Nanni starting problems

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Independence

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Can anyone suggest reasons why my Nanni 21hp engine with 190 hours on it has begun to start poorly?

This is the second year I've experienced a problem. First start of the year it fires up after only turning over twice but then gets progressively worse and today took 2 attempts after turning over approx 6 times on each attempt (only 3rd time out this year).

This is similar to symptoms experienced last year which continued despite replacing filters and filtering fuel in tank which were both found to be clean!!.

Work this year prior to launch included:
• Replaced lift-pump
• New fuel pipes
• New fuel tank which is spotlessly clean
• Clean fuel which has been fine filtered through cotton gauze (white diesel)
• Primary filter dismantled and cleaned
• Secondary filter changed
• Glow plugs checked
• Checked that glow plugs receive power supply

• Professionally winterised and re-commissioned each year. Although I carried out the above work this was double checked when re-commissioned.

Thanks
 
Thanks everyone,

When it starts it runs fine....normally!! Although twice last year I gradually lost revs after running it for 40-50 minutes before it began to lose revs and it came to stop a minute or so afterwards. I bled the system and changed the fuel filter and it seemed to be OK again and seemed to start better although that may have been because the engine was still warm. So far this year it has not stopped but the symptoms for stopping seem a bit too familiar. Once it has been started it starts first time thereafter unless it has been allowed to cool (say overnight). Last year I purposely motored for about an hour and half and all seemed well.

When it's turning over it's fine and does not feel sluggish in anyway.

Fuel tank is not significantly below the engine and higher than it would have been last year with my old tank. There is a bit of a climb to the primary filter but I'd say it was no more than 6 - 8 inches

It's worth mentioning that before I had problems last year I'd motored on 2 occassions for 14 hours without a blip!! About two weeks after that I began to experience problems.

Thanks again
 
Independence said:
Thanks everyone,

When it starts it runs fine....normally!! Although twice last year I gradually lost revs after running it for 40-50 minutes before it began to lose revs and it came to stop a minute or so afterwards. I bled the system and changed the fuel filter and it seemed to be OK again and seemed to start better although that may have been because the engine was still warm. So far this year it has not stopped but the symptoms for stopping seem a bit too familiar. Once it has been started it starts first time thereafter unless it has been allowed to cool (say overnight). Last year I purposely motored for about an hour and half and all seemed well.

When it's turning over it's fine and does not feel sluggish in anyway.

Fuel tank is not significantly below the engine and higher than it would have been last year with my old tank. There is a bit of a climb to the primary filter but I'd say it was no more than 6 - 8 inches

It's worth mentioning that before I had problems last year I'd motored on 2 occassions for 14 hours without a blip!! About two weeks after that I began to experience problems.

Thanks again
Click to expand...


This is so obvious I'm sure you've checked - but I got caught by something equally obvious last year! Is the fuel-tank breather clear? My gotcha was not realizing the fuel cock had been switched off :o But your stopping after it has been running a while, then clearing after you've poked around a bit sounds a bit like some kind of fuel starvation.
 
I have a starting problem with my Beta Marine 28 (Kubota) that has gradually got worse from new. It is only after a day or more of no usage, the bottom of the tank is 2ft or so below the secondary filter inlet. I first fitted a non return valve to the supply, ok for a while, then after discussing it with Beta an electric pump on the inlet after the primary filter, no significant improvement. Discussed it this morning with a different engineer who thought the problem was not with the supply but the return from the engine. I do have the loop in the return below the bottom of the tank which they recommend in the manual, but he has recommended a tight 360 degree vertical loop where the flexible leaves the engine. This is done on some machine plant that uses the Kubota with low tanks. Difficult to see how it would work but it is a simple thing to try. When I have tried it I will report back ! My return is to the top of the tank, I guess a dip pipe to the bottom would help as the system would then be air tight, assuming no leaks.
Hope my experience helps.
 
I had a similar problem with my Nanni twin and found the cause to be a partially blocked exhaust water injection manifold. It was filled with a hard black carbon deposit which had to be chipped out. This is the manifold attached to the heat exchanger before the rubber exhaust pipe.
 
the exhaust ....If she's been running a little sooty or blue this could well be the problem.

also from http://www.aa1car.com/library/diesel.htm
To start and run properly, injector timing has to be accurate. A quick visual inspection will tell you if the timing marks are lined up. Refer to the vehicle manufacturer's timing procedure if you suspect timing is off or the pump has been replaced recently. On newer diesels with electronic injection pumps or direct injection, you'll need a scan tool to make any changes.
Air in the fuel can also be a cause of hard starting or a no start condition. Air can make the engine die after it starts, and make restarting difficult. Air can enter the system through any break in the fuel line or via a bleedback condition.
To determine if air is the problem, install a clear return hose on the return side of the injection pump. Crank the engine and observe the line. Air bubbles in the fuel would tell you air is entering the inlet side of the pump. The injection pump itself is usually not the source of the air leak, so check the fuel lines and pump.
good luck
S.
 
