CAT C18 1150's - High fuel pressure alarm

[MedMilo]

Was sea-trialling my Squadron 65 with local Caterpillar engineers yesterday (post them servicing the engines) and at around 1500rpm both engines' alarms sounded with a 'high fuel pressure' message. Seemed to somewhat mystify the Caterpillar mafia who tried a few things with their laptop etc but didn't have many bright ideas as to what it might be! They've now ordered two new senders however I'm not convinced - seems a bit implausible that both senders packed up at the same moment?! The main thing common to both engines is, of course, the diesel! I put some Fuel Set into both tanks at the end of last season and I know that this can sometimes clog up the filters a bit but yesterday the filters were brand new, of course.

Caterpillar are kind of on the case in Amalfi but I just wondered whether anyone on here had any initial thoughts or suspicions as to what it might be?!

 

[Hurricane]

I would have thought it would be low pressure if the filters were blocked.
They did put new ones back in I suppose????
Pre filters (Separ/Racor) - I mean.

My MTUs often take a few runs to purge the air through the system after new filters.

 

[MedMilo]

I would have thought it would be low pressure if the filters were blocked.
They did put new ones back in I suppose????
Pre filters (Separ/Racor) - I mean.

My MTUs often take a few runs to purge the air through the system after new filters.

Yes they put the new ones back in but said that the ones they took out (which had been in situ for one season) were pretty black and cruddy. There was a bit of air in the system from the filter change which caused one engine to stall a couple of times but this soon cleared through. Then we had this high pressure issue on both engines simultaneously - very odd!

 

[volvopaul]

Yes they put the new ones back in but said that the ones they took out (which had been in situ for one season) were pretty black and cruddy. There was a bit of air in the system from the filter change which caused one engine to stall a couple of times but this soon cleared through. Then we had this high pressure issue on both engines simultaneously - very odd!

Air in the system being compressed by the high pressure pump will create higher pressure as the air is being compressed , I’m sure after a good run when the air has dissipated all will be ok.

 

[jrudge]

The only thing i can think of would be blockage downstream of the pump - ie injectors, however the odds of that happened on both at the same time would seem low to me.

 

[MapisM]

Are you folks suggesting that air in the fuel lines should be self-purged with the engines running?
I am asking because a MAN engineer recommended me to fill fuel prefilters to the brim after replacing the cartridge, using the bleed screw on the top of the filter covers (Separ, in my case).
According to him, if air gets stuck anywhere in the circuit and an engine gets stalled, it can only be restarted using the manual priming pump (and a lot of patience, i.e. several minutes!) located near the HP pump.
Which means right in between the "V" of the cylinder banks - not something I would fancy doing with hot engines and in open sea... :ambivalence:
I understand that the engines discussed so far are fully electronic and mine aren't, but I can't see why that should make a big difference with regard to air dissipation?

 

[MedMilo]

Air in the system being compressed by the high pressure pump will create higher pressure as the air is being compressed , I’m sure after a good run when the air has dissipated all will be ok.

Okay that's very interesting, and encouraging! Thanks for the input, am heading down to the boat again next week so let's hope it's as simple as that. Am surprised the Caterpillar chaps are so confused by these alarms given they know the filters have just been changed etc. Anyway, fingers crossed...

 

[volvopaul]

Are you folks suggesting that air in the fuel lines should be self-purged with the engines running?
I am asking because a MAN engineer recommended me to fill fuel prefilters to the brim after replacing the cartridge, using the bleed screw on the top of the filter covers (Separ, in my case).
According to him, if air gets stuck anywhere in the circuit and an engine gets stalled, it can only be restarted using the manual priming pump (and a lot of patience, i.e. several minutes!) located near the HP pump.
Which means right in between the "V" of the cylinder banks - not something I would fancy doing with hot engines and in open sea... :ambivalence:
I understand that the engines discussed so far are fully electronic and mine aren't, but I can't see why that should make a big difference with regard to air dissipation?

Answer to your last paragraph, when fuel and air mix it gives a pressure imbalance both inside the pump, unit injector or plain injector , if the fuel flow and pressure are not stable you get delayed injection , poor atomisation and misfire .
On a common rail engine the Mprop valve is bouncing off its seat because it can’t makntain a stable pressure to tell the ECU to inject therefore you get uneven combustion .

