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TerrygTerr
Joined: 29 Aug 2024 Posts: 1 Location: Ireland
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Posted: Sat Aug 31, 2024 12:14 am Post subject: Hello and help please |
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Hi Everyone,
I have had a 924 for about 10 years but took time out to mess with Boxsters. I am now trying to resurrect my 1980 auto but have hit a snag that hopefully you guys know the answer to.
The fuel pump relay is kaput, no problem I thought, just order a new one, no joy at my local factors so I call Porsche Dublin, only to be told it was discontinued in 2019 and although there is a replacement, they cannot get them.
So does anyone know of an alternative for 433 906 059 relay?
Many thanks,
Terry |
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Raize
Joined: 18 Sep 2013 Posts: 229 Location: Scotland
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Posted: Sat Aug 31, 2024 6:24 am Post subject: |
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Not currently and they're really expensive used.
I just re-wired mine to take a 4-pin relay. Small risk of dying in a fire vs over a 100 pounds saved. |
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chuck21401
Joined: 20 Feb 2005 Posts: 557 Location: Annapolis, MD
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Posted: Tue Sep 03, 2024 5:56 pm Post subject: |
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(EDIT: Please see the post below with an update)
I bought one of these and have it on my desk—but haven’t tried it yet.
https://www.ebay.com/itm/166938041789
Will report back. I’m hopeful based on the feedback specific to this relay on the seller’s profile _________________ 1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler
Last edited by chuck21401 on Fri Sep 06, 2024 9:37 am; edited 2 times in total |
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scm924s
Joined: 22 Oct 2010 Posts: 270 Location: Gloucester UK
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chuck21401
Joined: 20 Feb 2005 Posts: 557 Location: Annapolis, MD
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Posted: Fri Sep 06, 2024 9:28 am Post subject: |
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I installed the relay that is being sold on Ebay (adding a screen cap, Ebay URLs go dead after awhile) and elsewhere as a replacement for 433 906 059.
I had high hopes for this relay since the original relay is hard to find, same with KAE 3.300.300.
I pulled the KAE relay and took some pictures for comparison, see below. Installed the relay into the relay board and started up the engine. I was surprised to see that it glowed green and blinked green. That's cool.
I let the car idle for a couple of minutes, everything seemed fine. Decided to drive to the beer store to pick up a six pack. Drove to the store, maybe three miles down the road. Did a couple of boost runs on the way there...everything worked fine. Parked the car, turned off the engine and went into the store. Three minutes later, returned to the car and went to start it. No joy. Starter ran and ran but engine would not fire. Tried this a couple more times. Nope. I did notice that the relay was glowing and blinking green. The relay was snug as well.
Decided to pull the new relay and replace it with the KAE 3.300.300. Started right up....drove home.
I don't get it. I'll contact the seller on Ebay. At this point I can't recommend this relay.
_________________ 1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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coup85
Joined: 12 Aug 2024 Posts: 18 Location: Madrid
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Posted: Fri Sep 06, 2024 4:50 pm Post subject: |
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With these prices, I think we are entering a phase where sending the relays for repair might be a better option than looking for a new one. Does someone have any experience with this type of service? _________________ 924 - 79' |
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morghen
Joined: 21 Jan 2005 Posts: 8944 Location: Romania
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Posted: Fri Sep 06, 2024 5:23 pm Post subject: |
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Chuck, I think that ebay relay works, you just had a hot start problem. Did you try the relay again after that?
At this point my EFI kit does not control the fuel pump relay, but i think in the future i will make it so that the ECU controls the fuel pump and then we can just use a simple 12V relay instead of the special one. _________________ https://www.the924.com |
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Mike9311
Joined: 14 Dec 2004 Posts: 1700 Location: Chicago-ish
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Posted: Fri Sep 06, 2024 10:36 pm Post subject: |
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morghen wrote: | Chuck, I think that ebay relay works, you just had a hot start problem. Did you try the relay again after that?
