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Volvo Penta MD6b Cold Start System
My first post- most assuredly not the last!
I have a 1977 Volvo Penta MD6b in my new-to-me 30' Santana (W.D.Schock) she takes a LOT of cranking to fire up when cold. Once she has been started she runs perfectly. If she is restarted within a few hours she starts up easily. But if she sits a few days, its back to 10 minutes or so of cranking (during which she fires intermittently and displays burnt exhaust smoke). This was completely disclosed by the previous owner, no issues there, I knew what I was getting into. Getting her home took two 6-7 hour runs during which the engine ran fine (once started)
I have been told if she runs fine once started, that the injectors are nominally OK. I believe this person as they are a mechanic and could have sold me new injectors if he wanted to, but he didn't. He is an honest guy.
I also had diesel in the oil, so this led me to believe that the lift pump had a bad diaphragm which caused the fuel in the oil and the hard starting.
I have replaced the lift pump and the fuel filter, and the pump did indeed have a very small tear in the diaphragm. Buttoned all up, no leaks bled everything and- itís better but still hard to start - as in I have to crank for a while. So the fuel in the oil is probably fixed, but the fuel system must be leaking pressure somewhere over time.
I am going to do two things- First, create this post , to solicit ideas and second , I am going to crack the injector nuts and use the hand pump to try to bleed everything up to the injectors BEFORE I start cranking- and see if this helps.
I have read in my searches that there is a cold start system fitted to the engine - as there are no glow plugs it must do something with the fuel. It is supposedly activated by shutting off the fuel when you stop the engine, which sets the cold start system for the next start, No mention of this is made in the service manual. I am dying to know how this works and how I can determine if mine is functioning correctly.
Second, where should the throttle be when the engine is being started? I typically have it at idle but I have read about people using 1/2 or even full.
Thanks in advance!