fuel pump relay switch

[Rog___Nan]

We have a '96 Georgie Boy on a Chevy P30 chassis ('96) and a chevy 454. Does anybody know where the fuel pumpr relay switch is and also the fuel pump ? Thanks in advance.


Nan

[MEXICOWANDERER]

As a safety protocol many fuel pumps DO NOT DO ANYTHING when you turn the switch to "ON". The switches are controlled (overridden) by an oil pressure sensor. When the engine is CRANKED by the starter motor the electrical power enables the relay and the pump. The engine starts. Oil pressure rises. The safety oil pressure switch closes and then current goes directly from ignition to fuel pump.

If for some reason the CRANKING override becomes dysfunctional then the fuel pump will not work and residual fuel pressure, luck and crossed fingers will enable an engine to somehow start then run normally.

Just a thought...

[Rog___Nan]

Update. Fuel filter changed both relay switches tested and are good. Unit goes in Tuesday for a tuneup. We head for Covered Bridge Festival , Rockville IN on Thursday. We have never had this done since we purchased it new in '96. We have done all other maintenance belts, brakes 2 sets of tires replaced air bags etc never touched the motor other than normal oil changes etc. so we will see!.

[enblethen]

The relay only operates to prime the engine. It does not operate the fuel pump after intial start up.
That is when the oil pressure gauge sending unit becomes the fuel pump operator.

[64thunderbolt]

If it runs at all the relay is good. Fuel may be siphoning back to the tank. That would probably be the pump.

[sum1]

Rog & Nan wrote:
...We have a long cranking period after it sits for a while, then runs great...

I wish mine would do that. Starting a dry engine does more damage in 7 seconds than we could do by beating it silly for 5000 miles. Back in the carb days, I would set my idles slightly on the lean side and crank the engines without ever touching the pedals if the vehicles had beeen sitting. When I saw oil pressure come up, I would hit the pedal to give it a squirt and allow the choke to close so it would then fire.

[Rog___Nan]

Update - With Bud's help we did find the relay switch!! DH decided to try another local mechanic and he can work on the MH! Hurray only a few blocks from our house. So it goes in tomorrow and they will change the fuel filter (which should be done after 17 years -right!) and then will do a pressure test.
He personally doesn't think it is anything to do with fuel system - because once it starts (which it has started right up every time DH has tried it since I posted) it runs fine. So anyway they will check it out tomorrow - really thanks for the help because it really was helpful. We have put the elemination process in sequence!!!!

[MEXICOWANDERER]

I looked at that relay and it is NOT sealed. Easy to resolve. Purchase SILICONE GREASE at the auto parts store, it is white translucent in color and used a lot of spark plug boots. Glob a bunch of it into the relay socket and then into the plug's electrical terminal slots before you attach (connect) the plug to the socket. Really glob the silicone grease on.

All this is of course pertinent if you need a relay. 🙂

[Rog___Nan]

thanks again. He tried to change filter BUT when big foot levelers were installed one is in the way. So he headed to local mechanic but he can't work on MH's so he just left to see if the place we just had tires installed at will do it if not RV dealership that does repair on Chevy chassis is just up the road from them -- so he will head up there. You sure have been helpful!

[enblethen]

This is what it looks like. Laying on engine from the back, It is just forward of the air cleaner, to the left of the air conditioner pump, mounted on the small wall. It could be partionally hidden by wiring harness.
Fuel pump relay

[Rog___Nan]

Sorry the label has a discription of what he thinks is the switch and where it should be but no luck finding it yet.

[Rog___Nan]

Thanks -- He is going to do that also. Did find a label on the air cleaner under the dog house but still can't locate where the switch is. He is keeping at the problem though and you have been a big help. Thnaks again Nan

[enblethen]

Pressure could be leaking back to the tank. You could try turning the igntion switch on for a few seconds two or three times. This will give the pump more time to get the fuel to the TBI.
Have you changed your filter on the frame rail recently? A clogged or partially clogged filter will restrict the fuel flow.

[Rog___Nan]

Oh yes we are just about to turn over 68000 miles. This has been one great motorhome for us.

[Rog___Nan]

We know it is a 7.4.V8 TBI L19 Engine. We have a long cranking period after it sits for a while, then runs great. Thanks everyone - he has looked in both areas and so far cannot find the switch. Will keep trying. We have the manual that came with the motor home as we purchased it new in '96. We have called Chevy and they switched us over to a mechanic who said take it in for a pressure check -- but if we can fix it without all that cost we sure would like to do that lst. What do you think Bud?