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Subject: Why 2 fuel pumps? 1 electric 1 mechanical

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stacey honn User is Offline

Not a Newbie
Posts:28

Registered Users

03/08/2008 7:08 AM
Hi Guys, Bought a 29' Vogue last year and I'm starting to fix and poke around on her now. I have the 2 pumps but my electric one is hooked up to a toggle instead of the ignition. What I've typically been doing is turn the key, let fuel build up, start her up and shut off the pump. The electric pump also seems to get fuel to the onan so that fires up really quick also. Running down the interstate at 65-70 without the pump on seems to have no effect on performance at all. Any thoughts on that? Another thought I'm pondering is the alternator and the sustained switch to charge the house battery. I notice my my volts fall a bit and I'm wondering if it's healthy for the charging system to do that? Stacey

rnr42005

Classic Camper
Posts:105

Registered Users
melbourne, fl.

03/08/2008 8:14 AM
the mechanical pump becomes "strained" trying to pull fuel that far. our MH has the mechanical and an electric run through the key switch. still have to let her sit with the key on for about a minute before she has the pressure to start up. our genset draws straight from the tank. sort of scary to think about it being fed from the chassis pump. pressure being to great would be a first concern. second, if you were boondocking, you could run the tank dry and be stranded!

1986 Fleetwood Pace Arrow Me, Wife, Daughter and two dogs EVERYTHING IN MODERATION...INCLUDING MODERATION

stacey honn User is Offline

Not a Newbie
Posts:28

Registered Users

03/08/2008 8:22 AM
I've read the onan shuts off at a 1/4 tank.

COOPERHAWK User is Offline

Moderator

Expert
Posts:838

Administrators
East Central Minnesota

03/08/2008 10:38 AM
I'm going to date myself here, but when I was a lot younger I drove tractor-trailer for several years. The first large rig I drove was gasoline powered and was huge. It had two fuel pumps as well. The reason was that during the Summer when it got really hot the gas would boil in the carburator bowl and cause "Vapor Lock". Then I would switch on the electric pump and it would provide enough pressure to overcome the problem. I was really happy when I was moved into a diesel. They don't vapor lock.

1985 Airstream 345 Turbo-Diesel VFW,Legion, NRA FAA Air Traffic Control Supervisor (Retired) http://www.cooperhawk.net mailto:jimcooper@cooperhawk.net "People are okay in ones and twos. After that number they tend to choose up sides and wear arm bands and berets."

GordN

Camper
Posts:87

Registered Users
Pictou County, Nova Scotia

03/08/2008 12:44 PM
Posted By COOPERHAWK on 03/08/2008 10:38 AM I was really happy when I was moved into a diesel. They don't vapor lock. That is true but be aware that if you are doing any driving in sub zero weather the fuel that you normally get in the summer will turn to gel. If you are going north, only buy enough diesel to get you to the areas where you can buy weather adjusted fuel. We change our diesel configuration 3 to 4 times a year depending on how cold it gets. The basic difference is that the amount of parafin is reduced and replaced with a conditioner lubricant. Otherwise the parafin will solidify and block your filters. DO NOT USE METHYL HYDRATE. Use only 95% or greater Isopropyl alcohol or a commercial diesel fuel conditioner. I operate 2 diesel tank trucks and even here in "mild" Nova Scotia we get gelling.

1996 Georgie Boy Cruise Master semi retired heating oil distributor Rotarian

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