Diesel lines bleeding help

[topmast]

Back to the OP's post, that droplet of fuel is a metered amount from the HP pump. Don't expect a squirt. Get a steady flow (no bubbles) from the low pressure side and those droplets will show you some action. As an aside I had a very small aqua muffler which drained to bilge unless we had oil pressure .ie engine running. Just another system but never failed as anti syphon vents are prone to do.

[captmikem]

sounds to me like you may have a clogged filter, not a problem with a vent. a clogged vent would not cause air in the system unless it sucked it in from a lose line. you mentioned you had fuel before the injector pump, give the fuel pump a few plunges to make sure it pumps fuel freely. Won't hurt anything to check the filters while you are trying to bleed it. Both the primary and the final.

M

[Sandibar]

Ok. Loosened the banjo and started the lift pump. A lot of diesel coming through and the pump assy is full. Still not able to get fuel to the injector lines by cranking the engine. Will leave it for the night. Apprecciate any additional ideas. Only thing I can think of is that the overflow pipe back to the tank could be blocked, would that matter?
Will try to find a local mechanic tomorrow.

[Scout 30]

I have to second adding an electric fuel pump, with a switch, before your primary fuel filter. They're cheap, last pretty much forever & usually solve problems like this. Plus, if your mechanical pump goes bad you can run your motor off of it. Most of the time you can just turn the pump on & the motor will self bleed. NEVER try to bleed your motor by cranking the engine. As previously stated it will back fill & hydrolock.

[Qayaq]

Just in case the reason it stopped is not a plugged breather. It looks like that solenoid on the top of the pump is an energized to run type. You could check it's got a 12v feed. Good luck with it.

[Sandibar]

Originally Posted by captmikem

sounds to me like you may have a clogged filter, not a problem with a vent. a clogged vent would not cause air in the system unless it sucked it in from a lose line. you mentioned you had fuel before the injector pump, give the fuel pump a few plunges to make sure it pumps fuel freely. Won't hurt anything to check the filters while you are trying to bleed it. Both the primary and the final.

M

Thanks for the idea. I get a decent flow after the filter, so did not think that would be an issue. Will change it tomorrow. Still, I have diesel on the hp pump but it does not flow to the injector lines. I have an electric lift pump and have removed the water pump belt temporarily, so should not flood the engine.

[AndyEss]

If the tank vent was clogged for some period of time, you can collapse the fuel tank itself by drawing fuel (running the engine) out of the tank. No air coming in through the vent means the tank starts developing a vacuum inside it. If the vacuum is high enough (long period running the engine using large volumes of fuel) and the tank has thin enough walls, the tank walls will start collapsing. This happened once to one of my company drivers on a diesel vehicle he drove with the tank vent clogged.
After you get your engine running, I'd check the tank for any possible damage. The tank collapsing shouldn't have anything to do with the lack of fuel at the injectors - unless the tank walls flexed under partial collapse and a bunch of crud flaked off the inside tank walls and then clogged the fuel lines. If you are getting good fuel at the filter, this doesn't sound likely.
Check the engine manual - many diesel engines have manually activated fuel primer pumps right at the high pressure fuel pump to prime the pump and injector lines when air gets into the system - most commonly when you run out of fuel.

[captd44]

Originally Posted by Qayaq

It looks like that solenoid on the top of the pump is an energized to run type. You could check it's got a 12v feed. Good luck with it.

I agree if it has a solenoid for shutdown it must be energized. If so I would still make sure it is working, even remove and test.

[Sandibar]

Originally Posted by Qayaq

Just in case the reason it stopped is not a plugged breather. It looks like that solenoid on the top of the pump is an energized to run type. You could check it's got a 12v feed. Good luck with it.

Ok thanks, did not think of that. The idiot that I am, while trying to crank the engine with open throttle, I had the reverse gear engaged on the outside steering station ( from sailing earlier) . After putting the gear to neutral, did manage to get diesel to the injectors. By then we were running low on amps and could not turn the engine fast enough to start. Turns out there's also cabling work to be done. Got towed into a marina today and charging now. Fingers crossed the engine will fire tomorrow morning. Will update and thanks for all the support so far! Learned loads from this thread while playing with the engine.

[thunderhoof]

For my 29 hp Perkins diesel I added a bulb priming pump in the line from the tank filter to the lift pump. To bleed the system - with the engine off I use the bulb to pump through the lift pump and engine mounted filter to the bleed point at the top of the filter, the highest point in the fuel system, until no air is seen. I find the engine will then usually run so I then start it and run it just above idle. Then I bleed each injector until there are no bubbles as each one opened. Then I raise the speed to near operating rpms and repeat the injector bleeding process. I agree that this usually needs to be done more than once to completely bleed the system.

[Sandibar]

Hmm. I changed the fuel filter (clean) and rewired the starting circuit. Some connections were horribly corroded and cranking was lame. The engine fired for a few seconds but then died. Would a blocked exhaust cause sich symptoms? Cant really think of anything else anymore.

[DeepFrz]

Give bleeding one more shot.

[belizesailor]

What blocked your vent tube?

[Sandibar]

Originally Posted by belizesailor

What blocked your vent tube?

Did not get to checking that, it's not easily accessible. I was venting through the fill line while I was trying to start the engine. That said, I'm not sure if that was the root cause after all, although venting did fix the first problem of diesel flow to the HP pump. I suspect the engine has come to it's natural end now after 30+ years of service. Will let a mechanic have a look at it, before deciding what to do.
We got home the traditional way on a perfect broad reach and landed with the 3,5hp dinghy engine pushing the final 2 miles to dock.

[Sandibar]

Today I removed the exhaust line from the engine, to see if that makes any difference. There was just a little water coming from the pipes. The engine was close to firing after that but with heaps of grey smoke coming out. Subsequent tries with normal cranking and spraying wd-40 into the air intake did not improve things. Now cranking does not produce any result except turning the engine. It seems there is air and fuel, but no heat/compression. Will get expert advice, but if anyone has any more pointers, I'm happy to listen. I guess the engine's toast