For the Yanmar experts.

[rotrax]

Could it be time for an injector pump service?
If it starts instantly when cold then can't see it being a compression problem and even less so when hot.

As injector pumps are really good quality and long lasting these days I tend to think not. By the way, the rotary injector pump is water cooled. My filter regime has been immaculate.

I have never known a defective rotary type injector pump only cause occasional non starting. Poor starting and bad running/missfiring yes, serious noise issues, yes, but outside my experience for a defective pump to be the cause of my problem. Not completely ruling it out, but will test/check other things before going down that route.

I am going to investigate the stop solenoid further as Springer suggests. It is really hard to get to, tucked under the inlet manifold and behind the four injector pipes and throttle control bracket.
It might be possible to disconnect it at the button end if it is 'energise to stop' as Springer suggests and see if the problem goes away.
I can stop the engine with a brake pipe clamp across the injector pump fuel line.

Thanks for your input, appreciated.

 

[tico]

Just a thought (and I am probably talking out of my fundament ) The symptoms that you describe could be accounted for by a sticky stop switch or solenoid valve.
on operation it supplies the stop solenoid with power to shut off the fuel but does not retract sufficiently to allow enough fuel for starting until either it slowly retracts over time OR is vibrated to retract by the easystart whiff.

 

[BruceK]

To me it sounds like restricted fuel access. The lift pump is creating a vacuum pressure in the line. The vacuum eases overnight. I'd be very tempted to put vacuum gauges on the racors and see if you have a blockage somewhere restricting fuel flow. I've seen this sort of trouble when a pickup fuel line was partially blocked with a jelly like diesel bug

EDIT
and yes in that instance the racors were clean. The jelly had yet to be broken up.

 

[BruceK]

jelly strings that looked like this in the lines

 

[lynallbel]

As injector pumps are really good quality and long lasting these days I tend to think not. By the way, the rotary injector pump is water cooled. My filter regime has been immaculate.

I have never known a defective rotary type injector pump only cause occasional non starting. Poor starting and bad running/missfiring yes, serious noise issues, yes, but outside my experience for a defective pump to be the cause of my problem. Not completely ruling it out, but will test/check other things before going down that route.

I am going to investigate the stop solenoid further as Springer suggests. It is really hard to get to, tucked under the inlet manifold and behind the four injector pipes and throttle control bracket.
It might be possible to disconnect it at the button end if it is 'energise to stop' as Springer suggests and see if the problem goes away.
I can stop the engine with a brake pipe clamp across the injector pump fuel line.

Thanks for your input, appreciated.

Looking at some intenet pics the yanmar inj pump looks very similair to the bosch ve inj pump, as fitted to many makes of cars from years gone by, and specifically land rovers up to 1998.
Stop solenoids are a favourtite.

I have persoanlay known of bosch ve inj pumps causing rough running, one (my own) would even drop a cylinder, then after 20 odd miles chime back in on all four, and stay like that all day regardless of miles until you switched it off again, then the next trip/day it would start just fine but only on three.
Stop solenoid out bit of swarf (as mentiened above) meant pump had had it, I stuck a 2nd hand one on and 10 years later it is still fine.

Our current boat has bosch ve pumps fitted, starbpard pump caused previous owner all sorts of issues, in the end he had to get a new unit.

 

[rotrax]

To me it sounds like restricted fuel access. The lift pump is creating a vacuum pressure in the line. The vacuum eases overnight. I'd be very tempted to put vacuum gauges on the racors and see if you have a blockage somewhere restricting fuel flow. I've seen this sort of trouble when a pickup fuel line was partially blocked with a jelly like diesel bug

EDIT
and yes in that instance the racors were clean. The jelly had yet to be broken up.

Thanks for that.

I have shone a light down the fuel gauge hole, appears perfectly clean. I have sucked samples from the bottom of the tank and two reachable corners, all clean, no bug. It was dosed before lay up October 2019 to June 2020 with Marine 16. This is always added at refueling too. The tank has perhaps 700 litres in it at the moment.

When running the engine will keep running until I stop it. At up to full RPM at WOT, for periods of up to one hour in ahead, against the springs. Not tested longer than that - I though that was enough, plus with the lid up and the access covers off, its bloody noisy!

This suggests fuel supply is reliable and clean.

As I noted in the OP, there is no conventional lift pump. I believe it to be integral with the rorary injector pump. I fitted a Facet type electric low pressure pump as some yachts fitted with the Yanmar 4JH4-HTE power unit have starting troubles after being sailed on one tack for extended periods - days rather than hours. It is a reccomended fix for that issue and causes no issues with the integral pump.

