Does the power unit act like it is under a load. I ran across a case were the trans was pulling an excessive load when engine was just started. Bleed valves in packs backed out.
Maachine is running on propane. All ignition components and timing are all good.
We ahve adjusted the settings in the dashpot, the only problem is that the engine stalls out before there is a chance to lose vacuum.
We are pretty much going to start some swaptronics and see what we can find...
The FICD will perform it job when manifold vac is greater then 15 inches Hg. The important part of scoot comments are that engine, fuel and ignition have to be working in harmony with each other. If you don't have the valves adusted properly hot, if you don't have an engine's timing adjusted for the correct fuel, if the PCV valve isn't working correctly, etc. Which I would believe your personel have all looked at. There were two FICD devices offered which include with the vac piping and the delay valve play a part.
There is a vacuume solenoid on the carb that kicks up the idle and prevents stalling on these units when the steering or hydraulics are deadheaded.
Make sure that the DASHPOT is functioning correctly and adjusted correctly and your problem will be solved. Test the part with a vac pump to make sure the it holds vac. check the vac source from the manifold and make sure that is good.
Common occurance on these more often than not just replacing a worn out or adjusting will fix the problem.
Naturally you will need to make sure that your gov, Idle, and other settings INCLUDING ENGINE TIMING are set correctly.
Typically NOT a Hydraulic or Engine Issue, particularly based on the reading you are indicating.
Good Luck
Scoot (22 Year Nissan Dealer)
mowers;
The engine you have is an H20 II. What type of fuel are using?
The compression reading, is it on a hot or cold engine? Did you take wet - hot compression readings? The reading of 150 psig is just 1 point above minimum allowed for this power unit. The maximum reading when it come off the line was 178 psig at 300 rpm.