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2008 MD90B not starting

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GregMD90B

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First try from winter storage, in Texas so not terribly cold but been 6months. I replaced Spark Plugs, getting fire. Rebuilt Rail, high pressure fuel pump 3-years ago. I’m suspecting fuel pump again? How can I test to see if it is working? After trying for a while, gas started coming out of bottom of air compressor filter hose connection, looks like a hose should be on the bottom of it, but none is there. Any help appreciated.
 
Likely pressure regulator. If the fuel gets to the air pump, it will be expensive. Air and fuel rails have schrader valves to check pressures. The Tohatsu gauge set is pricey, but you can get static readings with a tire gauge.
 
Thanks, I’ll check that later today. Will I need to be cranking the engine to get static pressure readings? Or just with key in on position?
 
Sorry, I'm not a Technician, just an avid DIY'er, and electrician by trade. I appreciate any help, but will take it to qualified person if it appears to be over my head. lol
 
I pulled the regulators, fuel regulator had a tear in one screen, air regulator had fuel in it, is this normal? I am going to take off the rail and go through the whole thing again. Thanks for your input.
 
pvanv said:
Replace the fuel regulator. no fuel should get into the air. ever.
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Hey, Thanks, I pulled the rail and the Fuel Regulator was definitely bad the screens were torn pretty badly. Between Hernia Surgery and waiting on parts, I finally got it all back together. I tested it yesterday and it ran for a couple minutes, I slowly went to a higher rev with lever and it sounded great, but when I went back to normal idle the motor quit and wouldn't start again. I got it home and have done some testing. Oddly enough when I turn the key on I didn't hear the High Pressure Fuel Pump come on. I put 12V directly to it and I could hear it run smoothly. I tested voltage at the connector while disconnected and with key on it was only getting a little more than 10V and when I connect pump up to connector it doesn't run. Any suggestions please
 
OK, Nothing has moved on the wiring end, it should be 12V coming directly from ECU, is that correct? Do you know what pins and connector for this from ECU? Sure hope its not ECU.
 
I am an electrician so pretty comfortable working with wiring. Do you know where I can find schematics and diagnostic values. Everything looks good.
 
Ok, I got it running. Along with the pressure regulator problem, I also had an air compressor problem. Was able to find some used parts for it and got it running good for several outings, and it quit again. No air pressure, so I pulled it off, inspected it and it appears to be ok, I pulled it off before I realized the small rubber hose that connects at the bottom of cam side of piston was split and probably leaking. I am going to replace the hose, put it back together and see if that was the only problem this time. My concern is, is there a specific orientation of the belt gear placement in relation to the fly wheel when reinstalling? There is an arrow on the gear. Last time I put it together and didn’t do anything special and it ran, so just wondering.
 
Thanks, going to put it together in next day or so. It’s hot here in Texas 106 degrees so when I get an early morning or evening, I’ll update soon.
 
Well the hose was not the problem. Everything inside Air Compressor looks good except I'm not sure about the Reed Valve. The side with the two hard valves seem to be bending upward. I'm not sure if this is what is suppose to look like. I will attach a couple pics, please let me know what you think. Don't laugh at my homemade gasket, couldn't find one anywhere. Would the Reed Valve keep it from working? With the Compressor apart, I can put my hand over the top of the cylinder and turn the shaft and I get good suction and pressure.
 

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Thanks again. You've been a great help. Do I need to be concerned about what may have caused it to go bad? I ordered a new one, and I also ordered a new cylinder and piston rings, as those were the used parts I put together and got it to run about 6-outings. Just wondering if something could be causing the Valve Plate malfunction other than age.
 
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