Like all tricky problems it is intermittent and random.

Thank you for your input, much appreciated.

 

[rotrax]

Looking at some intenet pics the yanmar inj pump looks very similair to the bosch ve inj pump, as fitted to many makes of cars from years gone by, and specifically land rovers up to 1998.
Stop solenoids are a favourtite.

I have persoanlay known of bosch ve inj pumps causing rough running, one (my own) would even drop a cylinder, then after 20 odd miles chime back in on all four, and stay like that all day regardless of miles until you switched it off again, then the next trip/day it would start just fine but only on three.
Stop solenoid out bit of swarf (as mentiened above) meant pump had had it, I stuck a 2nd hand one on and 10 years later it is still fine.

Our current boat has bosch ve pumps fitted, starbpard pump caused previous owner all sorts of issues, in the end he had to get a new unit.

You might be on to something.

Possibly a Bosch pump made in Japan under licence. Their petrol EFI kit was made by JEC - Japan Electronics Corp - for Kawasaki motorbikes.

Thanks.

 

[lynallbel]

You might be on to something.

Possibly a Bosch pump made in Japan under licence. Their petrol EFI kit was made by JEC - Japan Electronics Corp - for Kawasaki motorbikes.

Thanks.

If you google Bosch VE injection pump, there is loads of info out there, both land rover and cummins 4 and 6 pots, the yanks are mad on them.

 

[BruceK]

Thanks for that.

I have shone a light down the fuel gauge hole, appears perfectly clean. I have sucked samples from the bottom of the tank and two reachable corners, all clean, no bug. It was dosed before lay up October 2019 to June 2020 with Marine 16. This is always added at refueling too. The tank has perhaps 700 litres in it at the moment.

When running the engine will keep running until I stop it. At up to full RPM at WOT, for periods of up to one hour in ahead, against the springs. Not tested longer than that - I though that was enough, plus with the lid up and the access covers off, its bloody noisy!

This suggests fuel supply is reliable and clean.

As I noted in the OP, there is no conventional lift pump. I believe it to be integral with the rorary injector pump. I fitted a Facet type electric low pressure pump as some yachts fitted with the Yanmar 4JH4-HTE power unit have starting troubles after being sailed on one tack for extended periods - days rather than hours. It is a reccomended fix for that issue and causes no issues with the integral pump.

Like all tricky problems it is intermittent and random.

Thank you for your input, much appreciated.

Fair enough, although I said jelly strings where I have witnessed this behaviour, it's an example and not a fixation point. Having vacuum gauges would be useful going forward as even if not diesel bug, you could very well find some well meaning pump attendant has had a bit of kitchen roll he uses to wipe the diesel pump nozzle off so as not to spill diesel on your boat. These have a lovely habit of ending in the fuel tank where they do not degrade in diesel and invariably get sucked up / example ad naseum. You wouldnt be the first to be caught out with this and there are plenty here who have had to revisit a diesel bug issue because the towelling the used to wipe the sludge up off the tank floor, yes, you get it. No names, no shaming

 

[springer]

Hi Rotrax, Please do not stop the engine by starving it of diesel. The injection pump uses diesel for both cooling and lubrication, every time you allow it to run dry there is a chance of internal damage. Engine stop is achieved in these pumps by output being recirculated away from injection pipes within the pump, Done by pushing the fuel rack to the no fuel position. (Very vague description because VE type pump does not actually have a fuel rack in the same way as an in-line inj pump.) This is one of the reasons why we get so paranoid about fuel supply systems. On the side of the injection pump should be a spring loaded lever which when rotated against the spring operates the stop function. The lever may look cruciform in shape with 2 long arms and 2 short. For info it is possible to rig a Bowden type push/pull cable to this lever for an additional mechanical stop to back up the electrical solenoid. Good luck with ongoing efforts.
Springer

 

[spannerman]

As previously stated there are no sensors that will stop the engine. You could try disconnecting the stop solenoid by removing the energizing wire and then try stopping the engine with the mechanical stop lever on the side of the injection pump and see if you have the same starting problem. If you do then this would point towards a fault in the injection pump. The fact that your extra pump curculates fuel through the system eliminates an air leak problem.

