priming fuel system troubles

[Westie]

I have recently replaced an oil pump on my generator's Ruggerini diesel engine after a loss of pressure. The diesel is a 2 cylinder 19 hp unit 22 years old. After replacing the pump and reconnecting everything I tried to start the engine after turning it over several times to establish oil pressure. The unit started immediately and shut down like it was running out of fuel. I have tried the following with no luck - turned on the electric fuel pump and opened the bleed screw adjacent to the pressure pump to remove air - with the pump running I cracked the nut on one of the 2 injectors while turning the engine over = no or little fuel - tried the same with the other nut same result - repeated the bleeding at the pressure pump, cracked the nuts again same result. The engine almost starts or does for a few seconds then seems to run out of fuel again. I have replaced the fuel filter with a new unit and checked the old one by emptying the fuel from it into a clear bowl - no sediment etc. apparent. I checked to make sure that only 1 gasket was on the filter. Filter was filled to the top before installation. All unions etc. have been checked to ensure air was not being pulled into the system. By the way, the original mechanical fuel pump ( lever type) had been removed by a previous owner and replaced with an electric pump. Before the oil pump troubles I had no starting issues. While replacing the oil pump I checked all oil passages etc. as much as possible, removed the oil filter housing to ensure it was clear, removed the oil pan to check the sump screen, replaced gaskets etc. and re-assembled. During this process the engine was turned on it's face ( flywheel?) to allow me to work on the oil pan etc. then sat back upright. Could this "turning" of the engine have done something to the pressure pump? The oil pump failed because of a " pin" joining the parts of the inner pump ring scored the pump. I'm not sure how many hours are on the unit but the previous owner told me it was lightly used!!?? I'm out of ideas!

[Alan Wheeler]

Is the start and stop electric or is there just a manual stop. Ensure the stop is not in Stop mode and ensure the key is on if it is electric start/stop. The stop works by shutting off the fuel rack, so you will have no fuel to the injector.
The issue you have sounds like a classic air in the injector line scenario. Do the bleeding while the engine is trying to start.

[Charlie]

Check all fuel hoses and make sure that the clamps are tight and have not ruptured the fuel lines. I recommend that fuel line clamps are the AWAB (sp?) type b/c they don't cut holes in the fuel lines. Also check the O rings on the primary filters. I had the same problem but couldn't figure out wher the problem was but something that I did fixed it. Caulder sayys to take the fuel line that feeds the injectors and put it in a glass jar filled with a little bit of diesel. If you see bubbles coming out of the fuel line you have an air leak.

[Alan Wheeler]

Caulder sayys to take the fuel line that feeds the injectors and put it in a glass jar filled with a little bit of diesel.

That is easier said than done. IMO, don't take those lines anywhere. They are too easily broken and you certainly won't be able to get an end of one in a jar unless you bend it. I would say leave well enough alone.
In Westies situation, I would doubt he has an air leak. I think he has a simple air bubble in the injector line and needs to get it bled.

[drh1965]

Originally Posted by Alan Wheeler

That is easier said than done. IMO, don't take those lines anywhere. They are too easily broken and you certainly won't be able to get an end of one in a jar unless you bend it. I would say leave well enough alone.
In Westies situation, I would doubt he has an air leak. I think he has a simple air bubble in the injector line and needs to get it bled.

I don't think he means the lines from the injection pump to the injectors. Air bubbles (from air leaks) would only show up on the suction side of the lift pump anyway. On the output side, it would be a fuel leak. Right? If one places the fuel hose from the output side of lift pump into a bottle of diesel, you can determine if there is a leak from the fuel pickup to the suction side of the lift pump. I've done this. It works. I've also used the trick of sucking fuel from a bucket rather than the fuel tank to isolate fuel pickup leaks.

Having just gone through a similar ordeal, I'd make sure you're getting proper flow at all the intermediary places in the fuel delivery system. That is, yank the input hose to the secondary filter and check it for proper flow (and bubbles). Then yank the hose of the input to the injection pump and repeat. Diagnosing these problems calls for being very methodical and making no assumptions (a mistake I make repeatedly).

Good luck. It'll probably turn out to be something simple.

