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Heath, Technician
Category: Heavy Equipment
Satisfied Customers: 147
Experience:  Certified in detroit, caterpillar, mercedes and everything freightliner offers
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I have a 1995 n14 cummins that is not keeping fuel..ECM..cooler..tanks

Customer Question

I have a 1995 n14 cummins that is not keeping fuel when shut down. It has had a new pump put on and there was contamination in the check valve which was cleaned out and replaced, also a filter was installed before the ECM cooler plate to prevent dirt from getting in the check valve. It has had a couple of tanks of fuel run through it and the problem still persists. It runs fine and has good fuel pressure, but when shut off fuel pressure drops within seconds and it has to be cranked to obtain fuel pressure at which time it starts. Need ideas.
Submitted: 8 years ago.
Category: Heavy Equipment
Expert:  Heath replied 8 years ago.
Hello my name is XXXXX XXXXX i would enjoy helping you with you problem. First i need some information from you. I assume the truck is hard to crank when you turn the key off, How long does it need to set before it actually does this and how does the engine run under a hard pull.
Customer: replied 8 years ago.

Runs fine loaded under a hard pull, and once it is running all things seem to be fine.

If you shut it off and leave it sit for say 1 minute it has to crank for say 30 to 45 seconds to get fuel pressure to start.

Expert:  Heath replied 8 years ago.

OK First thing i would do is get a wrench and tighten every fitting haveing to do with fuel making sure your not suck air . CK all the fitting at engine and also around the fuel tanks. To me it sounds like you have an injector going bad Causing the fuel pressure to drop when unit isn't running. The best way to find out is run your truck by the nearest freightliner and have them run a diagnostic ck, have them run a cylinder cutout test to determine which injector could be acting up. They should only charge you 1 hours labor. And if you want to ck to see if your truck is sucking air you can install a clear line in between the fuel filter fitting and the line itself if there are alot of bubbles present you have a line leaking causing your engine to suck air and drop fuel pressure when unit sets.



If this has helped you in anyway Plz ACCEPT the payment tab and also the FEEDBACK tab aswell. If you have anymore questions plz fill free to ask and thanks for visiting us at JA


Thanks, Heath

Customer: replied 8 years ago.

Injector balance check shows no problem and all lines from check valve foward have been checked and no problems have been found. To me the lines behind the check valve do not seem to be a factor in this problem.

Expert:  Heath replied 8 years ago.

Hmmm well sounds like your loosing your prime somewhere, Did you ck your cross-over fittings above the transmission. And has a clear line(site glass) be used on the unit yet.

Customer: replied 8 years ago.
I think that we are loosing prime also. But wouldn't the check valve keep this from happening. The lines behind the check valve should not be a factor as I see it. The check valve should hold the fuel from the valve foward to the engine, which includes the line, fuel filter, and the pump and lines to the injectors. That should be enough fuel for it to start up with.
Expert:  Heath replied 8 years ago.

Also away to ck and completely elliminate the sucking air possiablity is to make a fuel line and run it from the back of your fuel pump where the fuel supply goes and run it into a bucket of fuel and that will tell you if it is sucking air. ALso you even tho the pump is new doesnt always mean its good. I've myself have put many new parts on and they are bad. I would have all the pressures reckd at the pump to make sure that isnt the problem aswell. Your completely right about the ck valve it should keep fuel from draining out of the head, ALso if there has been any trash in your fuel system it might have went through your head and gotten suck in the ck vavle again and also if the ck valve has an oring it might have gotten torn or rubbed during installion causing this problem aswell.

Customer: replied 8 years ago.
The check valve has been checked and cleaned several times. The pressures are good and constant once it is running. I'm going to do a little more research and will get back to you.
Expert:  Heath replied 8 years ago.

Hope something i gave you helped at all, And just keep in touch and tell me how it works out, and if there's anything else i can assist you with plz fill free to ask.

Customer: replied 8 years ago.
Ran another fuel source through a clear line connected where I know the lines are good. No air in fuel and the problem is the same. Any way we could be loosing pressure through the return side?
Expert:  Heath replied 8 years ago.

No sir the return line doesnt hold any pressure it just returns fuel back to the tanks


Expert:  Heath replied 8 years ago.

One more thing check your cam shaft sensor, The sensor has alot to do with the delivery of your fuel. ALso there is a return ck vavle in the back of your fuel pump have you ckd or replaced that one.

Customer: replied 8 years ago.
The pump we installed is different from the original. Where should the check valve be? Quitting time here-have to move to my home computer. More later.
Expert:  Heath replied 8 years ago.
The ck vavle should be in the back of the unit pump!! ALso we have been seeing alot of problems with aftermarket pumps, I probably would go back with the orginal oem cummins pump excpilally with something like the fuel system and since you have had alot of problems with the fuel system already
Expert:  Heath replied 8 years ago.

I hope this has helped you out