So I have tried to bleed the diesel side on my 1953 MD per the manual. I have the tank about one third full and noticed that the the water seperator filled very slowly but eventually filled. When I try and bleed the system I open the bleeder and get fuel from the water seperator. I then bleed the primary filter and get air but eventually fuel. I then loosen the bleeder on the auxillary and eventually get fuel. When I go to the injectors their is no fuel with the speed lever slightly activated. I then go back and get more air from the primary filter and then takes a bit to get fuel from the auxillary filter again. My question is a preety simple at this point. Is the fuel from the tank through all of the filters just gravity fed or is somewhat pulled from the pump? At this point I am thinking I just have poor flow through the water seperator but not sure. Sorry as I am a diesel newbie.
- Thread starter Hattrick
- Start date
If you have a pressure gage on the pump it should go to the run zone when running on gas. Fuel goes to the primary pump on the rear of main injection pump before it goes through the final filter. If you don't have a leak or blockage on the suction side of the primary pump and all the air out you should get pressure to the injection pump. Its gravity flow but you can double check for air at the final filter when running on gas.
Interesting. The pressure gauge starts low and gradually increases and then pegs way high. Is that any indication? It just seems there is no fuel at the aux filter. Do I need to prime the primary pump somehow?
Just looking at it it looks like it goes tank to water seperator and then to primary filter. I just assumed it went to aux filter and them pump and then return.
I really appreciate the help on this as I think I am close.
Just looking at it it looks like it goes tank to water seperator and then to primary filter. I just assumed it went to aux filter and them pump and then return.
I really appreciate the help on this as I think I am close.
I mixed the filter names up. Should be fuel to water trap, aux. filter, primary pump, final filter and to injection pump. Does the gage peg or just go to the high side. On the small pump on the back of the injection pump, do you have 3 lines or 2 conected? Line looking to the left has a screen, but don't think you would get gage pressure if pluged.
The small pump on the back of the injector pump has 2 lines. The one towards the outside of the tractor goes to the diesel tank and the inner one goes to the filter base. I did take the screen out of the injector pump and it was clean. This is on the main pump though. There is a fitting on the smaller pump that has a big hex head but I have not yet taken it loose. I would say that the guage is beyond the high side.
MD A pump should have tank supply line to a fitting just to rear of the water trap. A line from the auxilary filter to the lowest opening pointing left on the primary pump. A line from the top opening on the primary pump to the final fuel filter. A line from the final fuel filter to the injection pump and the pressure on the gage is on this line. Should be another opening pointing left on the primary and scavaging pump sending fuel back to the tank. Not clear if you have 3 total lines like described from the rear pump or just 2. If just 2 a B pump was installed sometime and the plumbing is just a little different.
You are correct. I have 3 connection off the rear pump and all lines as you have described. Mine had an "A" pump on it and it was stuck and I am using all of the same lines on a new "A" pump. If the guage is showing good pressure(or maybe too much) does that indicate that something is plugged? Like I said I can bleed air from the left most filter and not so easily from the aux filter which is kind of strange.
I think the gauge being pegged when running on gas or on deisel at low idle is normal. Both my MD and 450 diesels seem to have the gauge pegged at idle. When the auxilary filter on my MD started to get restricted, the gauge would go to the low side (in the red) under a heavy pull. I think the operator's manual says to check the gauge at high idle and it should be in the white.
Is it possible the primary filter is restricted causing the gauge to read high but no fuel being pushed through. I have never changed the final filter on my MD and I have owned it for over 45 years. Have you checked or replaced the final? Al
Is it possible the primary filter is restricted causing the gauge to read high but no fuel being pushed through. I have never changed the final filter on my MD and I have owned it for over 45 years. Have you checked or replaced the final? Al
Like rusted said, bleed all air out at the water trap then the auxilary. Then start and running on gas bleed the final. Then open the throttle some and bleed at the injectors. Can remove the pin from throttle linkage on the pump and move the lever by hand when bleeding the injectors.
So I know a little more about how this system works now. I had some flow issues in and out of the water trap and have resolved those. When running on gas the guage is still pegged and I have bled the trap and AUX filter. With it running I am able to bleed the Primary filter but still nothing to the injectors. After a minute or so if I bleed the primamry filter again it has air again. If I have pressure from the lift pump through the prmary filter to the pump is it saying that my main injector pump is bad? It also does not seem to matter if I pull the trottle or manually pull the pump arm. Is there anything that I can do to isolate this a little more?
You might want to start a new thread. There aren't many of us that use the modern view.
You may also want to go to Red Power Forum. There are a lot more gas start diesel guys there. There is a lot to learn by just reading over there. Be sure to search BEFORE asking a question.
Couldn't that possibly be a stuck rack? I think the symptoms are similar.
You may also want to go to Red Power Forum. There are a lot more gas start diesel guys there. There is a lot to learn by just reading over there. Be sure to search BEFORE asking a question.
Couldn't that possibly be a stuck rack? I think the symptoms are similar.
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