Onan Marquis 7k fuel pump

[billr30656]

Does anyone have the troubleshooting procedures for the electric fuel pump on the onan? I know it has to have 1/4 fuel in the tank. It has 1/2 tank of fuel. I am not getting any fuel up to the filter on the carb. I don't have a wiring diagram for the fuel pump. Is there a fuse on the cab somewhere for this?

[billr30656]

Guess no one has worked on this one. I searched the forums but didn't find anything.

[Flagelpater]

FWIW I would have a lot more than 1/2 tank before I wasted any time troubleshooting. My unit will not run with just under 1/2 tank indication.

[billr30656]

There should be an electronic adjustment for when the electric pump no longer works. Such as a potentiometer to turn down or up allowing us to determine when the pump will not run..ie 1/4 or 1/2 a tank.

[Flagelpater]

FWIW On my rig it is a stand-pipe mounted on the top of the tank extended down to a point above the bottom of the tank floor. It is a ridged pipe near the center. I too would like to see a valve allowing full use of the tank.

[Flagelpater]

On my GenSet switch I can push the rocker the opposite way from Start to run just the Pump for Priming Only. If you have this option you should hear the pump running when this is selected.

[GaryKD]

Hi Bill,
I think Flagelpater has your first step. Try the cheap and easy stuff first. Fill the tank and see what happens.

[Iron Man]

check your flexible line from the tank to the generator. with a 97 model coach the fuel line may have a crack letting the fuel pump suck in air rather than fuel. Have you had problems before with the tank at this level. Had a friend that had a squirel chew throught his generator fuel line.

[billr30656]

IronMan,
No I haven't had this problem before at this level. It use to shut down at 1/4 a tank. I was in Afghanistan when it happened. My wife was running it and it just shut off. I am going to check the fuel line and replace it if necessary. It is steel from the tank to the back of the genny. It is rubber from that point on. When I checked the oil it was very low. I thought that it was low oil because it had nothing on the stick. The troubleshooting chart in the manual says to check the oil in this condition. When I added the oil it still didn't help.

[dajudge]

Bill, try disconnecting the hose from the metal line that goes to the tank and put it in a small gas can full of gas. If the generator works, then you have a problem with the pickup in the tank or need to add more gas. Use a new line from the fuel pump to the gas can.

[Flagelpater]

At risk of stating the obvious, make sure the rig is perfectly level. My rig has the tank fuel sensor only one side. I can get 1/2 full and be well below the stand-pipe very easy. Also, if you had an Auto-Shutdown due to Oil Level is there a Reset required?

[billr30656]

I used your idea with the fuel can. It ran with no problem. The RV is completely level. I fear it may be the pickup in the tank. How hard is that to get to or even to check it?

Thank you all for your assistance on this. I only get home every now and then from Afghanistan for very short periods of time. I just got a new job as an instructor for the soldiers. I will fly to Oshkosh, Wisconsin for 30 days, then to Texarkana, Ar. for 5 weeks and on to Georgia for a week where I will leave to return to Afghanistan. You guys and this site is great for a guy like myself who is limited on time, thanks again.

[Flagelpater]

FWIW Don't trust the Gage. If you can put your mouth on the tube leading to the tank, try to blow into it. I watched Monaco build the tanks and the pipe did not have any type of screen on the pick-up that I could see. Your unit could be different. Just because the GenSet worked okay from the fuel can does Not confirm you are not below the stand-pipe in the vehicle.

[billr30656]

Thank you, I will blow through the tube tomorrow. I got under and gave the tank a look and could see nothing but the steal tube going over the tank. It looks like I need to drop the tank if I have to get to the top of it. Would be nice if there were a door in the floor over it (I wonder). I saw some other problems that I will repair when I get back in 8 months. I have a list of things. I decided to put the "to do" list on a roll of toilet paper. I can tear off a square and repair the ones on it and continue until the list is complete or the roll is used up. Yes I have a lot of crap to repair.