Onan Generator Won't Start

[JLR]

Went down to the boat yesterday an my 8KW Onan mdkb diesel genset won't start. When I shut it down last week, it worked fine. Now, it cranks fine but won't catch, almost as if it was receiving no fuel. Does anyone know whether these units have electric fuel pumps? Any other ideas are also welcome. BY the way, I do hear the glow plugs pulling on my charger so I am pretty sure they are working fine.

 

[Trojan]

Sounds like a fuel problem. Try priming the pump by hand, maybe it lost its prime from setting. You could also measure the voltage at the glow plugs just to be sure.
BILL

 

[JLR]

Had the genset repair people coming this week for another issue so I guess I will leave it to them. Very unusual symptoms for a diesel genset that had been working fine when last shutdown.

 

[34Hatt]

Did you mean to type Mdkd If so that is what I have and it does have a electric fuel pump. I also hear it come on when you hit the switch.

 

[JLR]

Dan - yes, thank you.

 

[outnumbered]

Have experienced several problems with similar model -
One case:small red pop-out on reset didn't physically pop out but was interrupting circuit - replaced reset breaker , fixed.

Also, check fuel shutoff solenoid and linkage as well as real oil level.

Good luck, tight lines
Outnumbered38C352

 

[JLR]

Thanks as well. I know the red breaker did not pop out as I checked that- although you said yours did not either. While I am never surprised about failures on the water, the darn thing ran perfectly and shut down perfectly the last time I ran it.

 

[Jim_n_Naples]

Must be something in the air...Last week gen was fine all weekend yesterday went to light it off and nothing...not even a click voltage is fine, oil fine, coolant fine just nothing...not even a call back from the tech

 

[Captcoop]

There should be a white button at the panel on the unit. If this is out the unit will not start. There is a oil pressure switch that will not let the engine start without pressure. If the pressure sending unit has failed it will trip this breaker and not allow the engine to start. I just replaced mine and now it starts fine. Good Luck

 

[Dave Phipps]

Had a problem with my 15 KW unit last year...same thing; wouldn't even turn over. Has run fine since I bought the boat 5 years ago. Battery OK, etc. Called Onan tech....young guy...factory authorized serive center; didn't know what to make of something you can't hook a computer diagnostic cord up to and read a failure code. Had to order fax of factory wiring diagram from Minneapolis. Eventually, some two weeks, 3 visits and $2300 later.....found a failed start relay inside the control box....

Then another fellow at the yacht club had a similar problem, called same authorized service folks, and you guessed it.....$$$$$ and no quick solution.

In a boat, not only is original quality important, but factory support with knowlegable tech support is equally critical.....even 20 years down the road on a weekend. That's WHY we buy the product...

You guessed it....I'll never buy another "OHNO" again!

 

[Brian Degulis]

Hi I'm not familiar with your unit but most have a mechanical/ electric solonoid that must activate either by pushing or pulling alowing the fuel lever to go into the fuel on position. Most onans have the solenoid pull up which allows the spring loaded fuel lever to come into the fuel on position. Sounds like your solenoid is not working so try pushing or pulling it in by hand and try to start it. If it comes to life then either something in the Oil presure or water temp shutdown system has gone bad or the solenoid itself has gone bad. It's prety easy to check just see if voltage is getting to the solenoid if so it's the solenoid if not it's in the shutdown. One last note some units have a wire running from the starter solenoid to the fuel solenoid. The purpose of this is to provide voltage to the fuel solenoid when the engine cranks until oil presure comes up and closes the run circuit to the solenoid. If you have that it's another posability.

Good Luck
Brian

 

[spartonboat1]

Hi I'm not familiar with your unit but most have a mechanical/ electric solonoid that must activate either by pushing or pulling alowing the fuel lever to go into the fuel on position. Most onans have the solenoid pull up which allows the spring loaded fuel lever to come into the fuel on position. Sounds like your solenoid is not working so try pushing or pulling it in by hand and try to start it. If it comes to life then either something in the Oil presure or water temp shutdown system has gone bad or the solenoid itself has gone bad. It's prety easy to check just see if voltage is getting to the solenoid if so it's the solenoid if not it's in the shutdown. One last note some units have a wire running from the starter solenoid to the fuel solenoid. The purpose of this is to provide voltage to the fuel solenoid when the engine cranks until oil presure comes up and closes the run circuit to the solenoid. If you have that it's another posability.

Good Luck
Brian

Good suggestions...if the auto shutdown oil pressure or water temp sensors malfunction, unit will shut down, or not start. My dumb suggestion includes WD-40 on any moving parts, esp. solenoids. My starter's solenoid that "makes up" the power to the starter had become stiff over the winter and some WD-40 and a few manual movements did the trick.

 

[TedZ]

Lift the rack up by hand i.e. the selenoid should get pushed in by that process. If it has fuel it will start and likely keep the selenoid retracted. Let go after it gets to speed...don't overspeed the generator. If it won;\'t stay retracted, now you know the problem and you can do the electrical trouble shooting, likely the selenoid ground.

Ted

 

[JLR]

Thanks for all of the suggestions. I should be in a position to report back on the solution by Thursday.

 

[JLR]

It was the fuel solenoid. Fixed now and up and running fine. Thanks for the help.

 

[Milacron]

1993 vintage Onan 20kw, two of them, after months on the hard, today back in water....both generators started and ran perhaps 30 seconds and then quit. Finally got the port generator to run and stay running by keeping the priming motor button pushed and opening the two small valves attached to hoses going to and from the priming motor. On the theory these valves should normally be closed to keep the fuel in the filter from draining back into the tank, I closed them after a few minutes and now the port generator starts and runs fine with them closed.

So, I figure, ahah..that's the trick. But the same procedure does not work on the starboard generator. Which is ironic as that one has less hours and previously ran perfect always. I can loosen the brass nut where fuel goes into the injector body and it is getting fuel via the electric prime pump....can small diesels like this get flooded with too much fuel ?

Also can some one confirm that the primer motor hose valves should normally be in the closed position ?

 

[Avenger]

No they can't flood. Did you crack any injector lines to see if the injection pump is delivering fuel to the injectors?

 

[nautibake]

1993 vintage Onan 20kw, two of them, after months on the hard, today back in water....both generators started and ran perhaps 30 seconds and then quit. Finally got the port generator to run and stay running by keeping the priming motor button pushed and opening the two small valves attached to hoses going to and from the priming motor. On the theory these valves should normally be closed to keep the fuel in the filter from draining back into the tank, I closed them after a few minutes and now the port generator starts and runs fine with them closed.

So, I figure, ahah..that's the trick. But the same procedure does not work on the starboard generator. Which is ironic as that one has less hours and previously ran perfect always. I can loosen the brass nut where fuel goes into the injector body and it is getting fuel via the electric prime pump....can small diesels like this get flooded with too much fuel ?

Also can some one confirm that the primer motor hose valves should normally be in the closed position ?

Interesting, I have a completely different genset, but very similar issue. Isuzu / Triton 21 Kw runs maybe a minute or two and then dies. The 2nd or 3rd try she runs for days at a time. Wondering if I have fuel running out of the filter when idle?