NorthStar pressure washer dies

[miketyler]

I have a very low time NorthStar pressure washer (Northern tools brand) that I just replaced carb on. This unit has the Honda GX160 and had set up for a few years with the fuel control on. Fuel had drained and filled the crankcase. After replacing oil I couldn't get the engine to fire off at all so I bought a new carb off of eBay.

The new carb works great but after 3-5 mins of operation the engine seems to bog down and then will die. I can prolong it by releasing the trigger on the wand but it wont return to full power and will still die. Tank was cleaned and I am unsure this new symptom is fuel related. Could this be a pump issue? There are no unusual noises and if I crank it back up its will go another 5 minutes or so before dying again.

This is an older model but has very low time and looks identical to the one pictured below. Any ideas on this one?

 

[IOWNJUNK]

Sounds like vapor lock. Will it stay running with fuel cap off? Is there supposed to be a vent in fuel cap?

 

[miketyler]

Not sure. I will certainly try it. I'm sure the system is vented but how can I tell if its a vented cap?

 

[justme-]

could also be a small restriction in the fuel supply. IE. the fuel is flowing into the carb bowl slower than it's being consumed by the engine but not a lot slower so that it takes time before the bowl is too empty to feed the engine. After shutdown the consumption is zero so the bowl recovers. I've seen this a few times. Similar symptoms to a venting issue. it's most likely not vapor lock which is when gas is vaporized in the lines and stops fuel flow, normally caused by heat.
The cap is vented by itself, there is no outside visible vent in those.
Make sure the fuel shutoff in the carb is opening all they way and is not blocked. The little bowl of the shutoff can accumulate contaminates and plug up.

FWIw, as a general suggestion stay away from Northstar products, especially the pressure washers and sprayers. Honda engines are great, but 90% of those Northern Tool items have junk pumps which have a high defective rate within hours. We're authorized warranty shop for Northern.

 

[kelpaso1]

^^^ couldn't have said it better. Might want to also check compression when its warm.

 

[fury9]

You might want to try a rebuild on your old carb. I replaced a carb on my snowblower with one from the auction site, total waste of time. I dug out my old carb with an actual brass float and a metal needle (not some plastic ****) rebuilt it and junked most of the new one. Old one works great now. Had the same symptoms you are describing with the new one.

 

[kelpaso1]

Re-reading your post I think it is a fuel delivery problem. Float needle/seat, Fuel line, Shutoff valve , or in tank screen.

Pull the fuel line off the carb and turn the shutoff valve to open. If you get a good stream then 3 of those is not your problem.

 

[miketyler]

Thanks for all the responses. The tank has new screen. This model does have fuel shutoff built in to the carb assy. It is a cheap China carb but purchased from outfit in Cali. Is there an easy way to bypass the fuel shutoff to test this theory?

 

[kelpaso1]

Thanks for all the responses. The tank has new screen. This model does have fuel shutoff built in to the carb assy. It is a cheap China carb but purchased from outfit in Cali. Is there an easy way to bypass the fuel shutoff to test this theory?

Just undo the bolt on the bottom of the carb float bowl and remove the bowl. This will allow the float to hang down. Then put a container under the carb and turn on the shut off valve. You should get a good stream of gas coming out.

 

[miketyler]

ok will check it. The engine pulls thru pretty strong and only has a few hours on it so I am hesitant to think low compression but who knows. I was very surprised to find the crankcase full of gas when I unearthed it from the back of my garage.

 

[kelpaso1]

ok will check it. The engine pulls thru pretty strong and only has a few hours on it so I am hesitant to think low compression but who knows. I was very surprised to find the crankcase full of gas when I unearthed it from the back of my garage.

Uhh, ok, if there is gas in the oil then the float needle is leaking and/or the fuel shut off valve is not shutting off. But the main thing is the float needle is leaking. There may be a small amount of dirt in the float needle/seat. Taking the bowl off and letting the gas run for a few secs may clear the debris. Also when you have the bowl off and the gas is running, lift the float up and the gas should stop.

Once you figure out that problem you need to change the oil.

 

[miketyler]

Past tense. If you read further up I changed oil and replaced carb with new unit. No longer leaking into the combuston chamber.

 

[justme-]

Never get a china copy of a quality item - china carb on a Honda is waste. Real Honda carb may not have been that expensive. Range from $35 - $150 so I can't be too sure without looking it up at work.

Also, float/needle/seat is the most common cause of gas in oil, but carbs will do it for other reasons from the seat being damages (corroded) to internal passages being corroded through. We don't generally mess with them much when they cause that - just put a new one on.

no there is no way to bypass the fuel shut off, but as was said drop the float bowl (or shutoff bowl) and check the flow.

 

[miketyler]

understood - the price was too good to pass up.

 

[aznxstazy]

Don't want to bump a old thread, but wondering if you ever figured out the issue. I have a northstar 8 hp that's doing the exact same thing. With a new carb etc after 5 minutes of run it will start bogging down and cut of and not cut back on. Gets spark when it cuts off and there still fuel in the bowl.

 

[MarlynOC]

There should be a screw in filter in the bottom of the tank. You cannot see it unless your actually remove the tank and look at bottom.