Many warranty issues occur often blaming the engine manufacturers when 99.9% of the time on new boats it’s the builder that’s to blame, where this falls foul is when the builder certifies the installation itself , a bit like booking yourself in for open heart surgery when really it’s indigestion and all you need is a rennie and keep,off the next curry and 10 pints to wash it down . Sadly When Sealine we’re building in the UK they were the biggest culprit , no doubt for 2 reasons , they’re quality control and build wasn’t what people expect, they placed items like HCU and PCU in hidden places at a stage of build you just couldn’t get at , I remember a D3 running rough cutting out once you gave it the beans , the result was half a tube of sikkaflex bunged up the fuel tank stack pipe, no vodia diagnosis or strip down of the engines fuel system on the engine would tell you what the fault was. Luckily since the Germans took over the quality is much better.

 

[MapisM]

Answer to your last paragraph...

Interesting reading, thanks.
But am I right in understanding that electronic/CR engines should be - if anything - MORE sensible to air anywhere in the fuel lines?
I mean, since you suggested that a "good run" should be enough to dissipate air in the OP C18, and Hurricane said that it takes "a few runs" to dissipate air in his MTU (which are also electronic), why should mechanical engines require manual priming instead?
With apologies for the slight o/t, but I'm just wondering why air shouldn't dissipate automatically (so to speak) while running also on mechanical pump/governor engines...

 

[Portofino]

You need to develop a deep understanding of the air bleeding aspect of the fuel ( filters inc ) of the pipage side proir to the pump .
Once that’s registered start DIY . With OEM parts of course

Additionally learn and with a mate ( optional) do the annual oil change + filter(s) .

At the mo there’s air in there .


Fwiw
I leave enough fuel in the two day tanks sos the level is greater ( sight glasses ) than the top of the racors .
Close the cock from tank to racor - switch new cartridges.
Turn open the cock , let it fill and start to spill over the semi tightened racor lid .
When it’s overflowing final tighten the racor lid = no or not very much trapped air ? - probably none ?
Then with the engine cartridges ( solid metal ) fill them up as best froma Jerry can of diesel from a garage then open the 10 mm bleed screw and pump the priming pump until it flow s out before nipping up.

Thus in theory supposedly all the air is bleed out , but remember I prefilled the engine cartridges and opened the higher tank ( cock ) level to overflow the racor ( could be separ or racor let call it a primary ) .

Starts and runs uneventfully every time .

This is because any air Ok a small amount inevitably has been mitigated and bled out at both stages .

Killer Q - did those guys , or did you leave sufficient fuel in the tank(s) to fill

1- fill the primaries by gravity ?
2 - have a Jerry can to prefill the secondary (s) ? Before screwing on ?
3 - be arsed to open up the bleed screw and do the deed ? With a manual lift pump if CAT fit one ?

All your issues sound very iatrogenic.

Google that word .

 

[MapisM]

All your issues sound very iatrogenic.
Google that word.

I still get by with words which are actually Italian without resorting to Google, thank you.

Otoh, I can't for the life of me understand what you mean by "all your issues", since I have none.
My question was pretty simple - if Cat C18 and MTU engines can self-dissipate some air in the fuel lines, why should MAN engines need manual priming instead? The reasons why air entered where it shouldn't are irrelevant to the question as such, btw.

 

[Portofino]

I still get by with words which are actually Italian without resorting to Google, thank you.

Otoh, I can't for the life of me understand what you mean by "all your issues", since I have none.
My question was pretty simple - if Cat C18 and MTU engines can self-dissipate some air in the fuel lines, why should MAN engines need manual priming instead? The reasons why air entered where it shouldn't are irrelevant to the question as such, btw.

Re read my 1st post here on this thread as the “ you “ and “ your “ as the OP , for ease of understanding that’s a chap registered under the username of “ MedMillo “:.

If I was directly referencing you MapisM I would have followed what I thought ( happy to be corrected ) your post in a quote - just like this - this post again for ease of understanding is primarily directet at you .

So if it helps my initial post was directed at the OP .

