Thread Tools Display Modes
Old 08-18-2016, 03:43 PM   #1
Junior Member
smitty31093's Avatar
Join Date: May 2016
Location: Warner Robins, GA
Posts: 16
Onan Cummings 5500 EFI Generator

FYI, If you buy a trailer that is "prepped" for an Onan generator be aware that it is only prepped for a carburetor generator. I recently bought an Onan 5500 Electronic Fuel Injected (EFI) generator for my 2016 Vengeance 320A Toy Hauler. The generator looks just like a carburetor model and bolts up in the trailer exactly the same. The differences are in the fuel lines and the fact that the EFI units have to have an external electric fuel pump. The carburetor units only need a fuel supply line and a return line to the catalytic vapor canister for fuel vapors (only). My EFI unit has to have a fuel supply line and a return to fuel tank line for liquid fuel. Since I didn't know this, I had two fuel line barbs on my generator set (1/4" and 5/16") and the prepped hoses on my trailer were the same sizes. I naturally connected the small hose to the small barbed fitting and the larger hose to the larger barbed fitting on my generator. The generator would not prime nor start. Convinced the generator was not getting fuel, I dropped the fuel supply line into a 5 gallon gas can. The generator primed and started immediately and ran like a champ. The generator quickly sucked the gas can dry and returned most of the gas to the on board fuel tank just like it was designed to do. I talked to the techs at Camper's Inn in Byron, GA where I bought my trailer and they told me to reverse the fuel lines. I used some adapter fittings and changed the large hose to the small barbed fitting and the small hose to the large barbed fitting on the gen set. The unit primed right up and ran like a champ. After a couple of minutes I decided to turn on an AC unit to see how the gen operated under a load. As I walked to the side of my trailer I noticed gasoline spraying out on the ground at the rear of my trailer. I immediately turned the gen off. Long story short, no one at the dealership had ever had any experience with an EFI generator set. When the liquid fuel from the return side of generator went in the fuel vapor line it filled the carbon canister with gasoline and it then came spilling out the vent line. That being said, if you buy and EFI generator be prepared to run an additional liquid return line to your on board fuel tank. My gen set does not have a vapor return line. Vengeance/Forest River factory offered no help. The dealer is going to replace my carbon canister since their techs told me to switch the fuel lines around. I will be dropping my on board fuel tank and adding a return liquid fuel line myself. Hopefully the manufacturers will start offering units prepped for EFI generators since they are the wave of the future.
Steve & Paula Smith
Warner Robins, GA
New 2016 Vengeance 320A
Previously owned: 2014 Vengeance 25V, 2011 KZ 184,
2011 DIY 7 x 14 Enclosed Trailer,
Motorcycle pull behind cargo trailer with tent
smitty31093 is offline   Reply With Quote

500, generator

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Virginia Campgrounds

Reviews provided by is not in any way associated with Forest River, Inc. or its associated RV manufacturing divisions.

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 08:28 AM.