Starboard Cummins Diesel Quit ...

rossjo · Post by **rossjo** » Thu Aug 06, 2009 11:55 am

My starboard engine (Cummins) quit last week. Restarts after cooling and then quits after about 10 minutes. I replaced both filter and Racor water separator filter (on both engines as well), and it still quits. Now I can't start it because I can't bleed and prime the system, so the mechanical lift pump (engine driven fuel pump in gasoline enigne terminology) seems to be the culprit, as its hand operated primer pump no longer primes.

I haven't ruled out the fuel run solenoid, or the injector pump yet.

And I thought diesels were simple. Any diesel guys/ideas out there?

prowlersfish · Post by **prowlersfish** » Thu Aug 06, 2009 12:11 pm

Ross, first for priming Install a outboard pimeing bulb in the fuel line be for you first filter . not only is the a great way to prime the filters .It also is a easy way to see if there is a proplem pulling fuel from the tank. thats how I found a broken pick up tube on my boat . it works much better then the lift pump for priming. ( you still need the lift pump) if you get fuel will the priming bulb then you may have lift pump . if you done get ful with the bulb then you know you have a line or thank issue ( you have fuel right ?)

On you fuel sol can you send me a photo I maybe able to tel you how to bypas to check it '

BTW you can leave the bulb inline and it is a Tony aproved idea .

rossjo · Post by **rossjo** » Thu Aug 06, 2009 12:40 pm

Good idea, let me look. The fuel lines after the lift pump are all metal. Did you put yours before the lift pump?

Yes - have fuel. I even poured in 10 gallons of fresh diesel to make sure I wasn't sucking junk out of the tank or something. Gauges reads 5/8 full.

If I shutoff fuel at the Racor, remove the filter, and open the valve, fuel pours into the Racor from the tank, so that rules out fuel starvation from the tank.

I no longer have any resistance on the lift pump primer handle. If I loosen up the bleed screw on the fuel filter, I can pump fast, and get it to dribble a bit. It should pour out!

My injector pump is a Lucas CAV DPS rotary model. Very difficult to find much about them (and especially the fuel run solenoid, except in the UK for tractors and Vauxhauls). I'll send some pix direct to you ...

I really appreciate someone to brainstorm with.

jav · Post by **jav** » Thu Aug 06, 2009 1:29 pm

Captain Ross-

Did you check the on engine fuel filter when the engine died?? If it was not full of fuel (had an air gap), then it's likely NOT the solenoid. When the fuel solenoid fails, the rest of the fuel system usually appears fine.

If the fuel filter WAS down a little- then I would suspect a problem at or before the filter. Any work done recently that could have introduced an air leak? Any fuel leaks?

BTW- Great idea on the priming bulbs- I also read Tony's article and have 2 on order for my boat.

Stripermann2 · Post by **Stripermann2** » Thu Aug 06, 2009 1:32 pm

There's a simple article on http://www.boatdiesel.com about the primer bulb used for diesels. If you're not a member, sign up, it's quick and read it. Maybe this link will work...also I included a diagram, courtesy of BD.

http://boatdiesel.com/Articles/Articles ... uction.cfm

rossjo · Post by **rossjo** » Thu Aug 06, 2009 2:26 pm

The engine mounted fuel filter was full of fuel - and is now as well. So, I'm suspicious of:
1) Lift Pump diaphragm,
2) Fuel Run Solenoid failing when it warms up, shutting off fuel,
3) Relay feeding the Fuel Run Solenoid may fail when warmed up.

I still have some air in the lines, but can't push fuel up to prime/bleed it with the manual pump.

My prior drawing was wrong - it said DPS, but its really a Lucas CAV DPA pump ... I corrected the drawing.

jav · Post by **jav** » Thu Aug 06, 2009 2:57 pm

Sounds like your on the right track.

I would be surprised if it was the lift pump though. Normally the injection pump can overcome a weak lift pump (if there are no leaks) at least enough to run the engine even if full RPM can't be reached. And, if the diaphragm were bad, I would expect a leak of either fuel or air which should manifest itself either with visible fuel OR air entering the engine fuel filter which would be on the suction side of the injection pump. If this happened, the engine would NOT restart on its own when cold (which you said yours did)

It's worth checking but I think items 2 & 3 make more sense given your description.

BTW- if your engines are 250HP or under- you can do the prime bulb in-line without any other valving/plumbing. The diagram shown above is for engines that require more fuel flow so the priming circuit needs to be seperate.

rossjo · Post by **rossjo** » Thu Aug 06, 2009 6:12 pm

Good point ... it dies when running at low RPM (on the creek) after about 10 minutes, or even at the dock running steady at 800-900 RPM.

The squeeze bulb should overcome my priming/bleeding issue ... and I can use a Sierra bulb with no negative consequences, since I only have 220HP?

Longer term, I like the idea of the bypass, and taking the flimsy squeeze bulb out of the system.

I'm going out to see if I get any pressure from my primer handle ... then will get a Sierra bulb ...

prowlersfish · Post by **prowlersfish** » Thu Aug 06, 2009 7:05 pm

Ross you can run the bulb in line no proplem with a non-inline pump . I put on one mine when I had the pick up proplem and I have the hi-flow inline pump . I would put it before your first filter , that way it real easy to fill/prime the new filters . Its much easier to push the fuel thru the filter then to try and pull it thru .

And rejoin boatdiesel

rossjo · Post by **rossjo** » Thu Aug 06, 2009 8:42 pm

Thanks again Paul (for the email too) ... Tony knows his stuff.

Yes - my logon to BoatDeisel expired (or I lost it when my old laptop died). I'll renew - its well worth the $25/year.

Working all day tomorrow, then I'm going to be out of town for a week, so I probably won't get to this until I get back ...

Bottom line - I still have a run problem, and the lift pump, solenoid or solenoid relay must be the problem.

RWS · Post by **RWS** » Thu Aug 06, 2009 10:37 pm

Is it possible to have a loose fitting or chafe in the fuel line between the tank and the pump causing a vacuum issue where the pump is pumping air instead of fuel?

Maybe even an airleak in the Raycor?

Just a thought, otherwise it seems everything else has been covered.

Could you rig up a seperate source and plumb it into the system just before the mechanical pump?

That might eliminate some issues before you tear into them.

RWS

mtwolf · Post by **mtwolf** » Fri Aug 07, 2009 7:52 am

I ran into a problem, years ago, with a Cimmins diesel in a truck crane. After bleeding the injectors (they had run the engine out of fuel) it still wouldn't start. I followed the injectors return line down to the pump and this was were it was air bound. Loosened the line at the pump, followed by a hiss of air, and the engine fired up. Although, this doesn't sound like your problem. Just throwing some things out there. Someone I knew, years ago, fired up there engines with the tank valves closed and it pulled the balls out of the anti-siphon valves. With the filters full the engine would run until it ran out of fuel. Replaced the valves and all was well. Sounds like air getting into your system somewhere.

John
F-31
Middle River, MD