[Amel Yacht Owners] Onan Cranks But Won't Start


Mike Ondra
 

Hello Gary.

Aletes’s Onan suffered similar symptoms this last spring after not being used for over 6 months. Check my posting Aug 1, 2015 “Onan generator will not run”. Carbon buildup at exhaust manifold/mixing elbow junction had restricted exhaust flow to the diameter of a pencil. Once relieve she started on the first bump.

Mike Ondra

Aletes SM#240

 

From: amelyachtowners@... [mailto:amelyachtowners@...] On Behalf Of amelliahona
Sent: Tuesday, January 19, 2016 9:21 PM
To: amelyachtowners@...
Subject: [Amel Yacht Owners] Onan Cranks But Won't Start

 

 

 

Hi All:

 

My boat, SM #335, has an Onan 7MDKAL-431 Spec B, 7 kW genset.  It has 2,300 hrs on it and it has been basically flawless with normal matinenance.  6 months ago I changed the oil, it operated fine and we put it on the hard in Puerto Rico for the hurricane season.  Now, having splashed yesterday, I can't get the darn thing to start.  It cranks, attempts to start but will not sustain combustion.  Inspection of the water pump reveals all impeller blades intact (new impeller), no missing blades to account for since last change.  The oil level is good, oil is clean.  It seems to crank a bit slow, so I took the starter off, cleaned up the brushes and commutator and re-installed it cleaning up all the terminals as I went.  Still cranks seemingly slow, but realy plenty fast to start if somehting else wasn;t wrong.  I changed the fuel filter and bled the system.  I checked all the sensors (mine doesn't have the fault flashing light sytem).  I installed my new spare electric fuel pump (what a pain in the a..), the engineer that designed that location should be keel-hauled.  I'm kind of running out of ideas.  Browsed the forum back a year or two and didn't come up with this scenario or additional ideas.  Any additional thoughts?

 

Appreciate the help. 

 

Gary Silver,  Amel SM #335   Puerto Del Rey - Puerto Rico


Germain Jean-Pierre <jgermain@...>
 

Hi Gary,

Think simple… if your engine starts then shuts down,  it is likely a fuel problem.

Good luck,


Jean-Pierre Germain,
SY Eleuthera, Amel Super Maramu 007


On 20 Jan 2016, at 04:57, 'Mike Ondra' mdondra@... [amelyachtowners] <amelyachtowners@...> wrote:

 

Hello Gary.
Aletes’s Onan suffered similar symptoms this last spring after not being used for over 6 months. Check my posting Aug 1, 2015 “Onan generator will not run”. Carbon buildup at exhaust manifold/mixing elbow junction had restricted exhaust flow to the diameter of a pencil. Once relieve she started on the first bump.
Mike Ondra
Aletes SM#240
 
From: amelyachtowners@... [mailto:amelyachtowners@...] On Behalf Of amelliahona
Sent: Tuesday, January 19, 2016 9:21 PM
To: amelyachtowners@...
Subject: [Amel Yacht Owners] Onan Cranks But Won't Start
 
 
 
Hi All:
 
My boat, SM #335, has an Onan 7MDKAL-431 Spec B, 7 kW genset.  It has 2,300 hrs on it and it has been basically flawless with normal matinenance.  6 months ago I changed the oil, it operated fine and we put it on the hard in Puerto Rico for the hurricane season.  Now, having splashed yesterday, I can't get the darn thing to start.  It cranks, attempts to start but will not sustain combustion.  Inspection of the water pump reveals all impeller blades intact (new impeller), no missing blades to account for since last change.  The oil level is good, oil is clean.  It seems to crank a bit slow, so I took the starter off, cleaned up the brushes and commutator and re-installed it cleaning up all the terminals as I went.  Still cranks seemingly slow, but realy plenty fast to start if somehting else wasn;t wrong.  I changed the fuel filter and bled the system.  I checked all the sensors (mine doesn't have the fault flashing light sytem).  I installed my new spare electric fuel pump (what a pain in the a..), the engineer that designed that location should be keel-hauled.  I'm kind of running out of ideas.  Browsed the forum back a year or two and didn't come up with this scenario or additional ideas.  Any additional thoughts?
 
Appreciate the help. 
 
Gary Silver,  Amel SM #335   Puerto Del Rey - Puerto Rico




Olivier Beaute
 

Good morning Gary,

the Onan sometimes starts with difficulties because of electric power (although the main engine starts easily).
Is your starter battery in good condition (how old is it?)? Did you charge it while your 6 months on the hard.
To make sure this is not a battery problem, start your engine first, run it at 1200 rpm, then try to start the genset.
The problem could also be the pre-heating plugs that are dead (is the starter battery voltage going down when you're pre-heating?).

