No Fuel Out Checkvalves

[ORCoaster]

I have replaced the O rings on most of the injection pump, replaced the cast iron distribution head and the matched high pressure portion of the pump.  I can get fuel into the body of the high pressure side but nothing comes out of the check valves.  Like there is an airlock.  But I open the valves a bit and get fuel to seep out when I am spinning it with a drill.  Also can get it out of the timing adjustment check port.  I have no bubbles in the incoming or outgoing fuel when it is spinning.  I don't know the internal pressure as I have no gauge fixed up to do that. 

Any ideas how to get the pump to spit fuel out the high pressure side.  I have the throttle lever to the max and the fuel adjustment screw all the way in.  Can't figure this baby out.

Oh yea, the pump was working before I started replacing the leaky seals.  Fuel was pouring out at several places, mostly the back and the cold start lever.

Any help would help.  I am puzzled out after a week of this.

DAS

[Vincent Waldon]

(Assuming you're powering the stop solenoid)

Fuel will dribble out the loosened delivery valves and the dial indicator port with ease, but the delivery valves won't open without significant pressure... well over 1500 psi of memory serves. So, the high pressure side needs to be working properly *and* the pump needs to be cranked with enough HP to generate the high pressures required.

Andrew was working on a powered test bench with a pretty substantial motor... the real Bosch test bed has a large 220V motor as well... I'm wondering if you'd tried the pump in the car or just spinning it with an electric drill and are not able to generate enough pressure?

[ORCoaster]

Thanks for the get backs.  And by such distinguished gentlemen at that!

I was running the power solenoid with a jumper to the battery but that got cumbersome with a one person show and the pump on a 2 by 6 across the front of the engine bay.  So I just have the little plunger and spring out for now.  Figured that would allow fuel all the the time and not need the power.

Spinning the pump is done with a 1/2 inch drill running at 850 RPM.  Is that underpowered?  I can't see how cranking the starter would do any better.  I was trying to get away from the issue of sticky vanes by not spinning it fast enough.

So to answer the two questions above.  No power, open valve.  Not willing to hook up the old washing machine motor just yet.  But that may become an option as I have talked to the local VW shop and he said he had two pumps sitting in the back and had no idea if they were good and didn't have customers to send them off to Portland for a rebuild.  I may look at those if my son can't find the old pump he had at one time and send it to me.

Again thanks for the ideas, but I think I got that far in my thinking.  Any others?

[burn_your_money]

Have you taken apart the delivery valves? If not I would do that next. You should have gotten 4 or 6 new copper washers in your seal kit for them. The torque spec is posted in the FAQ or it is in the MK3 bentley. Often those get gummed up with old fuel and lock shut. If you find some that are locked up only replace them as complete assemblies and replace all 4 of them from the donor pump. You do not want to mix and match! Inside the holder there is the delivery valve, a spring and a shim/wear washer and a copper washer.

I think on the 1.6's it's only something like 30 psi to open the delivery valves.

[ORCoaster]

Well Tyler,

I did get a kit and did take each of these valves apart and cleaned them up.  Not much of anything in them.  Wouldn't expect it really.  But the psi information is good to know.  Bentley?  What do I need that for?  You guys have it memorized.  I will try some air pressure on the valves tomorrow.  I know that they are mobile as I can poke them from the one end before I install them and they do move.

I will also pop the governor top on this nasty boy and double check triple check that the collar and tab on the gov lever are in the right place.  Could the distance between the governor and the control stop be out to far and it is just spilling the fuel before it gets up to pressure?

I was studying a VE diagram in the manual and that seems a possibility I hadn't thought of before.  I didn't change any settings when I did the seals because I didn't want to deal with this kind of a project.  So much for that big idea.

Thanks for thinking.  DAS

[Vincent Waldon]

I think on the 1.6's it's only something like 30 psi to open the delivery valves.

Could be... I'm an AAZ/ALH dude myself these days.    

In any event if you're spinning it with a 1/2" drill and able to maintain 800 RPM pressure delivery is probably not the issue...oh well.

I've seen delivery valves gummed up before as well, so I'd say Burn's given you a great next step.  

I suppose you could also leave the guts out of one to see if fuel will pass straight thru?

The usual cause of no fuel out the high pressure end other than a trickle in my experience has been when I mess up getting the control collar hooked up correctly...just another thought.

[ORCoaster]

Yea that is why I think I will pop the top and look in there just to be sure I didn't slip it out of place when I eased the pump in place.  Two sets of springs to watch along with the main delivery shaft and then give it a squeeze and hope for the best.  I do glue the small springs to the cast body with petroleum jelly.  But even with the slow and easy approach I can see only one thing at a time.

DAS

[Vincent Waldon]

You'll get 'er.  Complex as they are they are actually pretty simple machines... just high high high precision.

I recently inherited a box of parts from someone else's teardown... they had tried to use silicone sealant to seal the big o-ring on the high pressure end with predictable results.  Box of parts looked like a total disaster, but I figured WTH, and after cleaning and a rebuild it fired up perfectly, first try.

[ORCoaster]

I envy your success.  I was hoping for a simple afternoon under the hood and I got a weeks worth so far.  Some vacation.

[burn_your_money]

If everything looks normal when you take the top off you should remove at least one of the delivery valves. If they are overtorqued they crush and break.

[ORCoaster]

Planning to test each Check valve with air pressure to see when they pop open as well as governor placement/alignment.  Will report back later.   

[ORCoaster]

OK, got out the compressor and the gauges and the hoses.  Are you sure about that 30 psi check valve pressure?  Mine crack about 58-60 psi. 

Am going to try to measure the output on the pump itself next.  Without the check valves in place to see what is being delivered in the first place.  Isn't it supposed to be pretty high?  Like 130 bar for the injectors to work?

Later DAS

[rallydiesel]

You'll get 'er.  Complex as they are they are actually pretty simple machines... just high high high precision.

I am always amazed at how simple yet how complex Bosch VE pumps actually are. No electronics yet so many parameters are finely controlled just by internal fuel pressure and rpm. I have seriously thought about getting a tattoo of a Bosch pump someplace. 

[ORCoaster]

I wouldn't want to be continually reminded about a Bosch VE pump right now. 

I spun the pump with a drill and measured 58-60 lbs at the back of the check valve without the internals in it.  So either the gauge I am using is not picking up the suttle difference between the pressure to open the valve and that which is being delivered to do the job.  Seems with them so close in pressures I should be seeing some sort of weeping of fuel.  But then again, it is a Bosch and if they want 62.5 lbs to be delivered it best be there or nothing is going to happen.

Anyone else ever measure their pump in this manner?  Or are there specs available on the pressures I should have?

Getting tired of being immersed in diesel all day.  I want to go for a ride!

DAS

[fatmobile]

Accelerator lever on the right splines?