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I have a pressure gauge rigged to the test port of the fuel regulator. If you watch the video I get 62 psi (blue spring) initial KOEO but then it drops once all the the self test are done, injector buzz glow plugs etc. It also does not come back up during cranking. Am I not suppose to always have the 62psi once KOEO?

 

The fuel pump shuts down after approximately 20 second after key on if the engine is not started.

 

As Brett said, and it will not hold constant fuel pressure with the key off. Even though it has a pressure regulator it also has an air bleed in the secondary filter housing that will let air/fuel go back to the tank.

 

Good info thanks, makes sense it would have a cut off limit. but it should come right back up during cranking right? what would cause it not to build up pressure during cranking?

 

That's a good question. After it times out you should be able to key off and key right back on and the pressure should come back up. Cranking has nothing to do with fuel pressure, technically.

 

before starting, I often manually wake up my SG2 with key in run position, Oddly, i observe my SG2 and analog gauges loose power when i then turn key from run to start.. wonder if there is a built-in power cycle that amongst other things re-triggers the fuel pump.

I have fuel pressure gauge, i get 65-70 psi before starting (and 55-68 while driving), and if i wait too long fuel pressure drops to zero. I then cycle key again and start

 

Seems like that may be a problem to me. In cold weather I often leave my key in the run position long enough for the fuel pump to stop and then go right to start from there. Cranks right up. I've never done that with a fuel pressure gauge attached. I can see it dropping if it "times out" but once it starts cranking it would have to have fuel pressure to start and run...wouldn't it?

 

That is why I always start it before the fuel pump shuts off, the fuel pressure drops like a rock after the pump shuts down and it takes a bit for the pressure to return once the engine starts.

 

I have to ask, why not do what you are supposed to do and crank the engine as soon as the glow plug light goes off? Waiting longer does nothing useful, and just runs the battery down. The engine is designed to have the glow plugs on for a short period after starting, if you let them cycle off that may not happen properly.

Brian

 

That is what I usually do, crank as soon as the glow plug light goes out, this was just something I noticed during troubleshooting a no start that may be contributing to that no start