Our diesels still down from several days ago. Got to work to make the bucks it may cost if trouble is VP44! So no time for few days to get back after it. Still frustrated to say the least!
We have been reading all threads on two sites to gain insight and hopefully knowledge, on our problem.
Wonder to if LP running like crazy and not shutting off, maybe sign of valve on fuel return stuck open? Would then act like an air leak? Found small section rubber hose on return line, going to pinch this down, next hour free in daylight that is. The going from running excellent to cranking fast, running LF and hard starting last Saturday to Dead by Wednesday. Would or could this be a usual / normal symptom of a dying / dead Vp44? Still looking for any and all suggestions.
We posted also on Wednesday 25th about this. With more details. Diesel Down
We've learned alot, if nothing else just from reading back postings. Thanks Much.

 

Pressure valve on lift pump....could be. Have you checked the pressure at the VP? Disconnect the supply line and see how much fuel is coming out. Can you easily stop the fuel flow with your thumb and finger (one each side of the banjo fitting)? Easily is really easy. The pressure valve in the lift pump is supposed to lift around the 15psi mark or so. How's the fuel filter?

The pressure valve I've found on the VP44 is in the return banjo bolt. Even with the return line off the injector pump, the lift pump would still hit 16psi read at the VP44. There was some diesel fuel being pumped out of the VP return line, but not alot, so there's interior restrictions (at least on mine) that allowed for the lift pump to develop full pressure. That "at least on mine" part was because I'm experiencing "technical difficulties" so, the VP44 may not have "internal restrictions" if it's OK....?????

It's easy enough to check the pressure valve in the banjo bolt. Simply remove the front most bolt and inspect/test the ball. Note there are two washers, one on each side of the banjo fitting that need to be reinstalled or fuel mileage might go down.

Good Luck
Ol Blue

 

Thanks much we'll give it a try. Monday's to be our' let's get back to figuring this thing out!' We both hope anyway. Soon going to need it for heavy hauling for work!
Thanks again

 

Have you checked for codes? Just because the check engine light is not on does not mean there are no codes set.

Really need to check for LP fuel pressure. LP can be running and still have no pressure. They have a designed shaft that will break if the impeller gets seized or clogged.

Clogged pick up screen in the tank from algae or other debri.

Ditto above, clogged fuel filter.

Loose banjo fitting somewhere in line allowing air to get in the lines.

 

Did check for codes after first posting on 24 March 12:12GMT 'Diesel Down'. Was suggested to us to how to check codes and also to try and start after disconnecting Elect. Power to Lift Pump. Only code was 'P doNE' until we disconnected LP then Code also 'P1693' Which we do not know the meaning of. Now we also do not know how to reset codes.

Fuel flow / pressure appears fine through fuel filter. Is a good flow not a trickle. But do not have Gauge YET to give exact.

Religious about changing fuel filter. Have always know importance of this. Changed again when this trouble started. With less than 3K miles since last change!! Wiped resevoir with care also. Always bleed air before trying to start.

So we know fuel is getting past filter. Question is then what is happening? This is why we're wondering about stuck check valve on the return side of VP44? Hypothetical thought, if this check valve on return was stuck open, fuel running through as fast as can be, would not LP run abnormally long? Also would seem could never build pressure neccessary to fire up?

Come on folks help us out here. Grasping at straws and about to head out and tackle this thing again. If it is the VP44 so be it, just need an answer to get back up and running and earning at this point.

Thanks Much

 

Lift pump should be running when the engine is running.
Lift pump will run for 20 seconds if the starter is bumped, but engine isn't started
Depending on ECM "character" the lift pump will run from momentarily to several seconds, then stop to allow lower pressure for starting.

What is abnormally long?

I don't think that an open pressure valve (ball and spring) in the return line would keep the engine from starting. I suppose it could allow air to get back into the VP if it doesn't seal somewhat. Don't look for a perfect seal, the ball won't seal perfectly against the banjo bolt shoulder.

Pull the banjo bolt from the return line and cycle the lift pump (bump starter but don't start engine). Lift pump should run for about 20 seconds. Is there a slow trickle of fuel coming out of the pump? Try a couple of times just to make sure. Does the lift pump sound like it's "working"?

If no fuel this way, it could be the lift pump. If fuel is there, put the return line back on and loosen a couple of the high pressure fuel lines on the back of the VP, crank the engine.....have fuel? If no fuel here, but had fuel at the return, I'm guessing the VP took a vacation.
I'd play with bumping the starter to cycle the lift pump and cranking (for no longer than 20 seconds at a time) to see if fuel wouldn't eventually get to the injector line if there was fuel at the return line. I'd keep at it for a good 20 minutes or so before deciding it's dead. If you eventually get fuel at the back of the pump (injector lines), there could be an air leak letting the system bleed down.

Good luck