924Board.org

[TerrygTerr]

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

[Raize]

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.

[chuck21401]

(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
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler

[scm924s]

Same relay available in UK here - https://rareporscheparts.co.uk/products/porsche-924-2-0-n-a-fuel-pump-relay-new-433906059-433906060-321906059c

Bit dearer than you get it in USA but useful, hoping someone gives feedback on it's use.
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1984 n/a Ruby Red Metallic
1988 924S Guards red- sold
1986 924S Guards Red - sold
1984 n/a Black - sold
1980 n/a Le Mans#1 - sold
1980 n/a Le Mans#2- sold
1977 Martini - sold

[chuck21401]

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.










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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler

[coup85]

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?
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924 - 79'

[morghen]

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.
_________________
Supercharger and EFI kits
https://www.the924.com

[Mike9311]

[Beartooth]

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.
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1980 931 diamond in the rough

[chuck21401]

[chuck21401]

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.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler

[morghen]

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.
_________________
Supercharger and EFI kits
https://www.the924.com

[chuck21401]

[morghen]

Seems like there is some flaw with that relay after all, you were correct.
_________________
Supercharger and EFI kits
https://www.the924.com

[norx]

[Greetings, everyone.

Regarding the fuel pump relay sold on eBay, please allow me to respond briefly:

These relays are manufactured by us, and they are NOT made in China.

We have been selling these relays since May 2024 at the request of a Porsche club. However, I must admit that an issue arose in our first production batch (approximately until November 2024). Here’s what happened:

During the design process, we only had access to two cars—a Porsche and an Audi. Since we didn’t simply copy the first-generation relay (which does not perform a fuel pre-charge when the ignition is turned on), we designed our own electronics with a microcontroller (12F683). The problem was that some vehicle models generate higher inductive voltage on the relay from the ignition coil than the models we had for testing. As a result, some customers indeed experienced relay failure within minutes or hours of use.

IMPORTANT: So far, only three (yes, 3!) people have reported this issue after purchasing on eBay. I immediately shipped a revised version to two of them the next day, no questions asked, and I refunded the full purchase amount to the third.

The relay currently listed on eBay has been fixed and no longer has this issue. The problematic relays can be identified by the presence of a mechanical relay inside. The revised version no longer has a relay—instead, it uses an FET switch.

Now, about the price:
Many people don’t realize this, but eBay takes a 23% cut from both the sale price and the shipping fee!

So, for example, if you pay $19 for shipping, I only receive about $14.50 from that. This does not even cover the shipping costs!

On top of that, we still have to pay taxes, and of course, the time spent on production and shipping is also a cost.

One more important detail: Shipping one relay from Hungary to the USA costs a minimum of $21, and that does not include tracking or insurance! The cheapest online tracking option is $31. There is no cheaper shipping option available from our location—this is simply beyond my control.

Alternative options:
You can place an order via email at a lower price since we don’t have to pay eBay’s commission.

We are actively looking for resellers in the USA, as selling and shipping in larger quantities would allow us to offer better prices.

If you have any questions, you can find us on our website: norx.hu

Best regards! 😉