Car will not start? - Page 4 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

woodsman · 05-23-2015, 12:11 PM

Anything's better than having to put it back on jackstands and pull the tranny.

Timco · 05-23-2015, 12:13 PM

Quote:

Originally Posted by woodsman

Anything's better than having to put it back on jackstands and pull the tranny.

More worrisome than getting back together with my wife!

(Almost)

BFeller · 05-23-2015, 03:23 PM

Fuel pressure pump cuts off if the engine does start for safety reasons. Durametric or the RPM Gauge doesn't register until the engine is turning over 800 RPM - one or the other - I can't remember. The starter doesn't turn the engine fast enough to register. My CPS quit without a single hiccup. The car started - an hour later nothing.

My fuel rail would build pressure - if released - when the pump ran for the short burst it would build pressure. So for me that ruled out fuel delivery issues.
If I remember correctly - there was compression - so I semi ruled out timing.
No error codes showed up in the Durametric to indicate any other issues.
So I tossed in a Pelican CPS. She started fine after it was installed.

Timco · 05-23-2015, 04:25 PM

Quote:

Originally Posted by BFeller

Fuel pressure pump cuts off if the engine does start for safety reasons. Durametric or the RPM Gauge doesn't register until the engine is turning over 800 RPM - one or the other - I can't remember. The starter doesn't turn the engine fast enough to register. My CPS quit without a single hiccup. The car started - an hour later nothing.

My fuel rail would build pressure - if released - when the pump ran for the short burst it would build pressure. So for me that ruled out fuel delivery issues.
If I remember correctly - there was compression - so I semi ruled out timing.
No error codes showed up in the Durametric to indicate any other issues.
So I tossed in a Pelican CPS. She started fine after it was installed.

So, scenario. Key is turned but no crank. Doesn't the fuel pump instantly make 55lbs or 3.8 bar? I'm not getting any pressure at all.

Second, Bently described how to pull the fuel pump relay, and jump the two terminals that would kick the fuel pump on, but I can't make it run with key in or out or turned to run position.

Bought new battery just in case.

Steve Tinker · 05-23-2015, 04:57 PM

As you have probably guessed, the fuel pump will not start until the engine is running, apart from the initial few seconds run when the ignition is first switched on.
To get the pump to run, are you removing the relay and jumpering pins #30 & #87 (they are labelled #3 & #5 on the relay).
When you switch on the ignition, the pump should run - if not you have a pump problem....

Timco · 05-23-2015, 05:04 PM

Quote:

Originally Posted by Steve Tinker

As you have probably guessed, the fuel pump will not start until the engine is running, apart from the initial few seconds run when the ignition is first switched on.
To get the pump to run, are you removing the relay and jumpering pins #30 & #87 (they are labelled #3 & #5 on the relay).
When you switch on the ignition, the pump should run - if not you have a pump problem....

Pulled the harness. 13v for a second then 9.8v while cranking. I'll pull that relay and check voltage with the jumper in place. Then if it has juice, it's the pump.

With that jumped out, I only ever see 3-4v. Never says 12-13.

Then with relay back in its as described above.

BFeller · 05-23-2015, 05:19 PM

Quote:

Originally Posted by Timco

So, scenario. Key is turned but no crank. Doesn't the fuel pump instantly make 55lbs or 3.8 bar? I'm not getting any pressure at all.

Second, Bently described how to pull the fuel pump relay, and jump the two terminals that would kick the fuel pump on, but I can't make it run with key in or out or turned to run position.

Bought new battery just in case.

I don't recall how much pressure it would build. I was running off of data from Bentley or 101 Projects.

Jamesp · 05-23-2015, 07:19 PM

I'm not versed enough in the fuel system to know that this is correct, but it sounds a whole lot like a pump problem, pump not running with startup power and zero fuel pressure. That said, you are using and AC Schrader fitting to measure the fuel rail pressure and the AC Schrader fitting may not depress the valve core in the fuel rail Schrader valve sufficiently to allow a pressure reading. One way to find out is to depress the Schrader valve core to see if fuel comes out. If the system is up to pressure the pump may not run when the key is initially turned on.

Deserion · 05-23-2015, 07:42 PM

Timco, just a heads-up. If the fuel pump is indeed bad, you may also want to change out the sending unit as well. I went through 2 or 3 new OE pumps on mine when the fuel filter (inside the sending unit) was clogged and I didn't get any fuel pressure. Pumps lasted all of 15 miles each after swapping.

I ended up with lightly-used pump and sending unit from DC Auto. No problems since.

