Onan Marquis 7000 cutting off

[sqzdog]

Hi- I am new to the forum with my first Class A. It has an Onan Marquis 7000 that is running sluggish. It only runs for no more than 5 minutes at a time. Sometimes the exhaust is black.

I have never had a generator before so I don't know where to start. I am fairly handy and willing to tackle this myself with the proper guidance.

Thank you!

[ga traveler]

it is almost impossible to troubleshoot with this little imformation. However black exhaust is a sign of running rich. I have had a big problem with chokes hanging up on the marquis gen. Start the gen. then check to see if the choke is coming off. If it is, next check the air filter. make sure it is not blocked. This is the place I would start.

[sqzdog]

Sorry, not sure what other info is needed to help diagnose the problem. Will check the choke tomorrow and post back. Thanks

[RJay]

I'm assuming you have a gas generator. There is usually a winter/summer setting on the choke. Could it be it's still set for winter from the end of last year?

[sqzdog]

It is a gas generator and is not in winter mode. The guy that had it before told me he had some recent trouble with it running and showed me that he loosened three screws on the round thing that has a wire attached to it. As he cranked the starter he slowly turned this round thingy until it started. Once started, he would tighten the three screws. From my service manual this appears to be a choke heater? Regardless, I didn't find this method much help.

The previous poster mentioned checking the choke but I will have to read the manual to see how to do this.

[RJay]

It sounds to be like the previous owner was playing with the choke to start it. I suggest you consult the manual on adjusting the choke. I wish I could tell you how to do it but I never had to adjust the choke on my gas genny.

[ga traveler]

Quote:

Originally Posted by RJay I'm assuming you have a gas generator. There is usually a winter/summer setting on the choke. Could it be it's still set for winter from the end of last year?

rjay the summer/winter selector on the air filter housing, has nothing to do with the choke. It has to do with the EPA. In summer setting, cool air is drawn in around the filter housing. In winter setting a diverter flap closes and brings heated air through a black plastic hose that runs back to the cooling shroud. It is important to change to summer setting, so you don't draw in the very hot air to the engine.

[ga traveler]

Quote:

Originally Posted by sqzdog It is a gas generator and is not in winter mode. The guy that had it before told me he had some recent trouble with it running and showed me that he loosened three screws on the round thing that has a wire attached to it. As he cranked the starter he slowly turned this round thingy until it started. Once started, he would tighten the three screws. From my service manual this appears to be a choke heater? Regardless, I didn't find this method much help. The previous poster mentioned checking the choke but I will have to read the manual to see how to do this.

I went to Onan school in Mobile, Ala. The choke was one of the first classes we had. The round thing with the three screws is the choke. the wire running to it, is a heater wire. When the gen. starts the choke heater comes on to realease the spring tension and turn off the choke. If the heater wire is burned out, the choke stays on too long and can flood the engine and kill it. First remove the three screws and unplug the wire. remove the choke. Now check the heater coil with a meter and make sure it is not burned out. If it is, you can buy just the coil and plate from Onan. If it is OK, Reinstall the plate and heater assy. Make sure you put the choke spring end over the choke shaft. It must be interconnected or the spring will not release the choke. Connect the wire and loosely install the three screws. Now rotate the cover until the choke just closes. turn the cover about 1/8 of an in. more if the weather is cool. 1/2 of an in. if it is warm weather. Tighten the screws and you should be good to go.

[sqzdog]

I have attached two pictures with markups on parts I am trying to identify.

I ran the genset for a few minutes. At certain times, I purred like a kitten, then would start running rough and spitting out black smoke. At was at these times I noticed that the vacuum thing was pushed out. When the vacuum thing was pulled in, it ran fine. Once that rod pushed out, it would sputter and stall.

If you click on the images, they get larger and you can read the text I inserted.

[ga traveler]

the vacumn thing is your probem. It is a vacumn operated servo. after your generator starts, the vacumn builds up and manually pulls the choke off. (sorry I forgot about this, but I went to school on this in 1994) (also I am 71 and have a lot of senior moments) Pull the black hose off the servo while the gen is running. feel the hose and see if it has vacumn on it. If you don't have vacumn you need a new hose. if you have vacumn, you need a new servo.

[sqzdog]

I finally had some time yesterday to work on the generator and fixed it right away.

I took the filter housing off the carb and the choke flap in the carb was stuck. Sprayed some carb cleaner on it to free it up and now it runs like a champ.

Thanks for all of the advice.