Onan marquis gold 7000 questions

[scotty_vince]

I have an opportunity to buy an onan Marquis gold 7000 for $700 from a close relative. He said that it hasn't been used much and that it ran great last time he used it. It has been sitting for about five years and I'm sure it was put away wet. It will start and run when you spray a little ether into the carb. I can here what sounds like an internal fuel pump whir on when I go to start it. Would it be safe to say the carb just needs cleaning, if so are there any tricks or things to watch out for when taking apart the the carb on one of these. Also is this a good deal and are there any other things to watch out for with this? Any info appreciated. Thanks

[Zeroclearance]

Onan units that I have seen that aren't running good take a hit in the asking price.

I will tell you that when you use Ether to start a gas engine you will break the top ring.   Typically a gummed up carb will force one to grab the Ether.   Instead of rebuilding the carb, you now get to pull the engine apart to replace the ringset.   In severe sitaution you will knock the ringlands out.

Of course I am talking from my experience.

[robertglines1]

Dito

[scotty_vince]

So assuming I get it running how can I tell if the top ring is broken?

[robertglines1]

won't have power to carry load...ck compression that should tell you...blow by out of crank case....you might have got lucky..

[James77MCI8]

That is a good genset, if you haven't damaged it yet. I have had one for several years in S&S and it has performed well. Hint: medicine dropper with fuel in it is better on the engine than the ether. Put a few squirts in the carb. Turn the engine over until it runs and nurse it along with the dropper. Most of these units have and electronic fuel pump, You could rig up a hose and feed it from a gas can.

[Zeroclearance]

As Robert mentioned a compression test will tell you that something is amiss.   However, my tool of choice is a leakdown tester.  Roll the enigne to TDC and install the gauge and 100PSI.   You will quickly tell the health of the engine.   The air will either stay in the combustion chamber or leak out the valves or sump vent  ALA your broken or damaged ringset.

[TomC]

Ether should only be used to start a very cold Diesel.  For trying to start a gasoline engine, spray just gasoline into the carb-gasoline is already plenty explosive.
After 5 years, don't even goof with the carb, just go buy a new one-in will eliminate most all your problems.  Also install new plugs and plug wires.  Good Luck, TomC

[tomhamrick]

I had a gas 7000 Onan Marquis for 10 years and had to replace the carb 2 times due to gumming up. One problem is they seal the adjusments screws so you can't work on them. I did have a mechanic friend tell me AFTER I traded for a diesel genset that in order to clean the carb you can drain the bowl and fill it with carb cleaner. May have to do that a few times for a real dirty one. I cannot validate this since I never tried it. The 7000 was also borderline for my use and on long and hot trips would just quit and I would have to let it rest. I now have a 12K Martin with a Yanmar engine and have been very pleased.
Tom Hamrick

[eddiepotts]

I blew my sons go-kart up with ether once. It pulled the bolts out of the rod. It did run good on it for about 1 second and locked up. You would probably get the same look telling someone they don't get AC as I got when I told him he could not ride anymore. It made me buy a new one

[JohnEd]

Before I put up my gen for a long period I run the crab dry.  Next, I put the fuel pick up hose in a gallon can of Laq. thinner and start that bad girl back up.  After running for a minute I pull the hose out and let her run dry again.  My dirt bikes and all started on the third kick or pull after siting for 6 months.  Laq thinner leaves no residue and is a solvent for the gum that gas leaves behind so start a gummed up carb with Laq thinner and if it won't light off use carb cleaner spray in the carb to get it started and keep it running long enuff to get fuel moving thru the carb till the gum is dissolved.  I have treated cars and lawn mowers and dirt bikes and genys like this and resolved many mamny problems without touching a wrench and I have never had a problem.  YMMV

John

[Ncbob]

Gentlemen, I keep advising you. Take the model and spec #s to your nearest Cummins/Onan dealer and buy the service manual for the unit for less than $15 and save yourself a lot of aggrevation.

NCbob