Hello everyone, i have been pulling my hair out over a 302.5. Rebuilt engine reassembled and now it runs for 30 seconds then shuts off. I have tried everything know to man. It has been towed to a local mechanic now and they have had it for a week. i spend hours down there with them trying different things. They a leaning towards the inj pump even though it has gone to the injection shop twice and they say it is fine. Shimming down makes it worse shimming up causes it to run slightly longer. Mitsubishi s3l2 3 cylinder with mechanical fuel injection and injectors. Summary: Machine will start and run easily the first time, runs great throttles up, then aprox 30 sec it throttles down and abruptly stops. Restarting takes a bit longer, then runs for 10 seconds. Restarting takes allot longer, runs for 5 seconds. Then will not start at all and may even stop cranking as if it is locking up. Tried: Pull hydro pump to see if it was bogging down. New fuel pump running out a jar of pure fuel Governor disconnected to hold lever open Checked timing a hundred times. However the timing marks never line back up again while rotating.?? New fuel injectors , one was dribbling Marked all key ways on gears to see if slipping. Pulled injectors out and cranked. all firing and good mist stream. Pulled wire off of oil pressure sender. please help, thanks.
It is a caterpillar. Sorry forgot to put that. In case nobody knew that.
Try pulling the return line fitting off at the pump and running it. The last one I had do this was a brand new crate engine, the return line elbow at the pump was stopped up.
Then blow air back to tank and make sure the line is clear. Does it bog down under load or starve for fuel? Hold hand over exh to find out. If it's an external load you will pull your hand away. If it's starving for fuel exh will stay cool. Later Bob
Thanks for the reply. I tried that. The fuel comes into the fitting. There is a bleed screw there and then the return exits through a smaller orifice to restrict it. I tried both removing that line and crimping the line (I thought it would raise the pressure). No change.
Bob, i pulled the pump off so there would be no load at all on engine. I will try the exhaust trick. Looks to be starving for fuel. That is why they are leaning towards the injection pump.
FYI: All i did during rebuild was to pull governor off of injection pump and front gear. Nothing else was disturbed. They said they slightly lifted the pump up and it ran a bit longer. Makes me think timing was off, but it is perfect per the book.
I saw a similar problem on a rebuilt 3306 with new scroll system. Did the exact thing. It was a clogged oil return passage for the fuel pump. After start up it just shut down. Took off cover to check rackmavel and found too much oil in it. Once the engine started lube oil filled the governor and forced the rack forward and shut off the fuel. Lucky the rack,a came back for more fuel not forward or would have had an engine go up,in smoke. I don't know about Mitsubishi engine but a 3 cyl Perkins with governor in the timing housing has a link to the rack that could be put on wrong and fall off. Later Bob