 

[Portofino]

I still get by with words which are actually Italian without resorting to Google, thank you.

Otoh, I can't for the life of me understand what you mean by "all your issues", since I have none.
My question was pretty simple - if Cat C18 and MTU engines can self-dissipate some air in the fuel lines, why should MAN engines need manual priming instead? The reasons why air entered where it shouldn't are irrelevant to the question as such, btw.

Detail This mysterious and miraculous “ self dissipating “ aspect.
Exactly where and what means or mechanics does the air from the semi filled or empty prefilter and the empty or semi filled secondary filter “ dissipate “; ?
Where does it go ?
Are you saying the pump just pushes or as VP infers compresses the air hence the code thrown ? “ high fuel pressure “
Which is infact an aberration of air pressure ( which i say there should be a system to bleed off ? )

If so we are an the same wave L , but can,t account why the CAT “ mafia “ guys don,t realise this ? They man ( scuse the pun ) handled the filter changes .

 

[MapisM]

So if it helps my initial post was directed at the OP

Ops, sorry, it's the post sequence which misled me...

Detail This mysterious and miraculous “ self dissipating “ aspect.

No idea from my part.
I just assumed from Hurric and VP posts that there's no need to manually prime the circuit on those engines - hence my question.
Fwiw, I never had to prime manually my old Cat 3116 in 17 years, but without ever wondering why, tbh...

 

[jrudge]

https://m.youtube.com/watch?v=XauPvGUb9SI

Video of how cat fuel system works

I can’t see how it can be air if it has been running. The return flow is large and this must purge all air from the system ?

Fuel pressure regularltor or blockage.

I don’t suppose they have touched or partially closed the return fuel valves?

Porto. What on earth is the point in using words and then telling us to google them. And no I didn’t bother.

 

[kashurst]

Iatrogenic = the service guys fixed it worse.

 

[kashurst]

I think it's just trapped air gurgling through. Just been serviced fuel filters off etc, both engines do the same thing. Extremely unlikely both sensors fail at the same time. I would give it the beans if possible, see how it goes then

 

[Portofino]

Iatrogenic = the service guys fixed it worse.

Yup the problem is induced by the actions of the mechanic / service guy .
There was no problem to fix before .The meddling of the service guy(s) had induced this .

It could be a vac leak downstream of a pump caused by a seal which is faulty .Sucking air in ?
Speaking generic hear .twisted o ring , folded gasket or a seal not fitting in a new part ( correctly fitted ) that’s not quite the right spec / dimensions etc etc .Bad batch of filters / gaskets etc .

Just strange this has never happened before and apparently the boats need bilateral identical sensors .
You can with the multitude of sensors on cars get hold of the resistance measurements and test them .
You don,t have to go down the shot gun approach and randomly replace them keeping gong until the “ issue “ clears up .

Some advanced diagnostic systems can run a scan and ID faults via fault codes .
Some manufacturers have an open policy to the software,others guard it and keep the public out .
Some do a 1/2 way they allow authorised dealers the primitive base soft where then contantly sting them €€€ wise for the correct updates .
In this case even though it sounds like a CAT tech ,we don,t really know what level of up dates his diagnostic softwhere had ? I,am guessing CAT guard there softwhere and milk apointed “ dealers “

All I,am highlighting be careful with the “man with the laptop “

Struggling to see how an authorised laptop guy of [ insert marque car or boat ] with the correct timely updates can fail to get a Dx —— for JRudge that’s short hand for Diagnosis save you looking up.

 

[MedMilo]

Thanks for all these thoughts, really very helpful.

Yesterday they changed the new filters for two new, new filters, fearing a bad batch too I guess! But this didn't help. When the alarms sounded at 1500rpm my instinct was to follow the diagnostic instructions and slow down immediately. It sounds as though I ought perhaps to have done the opposite! Will get down there again and see whether a good blast for an hour or so clears it. If not then will need to investigate airleaks or whatever, however, given the above, I'm hopeful it might just clear as it's unlikely there's a matching airleak appeared on both engines simultaneously! I suspect they didn't quite do the filter change meticulously enough and therefore got a bit of air into each fuel line... Muppets!

 

[Mr Googler]

Muppets is the same spelling in Italian......who knew!