Community Forums

TitanicPilot · 12-18-2009, 09:35 AM

I just received another email from Donna R. Roe, Sr. Administrative Specialist at Fleetwood customer relations. I'm really impressed with their level of support for our vintage coaches!

Anyway, here is the PDF file she sent:

Quote:

Fuel pumps—P-30 Chevrolet 1980’s

Electric booster gas fuel pump, (Fleetwood installed) 1980’s P-30 Chevrolet Class A
Chassis. This fuel pump was normally located on the outer passenger side rear rail, right
in alignment with the fuel tank. The fuel pump may be a Holly Model ST802 or a Carter
or a Walbro. The engine oil pressure switch normally controlled this electric fuel pump.
After the engine is started, the oil pressure switch sends power to a bulkhead Bosch relay
that then sends power to the electric booster fuel pump. There are two fuses in the circuit.
One for the oil pressure switch, and one for the bulkhead relay.

The Chevrolet OEM vacuum fuel pump was still used and located at the engine front,
passenger side lower area. The additional electric fuel pump was added for vapor lock
conditions and lack of fuel in certain situations.

When the Fleetwood installed electric fuel pump fails, the engine has a hard time running
as the engine is starving for fuel. By-passing the fuel line around the electric fuel pump is
ok for an emergency repair situation as long as a Dealer/mechanic does this as a
temporary repair.

(Note) We have found some Chevrolet chassis that have an OEM electric fuel pump in
the gas tank along with the side mounted electric fuel pump installed by Fleetwood.

I'm going to find a place in the relay circuit to add a momentary contact switch for bringing up the fuel pressure before I start the motor; this should save wear and tear on the starter yet still retain the safety feature.

We're almost there!

whem2fish · 12-18-2009, 10:00 AM

maybe a button you have to hold down that way you couln not forget to turn off
dave

Gary - K7GLD · 12-18-2009, 01:50 PM

AH!

Confirms the in-line electric fuel pump I thought I saw - now I just need to figure out if there's also the other in-tank pump on our '88 - as well as investigate where all the sensors and relays are, and possibly the addition of that momentary switch for starting, especially after longer storage/inactive periods - thanks!

TitanicPilot · 12-19-2009, 05:42 PM

Progress Report & YAHOOO Number 1

Yesterday Marilyn and I combined a trip into town(30 mile total round trip.) for groceries and a visit to Autozone. I got a momentary contact switch and a package of T-Tap connectors. These connectors make it easy to tap into a wire at any point without soldering or even cutting the wire. Vintage owners will recognize many elements in this picture that they may also have on their coaches; ugly splices for no apparent reason, and rusty fasteners.

As you can see, I tapped into the positive control wire of the fuel pump relay. For test purposes I just ran the other end of the wire over to the positive terminal of the battery. As soon as Marilyn turned the ignition switch to "Run", that pesky booster pump started running like a champ! YAHOOO! The fuel line filled up in no time and when I pumped the throttle we got a satisfying squirt of fuel from the accelerator pump... life is good. (*Note, for anybody trying this, the fuel pump relay will latch "On" and the pump will continue to run until you turn off the ignition.)

For the permanent installation I'll install the momentary switch in the dashboard and run a wire from one side of the switch to a +12 volt source under the dash and run the other side out through the firewall to the relay.

Next order of business, try to start the engine.

Dave

Gary - K7GLD · 12-19-2009, 05:50 PM

Where were those relays mounted on your MH? Undoubtedly not the same place mine might be - the only relay like that I have seen, is on the front right side of the engine bulkhead accessable from the "hood" side - but there's only the single relay visible on mine...

TitanicPilot · 12-19-2009, 10:36 PM

Quote:

Originally Posted by Gary - K7GLD

Where were those relays mounted on your MH? Undoubtedly not the same place mine might be - the only relay like that I have seen, is on the front right side of the engine bulkhead accessable from the "hood" side - but there's only the single relay visible on mine...

Ours are also located in the front-most compartment under what passes for a "hood" on the drivers' side, as can be seen in this picture:

Normally there is a cover over the fuse blocks.

Dave

leadman · 12-27-2009, 08:58 PM

We have a 1988 Itasca on a 1987 P chassis. This has a 454 that is carburated and does have a factory in tank fuel pump. This does run for approx. 20 seconds when the ignition is turned on, then will stop if the engine is not cranked. There is also an oil pressure switch on the engine that will cause the fuel pump to quit if the engine is stopped causing no oil pressure.

I would be cautious wiring in a switch that did not allow the pump to stop if the engine quits and the switch is still on.
I had to rebuild an engine once for my boss that was ruind by a customer that left the key on and the engine filled up with gas in the crankcase. The customer did not know of this and ran the engine until it quit. I worked for a rental company at the time.

TitanicPilot · 12-28-2009, 12:11 AM

Quote:

Originally Posted by leadman

....
I would be cautious wiring in a switch that did not allow the pump to stop if the engine quits and the switch is still on.
....

Thanks for the comments, leadman; but as I wrote, my switch is momentary and spring loaded to the off position. It has to be held "on" so there is no chance of the pump running by itself. I don't quite understand why "the engine filled up with gas in the crankcase" if the pump turned off after 20 seconds and there was also an oil pressure-triggered safety switch. The carburetor float and needle must have also failed to allow this to happen. In addition, on our coach, there is a return fuel line from the mechanical pump back to the fuel tank to prevent pressure buildup. Perhaps yours was a different motorhome than the one I am discussing.

I hope that everyone who reads my comments will understand that I am only talking about my particular coach and am in no way suggesting that they modify their own, without fully understanding the implications.

leadman · 12-29-2009, 12:15 AM

TitanicPilot, In post #18 you said the fuel pump stayed on until the ignition was turned off. This is why I thought your pump would be running ifthe engine stopped. Did the permanent wiring correct this?
The engine I had to rebuild was in a rental truck for the company I worked for. Prior to my employment there someone had wired an electric pump so it would run whenever the ignition was on. Your are right that the needle was also a problem. The customer was lucky that the engine did not catch on fire as the crankcase was filled entirely with gasoline. He ran it until it stopped, crank bearing were seized to the crank and turned in the block.
I have not had my "palace" as my wife calls it long, since September. I know there is probably a timed relay somewhere in the system, but will have to look at the wiring schematic to see if it is an add-on or OE.
I'm glad your installation of the momentary switch has correct your problem.