At this point my EFI kit does not control the fuel pump relay, but i think in the future i will make it so that the ECU controls the fuel pump and then we can just use a simple 12V relay instead of the special one. |
Your brain morghen! Love the way you think _________________ 1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Beartooth
Joined: 05 Apr 2022 Posts: 244 Location: Roberts, MT
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Posted: Sat Sep 07, 2024 4:08 am Post subject: |
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I'll wait for Chuck to chime in, but it doesn't sound like a hot start issue to me. "Put the old relay back in, and it fired right up." Sure sounds like no fuel. Unfortunately, that ebay relay is probably somebody having a factory in China turn out a cool-looking piece for $5 each. Most likely the quality is far inferior to OE, and probably well short of the KAE replacements that you also can't find anymore. Maybe it was just one bad module, but I won't throw money at one until I hear some positive reports.
I've got a non-functional OE relay, and I'm thinking of replacing components on it to see if I can get it to work. Electrolytic capacitors would be the most likely target. I don't know enough to say how they work, except that there is an integrated circuit that controls the relay (just very simple logic: I think it counts ignition pulses and turns on once it gets over one per second or something). It's very possible that a failed capacitor could burn up the IC, but if not, repairs should be possible. If it's the IC that's failing, then we're SOL on repairs...
I'm still a long way out, but my plan is to integrate a microsquirt to replace the lambda control on my car, and that has a low-level fuel pump output (meaning you still need a relay, but just a standard relay). Same thing morghen is talking about; I think basically all stand-alone fuel injection controllers have a fuel pump output. I'd be all about eliminating the original fuel pump relay: it'd perform the same function (shuts the pump off if the engine stops), plus you should be able to add some things (like a run cycle on power-up, like KE-jet relays). You could also eliminate a possible failure point in the original wiring, provide more voltage to the pump, and allow more power for bigger pumps - for those who need it. _________________ 1980 931 diamond in the rough |
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chuck21401
Joined: 20 Feb 2005 Posts: 557 Location: Annapolis, MD
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Posted: Sat Sep 07, 2024 5:40 am Post subject: |
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morghen wrote: | Chuck, I think that ebay relay works, you just had a hot start problem. Did you try the relay again after that? |
No, I didn't try the relay after that. I was happy to make it home without calling a rollback...and proceeded to drink the beer I purchased.
I'll try it again today after work. I'm puzzled. I haven't had any problems starting the car in recent history (hot or cold). At least two years ago I had a melted fuel pump fuse, and a bad relay where the soldering broke loose. At that time I also replace the wiring harness from the battery to the starter to the alternator and replace the alternator and the electrical gremlins seemed to have disappeared.
When I went to start the car...it really seemed like it wasn't getting any fuel. Pulled the new relay...put in the old one....fired up immediately.
I'm thinking about starting the car with the KAE relay....let it idle for a couple of minutes...then try the new relay and see what happens. Will report back.
I did hear from the seller on Ebay:
"hi Chuck,
fortunatelly, i didnt got any negative report yet.
today i will send you another relay.
can You send me your fault relay? i would like to inspect, what is the problem with it, its may help me for improve the future quality. naturally, i pay the shipping fees." _________________ 1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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chuck21401
Joined: 20 Feb 2005 Posts: 557 Location: Annapolis, MD
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Posted: Sat Sep 07, 2024 8:54 am Post subject: |
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I started the car with the KAE relay in place. No problem.
Pulled the KAE relay and installed the Ebay relay (433 906 059 replacement). Started right up. Hmmm.
Went for a ride...the same loop as yesterday but didn't stop at the store. Looped back to the house and turned off the car. Waited 5 five minutes....and started the car again...no problem.
Decided to take another drive...probably 15 minutes on the back roads with several boost runs. Returned to the house....turned off the car and waited 5 minutes.
This time the engine stumbled...but then didn't start. Same problem...doesn't seem to be getting fuel. Tried to restart three or four times. No luck.
Rather than pulling the relay and reinstalling the KAE relay....I decided to disconnect the battery. Did that...waited 5 seconds....reconnected the battery.
Turned the key...and it started right up. Um what?
