I have a '70 MF150 with the AD152 diesel engine. It has 4100 hours. The injector pump, engine, injectors are original. The tractor started leaking diesel into the engine oil last fall (about a quart of diesel every 7-8 hours operation). I replaced the lift pump---twice without effect. I assume it is the injector pump leaking, which I am removing and taking for a rebuild tomorrow. Is it possible that it is a stuck injector or leaky valve? The tractor doesn't have a miss but the engine seems to be weak. The engine rpm's increase slightly when I push all the way down on the clutch and stop the hydraulic pump. Would a leaky injector pump cause the engine to lose power? Thanks for any advice/input.
Oil & Fuel Injector Pump? Advice! Thanks
- Thread starter Mule Man
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Zork
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Here are some general thoughts.
If an IP is gear driven with the main seal inside the engine, when that seal fails it will leak into the engine. Getting the correct compression, timing, intake air, and fuel will give you the most power. Does your fuel system have a fuel return line to allow air to escape? Try bleeding them of air if it does not. Could be a stuck/weak/leaking injector not atomizing the fuel correctly (no/low power). IP pumps that I've seen have check valves at the injector line, if these leak/ siphon back you could be losing injector timing(no/low power). An IP main seal failure shouldn't affect this (unless fuel has drained; at start up air has entered). Additionally, if the IP plunger/s is/ are worn you may not get the right amount of fuel or pressure to open the injector properly(no/low power).
If an IP is gear driven with the main seal inside the engine, when that seal fails it will leak into the engine. Getting the correct compression, timing, intake air, and fuel will give you the most power. Does your fuel system have a fuel return line to allow air to escape? Try bleeding them of air if it does not. Could be a stuck/weak/leaking injector not atomizing the fuel correctly (no/low power). IP pumps that I've seen have check valves at the injector line, if these leak/ siphon back you could be losing injector timing(no/low power). An IP main seal failure shouldn't affect this (unless fuel has drained; at start up air has entered). Additionally, if the IP plunger/s is/ are worn you may not get the right amount of fuel or pressure to open the injector properly(no/low power).
Last edited:
rjmack
Platinum Member
i don't know how this could end up with fuel build up in crankcase (then again, i'm not a mechanic) but i have had experience with failing injectors and know that the engine will develop 'miss' symptoms similar to a gasoline engine, especially when cold/shortly after startup.
i don't know any situation where putting a load on a running engine shouldn't be at least a bit noticeable.
6sunset6
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Please post when you know whats up. I have that same engine in a MF 30E TLB and have replaced the lift pump 3 times, seems to get slugs of air in it. The diaphragms in the lift pump always seem to be pretty limp after a couple of years. I just took out the mechanical lift pump and put in an electric in line.
The mech pump is 7-10 psi and the electric is 10-14. I figured that would not matter much. It started with out having to bleed the injectors. That was a first.
The mech pump is 7-10 psi and the electric is 10-14. I figured that would not matter much. It started with out having to bleed the injectors. That was a first.
