Cummins Start up fault - Now doing my head in !

[superheat6k]

Periodically over the past two seasons I have been suffering a periodic 'fail to start' on the Stbd engine. Each time I think I have it sorted a period later the problem returns. This problem has now infected the Port engine

These are Cummins 6BT5.9M engines.

I think (!) the root of the problem is the Stop Solenoid dropping out during the start phase when the voltage drops away whilst the massive starter motor is running.

The manual states the minimum voltage to the starter during start up should be 10 v, whereas my panel VM bounces violently ~ 8-11 v during the start. With a digital VM today I was reading 10.2 v during the starter operation on the feed to the engine ancillaries. According to the Cummins manual the stop solenoid should be OK with this.

So this is what I have done so far ...

1 Stbd fuel pump completely stripped and checked - all fine (PB Asher -Southampton).
2 New battery stbd side
3 New battery isolator switch stbd side, then another.
4 Now complete rewire stbd side + VE, with re-route of engine ancillary power direct from the new isolator rather than the starter motor +VE connection terminal. All lugs replace, hydraulically crimped and soldered. New heavy duty better make isolator switches.

The original wiring layout was bizarre and is now more user friendly, and as a result the individual runs for both heavy power and ancillary feeds are up to 2m shorter than they were originally.

The engines spin freely on the starters, but the symptoms are those of no fuel.

An interesting note today (and one I have noticed previously) is that sometimes the stbd engine fires for a few seconds, then, just as the alternator excites, the engine promptly stops.

Could this be something with the alternator suddenly draining the 12v +VE away ?

Do I try yet more new batteries ?

I did replace the stbd earlier this year with a Hankook, which, although of similar CCA and AH to the one it replaced, was considerably smaller. The Port is the original since I bought the boat, so could be on its way out.

So what next ...

New stop solenoids ?

New batteries ?

Something else I have missed ?

I haven't replaced the whole -VE cabling, although I have fitted new lugs at the batteries so the only part not changed on the -VE is the lug to each engine block.

I wonder if the stop solenoids might be 24v and if so this would explain why they are dropping out, but without any reference to the coil resistance I have no way of checking this.


Quite a depressing thought that sometimes the engines might not start when needed, becoming now a paranoia. I would add that having spent most of the past three weekends up to my nuts in new cable, lugs and cable tools, I have realised that this problem lying at the back of my mind has been a significant factor in my thoughts on getting rid of her. I am now determined once and for all to resolve this issue.

 

[Portofino]

Back to first principles is there a 1st position of the ignition key that energises ( or deactivates depending on the set up ) the stop solinoids ?
If that’s so ?
Maybe the fault is from the ignition barrels worn or corrosion of contacts .
Or some sort of relay ( which it’s self maybe faulty ) from the barrel to the stop solinoid.

So have you checked the ignition barrels ? Had them out and twiddled them about at the back while attempting to start ?

Are there any relays between the barrel and the stop solinoid(s) wearing out ?

 

[superheat6k]

I haven't thought of dismantling the ignition switches, so good idea. There is no relay or secondary solenoid to the stop solenoid. Yes the 1st Position energises the Stop solenoid (Stop on de-energise).

When messing around earlier I did cross connect the stbd engine to the new Port ancillary feed to the ignition switch, and in this mode the engine fired without a problem. I guess the Port was also labouring a bit, so likely this is the battery.

The engines require a CCA of 800 amps. The new battery I bought meets this requirement on the stbd, although it is a leisure, so perhaps not quite up to the task, despite its label.

My thoughts are to buy a second identical battery to that already installed on the Stbd engine then use both these paired on the Port as this also supplies the domestics, and the charger can easily handle the extra capacity (I purchased this battery in April and have also found the specific model to match to). This would provide the Port with 1600 CCA capability, and at the same time provide me 220AH ancillary capacity.

Then buy another new Truck battery (rather than leisure duty) with 1000 amps start CCA (110 AH) as the stbd as start only, (plus windlass, but only when the engine is running), so this would easily serve the stbd starter, with no deep cycle requirement.

So next task Ignition barrels coming out.

 

[5teve]

You do know that the stop solenoids are twin coil? A heavy duty throw coil and a lighter weight hold.. could be that the hold has burned out or isn't operating as it should, remove the solenoid, use a cable tie to hold it up and try again... obviously cut the tie to stop. See sbmar for lots of troubleshooting... Tony has a lot of info.

The other thing you could try if you think it's voltage related.. as mine was.. is disconnected the air heaters as they pull something like 100amps on startup...

Steve

 

[Higgo]

In reading your thread, my first thought is what Steve suggested with the air heaters that draw a large amount of current at start up. On the top air outlet of the aftercooler, there is a squarish block where the air goes thru into the pipe/rubber connection into the intake manifold. On the side of the block, there is a thick "U" shape earth wire/strap to a screw on the manifold/block. Unscrew the nut from the side of the heater block and disconnect the strap and see if that fixes your issue.

