MF 245 OVER PRESSURE IN INJECTION PUMP "HELP"

[TOD MOHR]

I have a new to me MF245. I rebuilt the engine and put on a rebuilt IP. It ran great on a auxiliary fuel tank. I put the tank on and buttoned everything up and it ran great but slowly over about 5 min. lost power and RPMs. I had to idle back to the barn. After a month of screwing around I determined it was excess pressure on the injection pump. If I removed the front return line on the pump it would run great. I have checked all the lines for blockages but everything is fine. Now for my question: The front return line goes back to the filter housing not directly to the tank. The banjo bolt on top of the tank returns fuel from the injectors only not the IP. There is no hole in the banjo bolt to allow fuel in the pump housing to return only the injectors. Is the wrong banjo bolt in the filter housing? It looks original but who knows. I also put a new lift pump on, could it be over pressuring the system? Any help you experts could give me is GREATLY appreciated, Thank you.

 

[used red MN]

There is no hole in the banjo bolt to allow fuel in the pump housing to return only the injectors. Is the wrong banjo bolt in the filter housing?

Hello Tod, welcome to YT! If the line is in place but blocked by a solid bolt that is wrong. In fact that is not a banjo bolt at all. Masseys are notoriously assembled with fine thread bolts used in many locations that other manufacturers use course threads, this gives you a greater selection of fine threaded bolts that could be mistaken for a banjo bolt. I’m not sure where that thin headed bolt came from if it actually has a thin head, but it apparently fooled you. Or maybe the solid bolt got screwed in there as a plug to keep dirt out or fuel from flowing and
spilling but was forgotten to be swapped back to the proper banjo bolt.

 

[MFEngineer]

The banjo bolt in filter head has a really tiny hole in it, designed to let air pass through it but not fuel. If you look really carefully you'll see the hole which can be almost invisible if blocked, blow it out and make sure it passes air - in the field I use aerosol brake cleaner, and you'll probably find that cures the problem. If not I have come across incorrectly piped pumps which will give the same symptom as the lift pump fights the internal fuel transfer pump. The rear pump port (closest to the high pressure outlets) should go to the Out port on the filter and vice versa.