The infamous 15528707 fuel pump relay.

thomas · April 25, 2019, 07:38 PM

Latter this same day !!! I remember that I used a piece of "like gauge" wier to jump across diferent pins on the pig tale or wier end that plugs into the rely!! AND the pump dumped gas real fast into a bucket!!

Rickf1985 · April 26, 2019, 09:23 AM

Thomas, I wish there was more I could tell you but you are working on a coach that I don't have wiring diagrams for so basically all I can do is give advice based on GM and Winnebago diagrams. We have been over that stuff several times now. I would completely forget about trying to get the original relay working at this point and retrofit a standard Bosch relay into it. You can wire it so that when you hit the starter it will activate the pump while the starter is cranking and that way if the carburetor is empty you will get gas right away. Once you stop cranking it will revert back to the oil pump safety switch. You have to remember that the carburetor has a bowl full of gas and unless it is sitting for long periods you have a reserve in there which is plenty to get started on. Plus you have the mechanical pump on the engine which, if it is good, should provide some gas. The electric pump is supposed to just be an auxiliary. I have been really busy lately with doctors and trying to get my yard cleaned up so I don't really have time to talk on the phone unless it is absolutely necessary.

I suggest you read through this thread starting on the second page, It should give you all you need to know to retrofit in the relay and also will give you a picture of all the diferent Bosch relays and part numbers and explanation of the right one to use.

http://www.classicwinnebagos.com/forum/index.php?topic=8795.25

tmsnyder · April 26, 2019, 11:31 AM

Jumping the connector is the way to test the pump. It also means that the fuse is good, b/c the pump is getting power. But in case you didn't find it, the chassis would have its own fuse panel or panels. Try on the firewall near your left drivers foot. (assuming this a left hand drive?) Also under the hood may be one, it's been a while since I had an 80's chevy van though. Try YouTube for people working on 80's chevy vans to see where fuses are, or service manual.

So you've narrowed it down to the relay. Try the ones you have. Just b/c they look good inside doesn't mean they are. They could still be fried. If neither of them work then you need to get a good one or do the modification to use a common relay as a swap.

I'm not surprised that the relay referenced in the above post didn't work, the pins look to be arranged differently than the original.

tmsnyder · April 26, 2019, 11:37 AM

Here is an excellent excellent writeup, with a wiring diagram!! to show you how to wire a replacement generic relay to work.

The little bit that the relay won't give you is a 5 second priming of the carburetor, so this is done with a momentary switch which you would hold for 5 seconds before cranking over the engine. Then it will operate as original after that.

http://www.barthmobile.com/eve/forums/a/tpc/f/3631087061/m/5893981467

thomas · April 26, 2019, 03:33 PM

THANK YOU!!! Rick and T S !! I went to Phx. Az. yesterday and pulled two of those 707s from wrecked , 80s R Vs ,opened them up and they were like new inside (made in USA!) Pluged them in without the covers on to see if THe swithch with the set of points would work,nothing !! no buzz either! I will rewire the new type in real soon! but just wanted to see if I could ,is the blue one!use the original type relay, specialy if I could get 2 used one from other RVs... IF YOU are willing!!! I would like to try just a few more tricks!!?? the Plug end has 5 wiers,the one thats hot when the key is on is the blue one, I jumped it to the tan one and thats how I got the new pump to run! Ive read ALL the post on this subject way back when i first joined the fourn, s0 Im up on everything to that point! I just wanted to see if I could find original one!! ANYWAYS!! I also had a new relay th ................. I did something on the key board!!just now that cleared about 5 or 6 lines!! so ill stop now!!!??

thomas · April 28, 2019, 12:29 AM

O K !!! 04/27/2019 FOR those of you that are familar with the history on this relay like Iam! 1st: rick,did you ever get any of those relays so you could check them out like you said you wanted to? 2nd:Ive now have 3 of the "707" type relay and one rusted one from my RV, I need to know a few things to go on! IM not sure Im getting the right power from my ignition switch to run the relay! I have no hot wiers with key off, and I only have power to the blue at the relay plug! when the key is turned to "ON" should I have another hot wier besides the blue one?? to run that original relay? the blue is at the "85" pin with key on.! When does the relay get power to the "30"pin to switch between "87/87a" ?does it happen when I go to "start"?? Should I at least hear AND see ( I have the cover off the relay) see the contacts start clicking?? WHEN I first bought this RV it workred fine ,I lived in it all for my work, not much travel at all! I did clean the motor occastionaly at car wash then park it again,I think thats when I forced water into the relay,, because it got harder and harder to start over time, I tried to run it every few weeks!! SO IM thinking that all I need is to replace the relay with a clean dry one, the 3,I have are like new inside ,even that week spot in the solder that evryone was posting about in 2016!!are not a problem !! I cant get acess to the electrical manuals yet to see what wiers are in the ignition switch!! OR to read how the starting steps are when the key is turned! THANKS!!

thomas · April 28, 2019, 12:35 AM

P.S. I have a paper clip jumping the oil presure switch,! so the power goes right on through without the motor being on first!

Rickf1985 · April 28, 2019, 10:46 AM

Do you have the 86 pin running to ground? You have to have that pin grounded for the coil to close the circuit when power is applied to pin 85. This will activate the relay and close the circuit between 30 and 87 and send power to the fuel pump.

The CORRECT wiring for a Bosch relay is as follows. Ignition in on pin 86 (this will be the wire from the oil pressure safety switch). Ground out on pin 85. This is what will actuate the relay to power up the pump.

Battery power through a 25 amp fuse in on pin 30. Power out to pump on pin 87.

NOW, You might or might not have a magnetic starter relay on your coach, most heavy duty GM's had one mounted over top of the alternator. If you do then you run a 12ga. wire from the STARTER side heavy battery terminal to the pin 87A terminal, This will run the pump only while cranking.
If you do not have that starter relay then the safest way to do it is to put in a primer button. You really should not need this anyway.

Here is the relay you need and I strongly suggest you get the matching plug to go with it.
https://www.amazon.com/Bosch-332019150-Relay/dp/B0010ADJIE/ref=asc_df_B0010ADJIE/?tag=hyprod-20&linkCode=df0&hvadid=312026024613&hvpos=1o3&hvnetw=g&hvrand=4453006682325298170&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003783&hvtargid=pla-568137619883&psc=1

thomas · April 28, 2019, 07:07 PM

IN the motor home manual is a diagram at (A7-7-7 ) for the oem relay! what I need is to know what nunber to put with the 5 wiers, 30,87,85,ect:I know Im looking at a contcts and a coil, but I dont know how to label!! Then i can make sure each wier goes to right place!! SO, Pin #4 on original relay is drk blue wier,andcomes from oil switch, so you said that makes it #86 ?? I would like to find out how to label the other 4 wiers! ( HEY! IS there a manual of the p30s that just has the elestrical?? I thought I read that GM split up the manual that way!! is there one in our library??) I wish I could find out how that other member ,recently, just pluged in the replacement relay,and it worked just fine!!!???(1r1240)? I did try manualy squezing the contacts closed with both relays pluged in and key on, nothing! That new replacement relay (1r1240) looks exactly the same out side ,but inside it doesnt have the small circut board inside ,,just coil,and contacts! I also had said that I need a diagram of the ignition switch,to see if I have all the wiers that its suposed to have!