I have disconnected mine completely but I'm in a warm climate so don't need the air heaters to assist with starting. But they do draw a hell of a lot of current. There's a module/box above the starter motor. If that's the problem, chances are you'll see scorching around the connections. Hope it helps. Cheers

 

[superheat6k]

You do know that the stop solenoids are twin coil? A heavy duty throw coil and a lighter weight hold.. could be that the hold has burned out or isn't operating as it should, remove the solenoid, use a cable tie to hold it up and try again... obviously cut the tie to stop. See sbmar for lots of troubleshooting... Tony has a lot of info.

The other thing you could try if you think it's voltage related.. as mine was.. is disconnected the air heaters as they pull something like 100amps on startup...

Steve

Thanks, but on these engines it is a single connection to the solenoid, which cuts off fuel supply right at the injection pump (CAV DPA). It isn't a dual coil. The solenoid itself is inside a screwed in fitting, that also seals the plunger assembly it operates. These engines don't have air heaters nor glow plugs.

I am tempted to simply remove the cut off plunger and instead install a cable onto the otherwise disused manual stop lever. But this would not resolve the primary problem of why this is happening.

I am going to check the SG of the port battery and then see if I can sort out out a suitable load for a 20 hour discharge test (6a load). From fully charged the battery voltage should still be at 12v or more after this period. If it falls away sooner then that diagnoses the battery is the likely cause at least on the port engine.

 

[burgundyben]

Trev

We had a phone call about this ages and ages ago and concluded its V drop?

Mine are 24v, 2 pairs of 1000ccr 110ah batteries, one pair for each motor. So I have 1000amps * 24V = 24,000 watts, or 24Kw.,

You have 12, 800ccr which is 800amps * 12v = 9600watts, 9.6Kw.

Perhaps not much? Although I recall starter is 4.5Kw? (BTW - where did you get the 800ccr requirement from ? The workshop manual? Sounds wrong to me)

Both CAV and Bosh VE pump have solenoids on them, but I recall you have the CAV pump? In which case, I have a pair of solenoids that I removed that have had the plastic pin trimmed off the ends, this allows the pump to run the engine without being energised, it does mean to shut them down you have to use the mechanical stop lever on the pump with a bit of string. I can pop them in the post to you, they are a right **** to change and you need a box spanner cut down to minimal length, I have that too and will pop it in the post. You could fit them and see if the problem goes away.

I suspect that you are sensitive to battery and need more amps.

 

[superheat6k]

Trev

We had a phone call about this ages and ages ago and concluded its V drop?

Mine are 24v, 2 pairs of 1000ccr 110ah batteries, one pair for each motor. So I have 1000amps * 24V = 24,000 watts, or 24Kw.,

You have 12, 800ccr which is 800amps * 12v = 9600watts, 9.6Kw.

Perhaps not much? Although I recall starter is 4.5Kw? (BTW - where did you get the 800ccr requirement from ? The workshop manual? Sounds wrong to me)

Both CAV and Bosh VE pump have solenoids on them, but I recall you have the CAV pump? In which case, I have a pair of solenoids that I removed that have had the plastic pin trimmed off the ends, this allows the pump to run the engine without being energised, it does mean to shut them down you have to use the mechanical stop lever on the pump with a bit of string. I can pop them in the post to you, they are a right **** to change and you need a box spanner cut down to minimal length, I have that too and will pop it in the post. You could fit them and see if the problem goes away.

I suspect that you are sensitive to battery and need more amps.

Thanks Ben. Although on the CAV the plunger can simply be removed, and access to remove it isn't too bad.

However, I am coming to the conclusion this is an issue of insufficient CCA, although the 800amps figure is straight from the Cummins manual.

What is your view of using a pure start (truck) battery for my stbd engine - this one is never supplying the domestics. My thoughts are one with 1,000CCA.

Does anyone have concerns with these Hankook batteries ? Should I opt for Varta or another maker ?

 

[Bouba]

When I had a starting issue on my single Cummins, it was diagnosed as the battery cut off. Now I know that you replaced yours, but what was recommended to me was to replace it with one of a higher amperage, as the amperage draw is very high on start up. Now, I know the obvious question is how does a switch suddenly need to be bigger when it’s worked before but I’m only passing on what was done on my boat.
I have two starter batteries for the one engine and they were replaced with spiral batteries and I love them
Have you tried linking all the batteries together on start up?

 

[burgundyben]

Thanks Ben. Although on the CAV the plunger can simply be removed, and access to remove it isn't too bad.

However, I am coming to the conclusion this is an issue of insufficient CCA, although the 800amps figure is straight from the Cummins manual.

What is your view of using a pure start (truck) battery for my stbd engine - this one is never supplying the domestics. My thoughts are one with 1,000CCA.

Does anyone have concerns with these Hankook batteries ? Should I opt for Varta or another maker ?

My batts are cheapo truck ones from ebay. 1000cca. Always worth trying Grumpy Tony for batteries, you know the little car parts shop opposite the grotty Vic pub in Woolston.

 

[5teve]

What spec 6btas are they?

Mine are the 330s with Bosch pump so easy to reach solenoid, I have 1000cca batteries, running just a single for each (12v) and they have no issues, if I remember the spec says 1100cca for colder climates. I use Bosch S4 batteries.

