NorthStar Pressure Washer gas engine not starting
I have a NorthStar pressure washer (model # 1578922A), with Tecumseh OHH55 gas engine and an Annovi Reverberi XTV pump (2030 PSI, 3 gpm, 3400 RPM, 4 HP). I have been using it for several years without a problem. However, now I am unable to start the engine. The last time I ran the pressure washer, I noticed that the washer would sometimes "drag", acting as though it wasn't getting enough water through the pump -- though I checked the hoses and they were fine, without any kinks or leaks.
Here's what I have done:
(1) replaced gas in tank with new gas (the gas was fairly old).
(2) replaced air filter (it was pretty dirty).
(3) replaced spark plug (I am getting spark).
(4) cleaned out water inlet screen (it was a little dirty, but not too bad).
(5) removed unloader valve and cleaned in soapy, warm water.
After doing this, I am still not able to get the engine to start. So I tried several other things:
(6) instead of using the gas/carburetor priming bulb, I just shot some starting fluid (for drying out spark plug wires in car engines) directly into the carburetor. The engine did startup briefly, but it never was able to go more than a few seconds before quitting.
(7) I noticed that the pressure washer's starter pull-rope-coil would feel some resistance after a few tries on the pull-rope. So I engaged the trigger on the gun while trying to start the engine. Perhaps there is a issue with the pump itself? Nevertheless, I was not able to get the engine to start, even though the resistance was now gone. I probably should never have to engage the trigger on the gun since hopefully the unloader valve should take care of any problems.
I am not sure what to try next. Are there any suggestions of what might be wrong, what can be done next to fix this?