Last edited:
Thanks everyone, some really good stuff here.

I've checked the breather is clear.

Haven't checked the fine filter in the lift pump as I didn't know it had one but as I fitted a new lift pump this season I'd be surprised if this is causing a problem. On saying that I'll take the old one to pieces again and look at the fine filter.....providing I can find it as this may be an indication to problems last year.

I got a lot of advice when ordering a new tank and built a wooden mock up so others more experienced than me could view the inside as well as outside. It was also recommended to me that the fuel return should reach the bottom of the tank. I'm not sure if my old one did as I never cut it open but the new one certainly does. Before I replaced the tank (when I also had the same problem) I also had a copper tube acting as the return feed and winding it's way in a big loop back from the engine. I've done away with this and now have rubber tubing feeding more directly to tank.
I've been told it unlikely the lift pump is unable to pump fuel from the tank to the primary filter and certainly the first year of ownership it was not a problem (now into my third year).

Blocked water injection mainfold sounds interesting. Out of interest why would this cause starting problems. I have heard of delamination of the exhaust hose causing a blockage when it heats up and contracts?

Exhaust hasn't been running sooty and appears very clean.....but will double check next time.

I've checked and double checked loose hose fittings but will check again as I agree everything seems to point to fuel starvation......but WHERE!!!

Thanks everyone.
 
Firstly why did you replace the lift pump after 190 hrs.... 1900 hrs possibly??
Your description to me suggest that you are getting air in the circuit somewhere either due to a poor joint or possibly a bad seal on a filter.
I suggest that you bleed the air out of the system, and then crank properly once you are sure that there is no air in the system. If it starts straight away you know the problem
 
Having re-read you original posting, I see that you have also renewed your pipework from tank to lift pump.
I got caught out by" new" fittings, which should be about 3/16th inch longer than they are, which results in them failing to make a completely airtight joint, which of course is crucial on the inlet (suction) side. I was told by a professional not to push the olive fully home onto the end of the pipe by to leave it slightly proud, so that when it is screwed down it makes a proper seal.

I actually found this problem, by pressurising the pipework from the inlet to the lift pump backwards to the shut off valve on the tank. In short, it would not hold air pressure
 
Thanks,

Regarding lift pump, someone knowing more than me suggested there might be some dirt or delaminated rubber caught under the diaphram preventing it from time to time pumping correctly (this is an intermittent problem - or it was last year when as described earlier the engine stopped twice). I stripped it down, couldn't see any dirt but being keen to sort it out before launching decided to buy a new pump anyway!! I now have a spare.

Tend to agree with air in system theory. Presumably, if there was an air leak the engine would start more easily once it was warm as opposed to the starting problems when it is cold? I seem to have no problem starting it again once it has been initially warmed up.
 
I also tend to subscribe to the air in the fuel line theory, but there is another possibility:-
You say the heater plug power supply was checked. Each plug, 3 in total?, could require ~10 amps. That's quite a lot. Did you confirm that they are getting this? A poor connection in the supply could limit their performance.
My 3 cyl. Beta, also Kubota base, depends on its plugs for the first, instant, start of the day, but thereafter doesn't require heating.
You could easily check by putting a wire direct from the battery +ve to the heater bus-bar for 10 to 15 seconds and then trying a cold start.
 
Kubota starting problem solved

jon said:
I have a starting problem with my Beta Marine 28 (Kubota) that has gradually got worse from new. It is only after a day or more of no usage, the bottom of the tank is 2ft or so below the secondary filter inlet. I first fitted a non return valve to the supply, ok for a while, then after discussing it with Beta an electric pump on the inlet after the primary filter, no significant improvement. Discussed it this morning with a different engineer who thought the problem was not with the supply but the return from the engine. I do have the loop in the return below the bottom of the tank which they recommend in the manual, but he has recommended a tight 360 degree vertical loop where the flexible leaves the engine. This is done on some machine plant that uses the Kubota with low tanks. Difficult to see how it would work but it is a simple thing to try. When I have tried it I will report back ! My return is to the top of the tank, I guess a dip pipe to the bottom would help as the system would then be air tight, assuming no leaks.
Hope my experience helps.
Click to expand...

Promissed to report back, problem solved with the raised loop of return pipe now as high as it could go in the engine box. Only 4" above the rocker box but it has done the trick and started first time after 4 days. Pity it was not in the engine installation instructions for those with low tanks !!
 
Now you think you have solved the problem, the next step is to run it under load on the pontoon, to make sure that it does not run out of steam, which would indicate an air leak.
You may just have two problems... test will tell.......
 
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