Fuel Issue
 

Hey guys,

I'll try my best to not make this too long winded. I have a 99 Boxster with the 2.5 motor. The car has 154K on it, but great shape, four owners all checked out on Car Fax. Car has run beautifully until two weeks ago. Suddenly it started missing, radically. Seemed like it was not picking up fuel. I took it to my boys who work on her for general maintenance, they thought it was the sensor for coolant temp that was bad, replaced and no change in the performance. At this time the 986 had 1/4 tank of fuel. I drove it for a few days and the worst occurred. It started sputtering and missing to the point where I had to have it towed back to the shop. They then put in a new Mass Air Flow Sensor with no change. I took it to the Porsche Dealer here in Oregon and they found no errors in the computer and told me to drive it until the check engine light came on again. In the meantime, I filled the car full of premium fuel, injector cleaner and octane booster. It ran perfectly for two days. When I reached 3/4 tank full, I refueled. Here is the key, the second I drove out of the gas station, it sputtered like crazy! Now, it runs, but not well. No one can determine what is wrong. Any advice?

Could be the fuel pump.

Sounds like
 

your Mr Fusion isn't getting the necessary 1.21 Gigawatts of power. Have you tired getting up to 88 Mph?

+1 on the fuel pump. I would even take it one step further and replace the fuel filter.

I just love the fact that the standard test for possible fuel issues is to connect a pressure gauge to the test port in the engine bay for the purpose, and check both fuel pressure and delivery volume, a quick and relatively cheap test, but no one has done this, preferring to swap out expensive parts instead................

If I recall correctly I did not get a Check Engine Light when my fuel pump failed (~150,000 miles on the odometer). It was an interesting ride home but the Jägermobile did not leave me stranded.

Thanks JFP. So true. All everyone wanted to do was talk electronics. Car now seems to be fixed and running well with the new fuel filter in place.

Thank you. I changed the fuel filter and it seems to have fixed the problem. Curious, does getting up to 88 mph do something to the systems?

And the test I suggested would have caught the low fuel delivery caused by the clogged filter............. Sometimes the simplest approach is the best one; and too many techs have become “sensor dominant” in their thinking……..

" Curious, does getting up to 88 mph do something to the systems?"

Just the flux capacitor, and only in time travel mode.

http://en.wikipedia.org/wiki/88_MPH