In french, we say: let's start with the beginning! The beginning is the starter battery. Then you will investigate the fuel supply line...

Good luck.

Olivier.


On Wednesday, January 20, 2016 7:25 AM, "Germain Jean-Pierre jgermain@... [amelyachtowners]" wrote:


 
Hi Gary,

Think simple… if your engine starts then shuts down,  it is likely a fuel problem.

Good luck,


Jean-Pierre Germain,
SY Eleuthera, Amel Super Maramu 007


On 20 Jan 2016, at 04:57, 'Mike Ondra' mdondra@... [amelyachtowners] <amelyachtowners@...> wrote:

 

Hello Gary.
Aletes’s Onan suffered similar symptoms this last spring after not being used for over 6 months. Check my posting Aug 1, 2015 “Onan generator will not run”. Carbon buildup at exhaust manifold/mixing elbow junction had restricted exhaust flow to the diameter of a pencil. Once relieve she started on the first bump.
Mike Ondra
Aletes SM#240
 
From: amelyachtowners@... [mailto:amelyachtowners@...] On Behalf Of amelliahona
Sent: Tuesday, January 19, 2016 9:21 PM
To: amelyachtowners@...
Subject: [Amel Yacht Owners] Onan Cranks But Won't Start
 
 
 
Hi All:
 
My boat, SM #335, has an Onan 7MDKAL-431 Spec B, 7 kW genset.  It has 2,300 hrs on it and it has been basically flawless with normal matinenance.  6 months ago I changed the oil, it operated fine and we put it on the hard in Puerto Rico for the hurricane season.  Now, having splashed yesterday, I can't get the darn thing to start.  It cranks, attempts to start but will not sustain combustion.  Inspection of the water pump reveals all impeller blades intact (new impeller), no missing blades to account for since last change.  The oil level is good, oil is clean.  It seems to crank a bit slow, so I took the starter off, cleaned up the brushes and commutator and re-installed it cleaning up all the terminals as I went.  Still cranks seemingly slow, but realy plenty fast to start if somehting else wasn;t wrong.  I changed the fuel filter and bled the system.  I checked all the sensors (mine doesn't have the fault flashing light sytem).  I installed my new spare electric fuel pump (what a pain in the a..), the engineer that designed that location should be keel-hauled.  I'm kind of running out of ideas.  Browsed the forum back a year or two and didn't come up with this scenario or additional ideas.  Any additional thoughts?
 
Appreciate the help. 
 
Gary Silver,  Amel SM #335   Puerto Del Rey - Puerto Rico






Alexandre Uster von Baar
 

Sorry to read about your problem Gary,

Read the other reply, did you check all the fuse/breakers, especially the "Field" were on?

Sincerely, Alexandre




--------------------------------------------

On Tue, 1/19/16, amelliahona <no_reply@...> wrote:

Subject: [Amel Yacht Owners] Onan Cranks But Won't Start
To: amelyachtowners@...
Date: Tuesday, January 19, 2016, 8:21 PM


 









 Hi All: My boat, SM
#335, has an Onan 7MDKAL-431 Spec B, 7 kW genset.  It has
2,300 hrs on it and it has been basically flawless with
normal matinenance.  6 months ago I changed the oil, it
operated fine and we put it on the hard in Puerto Rico for
the hurricane season.  Now, having splashed yesterday, I
can't get the darn thing to start.  It cranks, attempts
to start but will not sustain combustion.  Inspection of
the water pump reveals all impeller blades intact (new
impeller), no missing blades to account for since last
change.  The oil level is good, oil is clean.  It seems to
crank a bit slow, so I took the starter off, cleaned up the
brushes and commutator and re-installed it cleaning up all
the terminals as I went.  Still cranks seemingly slow, but
realy plenty fast to start if somehting else wasn;t wrong. 
I changed the fuel filter and bled the system.  I checked
all the sensors (mine doesn't have the fault flashing
light sytem).  I installed my new spare electric fuel pump
(what a pain in the a..), the engineer that designed that
location should be keel-hauled.  I'm kind of running
out of ideas.  Browsed the forum back a year or two and
didn't come up with this scenario or additional ideas. 
Any additional thoughts? Appreciate the
help.   Gary Silver,  Amel SM #335  
Puerto Del Rey - Puerto Rico









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amelliahona <no_reply@...>
 

Hi Mike:

 

I am thinking that exhaust restriction is a possibility. 

 

The fuel supply side checks out:

- New RaCore Filters prior to haul out and are clear

- Fuel topped up so condensation shuldn't have been problem

- Sumping the fuel filter revealed no water or crud

- Changed the fuel filter nevertheless

- Electric fuel pump puts out copious pressurized clean fuel at the bleed bolt

- Fuel shut off valve fully open and RaCore valve properly set to open

Only thing I can't/haven't checked on the fuel side of the equation is the injectors.

