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Posted by: boxsterfan Sep 28 2014, 03:45 PM

Getting my car back together after replacing the fuel pump with a 2-port Bosch 69133 unit from Napa.

Car starts as normal, but when I turn her off she just keeps running. I can remove the key from ignition and she keeps running. And of course, this isn't some sort of overrun condition....actual running. Pull the coil wire and she dies as expected.

Other notes, fuel pump is wired to switch power up front (previous owner did this).

:dunno:

Posted by: messix Sep 28 2014, 04:21 PM

did you reverse the wires on the new pump? it might now be grounding what should be the hot side.

Posted by: boxsterfan Sep 28 2014, 04:36 PM

Well, stupid question, should the hot wire be connected to "+" or "-"? Right now it is connected to "+" on the Bosch 69133 pump.

Haynes manual says possibly bad ground to 31b (car keeps running after ignition switched off). No idea where 31b is. Possibly my ground is no good? If so, that makes me so happy because now I have to drain the tank again and disconnect to get at that ground wire. I don't see another location to ground another wire that is handy.

Posted by: 76-914 Sep 28 2014, 04:54 PM

Pull that tank 10 or 12 more times and it gets easy. How do I know? I can pull/install my tank in less than 10 min's now. My only claim to fame.

Posted by: Rotary'14 Sep 28 2014, 05:14 PM

Did your car turn off before you swapped the fuel pumps?

Posted by: boxsterfan Sep 28 2014, 05:28 PM

Yes.

Posted by: Mike Bellis Sep 28 2014, 05:31 PM

31 on this schematic is the negative battery terminal. 31B might be the tranny strap? Check all your ground points first. 31B could also refer to a relay terminal or switch terminal.

Posted by: messix Sep 28 2014, 05:50 PM

the diagram for a '74 car might be better to work off of. this one is an early '73

Posted by: Mike Bellis Sep 28 2014, 05:54 PM

OK, but this one confuses some people.

Posted by: boxsterfan Sep 28 2014, 06:03 PM

I don't see any choice but to take the tank out again next weekend and start over. Of all things, I did take the battery to chassis ground cable off last weekend and cleaned it up. I just took that off again, had a look and put it back on. It's actually cleaner and nicer than it was before.

But the problem still persists...

Who knows? Maybe it is the tranny ground strap. The car has been jacked up on its front wheels for a couple weeks now. Maybe that wiggled the trans ground strap loose (or it even broke). Of course, that's really just wishful thinking on my part hoping not to have to take the tank apart and out again.

So before I take the tank out next weekend, how can I check the ground at the pump with a voltmeter?

Posted by: iamchappy Sep 28 2014, 06:11 PM

If your running an electronic ignition you may be getting current bleeding back in through the alternator gauge bulb blue wire. May need to place a diode in that wire. It happens....

Posted by: boxsterfan Sep 28 2014, 06:24 PM

Agree that this stuff happens, but not sure why? Replacing the fuel pump did that? Cleaning up the battery to chassis ground did that? I actually cleaned up the chassis ground next to the fuse box area a few weeks before the pump went out.

Posted by: boxsterfan Sep 28 2014, 07:43 PM

Well, from bad to worse. Won't even start now. Either one of the fuel lines is crimped or I may not even have enough gas in it. I put in about 1.5 gallons. Pump is very loud and sounds as if it is working extra hard.

I'm running 30R9 nearly everywhere (except the 12mm filter to pump section) That 30R9 hose is not very forgiving when coiling/turning it. I guess I'll just pick up some of the BMW 9.5mm fuel line from PP that is much more flexible for the tank supply line where it needs coiled. The 8mm 30R9 return to tank seems to be OK (has enough space to coil up properly).


Where can I find a list of all the chassis grounds to check out? One by the battery. One by the fuse box. Transmission ground strap. Others?

Posted by: ripper911 Sep 28 2014, 08:00 PM

The first things to check are the things that you touched during your last repair.