I checked the Ebay listing again, this is included in the description:
"Fuel pump pre-drive (after ignition) 1sec. Safety cutoff (after spark stopped) 1sec. Immediate off, when the ignition off, or fuse blowed/removed by 30 and/or 15."
I'm not sure what that all means, but maybe an important clue?
I was looking at the picture of the new relay....decided to google the brand and part numbers. The Songle SLB-12VDC-SL-CE relay sells for $1.50 on alibaba.com. _________________ 1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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morghen
Joined: 21 Jan 2005 Posts: 8944 Location: Romania
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Posted: Sat Sep 07, 2024 3:41 pm Post subject: |
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I find it strange that the relay would prime the pump when the engine is cold but not when the engine is warm, so at this point my money is on the following scenario:
It may be important as our relays have a 3s timer and on an old system like ours with degrading fuel acumulators and other components, that 1s may not be sufficient to re-prime the system.
If you can recognize the sound of the fuel pump, you can try to listen for it for that 1s when it is priming to hear if its actually on or not when that no-start situation occurs.
Do the following test: take that same drive, and get the car so that it wont start. At that point, just switch on and off the ignition 3-5 times without cranking, but when you switch it on leave it for that 1s so that the relay and pump run.
Listen for the pump working for 1s after switching the ignition on but dont crank.
Like this, you would simulate the 3s priming behavior of the original relay.
And see if the car starts like that, if it does, you have a hot start problem, if it doesnt and you dont hear the pump, then there is something weird going on. _________________ https://www.the924.com |
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chuck21401
Joined: 20 Feb 2005 Posts: 557 Location: Annapolis, MD
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Posted: Sun Sep 08, 2024 12:41 pm Post subject: |
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morghen wrote: | Do the following test: take that same drive, and get the car so that it wont start. At that point, just switch on and off the ignition 3-5 times without cranking, but when you switch it on leave it for that 1s so that the relay and pump run.
Listen for the pump working for 1s after switching the ignition on but dont crank.
Like this, you would simulate the 3s priming behavior of the original relay.
And see if the car starts like that, if it does, you have a hot start problem, if it doesnt and you dont hear the pump, then there is something weird going on. |
Good suggestion. Turned on the car with the new relay in place, fired up no problem. I did listen for the fuel pump...and it ran for a couple of seconds with key on as I started it.
Let the car idle for a couple of minutes. I needed gas so was about ready to drive to the station but was worried about restarting. So I tested it right then.
Turned off the car...would not restart. So I did your test. Interestingly the fuel pump did not run. Switched the ignition on and off. Fuel pump did NOT run. But after about the 10th cycle, the fuel pump ran for about a second. I cranked the engine but just not enough to get it running. I tried this five or six times. Fuel pump would run for a second, I would crank it, but would not start.
So I decided to disconnect the battery for a couple of seconds and reconnect. Did that. Turned the key...fuel pump ran for more than a second...car started right up.
So not sure what is going on with how this relay works vs. the KAE 3.300.00.
EBAY seller is sending another relay. At this point I'm going to reinstall the KAE and give it a rest. This relay on Ebay might work for others but not with my application, at least not yet.
To the original poster....these relays (either the original or the KAE) show up on EBAY from time to time. Good luck in your quest.
In related news, happened to see this discussion about these relays on a German forum (with a built in translate feature!).
https://www.pff.de/en/thread/2823875-circuit-diagram-or-defective-relay-for-fuel-pump-from-1979-kae-3-300-300-4339060/?pageNo=1
A member of that group created a replacement relay...including LED indicators.
Here's a link to the page via google translate: https://www-lehminger-de.translate.goog/?_x_tr_sch=http&_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp
More details: https://www-lehminger-de.translate.goog/kpr.htm?_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp&_x_tr_sch=http
_________________ 1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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morghen
Joined: 21 Jan 2005 Posts: 8944 Location: Romania
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Posted: Mon Sep 09, 2024 1:34 am Post subject: |
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Seems like there is some flaw with that relay after all, you were correct. _________________ https://www.the924.com |
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