I have just sorted out a steering problem with one of my Super np's through posting on her so I will now try to get another Super np sorted.
I have a 4595 fuel pump on this one and it starts brilliantly in the summer without using the excess fuel button, but come wintertime I have to use the excess fuel button and fires up straight away and runs for a second or two and then stops. I have to keep re-starting it like this for 4 or 5 time the it runs OK. I have replaced the lift pump and had the injection pump professionally rebuilt and as far as I can tell there are no loose unions where it could suck air in. Does any kind person out there have any ideas.
Kind regards
Peter
Super np bad starting in the winter
Re: Super np bad starting in the winter
Hello Peter,
The problem that you have with your NP which has the Minimec pump sounds very much like the excess fuel mechanism is not disengaging and the button is not throwing out when the engine starts. After it has started and stopped do you re-set the excess fuel button and if so do you hear a positive click as it sets? Start it from cold and if it stops check whether the excess fuel button has thrown out - there should be a positive "click" when you re-set it. If there is no click or the button feels "woolly" when you depress it then the excess fuel setting is not disengaging when the engine starts. This prevents the rack from returning to normal running position when the engine starts, it moves to the fuel cut off position hence your problem. After a few attempts it probably disengages and allows the engine to run. The issue will be in the excess fuel/stop/ governor mechanism or possibly on the rack itself. Take it back to whoever has "rebuilt" it if you still have any confidence in them! You can also do another check by depressing excess fuel button and then pulling the stop cable - the button should ping out, if it does not then that is another indication of where the problem is.
It is a bit difficult to explain, but basically the fuel rack, which operates the size of the fuel inlet openings on the pumping elements, is spring loaded to tend to move it to the fuel shut off position. When the excess fuel is depressed the spring operates to move the rack in one particular direction PAST fuel shut off and into maximum fuel setting in that direction for cold start. When the engine starts the governor and throttle mechanism moves the rack back swiftly in the OPPOSITE direction against the spring pressure, through the fuel cut off position and into running position in the other direction, with the rack moving further against the spring pressure depending on the throttle/governor setting and response. The design of the pumping elements allows fuel to enter the inlet ports in a sort of "maximum fueling - decreasing fueling - off - increasing fueling - maximum fueling" pattern as the rack moves from left to right. However, if the excess fuel mechanism fails to throw out when the engine starts then the throttle setting and governor can only move the rack back against spring pressure to the fuel shut off position and not into running position the other side of fuel shut off. This is why your engine stops. Repeated attempts at starting probably eventually result in the excess fuel disengaging allowing the engine to run.
The problem that you have with your NP which has the Minimec pump sounds very much like the excess fuel mechanism is not disengaging and the button is not throwing out when the engine starts. After it has started and stopped do you re-set the excess fuel button and if so do you hear a positive click as it sets? Start it from cold and if it stops check whether the excess fuel button has thrown out - there should be a positive "click" when you re-set it. If there is no click or the button feels "woolly" when you depress it then the excess fuel setting is not disengaging when the engine starts. This prevents the rack from returning to normal running position when the engine starts, it moves to the fuel cut off position hence your problem. After a few attempts it probably disengages and allows the engine to run. The issue will be in the excess fuel/stop/ governor mechanism or possibly on the rack itself. Take it back to whoever has "rebuilt" it if you still have any confidence in them! You can also do another check by depressing excess fuel button and then pulling the stop cable - the button should ping out, if it does not then that is another indication of where the problem is.
It is a bit difficult to explain, but basically the fuel rack, which operates the size of the fuel inlet openings on the pumping elements, is spring loaded to tend to move it to the fuel shut off position. When the excess fuel is depressed the spring operates to move the rack in one particular direction PAST fuel shut off and into maximum fuel setting in that direction for cold start. When the engine starts the governor and throttle mechanism moves the rack back swiftly in the OPPOSITE direction against the spring pressure, through the fuel cut off position and into running position in the other direction, with the rack moving further against the spring pressure depending on the throttle/governor setting and response. The design of the pumping elements allows fuel to enter the inlet ports in a sort of "maximum fueling - decreasing fueling - off - increasing fueling - maximum fueling" pattern as the rack moves from left to right. However, if the excess fuel mechanism fails to throw out when the engine starts then the throttle setting and governor can only move the rack back against spring pressure to the fuel shut off position and not into running position the other side of fuel shut off. This is why your engine stops. Repeated attempts at starting probably eventually result in the excess fuel disengaging allowing the engine to run.
1946 E27N, 1952 Major Diesel, 1959 Power Major, 1962 Dexta, 1962 Super Dexta, 1963 Super Dexta NP, 1964 Super Major NP, 1965 Super Dexta 3000, 1966 Major 4000, 1967 3000 PF, 1994 5640,plus Basildon built NH.
Re: Super np bad starting in the winter
Hello shepp,
Thank you so much for the time you must have spent posting your reply to my fuelling problem question.
I think your diagnosis of the problem is absolutely correct because the tractor performs exactly as you say and the reason I have no problems in the summer is because I never have to use the excess fuel to start the engine so the malfunction doesn't have an opportunity to manifest itself.
Well done shepp and many thanks
Kind regards
Peter
Thank you so much for the time you must have spent posting your reply to my fuelling problem question.
I think your diagnosis of the problem is absolutely correct because the tractor performs exactly as you say and the reason I have no problems in the summer is because I never have to use the excess fuel to start the engine so the malfunction doesn't have an opportunity to manifest itself.
Well done shepp and many thanks
Kind regards
Peter