Community Forums

Shore2Shore · 10-13-2010, 06:15 PM

Hi all

Our 1987 Bounder has been giving issues with starting( mainly with standing for long periods without running,will be sorting that out soon).

It seems to be as I've read on other RV forums to be centered around the oil pressure switch/sender on the engine. Where it signals oil pressure & starts the fuel pump. Only problem being it doesnt register pressure until the engine is running. Without that pressure signal the pump wont shoot fuel 34 feet to the carb!!

Have started it a few times last week, just put more fuel in, but again appears that its drained back down to the tank. So the engine turns over fine, just no smell of gas from the carb or any ignition. Electrics/ignition are fine as when the fuel is right the engine swings into life with no problems.

It has the pump in the tank plus an electric one mid way to the carb (in passenger side storage bay, as placed conveniently by fleetwood.

Just wondering has anyone done this conversion where a momentary switch is placed in the wires from the pressure switch,allowing the fuel pump to work & send gas up to the carb ready to start,turn on key push switch for 10 seconds to get gas then turn switch off & crank the engine.

any diagrams or good guides to do it? I know its a simple mod but never done it before & want to be extra sure before cutting into the wiring!

Thanks in advance for any help/advice

subford · 10-14-2010, 08:31 AM

The oil pressure switch has nothing to do with the fuel pumps until the engine starts.
The Oil pressure switch is bypassed while cranking by the "I" post of the starter solenoid.
If you want to prime the carb before cranking just put a push button (or toggle) switch to put power on the wire that goes to the "I" post of the starter solenoid and turn on the key.

Wire colors may be different:

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Shore2Shore · 10-20-2010, 05:16 PM

Thankyou for the info and the diagrams Subford

Checked it out today with more fuel canned in,still turning over just no firing. No fuel smell with all turning over so imagine it fuel related . Have checked the inertia switch (after spending a while trying to find it!!) that appears fine pushed button to make sure. Now going to find the fuel pump relay & fuse to see if they are an issue.

As it appears that all is original 1987 vintage could it be that the original intank fuel pump is giving issues?reading in other threads you have given advice in it appears this vintage of pump could have issues (aside from normal age factor)

As I've never done any sort of wiring like this before, would you still recommend the switch giving power to that wire on the starter solenoid? Would the power come from a new fuesable wire from the +ve of the battery?

Its just so frustrating that it turned over fine & fired and then ran for 20 minutes or so for 2 days in a row,leaving it a week or so and with some fuel to top off what was used running it no longer fires :( So with that and the lack of fuel smell leads me to believe its centered around the few things that provide fuel to the coach.

Sorry for rambling its just like chasing your tail!!

Dirtbuster · 10-20-2010, 05:41 PM

Will the engine run if you pour or spray fuel in the carburetor? I remember helping a friend 15 years ago on a Ford 460 engine. It had similar problems. If the oil pressure is below12 PSI ( Guessing ) it will stop the fuel to the carburetor. I think I remember a fuel solenoid, somewhere on the engine. We bypassed a few circuits to get it running to get him home. The bad news was his engine was shot. His cam bearings were shot, killing the oil pressure. This was on a older Coachman motorhome.

Try putting some type of fuel in the carburetor, to see if it will crank.

Be Careful!

Shore2Shore · 10-20-2010, 06:13 PM

Hi haven't tried fuel down the carb yet, or starter fluid for that matter.
Will try and find the fuel pump relay/solenoid,although judging by how fun it was to find
the inertia switch I could be looking for a while!!

Thanks for the info

Oh and theres definitely nothing wrong with our 460's oil pressure. Remember seeing on a forum where Subford had posted pictures with the oil pressure connector jumpered together.

subford · 10-20-2010, 07:33 PM

Quote:

Originally Posted by Pauland Ro

Hi haven't tried fuel down the carb yet, or starter fluid for that matter.
Will try and find the fuel pump relay/solenoid,although judging by how fun it was to find
the inertia switch I could be looking for a while!!

Thanks for the info

Oh and theres definitely nothing wrong with our 460's oil pressure. Remember seeing on a forum where Subford had posted pictures with the oil pressure connector jumpered together.

The in tank pumps can go bd but not both at the same time.
Jumper the oil switch for testing and the selected in tank pump should run with the key in the on position.
I could tell you where the relays are on a E-350 for your year but I have no idea where they are on a class "A" back then.
When you find them please post some photos or at least email them to be at:
subford@gmail.com

Oil swith bypassed:

Fuel tank selector valve:

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Dirtbuster · 10-20-2010, 08:20 PM

Before going on a wild goose chase looking for things, let's determine a starting point.

Verify firing, by using starting fluid. If it cranks, start with tracing out the fuel system.

If it does not crank, start tracing out the ignition system. This will at least get you started in the right direction!

Shore2Shore · 10-20-2010, 09:19 PM

Our class A has only one big 60Galon fuel tank and 1 intank fuel pump. It has an electric fuel pump a little past the fuel tank/intank pump to push it the rest of the way to the engine.

Doesn't appear to have a mechanical pump on the engine. There is a large canister fuel filter with unscrewable case(seperate filter element) before the electric fuel pump and then a Wix 33032 filter half way along the chassis & carries on up to the pressure regulator & holley/motorcraft carb.

As for the wild goose chase you cant help it on these old rigs! The wiring under the hood/dash/and even the instrument panel (which hinges up) is a maze of wires, connectors, relays and such, the manuals help, as does knowing the parts are from the E350 of the same era.

subford · 10-21-2010, 06:01 AM

OK one tank makes it not as complex wiring diagram for the fuel system.
You will not have the electric valve, dash selector switch and the tank selector relay.
You can still jumper the oil switch as in the photo above and turn on the key and both fuel pumps should run as long as the key is on.

Do not run the pumps very long this way as the one on the frame needs fuel for cooling or it can go bad.

If you hear the one on the frame run and the one in the tank not running check for power and ground on the pump wires first with a test light (do not use a meter as they will not load the circuit and will give a bad value). If you have power across them then the pump is bad.

If the pumps do run then go after the Fuel Pump Cutoff relay. It may have bad wiring to it.