Posted by: 57lincolnman Sep 28 2014, 08:56 PM

I had this problem and it was the ignition switch itself. The plastic ring cracks inside these and can cause this problem. Do you notice that there isn't the usual type of resistance in the switch? Hint: you can just stall the engine by letting out the clutch. It's easy to access (if you don't have a/c) with the access panel under the steering wheel.

Posted by: HalfMoon Sep 28 2014, 09:14 PM

For what it's worth that's exactly the sound my electric pump (on a sbc convert) makes when it's got no fuel to pump. Get's very loud and then....well you know the rest.

Posted by: boxsterfan Sep 28 2014, 09:36 PM

Lots of good suggestions here:

1. Trans ground strap - was going to do this anyway
2. Ignition switch - This could be related to the inability of the car to turn off after turning on.
3. Loud new fuel pump (this is either not enough gas in the tank or crimped lines after the reinstall of the tank).


Well, I need to get the fuel sorted out first in #3. I guess I am hoping that #2 or #1 above are why it won't shut off when the key is turned off. Where can I get a good ignition switch these days? I think have read before on these boards that quality can be an issue with these switches these days...

Posted by: boxsterfan Sep 28 2014, 09:38 PM

Well, my repair has been replacing a bad fuel pump. It ballooned into stripping/repainting the tank, replacing all the fuel hose with 30R9, replacing the fuel injector o-rings, replacing the intake runner boots and replacing the intake runner gaskets.

Posted by: boxsterfan Sep 28 2014, 09:40 PM

I'm starting the car (when it was starting earlier today) with gear in neutral and no clutch depressed. Ignition switch does turn freely, but I don't have anything to compare it too (ie. a brand new one turning "not so freely").

Posted by: etcmss Sep 29 2014, 03:44 AM

I had this happen when putting gages back in to the dash. car would not turn off...
Swapped the ignition switch--not it, swapped the fuel pump relay--not it. checked all grounds clean to the chassis.
Got out the 74 electrical schematic.
I thought to pull each fuse one at a time until car died and then trace all fused loads.
intent was to remove all fuse * wires with car running and see which one allowed the car to die.
Drop the fuse panel and start the car.
Went to fuse 8 (?) (supplies the fuel pump red-black wired that is switched thru relay panel) and pulled all output side wires one at a time. Then traced out what that supplied.
another would be the Pelican electrical link to regulator circuit--- this link does a 73

http://www.pelicanparts.com/914/parts/Electrical/914_electric_73E.jpg

regulator plate link http://bowlsby.net/914/Classic/TechNotebook.htm
http://bowlsby.net/914/Classic/zTN_Elect_RegulatorPlate_Circuitry.jpg
ground points http://bowlsby.net/914/Classic/zTN_Elect_GroundPoints.jpg

Mine was the generator light bulb and socket.

Another time a fuse kept blowing and it was the license plate lights being installed incorrect.
so be skeptical of what you recently worked on and thought all was well.
hope some of this helps.
Gary

Posted by: etcmss Sep 29 2014, 03:55 AM

added the 74 diagram--print in color then tape together to get it oriented right.


Attached File(s)
 1974_914_wiring.pdf ( 1.1mb ) Number of downloads: 18

Posted by: boxsterfan Sep 29 2014, 09:51 AM

I was thinking about my fuel pump installation....

The old 3-port fuel pump mounted up front was large enough in diameter that it fit perfectly in the bracket being used. The new 2-port fuel pump is a smaller diameter. I couldn't get the bracket tightened down enough to secure it. So....... I took an old bicycle inner tube and cut it up. I wrapped the tube around the new Bosch 2-port pump to give it some more girth (diameter) such that it now secures tightly in the bracket.

Question though....does the pump get any grounding from the bracket itself? As of now, with the rubber inner tube wrapped around it, it is totally isolated from ground except for the "suspect" ground wire I am working on.

