Former VWDieselParts.com Forum

Another vague "explanation" of how the fuel lines were checked without using clear lines.
Our cars don't have a helper pump does yours?
Our cars don't run fuel under pressure.
Do you know how much pressure you your system runs under? If so how much? Do you have a fuel pressure gauge?

yes engine has mechanical liftpump and fuelsystem is pressurised after the pump.
so not possible to be air in pressure side

i have not tested pressure with gauge.
but there is both lots of pressure and lots of fuel when opening banjobolts on pressure side.

i have now visited bosch workshop.

the pumphead is stuck. and has cracked the camplate in half.
bosch in germany has not these parts but i ordered from another country myself.

what could cause this to happen?
i have 3 theories but can not find these possible.
*water in fuel/water molecules? -we have no signs of water in filters, and the whole pump looked like new inside. also both engines run from same fuel feed.
*air in fuel system, so pump runs dry. - no air found in fuelsystem found
*dirt in fuel. - i have 3 fuelfilters before pump. and also if dirt comes in it should get out via return before coming all the way to highpressure side.

Do you use fuel from auto pump
and you know problem with marine fuel tanks?

Running dry most UN-likely...
Inlet to the high-pressure section is at the top of the pump, above most of the rotating parts.


The engine will stall before the IP goes dry.

More likely: Return line plugged, pump overheated from no cooling fuel circulating through... very fine tolerance on the plunger, heat expansion siezed the plunger and bang.

Oh, mechanical pump on the engine.
Just curious,.. filter, then mechanical pump, then injection pump?

or mechanical pump then filter then injection pump?

Tank-filter-filter(both with water separator)-pump-filter-injection pump

The reason I asked is because I connect a dash-mounted vacuum gauge to the fuel line, on all my cars.
It's saved me from being stranded several times. But mine doesn't have a helper pump.
I suppose a vacuum gauge mounted before the mechanical pump would give you an idea how clogged your first 2 filter are getting.
A clogged vent line can collapse a metal Rabbit tank.

I mean fuel miced with airbubbles

Still no stop in return

Has anyone of you heard of this pumphead gettong stuck?

TylerDurden wrote:Running dry most UN-likely...
Inlet to the high-pressure section is at the top of the pump, above most of the rotating parts.


The engine will stall before the IP goes dry.

More likely: Return line plugged, pump overheated from no cooling fuel circulating through... very fine tolerance on the plunger, heat expansion siezed the plunger and bang.

reimatic wrote:I mean fuel miced with airbubbles

Still no stop in return

Has anyone of you heard of this pumphead gettong stuck?

Fuel miced with air bubbles? Where did you see this?

A clear fuel line after the pump would be able to tell you a lot at a glance.
As you can tell a clear piece of fuel line somewhere in the system is very important to me.

I have never seen a plunger get stuck in the high pressure head on anything that wasn't sitting on the shelf for a long time, let alone break a cam disc.

fatmobile

i got the pump from bosch today
he gave me the stuck ¨pump head¨

he did also try to open it with hammer but it is so stuck that he only hit it once without result.
i will open it myself and see whats happened inside...

i will install this now this weekend and continiue.

Well it wasn't a simple solution but when you go to fix things like this it helps you understand how things work.
Might help you with a future problem.

rebuilt pump installed and angine still powerless
we switched injectors between the engines and after that engine feels little more stronger.

got it up to about 2000rpm

but now one of the injectors in working engine has a leak in the injector sleeve.

one other pump mechanic told me that when i increased the fuel screw i also increased the pump pressure and the pump/hydraulic head stuck

Again, not very likely. These pumps are good to something like >300bar in the high pressure section.

The only causes I've seen/heard of plunger failure are poor fuel circulation (cooling) and improper assembly.

It might be possible that a return-spring fails and the camplate moves off center.

Yeah, RPM determines internal pump pressure (if everything is working right, pressure regulator working correctly) adjusting the max fuel screw won't change that,.. and if it did how would that cause metal to grab metal?
As RPM increases it pushes the timing advance piston and controls the timing curve.
I really don't think it would run at all with a stuck head, but you said it was running until the pump was removed.
Your pump guy sounds sketchy to me.
Clear lines between the injectors?
Maybe a fuel pressure gauge at the front of the pump, compare with the other engine that is running great.

Fatmobile
You must have missunderstand me!

We increased fuel anount
Then after about 2 hour running engine stopped
Opened pipes to injectors and only fuel to cyl nr3 when run starter.
Thats about the pump!

Update
We switched injectors between engines
After that little more power !
And other engine less power. But still only about 50-60% power

Switched injectors back and engines condition back to where we started.

Then my mechanic tried leakdown test
5of 6 cyl leaking from inlet valve .
That would explane powerloss?
But we did test on other engine also.
Same thing here 6 of 6 cyl leak inlet valve

Mechanic was not expecting inlet valves, he mentioned already when i met him that exhaust valves possibly faulty

I see this as a combination of injectors bad and valves leaking?