So I've been trying to diagnose my hard-start issue and there was a test to check your fuel accumulator by putting the car in D and turning the key to run the fuel pump.
I tried various tests, but in no case could I get the fuel pump to run prior to starting the car. So I went to take a look at my Fuel Pump Relay. Relay in place is clearly a used junkyard part with 6 pins. Pulling it out, I noticed that there are 7 active pins in my fuel pump relay socket.
Ok, so an online search shows both a 7pin and 6pin relay are available, the 7 pin says "with kickdown". Interestingly, my kickdown switch on my pedal doesn't work - not sure if this is related or not.
So two questions - what's the difference between the 6 and 7 pin fuel pump relay.
7 PIN PN# 0015455305
6 PIN PN# 0015450605
Both show in the Mercedes catalog, but RockAuto says the 6-pin is for 380SL/SEL
And question 2 - is there a procedure to get the fuel pump to run prior to starting with the car, or test using jumper leads with the relay?
The "get ya home" method when a relay goes south or to pump the tank dry is to jumper 7 and 8 in the relay socket, don't forget to pull the jumper wire when ya park and shut down
Again, putting a jumper wire in sockets 7 and 8 should get the pumps running but as I said the wire needs to be removed when you get where you are going. If you have a bad FPR you'll need to get a new one, I was told that they are available at the dealer for about 30 bucks (this is what I was told also)
Answering the reply that was deleted here
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Thanks
Just checked. Neither Pin 6 or Pin 7 have power in my application.
Pin 8 has power with the engine off
Pin 10 adds power with the key in the On position.
Interestingly, Pin 6 is the pin that does not get used with the 6-pin relay that is in the car.
I deleted my response because my reading comprehension is bad and I jumped 6 <-> 7 instead of 8 <-> 7.
I'll try 7-8 next time
Does anyone have the actual wiring diagram for each of the pins? Again, in my car, Pin 6 was not used so I'm curious if that is for the trans kickdown since mine isn't working (I'm guessing it is)
7 <-> 8 works, and I confirmed with the relay that it also works (for a second) right when I hit the key. So relay works (I assumed it did)
Now I have a new problem - I think my hot-start problem is flooding related. When I left the relay on for a few seconds to "prime" the system (my assumption was the fuel accumulator was not holding pressure hence the hard starts), I now believe the problem is that I'm flooding the car.
Ok, normally if everything is working as it should when you turn the key and the ignition lights up the pumps will run for a couple of seconds to charge the lines. The accumulator helps to hold pressure on the line as well, the times I let the SE sit for a couple of weeks or longer I'd have to "prime" it by cycling the pump two or three times then it was an instant start. I have yet to have any problem with Ursula the Coupe, she'll spin over a couple of times and light right off (if that isn't "normal" I'm good with it as I know the oil is pumping through before she fires off.
I have no ideas on your hot start issue, in theory (my understanding) the pumps won't start back til the engine is actually running
If you would, I hate scrolling, edit your profile on "UserCP" and fill in your car, I do good to remember mine
Gah. Just posed on my other thread that now my Fuel Pump Relay is bad. Car starts and dies immediately, although it runs jumpered just fine. I have no idea why pulling the relay would suddenly make it go bad.
Dunno that either, the FPR in the SE went bad suddenly (and something in it controls the A/C compressor as well, this was a 6 cylinder car btw) so, went on a quest to get a replacement and a couple of spares from the yards, problem solved. I have two spares for Ursula as well as the one she's running with. There are several other items that as I find them will be added to my spares box that rides in the boot
You're almost certainly right - I'm just curious why. Seems super strange is all.
Does anyone have a wiring diagram for the FPR socket? I'm still curious what each of the pins do, and the result of not having Pin 6 connected in my application.
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