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EZ way to purge injector lines

8.1K views 13 replies 6 participants last post by  52wrench  
#1 ·
Here's what I did, it results in instant fire.

1) Do the low pressure purge in the normal method with the plunger until fuel is coming out the return port on the pump

2) With #1 at TDC and the pin engaged I made a pointer out of a piece of coat hanger and used one of the gear cover bolts to hold it in place. Bend the pointer so it is close to the damper or pulley, whatever you have. Then draw a line with a Sharpie on the damper or pulley in line with the tip of the pointer and mark "TDC" next to it.

3) wrap a tape measure around the damper or pulley and make another mark exactly 180 deg from TDC. Mark this "180". The circumference of my damper was 26" so the 180 was at 13" around the circumference from TDC.

4)turn the ignition on to energize the fuel solenoid

5) don't forget to dis-engage the TDC pin

6) turn the crank CCW to a point so the TDC mark is about 1" from the pointer. Loosen the injector line nut on #1 injector and pump the plunger until you have fuel coming out of the line at the injector. Retighten the line nut.

7) turn the crank CW until the 180 mark is about 1" from the pointer. Loosen #3 line nut and prime until you see fuel at the nut and tighten.

8) turn the crank CW until the TDC mark is about 1" from the pointer and purge line #4.

9) turn the crank until the 180 mark is 1" from the pointer and purge #2 line

The reason for the 1" from the tdc and 180 marks when purging is that puts the pump plunger in a position so fuel can enter the plunger barrel and exit thru the delivery valves.

When I did this I had instantaneous fire up. I then cracked each line nut quickly to get rid of any remaining air.

The crankshaft can be turned easily with a socket on the alternator nut.

The TDC mark on the damper also makes it easy to locate TDC when setting the valves.
 
#2 ·
Did I read that right? You said the EZ way right? Because that seems a lot more complicated than cracking the lines and cranking it over for 20 seconds.
Dave
 
#5 ·
The reason for the 1" from the tdc and 180 marks when purging is that puts the pump plunger in a position so fuel can enter the plunger barrel and exit thru the delivery valves.
I guess i don't understand how the pump works. I thought it's the pressure created by the pump (thousands of PSI) that opens the delivery valves. Is it the pump's cam that opens the delivery valves then?

My second question would be, what's the point of going through the whole exercise rather than cranking for 20 sec? Is it to avoid cavitation?
 
#6 ·
Well I guess I should have said an alternative way. No it's not something you'd do on the side of the road. I was marking the damper anyway to make it easy to find TDC for valve adjustment so I figured I'd try this instead of having fuel spray all over. The delivery valves are just check valves in the high pressure head to stop fuel from bleeding back from the lines. They open easily. The pop valves in the injectors are the ones that need high pressure.
 
#9 ·
Steps 1 through 6 in post number 1 of this thread are valuable in confirming that your pump is properly assembled and correctly in time after just doing a complete reseal. It also confirms the timing method that was first questioned many years ago when the forum first went online. Maybe everybody overlooked the value of this method?
 
#10 ·
Just having the TDC mark on the damper makes it so much easier to find TDC. Without it I'm watching the #1 valves to see when they are both closed then pushing in the pin to see if it hits the cam gear hole, nope, turn some more, nope, maybe I went too far, turn it back , crap, I broke the pin off, etc etc. You still have to watch the #1 valves of course to make sure #1 is at TDC but the pin should go right in or just be a hair off. Anyway I hope someone at least got something out of this.
 
#12 ·
A fluid, like diesel, is for all practical purposes, non-compressible. A gas, like air, is compressible. So if there's air in the line it will act as a sponge and absorb the pressure pulses from the pump plunger and not allow the pop pressure to be reached that is required for the injector to fire. Some of the psi from the plunger is being used up compressing the air instead of all of the psi acting on the injector pop valve. It still may pop but not like it should with no air in the line. I guess it would work it's way out eventually if the injector is opening at all.
 
#13 ·
It's not gonna make me sound like i'm the fastest thinker out there:) but it just occurred to me what the real value of this methode is. If you just crank it the air will work it's way out eventually but before that happens each cilinder will get e different amount of fuel. The engine may not even fire on all cilinders initially. All that unbalanced stress may affect the engine's longevity. Or so I think.

By the way, is this method going to work for both the VE an Ppump?
 
#14 ·
Yes, the engine runs smooth from the start. Not sure if it would work on a P -pump, I've never worked with one.