Generator doesn't run - where do I start?

Started by 76PRROW, May 10, 2015, 11:44 AM

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There is a 7K onan gen set. dont even know where to start with getting that to run. I assume I need house batteries to start it and potentially the aux. fuel tank.


As per your disconnected aux tank question, yes you do need the aux tank because that's what the generator is connected to for fuel delivery.  But... you can troubleshoot the generator without it, you just have to hook-up a temporary fuel source.  Then see if it will run.

As for where to start from there:

Get the manual.
We have a gazillion generator manuals.  You'll want to get the one for yours so you'll need the model number so you can get the right one.

It will give you the troubleshooting methods right there, rather than using guess, ask, wait, try, repeat method.. And, you can confirm what you're doing and get additional guidance from our members along the way!

1969 D22, 2 x 1974 D24 Indians, 1977 27' Itasca


Just realized something, apparently I have a really strong generator, according to the manual it puts out a whopping 56 amps.  I do not care for that. My plan was to purchase a 200w solar kit anyways. Silent power. Thinking I should attempt to get it running and sell it to finance my solar setup.


Think'n you might want to slow down a bit. Your enthusiasm is exceeding your ability to fix things . ONE PROJECT AT A TIME. Get it finished and then move on to the next one. Love it, love it when somebody gets excited about there rig. You may very well regret getting rid of your generator if you act to fast. Hm?


I was assured that my 2.5KW Onan ran and worked jus fine when I bought my D20. The seller tried to start it several times, said it didnt appear to be getting gas, but the engine was free and showed me that it was getting spark an all. Since the 440 started and ran jus fine, he thought the genny's fuel source was probably the rear tank, so he put several gallons in the rear tank, but it still wouldn't run. You could see fuel movement in the filter, and he thought maybe the fuel pump was weak. I took a chance and bought the RV anyway, figuring I could easily fix it. I nearly ran out gas jus a mile or two from home, as it sputtered up a hill, but I made it.

A few days later, I tackled the genny problem. I put a lil squirt of starting fluid into the carb, and hit the starter. It fired up a few pops and quickly died. I knew then, that the engine was jus fine and likely had a fuel problem. Filter??? fuel pump?? Lines plugged???

I removed the fuel line from the engine side of the fuel filter, and with my finger over the hose end, I hit the starter and could feel suction pulses from the fuel pump. Kinda weak and still wasn't sure if the pump might be a problem. I used a short piece of fuel line, and rigged up a small fuel can nearby as a source. Engine started right up, and I was delighted to hear it run.

So now I knew I had a fuel source problem. I removed the filter from the tank side, and blew into the hose end. I could feel resistance, but it quickly cleared and I could blow air thru with no problem. But I didn't notice any bubbling of air into any fuel!!! I sucked on the line a bit, but no resistance or any fuel was filling it. Blew thru it, and still jus air passing. So for some reason, I wasn't getting fuel from a tank source, although the line seemed clear, and I assumed I had sufficient fuel in the tank,... rear tank that is. Seller said rear tank supplied the genny, so I climbed under to trace and inspect the fuel line.

THAT'S when I found that the genny is supplied by THE FRONT TANK!!! The lines all the way to the front tank, seemed jus fine. And I knew the front tank was empty, I jus barely made it home a few days earlier. So I poured 5gal into the front tank, and blew into the fuel hose again. Still nothing. I had a helper blow into the line while I listened at the tank. I could him blowing into the tank, but NOT into fuel. The 440 started and ran fine. I thought I had lost a dropline in the tank for the genny. Something serious I would tackle at a later time.

Then I learned that the dropline for the genny was positioned in the tank higher than that of the engine. This is so you never get stranded by the genny running the tank dry. You'll always have enough fuel for the RV engine to get to a station. The rear tank, is an auxiliary, and may be an option!

Anyways, it took another 5gal in the front tank before i could blow bubbles into it from the gennys fuel line. New filter, connected the lines, and in jus a few moments of turning over, the genny came to life again and all was good.

I dont use the noisy genny much, I have a couple big 6V batteries, a 2000W inverter, and no AC. But it's jus me living in this, and the microwave and everything I need works fine. BUT the batterys alone STILL aren't enough. Offline, I can expect the batterys to last 2-3days with minimal microwave use. With fans or furnace running much, about half that sometimes. No way could run an AC system for more than 20min if I had one!!! I have a Boonedocker converter/charger to keep batterys up on shore power, and figured I needed at least an 800W solar system to assist in replacing what power I do use offline every day. Cant afford that yet. So I run the genny when needed, usually while driving on the road so it doesn't disturb anyone, and I'm REALLY glad I have one that works!!!

I'm also thinkin', that you'll be glad too!!! That converter/charger??? It will charge at 65Amps if my genny can supply it!!!
To The Crazy Old Crow Medicine Show
DR Mousseau - Proprietor
Elixirs and Mixers, Potions and Lotions, Herbs, Roots, and Oils
"If I don't have it,... you don't need it!"


The last thing you want to sell is the generator. You will find quickly that solar is not going to power your 110 volt stuff and on a cloudy day it will barely power your 12 volt stuff if at all. Keep the generator.