I have a BlackMax 2800psi gas pressure washer with a Mitsubishi engine that won’t start. The original problem started out when I would either squeeze the trigger or release it and the engine would stall. It got harder and harder to start the engine as well. I read in different places that the unloader valve could be bad as far as the stalling concern. I tried adjusting the unloader valve and that seem to be a temporary fix, so I ordered a new one and put it in, but now the engine won’t start at all. I have spark and the carburetor is clean as a whistle and the fuel is fresh. The air filter is clean as well. Occasionally I will get a pop out of the carburetor, but the engine will not start. The pressure washer is only about three years old and has been used maybe 8 or 10 times. What else should I check?
Pressure washer won’t start
- Thread starter d430
- Start date
nadogail
Well-known member
An engine needs; spark at the proper time, compression, and a fuel air mix. Some engines have a "low oil" cut out that grounds the magneto if the oil level is too low.
Most small engine starting problems are fuel related.
Most small engine starting problems are fuel related.
finn
Well-known member
Disassemble the carb and clean all of the small passages including the emulsion tube.
It’s probably cost effective to order a Chinese carb if there’s one available for your engine. The one for my Honda knock off was $13, and included three filters and a piece of fuel line.
I have also had to replace coils on some Briggs and Stihl products.
Fuel, spark, or air.
It’s probably cost effective to order a Chinese carb if there’s one available for your engine. The one for my Honda knock off was $13, and included three filters and a piece of fuel line.
I have also had to replace coils on some Briggs and Stihl products.
Fuel, spark, or air.
Pull the spark plug…….is it wet with fuel ?
While the plug is out* ……or put your thumb over the plug hole, pull the start rope, your thumb should pop off the hole if the compression is good. If there’s no compression one of the valves is stuck open.
* compression check with a gauge
While the plug is out* ……or put your thumb over the plug hole, pull the start rope, your thumb should pop off the hole if the compression is good. If there’s no compression one of the valves is stuck open.
* compression check with a gauge
You are starting it with the spray wand open right? sometimes they will get a conductive coating on the spark plug tip from repeatedly trying to start. Plugs are cheap, try one.
As I stated in the original post, I have spark, carburetor is clean as can be and fuel is fresh and making it to the carb, and the air filter is clean. Valve lash and timing seem fine. Is there any way the pump could be preventing the engine from starting? Like too much drag on the crank if the unloader valve isn’t properly relieving the water pressure?
AP514
Well-known member
some of those have an unloder..to help engine starting.
Either your missing one of the things already mentioned 10 times. SPARK! COMPRESSION! FUEL ! or your NOT able to pull it over fast enough because of the pump load.
Missing info
PLUG wet or dry
Actual compression
Spark blue and minimum 1/4” gap
Pull the pump off start the engine.
Walkers
Well-known member
the no start problem with a huge percentage of small engines is related to the main jet in the carb. Pull the bowl and run a jet cleaner, or a small wire into the main jet to clean it out.
Gigem
Well-known member
Since, per your OP, the problem seemed to get progressively worse over time, I am going to join the crowd in the "it's fuel related" camp.
velocipede
ALLIANCE MEMBER
Make sure the unit is on level ground. I spent hours trying to get mine started...until I discovered the low oil cut off was working because I was on a side hill.
Possible……yes………..progressively worse……might lead to valves and rings…….low compression ?
With out critical details it’s all an internet guessing game.
Lightning rod
Well-known member
All good things to check from the folks above
Based on your OP, I would check the valve clearances if not done so.
An engine with out of tolerance valves might idle but die under load.
A seized pump would keep the engine from starting but you would be able to tell this when you pulled the
cord.
Also, the unloader valve may still be causing problems if it is not unloading properly
This should however make the pullcord feel very heavy when trying to start
You can leave the unloader valve out to check for this
Is it extra heavy when pulling the start cord ?
Based on your OP, I would check the valve clearances if not done so.
An engine with out of tolerance valves might idle but die under load.
A seized pump would keep the engine from starting but you would be able to tell this when you pulled the
cord.
Also, the unloader valve may still be causing problems if it is not unloading properly
This should however make the pullcord feel very heavy when trying to start
You can leave the unloader valve out to check for this
Is it extra heavy when pulling the start cord ?
FredWanaker
Well-known member
check the oil level, then put a small squirt of fuel in the carb throat and try again. If it runs for a brief couple seconds then it is the carb or fuel pump. I have to drain all my small engines after each use or the ethanol in the fuel here destroys the diaphragms in a year or two. If I turn off the fuel and run them dry the parts last 5 - 10 years between rebuilds. I had one engine that a small bleed orifice unscrewed from and the engine would not run.
countrypapa
Member
Hit it with a shot of starting fluid. If you at least get a pop out of it or it tries to start you have a fuel problem.
Try to start without the wand connected, if it starts its a unloader issue.
kelpaso1
MEMBER EMERITUS
Won't make a difference as the wand and hose are connected to the washer with a quick connect like an airline. Needs to tie the trigger handle down to release the pressure.
rd65
Well-known member
Have you checked the key for the flywheel? Progressively gotten worse...maybe key was starting to shear and has now completely let go causing timing to be too far off.