I need some help with my small generator. Its a 7.5K unit with a 14 HP briggs and stratton gas engine. The problem I have is this: the engine will start and run but it will die after say, 5-8 seconds worth of running. It will run up to its operating speed of 3600 RPM. While watching the engine throttle control, when it starts to die I see the govenor open the throttle more all the way to wide open as the engine dies. It does not stumble or hesitate, when it dies, it acts like you hit the stop switch. I have cleaned out the carberetor twice now. I thought it may have been a sticky needle but I don't think it is that at all. The float moves freely, and the needle and seat are clean.

I am open to any ideas. I really want to get this running soon, especially since we had a power outage last night .

 

Good test, remove nowl and lightly pust float up, with fuel on, release the bowl gently if it no fuel comes out its sticking. I dont know if has electronic ignition but that can cause it as well, a local small engine shop can check your ign. Does it fire right back up ?

 

Yes it starts back up, kinda. It takes some cranking but it will start up and run like a champ until it dies again. AFAIK, it does not have elec ignition.

 

Sounds like it runs till the bowl is dry, then time elapses giving the bowl long enough to fill back up, then runs till dry again.

How about the line from the gas tank to the carb, or is there an inline filter between the two that could be partially plugged?


phox

 

the bowl won't run dry in 5-8 sec. does it have an auto idol switch? if so turn off, then try. lots of gens that I've used have had bad senders for the idol feature-causing them not to stay running

 

I agree with everyone else, if it's running great then dies and the governor arm is saying "more power Scotty!", it's fuel. If it was running rough, I'd say ignition. Most issues I've seen with ignition is either the coil fails, or fails when it gets hot, or the capacitor is weak. Yours doesn't sound like either one. If it runs for a while then dies, it sounds like you're only running on what is in the bowl. So, you either have a float stuck or a fuel line restriction. Does it have a vaccuum assist fuel pump on it? Pull the fuel hose, run some gas through check and see you get good flow. If you can spray some carb cleaner in it right when it starts to die and it takes right off again, you'll know it's fuel for sure.

Edit: Does it have a "low oil" or "oil pressure" safety switch? It may have went bad and kill the engine if it thinks its out of oil.

 

1. Drain fuel tank, clear all fuel lines and refill fuel tank, clean carb with spray cleaner. Sounds like water in fuel syndrome, but fuel filters on newer models are in the tank.

2. Check oil level, fill until running out, drain and replace oil, fill until running out, disable oil sensor in that order.

Works for Hondas and I'm Honda certified

Rick

 

First of all I want to thank everyone for their suggestions.

I did some troubleshooting tonight, and here is what I found:

I first pulled the feed line off of the carb that comes from the tank. When I opened the tank valve, fuel flowed freely from the line. Tank, filter, and feed line eliminated.

I then re-connected the line to the carb and took the bowl off. I then raised the float and turned the fuel valve on. Every time I raised and lowered the float the fuel flowed and cut off normally. Fuel float and supply eliminated.

I then ran the engine and when it started to die I sprayed a burst of carb cleaner into the carb. It didn't change a thing. That made me think that the ignition was getting cut-off. When I re-started it, it took right off as it sucked down the residual vapors from the carb cleaner.

Now, when I ran it once I watched the oil pressure LED. When it died the LED lit up and went out when the engine stopped rotating. The LED is a joke, I was trouble shooting this thing at night and barely saw the light at all, and I only saw it since I was looking directly at it.

This is when I checked the oil pressure sensor. I pulled out my multi meter and checked it out. The oil pressure sensor is really a oil pressure switch. With no pressure the switch is shorted (closed). When the pressure comes up it is supposed to change states to open circuit. When I ran the engine again, the switch did not open. I then disconnected the switch completely. There is only one wire on the switch. After I disconnected the switch and started the engine (again), it ran normally and didn't die. So, it appears I have a bad oil pressure switch (the engine is full of oil and i don't hear any knocking noises to indicate loss of oil pressure).

And after reading the manual, it confirms the oil pressure switch, kinda. The manual says there is a time delay circuit on the control board that ignores the switch for the first 8-10 seconds of running, to allow the engine to start and build oil pressure. Also there is an ignition interlock that prevent the engine from starting 5-10 seconds after a low oil shutdown occurs. After the 5-10 seconds the interlock is reset. That explains the long cranking after it died, I would crank the engine until the interlock reset and enabled the ignition circuit. Also, the throttle control works on its own, its is controlled by the speed sensor only (to keep the output at 60 Hz). As the engine slows down the throttle opens wider to keep engine speed up.

So , thank you again to everyone, I appreciate the help.

 

so are you gonna go and get a new replacement just for the sake of having one on there in case oil pressure does die for some reason?

Good troubleshooting, that is what small engine problems is all about.

fuel, air, fire is all you need. Oh and a little compression helps too.

 

Pretty sure what you are seeing is the govenor working? Good work JRS!

Geico commentary: Briggs & Straton (BS ) are crappy motors. It has always made me mad that Honda is such a far superior motor than BS. Why can we make a good motor like Honda?

 

Yes, I do plan on getting a new sensor. I don't like leaving things broken like that. All I have to do know is find a source for the switch.

 

we have a 6.5kw on the boat. guy thought it was bad, it did the same stuff
as you described. we delved into it and found a bad o ring. works fine still!

 

most NAPA's can get parts for Briggs engines...

 

Thats where I found it. I am picking one up later today. We'll see how it works

 

Change the oil while you're at it! 30w nondetergent is Hondas recommendation , My new briggs recommends full synthetic.

Rick