 

[rotrax]

Hi Rotrax, Please do not stop the engine by starving it of diesel. The injection pump uses diesel for both cooling and lubrication, every time you allow it to run dry there is a chance of internal damage. Engine stop is achieved in these pumps by output being recirculated away from injection pipes within the pump, Done by pushing the fuel rack to the no fuel position. (Very vague description because VE type pump does not actually have a fuel rack in the same way as an in-line inj pump.) This is one of the reasons why we get so paranoid about fuel supply systems. On the side of the injection pump should be a spring loaded lever which when rotated against the spring operates the stop function. The lever may look cruciform in shape with 2 long arms and 2 short. For info it is possible to rig a Bowden type push/pull cable to this lever for an additional mechanical stop to back up the electrical solenoid. Good luck with ongoing efforts.
Springer

From memory no stop lever on side of pump. Just bought up the parts list on screen, no stop lever visible on that. The rotary injector pump is water cooled. The water cooling and pipes cover the area where the stop lever is on the Bosch ve pump.

I hear what you are saying about closing the fuel supply and understand the reason. I recently converted a Bukh DV20 to cable stop by using the burned out solenoid casing and guts to push the internal shut off in the pump. Before that I would stick my finger in the hole and push what the solenoid pushed. The nice thing about the simple 'ole Bukh is the pump is easy to get to at the back of the engine.

Should be able to get back to the boat soon, will let you know how I get on.

Thanks again guys, help appreciated.

 

[Jamie Dundee]

Deleted due to repetition.

Just for the record I suggested you might have an intermittent blockage on the filter of your fuel pick up pipe.

 

[rotrax]

Deleted due to repetition.

Just for the record I suggested you might have an intermittent blockage on the filter of your fuel pick up pipe.

Thanks for that.

That has been removed and checked - as best as I am able in an almost 900 litre tank with the only access through the gauge hole. There is no filter, just a 5/8ths ID tube an inch above the tank floor. This is screwed to a right angle block threaded to the tank top. A fuel tap exits the block and feeds the fuel system. The fuel tap has a 3/16ths hole. I have THAT fact noted for a potential blockage!

I rather discounted an intermitent blockage as it will run forever, at up to full RPM at WOT, once started and not stopped.

I believe the stalling has been cured by raising the idle speed.

If I stop it using the stop button it may start normally and instantly a hundred times.

Then again, it might fail to start. When this happens an IMMEDIATE check finds regular and reliable high pressure fuel at the 4 injector pipes. All other fuel system check and bleeding are OK. Cranking speed, volt drop when cranking, reliability of cranking are all good. Engine just had a 1000 hour service, including valve clearance adjustment. Two tight clearances were found, on the same cylinder,on adjusting correctly 100 RPM increase in idle speed.

Of course, when it fails to start it is always when you are halfway through a tricky manouver in a tight marina with a strong wind or tide!

The only way to get it going is wait till the following day or give it a half second squirt of ether into the inlet gauze.

Thanks for your interest.

 

[gordmac]

Does it turn over quickly enough when hot?
Will it start ok after say 5 or 10 minutes or does it have to be cold?

 

[rotrax]

There is no problem with cranking speed, voltage drop when cranking or anything related to that side of the starting.

I have never waited five or ten minutes before trying to start again, That is on my list of things to try when at the boat next week. I can stop it twenty times in a row, starts up instantly. Then it WILL NOT no matter what I try with the throttle position. It is a totally random and intermittent fault. As we all know, the worst kind to fix.

A half second whiff of ether, or the next morning, starts right up. Hardly cranks at all the next morning, a touch of the button and she is going. No need to set the throttle, at idle in neutral, touch the button with a gentle press, bingo.

Investigation of the stop solenoid, button and associated wiring next visit!

Thanks for your ideas guys.

 

[Jamie Dundee]

I wondered about that but would starting on ether override the stop solenoid? I have no idea.

 

[Fiddlesticks]

Probably not related, but we had a problem with our 4x4 mitsubishi delica stalling / not starting intermittently (even when warm). Turned out to be the fuel pump seal.

 

[rotrax]

Probably not related, but we had a problem with our 4x4 mitsubishi delica stalling / not starting intermittently (even when warm). Turned out to be the fuel pump seal.

Was that the lift pump or the injector pump?

 

[rotrax]

I wondered about that but would starting on ether override the stop solenoid? I have no idea.

That is one of the things I find extemely puzzling.

As I said in the OP, I have been fixing small engines for more than 50 years. I am a diagnostic specialist, teaching relevant techniques at two service schools during my career, the BLMC Service School at Cowley and a six year stint as Training Instructor for Kawasaki Motors UK Ltd.

This bugger is stretching my knowledge - and patience!

Thanks again for all your input guys, I need it!