Quick question

[Lost Parent]

We are on holidays and cannot get diesel to rev high it stops around 2500 rpm when it should reach 3200 , in neutral it is fine but tied to dock or running it only reaches 2500 in gear and does pump out some black soot in water exhaust
Any quick suggestions

 

[monkeybars]

fuel filters dirty

 

[RichH]

Quick Answers:
Fouled bottom
Fouled prop
Stuffing box that has become tightened due to swelling of the FLAX packing.
Soot fouled exhaust system, usually at or near the water injection elbow
Failing injector or injectors (uncommon)
Change of timing of the hi pressure injector pump (rare)

Clogged Fuel filters will create a 'lean burn' mixture which rarely has a soot emission problem from the exhaust.

 

[Lost Parent]

going to stop at next town a get new ones
anything else ?

 

[Lost Parent]

how do i deal with a soot fouled exhaust

 

[Scott T-Bird]

Is this a new issue or has it always been this way. Prop may be over-sized or over-pitched. Does it have to labor to get to speed? Do you eventually get to hull speed? Is your boat under-powered?

 

[RichH]

how do i deal with a soot fouled exhaust

Eliminate the possibility of the other causes first - process of elimination of the cause.

Best is to get a mechanic who will do an exhaust gas pressure check, if engine doesnt have an exhaust port pressure port, then the only way is disassembly of the injection elbow, etc. followed by a visual inspection for 'coke' and carbonate deposition in the water injection area.
The problem with exhaust system disassembly is that you usually 'break' something. The parts counter of diesel distributors usually have injection elbows conveniently stored under the front counter ... because they are replaced quite often.

 

[Stu Jackson]

? what engine do you have ?

 

[okawbow]

The most likely problem is a fouled prop. Even a couple barnacles could cause a problem. Second is a fouled bottom. if your motor achieves normal RPM's in neutral; then it possibly is not a problem with the motor.

Start with the simplest causes first.

 

[Lost Parent]

Sole' 16hp and the soot goes away if i lower rpm to 2000

 

[Winkfish]

Could it also be some type of fuel restriction? Check fuel intake line for blockage or even a small leak which would let air in. Low revs it would run, but when you rev it up under load, it cuts out. This happened to us once on a bareboat charter. Cause was a bit of algae in the fuel pick-up tube in the tank.

 

[Lost Parent]

Probably the prop ,,soot is only there when higher reving with prop turn even if boat is in gear and tied to dock and not moving but goes away with lowering revs

 

[Winkfish]

Sorry, I misread your post.

 

[JK_Boston_Catalina310]

Another thing to check is your air intake

Your air filter could be clogged. This is an easy test, take the filter off and run the engine without the filter. If you don't have the soot, you know the cause.

Good Luck.

 

[Lost Parent]

Re: Another thing to check is your air intake

Want to thank all for the help . Ended being combination of pushing a small motor , dirty prop and towning large dinghy.
Holiday was super until we ran out of fuel in a storm and strong current in Porlier pass and my wife said she loved me and the hung on for dear life . then when we finally got into shelter and used the dinghy and motor to tow the boat and then ran out of gas in the middle of setup for a fireworks display and then had to be towed to dock by the local police boat , oh well the rest of the trip to Desolation sound was great