# Pressure Washer Engine Questions



## Spit (Nov 3, 2006)

I have a 1996 model 3.5 HP pressure washer with a Tecumseh horizontal engine 
1. I want to make sure that I set the RPM high enough. I assume that I set it at a no load speed? I assume that this is done when the pressure washer hooked up to water, but is in bypass mode..otherwise the pump could be damaged by running dry. 2. I am noticing that when I first start the unit I have to hold the gun in spray position (pretty normal to relieve pressure for starting) but when I realease the gun/spray the engine shuts off. This will happen repeatedly...it seems like once it warms up and after I have fooled with the governor/throttle it will start to enter bypass mode and keep the engine running. Once It starts bypassing okay,it continues to bypass properly and not shut off the engine. I just put a new comet pump on it so I don't think it is the pump. Do I need to adjust the governor? Sorry I do not have the engine model number with me I can add it later. The carb is a fixed non adjustable model with a primer..no choke. There is an adjustment needle at the bottom of the carb..where the bowl nut goes. Any input appreciated

Spit


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## paulr44 (Oct 14, 2008)

Do you have a tachometer?

You'd have to post the engine spec. in order for us to determine the proper RPM setting, but quite often the pump mfg. will specify maximum RPM. Pressure washers are often reduced RPM, if you've ever seen a belt drive one you'd know (small pulley on eng., big one on pump). If you have the spec., you could try googling it.

The reason a pressure washer can load up when trying to start is the unloader valve is stuck. This can be for various reasons...new and not broken in (tolerances), lime/hard water deposits. It's not uncommon. I sold a brand new one the other day and had it happen to me during the demonstration.

YES YES YES, running a water pump without water (which a pressure washer is) of any type typically will damage it. Letting it run in bypass for more than 3 minutes can also damage it from overheating. Many newer units have a thermal dump valve to allow cool fresh water to come in and keep things calm.

So, if the only reason for your post is it loading up when starting, I'd live with it. Given the HP of it, a replacement unit would probably be around $300 or less. Unloaders can cost $50 up to $200, typically about $80. And if you're not a mechanic, I wouldn't try to work on the unloader. IF YOU DISTURB an unloader lock nut and turn the same screw the pressure control knob is on, you could end up with a setting that overloads the unit, or provides less than capable pressure.


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## Spit (Nov 3, 2006)

*Model number info*

Does anyone have any advice on adjusting the governor and or RPMs?
I took another look at it last night and I see an adjustment screw on the throttle lever that seems designed to make contact with the governor lever. 

I suppose that adjusting that will have some effect? I have the Tecumseh approved vibration based tachometer tool I have not used it much, and never on a horizontal. I assume I use it the same way? that is place it on the top of the starter? 

the Tecumseh Model number on the engine is H35 45696X (B) production date 6144N

As always any and all advice & comments appreciated

Spit


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## paulr44 (Oct 14, 2008)

Most Tecumseh horizontal engines have a small screw on the throttle control that contacts a bellcrank, and that is used to adjust the spring tension thus changing the maximum RPM. You say the screw on yours contacts the governor lever, but I think what you mean is it contacts the lever that connects to the spring that connects to the governor arm/lever.

A vibratory tach will work on any reciprocating device, such as an engine, be it horiz. or vert.

http://www.ccdist.com/_serviceManuals/tecumseh/695933.pdf


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## Spit (Nov 3, 2006)

Paul you are exactly right I misidentified what lever the screw tightens down on. thank you so much for the link, I have downloaded it and will print a hard copy for myself. I will use this to check the engine out. thanks again.

Spit


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