Fuel Pump LS `02 3.9

[Rko_01LS]

Fixed

I caved in and took my LS to a local auto-shop. Turned out not to be my fuel pump, however the filters where black they needed to be changed eventually after 95k miles. The starting & stalling problem was due to a dirty R&R idle valve, It was gunked up, They had to clean and replace the IACV gasket. This piece extends from the engine under the cover on the right side. Looks like a black hose. They also did a relearn procedure,the IACV gasket part about 6-9$, the relearn procedure 90$. Total cost $150 parts and labor. Thanks to the previous posts! The LS is back on the road.

and Dwizzle86 I got my fuel pump from partsgeek for 88$ and it was identical to the stock one, The process is tricky all together. Hope you can fit it in there! Good Luck.

 

[01LS3.9]

Glad you got it done!

 

[Hawk03]

Ok folks I need some help. If some of you have read my other posts you know I have been battling a cold start issue for the past several weeks. Here is what the car is doing:

Won't start on cold days after sitting for a couple of hours. I have to turn the key on and off and crank the car three or four times unitl I hear the fuel pump kick on and pressurize the line at which point the car starts fine and runs fine no problems.

Here is what I have done:

1) Replaced fuel filter.
2) Replaced Coolant temp sensor (car defaults to warm start if bad).
3) On to the fuel pump...

I am now to the fuel pump:

I pulled the back seat up to find two fuel pumps? Is this correct? I checked both for Voltage and they are both at 12v's. When I turn the key only the passenger side makes any noise. Is this correct? or should both sides make some noise? Does anyone have a wiring diagram for the fuel system? Also I believe this is more a matter of pressure leakdown rather than fuel pump. There is a diaphragm in the fuel line before it hits the fuel rail (round metal part splitting the fuel line, not the connector). Has anyone ever heard of this going bad?

My car is doing the same thing. It cranks but won't fire up. I don't hear the fuel pump turn on (I installed a new pump in '10 and filter last summer). Last week was the same issue except I cycled the key to the on position a few time, fuel pump turned on and it started. I didn't mess with it too much this morning and I will try the other key tonight to see if that will help it start.

I have no idea why it only acts this way in the cold weather.

 

[Hawk03]

Cycling the key didn't work. When I cycled the key, the windows kept rolling down a bit, wonky electronics. Its supposed to get above 40 degrees today and I'm hoping that will help with the issue somehow.

 

[joegr]

... When I cycled the key, the windows kept rolling down a bit, ...

That's a warning sign of a failing battery or bad electrical connection. Put a voltmeter on the battery. A good and charged battery will read 12.6 volts just sitting there. If it drops below 12.0 volts when you cycle the key, it is weak. If it drops below 10 volts, it is damaged. From you symptoms, I would bet that it is dropping below 9 volts.

Alternately, if the battery voltage is good at the battery, measure the voltage at the under hood fuse box. If it's low there, you have a bad connection somewhere.

 

[Hawk03]

Its a connection somewhere that gets weak when its cold. The fuel pumped turned on last night and the car started, no charge for the battery was needed and it sat for 5 days (its 3yrs old). I'm not sure really where to start looking since it only happens when it is cold outside. I would think if it was a rely or fuse connection, this would happen when it is warm as well.

 

[joegr]

Metal shrinks when cold. All connections and electrical devices (like relays) are subject to this, so it could still be anything. Battery voltage drops when cold.

 

[Hawk03]

True, thanks. This has been a problem for years, especially when I try and use my remote start. I think I will buy a new relay, pull the prongs out a little and see how that works. I will have to wait until the next cold day to see if it works.

 

[sowberry]

Additional tips

'02 V6 w/ 80k. Blew fuel pump fuse (in the trunk) twice in a week, so figured something was up. '01 LS 3.9L posted a step by step on the first page of this thread, which was very helpful (Gen II owners see this thread). However, I'd like to add some advice for anyone else that tackles this job (btw, very doable; I'd say medium difficulty for a novice like me).

Got a new fuel filter from local store ($10) and replaced that first to relieve the pressure in the line (took less than an hour; just remove front driver side wheel and back half of the plastic well. Stick a screwdriver in to pop the clips out, then pull the lines out and unbolt the bracket). The hardest part was getting the f*cking bracket back on the new filter (I held the filter upright w/ my shoes and grabbed both ends of the bracket with pliers to stretch it open).

• The clips holding the fuel lines on top of the pump basket are different! The red one is friction based (have to squeeze it constantly while pulling the line straight up and out). The white one is not friction based (squeezed my fingertips raw learning this the hard way). Squeezing the tabs can accidentally unseat the white ring, in which case the hose ain't going anywhere. That's because the ring must be seated for a squeeze to open the clip holding the lip on the hose!
• I saved a f*ckload of money buying just the pump motor (came with new strainers) off ebay (it was like $25 from global-automotive). Just a couple hex-head screws holding the basket together (I'd guess 4mm, but my smallest socket was 5mm; 3/16" worked). Scary when I opened it and saw it came with a separate power connector (I hate soldering), but the existing power connector fit perfectly.

I didn't bother disconnecting the battery before changing the pump (not the safest thing), but even if you disregard safety like me, you ought to disconnect it; when I road tested the pump, I started getting misfires. I only got one cylinder misfire code, no lean/rich code, but I guessed that maybe the computer had gotten used to the old weak pump, so I disconnected the battery so the computer would "forget." The next day, it ran perfectly!