[Charlie]

DRH:

Was able to interpert what I wrote. It was unclear. I meant the flexible fuel hose not the solid injector lines. To be more specific on my engine I would check the fuel line before it gets to the lift pump. And while there I would check to see that you are getting suction from the lift pump itself.

What seems strange to me is that you are not getting fuel to the injectors. Can you run the fuel pump without turning the engine? If so run the pump till you get solid diesel coming out of the nut you cracked belonging to the injector.

[S/V Antares]

Sounds like the issue is with the suppl side to the pump.

Many electrick lift pumps have a small filter in them.

I have a an outboard fuel bulb inline BEFORE the Racor so I can use it to prime the filters and bleed the system up to the High pressure pump.

After throughly bleeding the low pressure side try "Cracking " (Undoing one half turn) one of the injector lines and try starting untill you get a steady spit then tighten. I do not think the Rugerinni has comrpession relife but if it does you can spin the engine with the starter for a short period (10 15 seconds) in order to bleed the High pressure side.

[Alan Wheeler]

f so run the pump till you get solid diesel coming out of the nut you cracked belonging to the injector.

Lets keep this simple guy's. A lot of advice from guesses being thrown in here.
An Injector pump is a positive displacement pump. You can not force fuel through the pump. The low pressure supply side of the pump is seperate from the high pressure injector side of the pump. Westie has stated he has an electric fuel lift pump. He has bleed all the air on that side through to the Injector pump. So this leaves the problem on the high pressure injector side of the pump. That means two possible issues. Air in an injector line or the stop solinoid has not moved to open. Diesels are a fairly straight forward logical point to point machine. You locate and confirm point A is working and then move on to Point B.

[drh1965]

Originally Posted by Charlie

DRH:

Can you run the fuel pump without turning the engine? If so run the pump till you get solid diesel coming out of the nut you cracked belonging to the injector.

Sure. The electric pump will run when the ignition key is turned to "run". You'll probably hear "click click click ..." The fuel leaves the tank, through the primary, through the electric lift pump, through the secondary, through the injection pump, to the injectors where it is then all returned to the fuel tank (if the engine isn't running). Checking each stage along the way to make sure the fuel flow is good and air free will probably lead you to a solution. Hopefully

[MidLandOne]

Originally Posted by drh1965

Sure. The electric pump will run when the ignition key is turned to "run". You'll probably hear "click click click ..." The fuel leaves the tank, through the primary, through the electric lift pump, through the secondary, through the injection pump, to the injectors where it is then all returned to the fuel tank (if the engine isn't running). Checking each stage along the way to make sure the fuel flow is good and air free will probably lead you to a solution. Hopefully

I am no diesel mechanic so would you explain how the fuel gets through the injection pump if the engine isn't running?

Thanks

[drh1965]

Originally Posted by MidLandOne

I am no diesel mechanic so would you explain how the fuel gets through the injection pump if the engine isn't running?

Thanks

If the engine isn't running, the ALL fuel returns to the tank through the return. Is that what you're asking? By the way, I'm very far from a diesel mechanic. Just trying to help.

[Chief Engineer]

As was stated before check and make sure the stop circuit is not engaged....visually make sure that the stop assembly is in the run position.

[MidLandOne]

Originally Posted by drh1965

If the engine isn't running, the ALL fuel returns to the tank through the return. Is that what you're asking? By the way, I'm very far from a diesel mechanic. Just trying to help.

No, I'm familiar with the leak off return from the injectors. What I can't understand is how the fuel gets through the injection pump to the injectors if the engine isn't running.

[Alan Wheeler]

Correct MidLandOne. No fuel can get past the injector pump when the injector pump is not running. I discussed why in a previous post above. The lift pump does not continuously cycle fuel through the injector pump back to the tank. The return line is as Midland said, the Injector bleed off.

[drh1965]

Originally Posted by Alan Wheeler

Correct MidLandOne. No fuel can get past the injector pump when the injector pump is not running. I discussed why in a previous post above. The lift pump does not continuously cycle fuel through the injector pump back to the tank. The return line is as Midland said, the Injector bleed off.

Can you point me to that post? You guys are confusing me (unless we are talking semantics). On my engine, the fuel comes off the secondary filter to the injector pump which is then connected by rigid fuel lines to the injectors. The Injector return lines are connected to the injectors and goes back to the tank. How does the fuel get from the secondary filter to the return line without passing through the pump?