You sure there are no air heaters post aftercooler? Or do you have the jwac version which I believe still has an air heater?

Starting issue with mine was all voltage, corroded negatives from a leaking exhaust elbow, coupled with big current draw saw the crank voltage down to 8v which couldn't throw the solenoid..

Probably a different issue, but thought I'd mention it.

Steve

 

[Portofino]

View attachment 74973

This is what you need to eliminate 1st .
The Ver d Gris increases resistance.
Whole thing cleaned up well and now smothered with dialectic grease

 

[volvopaul]

Are your pumps inline or rotary?

I’m surprised they need voltage to place them in the run position as all Volvo Bosch in-line and rotary only need a feed to stop them ?

 

[burgundyben]

Are your pumps inline or rotary?

I’m surprised they need voltage to place them in the run position as all Volvo Bosch in-line and rotary only need a feed to stop them ?

5teve has the Bosch P pump. Inline.

Superheat and me have 180/210hp with the CAV rotary pump, DPA, they have an energise to run solenoid in the top of the pump body.

Some variants of Cummins @ the same 180 or 210hp rating do have the Bosch VE rotary pump, not sure how the solenoid works on those.

 

[burgundyben]

What spec 6btas are they?

Mine are the 330s with Bosch pump so easy to reach solenoid, I have 1000cca batteries, running just a single for each (12v) and they have no issues, if I remember the spec says 1100cca for colder climates. I use Bosch S4 batteries.

Nice.

Superheat and I have the same 180/210, CAV DPA rotary pump, no cold start of any sort and no intercooler. Holset H1E or HX35 turbo.

Another has the same, plus a Bowman sea water charge cooler and some pump mods, he's getting about 225hp I think.

I think the JWAC was fitted on 260hp. 330 and 370 had the big sea water cooler, think you might have HX40 turbo? I always thought the 4BTA 250hp with the sea water cooler and inline pump was a fantastic package, bomb proof and excellent power to weight, but it never went far in the market, although perhaps more so in USA than here.

 

[volvopaul]

Nice.

Superheat and I have the same 180/210, CAV DPA rotary pump, no cold start of any sort and no intercooler. Holset H1E or HX35 turbo.

Another has the same, plus a Bowman sea water charge cooler and some pump mods, he's getting about 225hp I think.

I think the JWAC was fitted on 260hp. 330 and 370 had the big sea water cooler, think you might have HX40 turbo? I always thought the 4BTA 250hp with the sea water cooler and inline pump was a fantastic package, bomb proof and excellent power to weight, but it never went far in the market, although perhaps more so in USA than here.

VE can be either, in automotive form it’s energise to start , in marine build energise to stop which makes sense if your at sea with a flat battery at least it won’t shut down . CAV needs power , a stupid idea in my view..

To test you can take the solenoid out and blank it but you need a means of shutting the fuel to stop it , some still have the lever front of pump.

I doubt this is the issue , sound like there could be a return issue or low transfer pressure inside the cam housing .

 

[superheat6k]

VP agree that an energise to run option is a PITA.

I have noticed that I had inadvertently kicked the fuel SOVvs shut whilst undertaking the electrics mods, which had meant the engines would not start because no fuel was being supplied. So once these were opened both engines did start, then after a stop refused to restart. I expect the fuel system may have pulled a vac so may have drawn some air in, so next task is to remove the stop solenoids, whip out the plungers, then vent the system.

BTW - not the Cummins ignition switch. Note to self - when dismantling the ignition switch DO NOT pull the upper and lower section apart with the switch the normal way up !!!

Amazingly I managed to suss out where the various linkages and springs went.

Now even with a direct feed from the non-start engine at 14v to the stop solenoid the (expletive associated with sex) )engines still won't start.

 

[Higgo]

I gather you have the M2 or M3 Cummins (330/370's). I have the same engine. You mentioned fuel flow was cut off for a period. My friend recently had a start issue on his 330. I pumped up the fuel pressure on the Bosch pump using the fuel plunger on the side of the pump just forward of the solenoid, till it was hard/firm, and it started up. In my earlier post I suggested disconnecting the strap from the aftercooler heater. Did you do that? Just trying to help you eliminate the voltage drag.

Cheers

 

[volvopaul]

VP agree that an energise to run option is a PITA.

I have noticed that I had inadvertently kicked the fuel SOVvs shut whilst undertaking the electrics mods, which had meant the engines would not start because no fuel was being supplied. So once these were opened both engines did start, then after a stop refused to restart. I expect the fuel system may have pulled a vac so may have drawn some air in, so next task is to remove the stop solenoids, whip out the plungers, then vent the system.

BTW - not the Cummins ignition switch. Note to self - when dismantling the ignition switch DO NOT pull the upper and lower section apart with the switch the normal way up !!!

Amazingly I managed to suss out where the various linkages and springs went.

Now even with a direct feed from the non-start engine at 14v to the stop solenoid the (expletive associated with sex) )engines still won't start.

Oh yo7 might have split the diaphragm in the lift pumps or misplaced the poppet valves off there seats causing no fuel to get to pressurise the injection pump.

 

[volvopaul]

Send us a pic of pump and set up