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Truck Repair/N14 seems to run out of fuel at operating temp


QUESTION: 99 n14 celect. Sputters and dies after reaching operating temp. No throttle. No cdes. Remove fuel filter half empty top off with fuel will start with little cranking and run for a little while. Replaced entire pump, plastic gear,o rings between pump and filter. By passed cooler and pickup tube with brand new fuel line. Problem persists. First start up will run perfect for hrs until temp reaches 180 degrees and then won't keep fuel. Sometime it will continue too idle with a severe miss and very little throttle response.


ANSWER: Going to be a matter of trial and error. If your running a davco filter I would start with taking off the inlet line and cranking it over and see if your getting good fuel flow. After that I would hook the inlet and outlet together and bypass that filter. then would run your return line into a bucket too see what the return fuel is doing when it starts to die out on you. Have you looked at the fuel jumper blocks to see if they are leaking fuel.  It sounds a lot to me like a oring is bad and as soon as that engine gets warm the oring expands and sucks air.

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QUESTION: My filter is mounted directly to the pump. Replaced or bypassed everything between pump and tank still pulling low suction. Decided to warranty out the new pump instantly vacuum jump up too 6 which I'm told is perfect. Now the truck is still spluttering and dying. Now filter remains full and motor will refire imediatly but die shortly usually instantly a few times and then no start no crank pressure until after it sits awhile. Fuel pressure holds steady at 160psi at 1700rpm and 120psi at low idle but the needle flutters at idle. I notice the pressure will drop briefly to about 80 after letting off a hard rev right before the problem starts. Suction holds pretty steady. Exhaust temps are fairly equal across all six. Return in bucket seams norm. Where are the jumper blocks you mentioned?

can you get me your engine serial number and I can do some more digging. The plates i'm referring to you won't probably be able to see them with the rocker boxes on but if their leaking you should see fuel coming out between the heads and you'll be able to see the cover plate on the top of the front head and the rear of the back head.

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Jeff Drumm


I Can answer any question pertaining to semi trucks and trailers. Have no experience in the automotive field so not able to help in that area.


My experiences in Semi Trucks is. I own my own truck and i presntly maintain a 80 truck fleet. Can handle any questions pertaining to a truck have tore apart and rebuilt every aspect on them. Fleet I deal with is Mainly Volvo trucks and a handful of freightliners. Work on automated transmissions on a daily basis along with carrier apu's. With engines my specialty is the 60 series Detroit but do work on the cummins isx the n-14 and the ism. and also the Volvo engines.

Have a College Degree from university of northwestern ohio in diesel and agriculture mechanics. Have 10 years behind the wheel driving a truck and 4 years working on trucks full time. Also have grown up on a farm so have been tinkering on trucks and tractors all my life.

Awards and Honors
I've gone through online schooling and have received certificates from webb wheel, Timken and Volvo academy.

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