Posted by: etcmss Sep 29 2014, 10:07 AM

your wrap won't cause an operational problem---no its not grounded--has 2 wires to run + and -.
did you also try changing the fuel pump relay? Mine did have this problem also and when changed out the car did run again.
Gary

so take a voltmeter and pull the 2 wires to the fuel pump and measure the volts when turning on the key---volts??? yes or no....
do you hear the hum when turning on the key? all mine used to do this (FI ones)

Posted by: boxsterfan Sep 29 2014, 12:16 PM

Thanks. Yes, my pump is running. The pump was wired up front off of switched power by the PO vs. the original fuel pump relay off the relay board in the back. My issue (from the first post) started with car would start but not turn off when putting the key in off position unless I pulled the coil wire. It further degraded to a no-start and noisy pump sound.

1. The noisy pump is likely a crimped fuel line. Also possible that I am very low on gas as I only put in 1.5 gallons and the car is on jack stands in the front. My first step might be to simply put some more gas in or lower it back off the jack stands and try starting again. I suspect it will start again and then I'll be back to the original problem (see #2 below).

2. Assuming I get her to start again, I'm trying to figure out why she won't turn off when I turn off the key.

Posted by: Java2570 Sep 29 2014, 12:37 PM

The noisy pump sounds like a kinked fuel hose under the tank.....I just went through that scenario myself. I was able to reach up through the access hole, under the belly pan and reroute the hoses enough to rid the lines of kinking. My noise went away and the bad hesitation/drive-ability problems ceased. And I didn't have to pull the fuel tank again! 30R9 hose kinks easily......

Posted by: boxsterfan Sep 29 2014, 12:52 PM

Yes, agree that the 30R9 does kink easily. I'll probably just replace it with some more flexible hose from Pelican. Kind of shame because I did 30R9 everywhere else on the car (exlcuding the 12mm or 1/2" line from filter to 2-port Bosch pump).

Maybe I need to locate the hard lines coming out of the bottom of the tank to a better orientation? If I am laying under car and looking at the tank supply and return lines coming out, they both are pointing at 4 o'clock-ish. Essentially, from under the car, they point to the passenger side where I am routing the fuel line hose and looping back. This is for both the return and supply lines.

Maybe pointing one in a little different orientation can help alleviate the kinking? Such as pointing the supply line more at 2 o'clock?

Posted by: Java2570 Sep 29 2014, 01:03 PM

I think both of my tank fittings are pointing toward pass. side and slightly toward back of the car. In my case, I just used a little too much hose length and there is a limited amount of routing once the tank gets back in. I was surprised how much luck I had checking the hoses for kinks by feel. I'd say be careful to keep your eye on those fuel hoses if you end up going with something not rated for ethanol.

Posted by: boxsterfan Sep 29 2014, 01:06 PM

I'd love to find some 30R9 12mm, but the way the hose routes (pump is mounted underneath by steering rack), I don't possibly see how 12mm 30R9 could be routed without it kinking there. Getting the 8mm (7.9mm actually) and 9.5mm 30R9 routed withotu kinks under the tank is probably a possibility still. I'll have to dig in again this weekend.

With so many hoses coming in and out of that access hole, I can't get my big fat hands in there. Perhaps I can get my 4 year old to do the job?

Posted by: Java2570 Sep 29 2014, 01:11 PM

Yes, 4 years old....that's about the right age to teach them the Porsche maintenance!!

Posted by: Dave_Darling Sep 30 2014, 12:58 PM

Electrical problems can be really strange. I once had a problem where the car would keep running as long as the left turn signal was on. I could remove the key, lock the door, and walk away from the car and the motor would keep running.

I eventually figured out that the "parking light" feature was feeding power back into the ignition switch, sending it to the fuel pump and oil and such.

The feedback was because I had swapped in a single-filament bulb for a dual-filament one in the taillight. I had done that a couple of months before noticing the problem, because I don't usually park the car with a turn signal on...

So, does the turn signal switch have anything to do with your symptoms?

--DD

Posted by: boxsterfan Sep 30 2014, 01:55 PM

Good question Dave. I'll find out more this weekend. I don't believe my turn signal was on and I haven't changed a bulb or done anything with the car in that area.