The infamous 15528707 fuel pump relay.

[Rickf1985]

You can buy the 5 pin Bosch style relays on E-bay ten for 15.00 or so but I would buy original Bosch for about ten bucks each. You can get them anywhere. If you are talking about the original relay for the coach they are unobtainium.

[tmsnyder]

Yes the original, like a NOS part.

[Rickf1985]

No longer available. Nobody has been able to find a new one for a few years. A couple members in this thread seem to think they can be repaired, myself included.

[M & J]

Junk or salvage yards would be your only option but that would be coin toss if it worked or for how long.

[tmsnyder]

Using a standard relay seems to not use the oil pressure switch shut off, safety feature.  And the old socket has to be cut off and a new relay socket attached.  Is that the gist of it?


Did anyone ever document pin for pin how they converted from 15528707 relay to RY109 or similar relay?


CDirk; do you have any more pictures of the insides of that relay? 


I like relay logic circuits.  I had an original three speed OD transmission in my 56 chevy sedan and designed a relay circuit to get the tranny to work just as original without having the factory control circuit and switches, which were expensive and difficult to find. When you floor it, the kickdown switch momentarily kills the spark to the engine, allowing the OD to disengage.  One disengaged, the circuit fires up the engine again.  It all happens in a split second, seamless. 

[M & J]

Yes. The oil pressure safety cutoff is removed as well as the 2 second initial key on fuel prime.

[CapnDirk]

Tmsnyder:  I don't have anymore pics of the relay.  There is a thread on another forum detailing the pinout of it.  The oil pressure switch winds up being a latch circuit, and something in there holds power for about 4 seconds to prime the fuel pump even in the absence of  oil pressure.  So, key on (crank or not) 4 second prime, hit the gas pedal to engage choke and crank it.  It will start even in the absence of oil pressure since it is a carb system.


My routine is to turn key on for 5 seconds, off, turn key on and crank.  This fills the float bowl in case it evaporated.


An off the shelf relay with the same plug, and wiring the latch side through the oil pressure switch would be do able.  getting the prime circuit would be the the effort part.  Some here have just rigged a momentary switch on the dash, but a replacement circuit diagram would benefit many who are not comfortable with chopping up their wiring, and these relays are on every 85 1/2 to 89? chev chassis. 


Edit:  Found the post from Dave showing the circuit.


http://www.classicwinnebagos.com/forum/index.php?topic=8795.0

[ClydesdaleKevin]

http://www.classicwinnebagos.com/forum/index.php/topic,8795.0.html



Skip to page 2 in the link above.  This is the relay I used.  Pretty straightforward, except instead of powering lights, it is powering the fuel pump.  Most of the info you will need is on page 2, but feel free to skip to the beginning.

Kev

[Rickf1985]

You can control the relay from the oil pressure safety switch by using the switch to trigger the relay. Another option is Arduino controls. I do not know much about them but I want to learn. You should be able to build a simple circuit to control the relays to get your precharge timeing, safety switch and automatic shut down all in a simple board.

https://en.wikipedia.org/wiki/Arduino

https://www.arduino.cc/

https://www.amazon.com/Arduino-Uno-R3-Microcontroller-A000066/dp/B008GRTSV6

[ClydesdaleKevin]

I kept it simple...and it works.  Haven't had a single problem since. 

[Rickf1985]

As you should, driving to the shows is your livelihood. You don't get there you don't get paid!  But just think, with those Arduino circuits you could build some really awesome catapults !! Let's see, remote controlled, self loading, auto-fire Trebuchet. :)rotflmao   If nothing else you could keep the dogs well exercised!

[ClydesdaleKevin]

As you should, driving to the shows is your livelihood. You don't get there you don't get paid!  But just think, with those Arduino circuits you could build some really awesome catapults !! Let's see, remote controlled, self loading, auto-fire Trebuchet. :)rotflmao   If nothing else you could keep the dogs well exercised!

LMAO!!!

Kev

[bluebird]

Another thing you COULD do is wire a relay to run off the oil pressure switch, and add a momentary switch to fire the relay when needed. That way you would have the safety cut off. You can fire the relay from two different sources without a problem. 


Or just wire it up using the two different sources that are already there.

[DaveVA78Chieftain]

Opps, I posted this on the wrong thread.   That's what I get for being in a hurry

Primer switch, fuel pump run on start, oil pressure switch cutoff?  You guys do realize you keep circiling this drain right?

[CapnDirk]

I THINK  the new question was in regards to duplicating the original for a direct plugin replacement.

[tmsnyder]

Yes it was

[CapnDirk]

I have the dog house open now to work on the heater issue, I'll pop open the relay again and get some more picks.  If I could get picks of both sides, and mirror the component side they could be overlayed and the circuit could be drawn out from that.

[tmsnyder]

No worries, I got one.

[CapnDirk]

An original one, or did you roll your own?

[tmsnyder]

Found one that is NOS.

[ClydesdaleKevin]

My solution...in glorious pictures.

















White wire to fuel pump with inline fuse.  Green wire to ground.  Black wire to battery hot.  Skinny little wire to ignition on, which causes the relay to open the fuel pump circuit when the key is turned on.  Simple and elegant.  Not sure what that other relay is up front...must do something...lol!

Kev

[ClydesdaleKevin]

I used all 10 gauge wire, all the way back to the fuel pump.  Overkill?  Yep!  But you don't know the struggles and sorrows I had with this system...so I used 10 gauge!!!  Except the skinny little wire that energizes the relay when the key is in the on and start position.

Kev

[Rickf1985]

The other relay should be the emissions relay for the pumps.

[legomybago]

Our 1986 P30 rig has that "other" relay...I wondered what it was for. I figured it was for the dash AC or something i?? never would of thought smog

[M & J]

And we love pictures.  Thanks Kevin.