KRAM36 · 05-23-2015, 08:11 PM

Quote:

Originally Posted by Deserion

Timco, just a heads-up. If the fuel pump is indeed bad, you may also want to change out the sending unit as well. I went through 2 or 3 new OE pumps on mine when the fuel filter (inside the sending unit) was clogged and I didn't get any fuel pressure. Pumps lasted all of 15 miles each after swapping.

I ended up with lightly-used pump and sending unit from DC Auto. No problems since.

I always thought the filter was in the pump. Learn something new every day. Porsche says it's a lifetime filter and never needs to be replaced lol.

Timco · 05-23-2015, 08:14 PM

Quote:

Originally Posted by Jamesp

I'm not versed enough in the fuel system to know that this is correct, but it sounds a whole lot like a pump problem, pump not running with startup power and zero fuel pressure. That said, you are using and AC Schrader fitting to measure the fuel rail pressure and the AC Schrader fitting may not depress the valve core in the fuel rail Schrader valve sufficiently to allow a pressure reading. One way to find out is to depress the Schrader valve core to see if fuel comes out. If the system is up to pressure the pump may not run when the key is initially turned on.

I absolutely tried manually depressing the stem and zero fuel. Nada.

In the words of Ted Striker.........

What a pisser.........

KRAM36 · 05-23-2015, 08:16 PM

healthservices · 05-23-2015, 08:55 PM

interesting...

I just happen to replace mine last week!!!!

I could not wait as it was my daily driver so I just got it from o'reillys. notice it does not come with the vibration insulators....

250.00 but you can find for up to $125 less if you shop online and wait

healthservices · 05-23-2015, 08:58 PM

Be sure to properly secure your pump to the bottom of the tank, I actually had a boxster that had one not latch to the bottom and it would always run out of gas at 1/4 tank until i pulled the pump.

Timco · 05-24-2015, 07:35 AM

Going to pull the pump and bench test it. Nothing better to do. Called around, none on the shelf anyway unless Porsche has one tomorrow.

So, with a Durametric, I can turn each of these items on and off and check them that way with key on? Is that a feature of this tester?

Ummm, no. Have to siphon gas out, get a glove, and I'll want to swap hose by hose with the new one. I'll order both. Thanks KRAM. I'll check locally tomorrow then order what I can't get. If a pump is local I'll do that since its easy to get to the sending unit.

Jamesp · 05-24-2015, 06:18 PM

Timco,

This is for a 2003 with 7.8 DME so your Durametric mileage may vary, but here are the activations available for the 7.8 DME.

Timco · 05-26-2015, 06:16 AM

So, under normal conditions, what sends voltage to the FP? If I can't get 12v constant to the FP connector with the jumper in place and relay removed, it seems I need to be tracking down an electrical issue, no? Parts guy at Porsche SLC said in 15 years he's never sold a fuel pump for a Boxster.

Is FP always on while car is on? It can only ever deliver the 3.8 bar or whatever it was?

Timco · 05-26-2015, 06:18 AM

Quote:

Originally Posted by Jamesp

Timco,

This is for a 2003 with 7.8 DME so your Durametric mileage may vary, but here are the activations available for the 7.8 DME.

Seems like that will kick on the relay and test the pump. If key is on pump should run. Going to buy one today me thinks.

healthservices · 05-26-2015, 06:23 AM

Quote:

Originally Posted by Timco

So, under normal conditions, what sends voltage to the FP? If I can't get 12v constant to the FP connector with the jumper in place and relay removed, it seems I need to be tracking down an electrical issue, no? Parts guy at Porsche SLC said in 15 years he's never sold a fuel pump for a Boxster.

Is FP always on while car is on? It can only ever deliver the 3.8 bar or whatever it was?

You only get fuel signal for a couple of seconds after the key is on, then it waits for a signal from the ecu.

Ive done several pumps for the boxsters, in general and if O Reilly stocked it, it means there is a demand for this style pump whether it is from Porsche or vw.

I noticed on mine as soon as you put the jumper on, the pump is on. Ill take a picture of the pump so you know which wires later.

Timco · 05-26-2015, 06:32 AM

Quote:

Originally Posted by healthservices

You only get fuel signal for a couple of seconds after the key is on, then it waits for a signal from the ecu.

Ive done several pumps for the boxsters, in general and if O Reilly stocked it, it means there is a demand for this style pump whether it is from Porsche or vw.

I noticed on mine as soon as you put the jumper on, the pump is on. Ill take a picture of the pump so you know which wires later.

But that's the thing. I didn't get pump on with jumper, key on or off.