2002 L300 - Unique starting problem

[trwolf]

I have a problem with the car not wanting to start when the fuel tank gets below 1/2 or if the car is nose-up on a slope. It will crank just fine, but no fire. The engine temp - hot, cold, or otherwise - does not seem to matter. If I roll it down the slope to level or nose down, it will fire right up.

When it first began (40k ago), the dealer gave me some smoke and mirrors story about adjusting the angle of the tank to compensate. When the problem was only below 1/4 of a tank, the issue was tolerable (I could live with it). However, the problem has slowly gotten worse over time. Now I can’t get much below 1/2 a tank.

That leads me to believe CPS is probably not the issue. I suspect fuel pump (pressure) or fuel filter (volume). Logically, if the tank has more fuel or the engine is lower than the tank (nose down), the pump doesn’t have to push as hard to deliver the fuel. Filter seems less likely, since I have no symptoms any other time...

Anyone else had a similar issue? I plan to have some work done, and I want to give the mechanic some idea of the cause to cut down on his troubleshooting time.

Thanks in advance.

[Partymmudasti]

Its a common problem with the L series.

Our 2000 LS did it, our 2005 L300 does it..

On both cars, under warranty- fuel tanks and pumps were replaced (twice on the 05 L300) trying to remedy the problem. Once they reprogrammed the PCM. It doesnt make a difference, its a design flaw.
I am concerned though that your L doesnt start under 1/2 tank on an incline... Ours was more problematic with 1/4 tank, for sure at 1/2 tank we had no problem.

Your mechanic is likely to look at it and replace the fuel pump. I firmly believe there are a lack of baffles in the gas tank or an baffle out of place.

[Ex-GMtech]

You may want to see if the fuel sending unit, not the fuel pump, is out of calibration. It could be reading high when it is nearer empty. My wife's 2000 LW2 has never had an issue starting even with it on E, in any postion. I wonder if poeple are looking at this frm the wrong perspective. I would rather have it read empty and still have some fuel in it.

[trwolf]

I completely understand your threory Ex-GMtech, but the miles traveled and the gas that will go into the tank say the guage is right.

[fdryer]

Well it was worth bringing it up to at least address the possibility of a faulty gas gauge sending unit.

Suspecting a fuel issue would require testing and the only way to remove all doubt of a fuel pump issue is to use a fuel pressure gauge attached to the fuel rail where the fuel test valve is located. Done correctly this can be used to monitor pressures at start, idling, driving (provision needed to have the gauge visible with the hood closed), and when you anticipate partial tank problems. Its either full pressure every time including at low fuel tank levels or not.

Be aware that attaching a fuel pressure gauge must be done with a known good reliable gauge, hose, and coupler to ensure that there won't be any possibility of gasoline leaking under pressure. Pressures can exceed 60psi and any leak can be considered dangerous near any source of ignition, low or high voltage. Normal fuel pressures with the engine running will be around 35psi, still hazardous if not familiar with fuel pressures and the inherent dangers associated with fuel pressure leaks.