rb101

All,
About three weeks ago, I arrived home and then needed to move my car in the driveway(5 minutes). The engine turned over as normal, but didn't instantly start up as usual. After about 4 long start attempts, I held the throttle to the floor and it started after a longer then usual cranking. I move the car, shut down and it started like normal. I decided that the crank sensor must be failing and getting a heat soak. I replaced the sensor (car has 150K miles). No issues for two weeks, then yesterday afternoon after work, it happened again. Normal cranking speed, but it didn't actually start up until I held the throttle to the floor. Then it happened again this morning. I have no error codes on the ECU. I can't find anything in the forums. Has anyone had a problem like this?
Thanks
Rick
99 996C4

Macster

While both of my Porsche cars have exhibited starting issues, all have been purely battery related.

Either the engine cranked a little slower than usual or the engine simply didn't crank at all and the other symptoms pointed to a low battery.

Since you report normal cranking speed I'm going to offer the WAG there's a fuel supply problem.

Which reminds me of one other starting problem with the Boxster, but the starting problem, failure to start, only appeared after the engine died and I had already half guessed the cause was a bad fuel pump.

Which leads me to: 150K miles... Could be fuel pump. Longer shot: how's the fuel filter?

Oh, a '99 eh? Even a longer shot: Idle air valve could come in for some suspicion too but I would think if so the idle would be a bit goofy at other times.

Sorry, I can't point you to a smoking gun.

rb101

It's a C4, e-throttle, so no Idle Air valve. I replaced the filter 40K ago. I'm thinking it's fuel related too. I have a feeling its the fuel pump slowly dying. I'm going to replace the fuel pump and DME relays. The car is starting to get a lot of mileage (replaced both lower front control arms 2 weeks ago, 2nd water pump 2 months ago).

DaveCarrera4

Saw something on the 996 turbo forum about fuel line in tank deteriorating iirc. Wonder if it's the same setup?

2003 Carrera 4S Speed Yellow / 1955 356 Continental 1500 Rust Red

Macster

I believe the C4 has the same fuel system, at least in the fuel tank, as the Turbo.

The symptoms do not to me suggest a problem in this area, but it doesn't hurt to eliminate the possibility given the opportunity.

If the OP is going to open up the fuel tank for a fuel pump R&R he can check the fuel lines for any cracks/splits or other problem signs.

Before I replaced the fuel pump, a new fuel pump relay is not expensive and would eliminate the fuel pump relay. If the behavior still occurred it would tend to elevate the fuel pump higher on the list of possible causes.

rb101

Relays will be in this week. I'll change next weekend and check the fuel pressure. See what happens

rb101

Relays made no changes. I did replace the Fuel Pressure Sensor for Fuel Tank 996-606-205-00. It's located under the battery tray. It's still kind of early, but replacing that sensor has made my idle much more stable once warmed up. Hopefully this will fix my hard start issues.

rb101

Well it's been three weeks and the problem has not returned. The Fuel Pressure Sensor for Fuel Tank 996-606-205-00 seems to have solved my issues.

Barn996

Nice fix. How many miles?

rb101

I have 3 or 4 tanks of gas since the sensor change so about 1K miles. The car has 152K miles total on the original engine.

roadsession

Hi
Did you get any codes before changing the sensor
Also has the sensor replacement been a permanent fix?

Thanks

rb101

The issues have not returned and never had a code pop up.

ynotony1966

Im having the same issue, So its under the bat tray?that seams an easy fix.?

Youri Ko

In my case, it was fuel pump and not pressure reg.

Easy to sort out the pressure regulator with a fuel pressure tester.

roadsession

RB101 - do you have a description of what the procedure was to replace this sensor?

Thanks