STILL A WEIRD SOUND FROM FUEL PUMP!

Your'e a few lbs per sq in out in your figures. The crack off pressure for the injectors is given as 185 atu. Multiply this by 14.7 and you get 2719.5 lbs per sq in so you have an extra 0 in some where.

If you can feel pressure pulses in the injector lines it is usually a blocked injector. Normally you can feel one pulsing more than the others. I always use this "feel" method to find a faulty injector on any diesel. Bit like a doctor taking your pulse.
regards
Brien

ok now Brien I have done the sums and have asked a friend that did a diesel engine course. Granted you are a lot closer than I was to the correct pressure but you are still wrong. The correct is higher than 2719, dont ask me exactly how much I dont know, I would estimate a couple hundred of pounds. The reason is you didnt take into account the extra pressure it takes to start the diesel moving in the lines ie. the kenetic energy of the diesel. Also you said the lines only vibrate when you have a blocked injector that is also wrong. The lines vibrate on diesel engines when the fuel is being pumped in regardless of a blocked injector or not. This I am %100 sure of. I have checked it on 8 differant diesel engines and my friend says the same. Granted it is a lot more noticable when the injector is blocked but it is not what causes it.
Also Brien please dont take this personaly it is not ment that way.
Regards
Lindsay

Sorry but your information is incorrect. The figures I quoted come from the Fuel Pump Test program issued by Ford Motor Company for the tractor concerned.

As regarding the pulsing in the fuel lines. I will take correction there. I have only been using that method of testing for 40 years on all forms of Diesel engine on tractors, trucks, combines, etc. Its nice to know after all these years that I have been doing it wrong as well as setting Ford pumps to the wrong pressures.

Brian

The pump plunger pressures the diesel in the line. The injector plunger comes off its seat at 185atu. At that point the pressure drops and as the fuel is injected and then, when the plunger starts its downward movement, the injector plunger returns to its seat. At no time in its cycle does the pressure in the line exceed 185atu or what ever pressure the particular engine requires.

The pulse in the injector line has been used for many years by experienced fitters to tell the condition of the injectors. I did not make this up, this came from fitters going back to the 1930's under who I served my apprentiship. If an injector is carboned up and the holes are blocked, the pressure in the line increases. This gives a greater pulse in the line where the blocked nozzle is situated. This can be felt by gripping the pipe with the fingers.

Sorry if you do not agree but I feel that you are clouding the issue with mention of kinetic energy. I too studied physics at my college and cannot see how this causes any increase in pressure in the lines. Certainly not to the 26,000 psi you originally quoted.

Brian

Guess I need a few hundred more engines, pumps and injectors to fix. Funny how these things were not mentioned during my Ford Factory training and my trade exams. Perhaps they kept things hidden from us old ones.

Brian

Lindsay said in the message posted 01-14-2002 at 21:46:20

"The ONLY I say again the ONLY time the lines dont pulse is when you have a faulty injector!!!!!"

Again Lindsay said in the message posted 01-15-2002 at 22:17:14

"You made yourself look like an idiot by not reading my message. You will notice that I said "the lines pulse all the time but it is more noticable when you have a blocked injector" or something to that effect."

I thought I should add my 2 cents worth: I agree with Brian in the matter of pressures. If the injector opening pressure is 185 atu, there is no way the pressure could be higher in any point of operation. When the pressure goes to 185 atu the injector valve will open preventing the build-up of any more pressure unless the amount of fuel pumped by the injector pump is greater that can be passed from the holes in the injector in the same time.

I'm not an expert in this matter so I shouldn't have opened my mouth in the first place so this information could be wrong. This is just what my common sense tells me. Please feel free to correct this.