I give it gas. Replaced the fuel filter, but it didn't help. I didn't think it would, but I was hoping.

[kamiller]

Yes, joegr, thanks for your reply on the 8th. It ended up being correct, but you only knew it to be true on an 03-05. I replied I had the '00 but never heard back again. I waited anxiously for a reply after getting you more info. I suspected you were correct, but wanted to verify it.

After reading some other threads, I'm starting to think it may be the jet pump (driver's side), but I'll start out with my original hunch (the primary on the passenger side) - ususally correct.

[egddiesel]

Try hooking up a fuel PSI gauge on your schrader valve on the fuel rail, if you have one, my 04 doesn't. Drive around and see if your fuel pressure stays constant or drops under load, you could also try just brake tourqeing it if you cant drive around, put in gear and hold brake down and give her a little gas to put some load on the engine. But again I would check fuel PSI before dumping money in pumps.

[kamiller]

I believe my friend has one of those. He offered to perform this test, but I haven't taken him up on it. Perhaps I should before I install the pump.

[kamiller]

For anyone paying attention still, turns out that danielsatur was right. Should have listened to him. Replaced the primary pump, tried to fire the car and got nothing. Opened up the shrader valve on the fuel rail and got nothingt. Played with lots of other possible answers including the reinstallation of the old pump. Still nothing. Which really is kind of odd since the car did just make it 2 miles to my friend's house. Anyhow, eventually I pulled the jet pump. Seems to have some weird doohicky thing that seems like a check valve of sorts in a little round plastic box attached to the jet pump. I bypassed that thing temporarily and the car fired right up. Apparently whatever that thing is was plugged, stuck, or otherwise malfunctioned. So, long story short I have ordered a jet pump.

I'll let you know how it works out since I hate reading these things when people don't post the resolution to the problem. What good is a bunch of think-we-know-it-alls if you don't know whether you were right or not. And that way us know-we-know-nothings can get more help.

[kamiller]

Yes, it was the jet transfer pump. Runs like a champ. Now I just need to fix the power steering lines underneath which have corroded and are now leaking. I love living in the Northeast.