location of fuel pump relay, '84 Sportscoach Cross Country P30?

[sandlappa]

No fuel to carb. Mech. fuel pump on engine, electric aux pump on pass. frame rail @ tank. No power to electric pump when key is on. I can't find any info that tells me this unit has 2 pumps. Can someone confirm that there IS a factory aux pump on this unit, or is this an add on by previous owner. Just want to know if there is a relay somewhere (and where) or if somebody added this on and I need to start tracing wires. All fuses have been checked, and the only relay I found under the dash that was obvious was the horn.  I did check the manual pump, finger over hole while turning motor over, and it seems to be in good working condition.


   Thanks Y'all!!

[DaveVA78Chieftain]

According to the Chevrolet MH Chassis Guide (appendix 7-7), they did not start installing a OEM electric pumps until 1985 1/2.  So, yours would have been added.  That manual is available to site members for free in the members section.

Dave

[sandlappa]

Thanks Dave!! Exactly what I needed to know. Just crawled out from under this beast, tracing already...and thanks for the heads up on the Chevy MH Chassis guide, was not aware.


      J.

[sandlappa]

ALRIGHTY THEN.... Hm? Seems the electric pump IS original, traced the wire ALLLLLLL the way to the AUX/MAIN fuel switch on the dash (chased it through what seemed to be factory wire shielding, bundled with 2 other shieldings and the fuel lines). If not installed by Chevy or Sportscoach, possibly by the dealer as an option?  i??   The rig has 2 tanks, 1 plastic tank centrally located just behind the rear axle, and an aluminum tank (smaller) under-mounted on the drivers side a few feet behind the drivers door (separate filler necks). No electric pump on the AUX tank, assuming the one on the main is a booster(?). I also located the tank switch on the outside of the passenger frame rail not far behind the front tire, it looks to be intact and functional.
I've tested the leads on the dash switch, and am only getting 5 volts or so on 2 of 6 (I think) (switching it also...of course). I'm tempted to run a line right to the fuse panel and find a switched hot for the pump, but have all ideas I'll be loosing the use of the dual tanks.


  Any advise is greatly appreciated!


                 J.

[cncsparky]

Are you sure the wiring you chased to the dash isn't the fuel level sensor?  My Cross Country also has an Aux tank, just for the generator gas according to the brochure.  The Aux/Main switch on the dash is for checking fuel level of the Aux tank.  My switch on the dash, press and hold for the aux tank level then release and it goes back to main tank level.  Its a 1988 model and has the factory in tank booster pump on the main tank.  There is a series of 4 bosch relays near the radiator, one of them is for the booster pump from what I understand. 

[sandlappa]

Thanks Sparky. Yeah, I'm sure. Traced it from the pump (main tank) right to the switch. And mine isn't a temp. toggle, it switches up for aux and down for main. The Aux tank line runs to the tank switch valve I found, I haven't traced the line that feeds the genny. I currently have the radiator out having it re-cored, and thought for sure I'd find relays in-line somewhere, but no luck. That wire runs right to the switch, no break. I'm thinking there might be a relay in-line before the switch (bad possibly, that would explain why my voltage on the switch is only 5 or so), but you have to be a contortionist to look up behind the dash there, and they added a coach alarm on this thing at some point in the past and left a rats nest of wires under the steering column. I did remove the instrument cluster late last night for access, but that was the end of my day, and won't be able to get back to it until later this evening.


  Again, thank you, every little bit helps!!


                    J.

[cncsparky]

Either the main/aux switch or the fuel valve will switch the fuel sending unit wires between the tanks.  If you are on one of the sending unit wires, it could read lower voltages like the 5V you are seeing.

[sandlappa]

Gotcha....that makes sense. Got some time today...gonna get to tha bottom of this!!


     J.

[sandlappa]

Had to trace all wires from switch to see what was what...found that someone did NOT know what the    they were doing when they did some re-wiring and had spliced the power wire to the switch to one of the wires to the oil pressure sending unit.  i??  Shot power to that terminal on the switch and  ....got power to the pump when it's switched to main. SWEET!!

[Stripe]

Groovy..  Good to know you got it licked..

[cncsparky]

Actually, it should be wired to the oil pressure sending unit.  It is a safety, if the engine dies then the fuel pump stops, critical if you were to wreck. That is the way the factory did it. 

-Edit.  It should be wired to a separate sending unit from the one that goes to the gauge.  Mine has two sending units.  Maybe that was wrong on yours?