 

On the intake side I am going to pull the intake manifold to see if there seems to be any obstruction like a delaminated hose etc.

 

On the exhaust side, that is where I am putting my money.  If there is an obstruction that would explain the low cranking speed (i.e. cranking agains an obstruction) and would also explain the failure to start.   Thanks for the failure mode history.

 

Sincerely,

 

Gary Silver   s/v Liahona   Amel SM #335

 


 


Mike Ondra
 

Hi Gary,

I pretty much went through what you did. Also had the injectors rebuilt all to no avail. Even checked for obstruction BETWEEN the exhaust mixing elbow and the thruhull. Ultimately loosening the exhaust manifold was the test that allowed an immediate start. After replacement, starts like a champ.

Lesson: Like the propulsion engine, the generator Kubota needs to see some load periodically to reach high enough temps to burn out the carbon on the exhaust side.

Will be interested to hear about what you find.

Mike

Aletes SM#240



From: amelyachtowners@... [mailto:amelyachtowners@...] On Behalf Of amelliahona
Sent: Wednesday, January 20, 2016 11:10 AM
To: amelyachtowners@...
Subject: RE: [Amel Yacht Owners] Onan Cranks But Won't Start





Hi Mike:



I am thinking that exhaust restriction is a possibility.



The fuel supply side checks out:

- New RaCore Filters prior to haul out and are clear

- Fuel topped up so condensation shuldn't have been problem

- Sumping the fuel filter revealed no water or crud

- Changed the fuel filter nevertheless

- Electric fuel pump puts out copious pressurized clean fuel at the bleed bolt

- Fuel shut off valve fully open and RaCore valve properly set to open

Only thing I can't/haven't checked on the fuel side of the equation is the injectors.



On the intake side I am going to pull the intake manifold to see if there seems to be any obstruction like a delaminated hose etc.



On the exhaust side, that is where I am putting my money. If there is an obstruction that would explain the low cranking speed (i.e. cranking agains an obstruction) and would also explain the failure to start. Thanks for the failure mode history.



Sincerely,



Gary Silver s/v Liahona Amel SM #335


amelliahona <no_reply@...>
 

Mike and all others who were kind enough to reply:

 

I verified there was no induction blockage (just two screws and three worm clamps to removed the induction box. 

 

Removed the mixing elbow and the elbow was cram packed with hard encrustations.  It took an hour to dig it all out.  There was no visible opening whatsoever.  There are also encrustrations and blockage at the exhaust manifold outlet.  I am working on those but I am wondering about the shape of the outlet of that box like exhaust manifold.  It almost appears to be a sort of venturi shaped outet.  Either that or the scale/encrustations/corrosion have mis-shappen it.  Can you or anyone comment on the appropriate shape of the outlet of the exhaust maniforld on the Onan.

 

I havn't finished up re-assembly but I can't immagine how the genset even ran previously. Pictures to follow when I get better band-width.

 

All the best,

 

Gary  s/v Liahona

 

PS I think a new thread with a discussion about running the genset under load vs running the genset with no load to allow the generator to cool down prior to shut-down, and preventative maintenance on exhaust elbows might be be in the offing.


Mark Erdos
 

An “ah ha” moment J

 

 

 

With best regards,

 

Mark

 

Super Maramu 2000

Hull #275

www.creampuff.us

Currently cruising:  Marsh Harbour – Abaco Islands - Bahamas

 

From: amelyachtowners@... [mailto:amelyachtowners@...] On Behalf Of amelliahona
Sent: Wednesday, January 20, 2016 4:18 PM
To: amelyachtowners@...
Subject: RE: [Amel Yacht Owners] Onan Cranks But Won't Start

 

 

Mike and all others who were kind enough to reply:

 

I verified there was no induction blockage (just two screws and three worm clamps to removed the induction box. 

 

Removed the mixing elbow and the elbow was cram packed with hard encrustations.  It took an hour to dig it all out.  There was no visible opening whatsoever.  There are also encrustrations and blockage at the exhaust manifold outlet.  I am working on those but I am wondering about the shape of the outlet of that box like exhaust manifold.  It almost appears to be a sort of venturi shaped outet.  Either that or the scale/encrustations/corrosion have mis-shappen it.  Can you or anyone comment on the appropriate shape of the outlet of the exhaust maniforld on the Onan.

 

I havn't finished up re-assembly but I can't immagine how the genset even ran previously. Pictures to follow when I get better band-width.

 

All the best,

 

Gary  s/v Liahona

 

PS I think a new thread with a discussion about running the genset under load vs running the genset with no load to allow the generator to cool down prior to shut-down, and preventative maintenance on exhaust elbows might be be in the offing.