Cat 941 has fuel leak and I cannot figure out how to fix. Local Cat dealer not been much help so looking for expert. Problem started when I changed fuel filters. Started leaking fuel at the vent hose used for priming. Currently if leave fuel valve at tank on get steady drip of fuel at vent hose. Engine starts and runs good but leak becomes steady stream (about a cup a minute). I have replaced the vent shutoff, valve seat, and completely rebuilt the transfer pump. Also Cat dealer told me the problem was because I did not use a Cat filter (suppose to have check valve in filter) but this did not fix problem. Looking for someone who knows how fuel flows up to point of going into injector body. Suspect check valve somewhere that I am missing. This model does not have over pressure line running back to tank and the best I can tell over pressure is controlled by check valve in transfer pump which I have changed. My service manual is not of any help. Anyone that has a. Suggestion of where else to look would be appreciate Thanks
thinking back but doesn't that 941 have 2 of those lines close to the same spot
Single line from tank to water separator. Best I can tell fuel flows water separator to priming pump and also transfer pump. From transfer pump to primary filter then to injector. However can't be for sure because most flow happens within fuel chassis. Only external lines are fuel tank feed and input/output from primer pump.
im talking about the vent lines seems like I remember their being 2
When you say you rebuilt transfer pump do you mean the gear pump in the front of the fuel injection pump. There are seals in the front of the injection pump that can leak out a drain line beside the priming drain line. The injection pump has to be removed to service the transfer pump.
Thanks MT I knew I remembered another drain line and I was thinking that might be the one leaking
Sorry for late response back. Did not know there was injector drain. The fuel is leaking from the drain associated with the priming drain line. On this particular machine the transfer pump is located in front of the injector assembly and is driven by what the manual calls a secondary drive which is the same drive that drives the injector pumps. On the top of the fuel filter assembly there is a control valve that you open to bleed air from the system using the manual priming pump. i have replaced this valve and also the seat that it screws into with no luck. Manual states that there is a overpressure valve located on the top of the fuel filter assy but this machine (SN80H02530) is a early model which did not have the over pressure valve. Trying to figure out how the fuel flows to the vent line. .
Let me get this correct its coming from the vent line that goes to the top of filter housing that you open up to prime the filters with the hand pump. and you have replaced the valve and it still leaks???
Or does your vent line come from a valve on aflat plate on side of inj.pump
Yes this is the place it is leaking. Replaced both the valve and the valve seat. Because the fuel flow is internal to this filter housing (not sure how it flows internally) I am trying to determine if the there is some alternate path that might have a check valve stuck open which is causing the leak. Talked to my local Cat service guy and he stated there was a over pressure valve on the front of the filter housing and that I needed to remove access bolt on top of housing to check. Problem is where he was talking there is no access bolt only a pressed in closeout plug because this model is early enough that the over pressure valve was not installed (my understanding is over pressure is handled by the transfer pump that is why I rebuilt the pump and replaced this check valve). Short story is local Cat guy is stumped so I was hoping someone who had used an early model 941 might have seen a similar issue sometime in their past.
Couple things that might help. First when you reply to a question click on the "reply with quote" so we know which question the answer is regarding. Above Hatchequip asked two questions about different things and your answer said "Yes this is the place" so I'm not 100% sure what the answer means. Second and most important if there is any chance of posting a picture showing the pump and where this leak is would also be very helpful. Cat has amde changes over the years to systems and who know what a previous owner has done to get going in a pinch. Not trying to find fault just trying to help.
:iagree get us a pic worth a 1000 words