Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 23-02-2014, 20:05   #181
Registered User
 
Oceanride007's Avatar

Join Date: Jun 2013
Location: Boat in Whitsundays, heading south.
Boat: Custom Perry Passport 41, steel
Posts: 339
Re: 50hp Perkins won't rev past 1900rpm

Yes, but he's given enough fuel bleeding and tried the aerostart stuff, so I'm casting the net further.
__________________

__________________
Oceanride007 is offline   Reply With Quote
Old 23-02-2014, 20:09   #182
Senior Cruiser
 
SkiprJohn's Avatar

Cruisers Forum Supporter

Join Date: May 2006
Location: Kea'au, Big Island, Hawaii
Boat: Cascade, Sloop, 42 - "Casual"
Posts: 14,192
Re: 50hp Perkins won't rev past 1900rpm

Quote:
Originally Posted by edwmama View Post
Hello sailors

I have the same problem with my 1968 perkins 4.236 85 bhp engine in my cal 46 sailboat

Thx to the internet I get tips advices and help on how to trouble shoot and fix problems

I seem to remember that I was able to rev my engine passed 1500 rpm before

Recently I'd only go to 1000. The engine starts right away. No black or white smoke. It runs smoothly. No water in the oil. It's not burning oil
It has 1100 hours ( almost new)

I had replaced my secondary fuel filter fearing ( on someone's suggestion) that I had reversed the O ring on the engine-attached fuel filter.... That was okay

But I did see that the O ring on the primary Racor 500 o ring had been TWISTED. After this I bled and ran the engine to 180 F temp and I was able to reach 1500

My stainless steel fuel tanks have been cleaned 5 years ago. The auxiliary
Electric fuel filter is clear and the fuel looks sparking clean coming out of the Racor before it feeds into the engine

Does anyone know why my rpm won't go passed 1500?


Thanks in advance

Edwin
Cal 46 Lahlia
MdR CA
I'll just be brief because we are hijacking a different thread. The 4-236 I am familiar with in a Cal 2-46 was never run very fast so do you know at what speed it's supposed to develop cruising speed and best power? I remember the engine I'm familiar with starting to overheat if about 1400 rpm so I thought there was something wrong with it.

Are you trying to increase rpm over 1500 in neutral or in gear?
__________________

__________________
John
SkiprJohn is offline   Reply With Quote
Old 23-02-2014, 20:29   #183
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Re: 50hp Perkins won't rev past 1900rpm

Ockham's Razor.
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 23-02-2014, 21:01   #184
Registered User
 
edwmama's Avatar

Join Date: Jun 2008
Location: southern california
Boat: cal cruising 46
Posts: 65
Re: 50hp Perkins won't rev past 1900rpm

Quote:
Originally Posted by SkiprJohn View Post
I'll just be brief because we are hijacking a different thread. The 4-236 I am familiar with in a Cal 2-46 was never run very fast so do you know at what speed it's supposed to develop cruising speed and best power? I remember the engine I'm familiar with starting to overheat if about 1400 rpm so I thought there was something wrong with it.

Are you trying to increase rpm over 1500 in neutral or in gear?
John tank you for your kind response

I'm only trying to rev the engine while tied up at dock

And in neutral. Supposedly at 1500 cruising RPM is the optimal for gas Economy
And is the sweet spot.

Someone on the web had suggested checking mixing elbow assuming the fuel side is clear, and also the lift pump filter screen

Thanks again
Edwmama
(Edwin)
Cal 46 Lahlia
__________________
edwmama is offline   Reply With Quote
Old 23-02-2014, 22:43   #185
Registered User

Join Date: Feb 2010
Location: Vancouver, BC
Posts: 33
Re: 50hp Perkins won't rev past 1900rpm

We had a similar experience with a Yanmar 4JH3HTE -- we had a Webasto heater installed and the installers cut into the plastic fuel tank that clogged the inlet for the fuel system. Beneteau put a very small fuel inlet hose into the tank -- perhaps 3 or 4mm in diameter. I had a new one made that's about 10mm across -- and after removing the fuel tanks and emptying them through a baja filter, got most of the plastic bits out. After that the fuel inlet we had made sucked up the plastic shards through the pipe and into the Racor filter. About a year later the Racor filter eventually clogged (not the filter but the actual mechanism that the filter fits into) some of the internal parts & I had to dismantle it as well. about a 1/2 hour of re&re and a half hour of cleaning with some compressed air and we were good as new.

The symptoms manifested themselves as a slight "cough" and loss of RPMs under load. Once I made the fuel pipe bigger we've had no problems -- other than the slight clogging of the Racor -- which I should probably put on my annual preventive maintenance list come to think about it.

Rule of thumb I would check to make sure that the fuel is getting to the engine true -- without air -- might be a crack in an older fuel hose letting in air. If this appears to be OK and after replacing the primary and secondary filters you still have the same problem -- then go to the back ... check out the exhaust and make sure that it's clear ... if that's OK then you should probably call a mechanic and get some serious help.

Cheers ...
__________________
marina.alex is offline   Reply With Quote
Old 24-02-2014, 00:53   #186
Registered User
 
edwmama's Avatar

Join Date: Jun 2008
Location: southern california
Boat: cal cruising 46
Posts: 65
Re: 50hp Perkins won't rev past 1900rpm

Thanks for that
I think a mechanic is needed

Edwin
Cal 46 Lahlia
MdR CA
__________________
edwmama is offline   Reply With Quote
Old 24-02-2014, 11:30   #187
Registered User

Join Date: May 2012
Location: Western Wisconsin
Boat: O’Day Daysailer II, 17'
Posts: 572
Re: 50hp Perkins won't rev past 1900rpm

Quote:
Originally Posted by Hoohaa View Post
Thought I would try to put some of my thoughts out their.
1. We are getting fuel to all of the injectors. Injector No1 (thanks Bob) still dribling allot of fuel when all the others are squirting fuel out (while bleeding, we have not removed any injectors or the injector pump). As discussed erlier, even if No1 injector is not functioning properly, the motor should still start.
2. We have gone over the system and cannot find any leaks. However, there did appear to be a moist vapour look to one of the clamped hoses at the first inline fuel filter. We trimed the hose, tightened the fitting and reclamped the hose. We now believe there are no leaks.

If you assume that we have no leaks. What else can stop it from starting?

I do not understand the internal workings of the governor and so far everyone thinks that it has no bearing on my starting problem. But.. The accelerator lever is clearly being obstructed by something internal.
Directly above this lever is the old engine kill lever which still works because I can manually operate it when we are cranking the engine and there is an obvious down turn in the engine.
Now, can the governor if malfunctioning, cause the engine to not start, as would the kill lever if jamed on but that lever cuts the fuel so I know thats not the cause. Correct me if I am wrong.
On another note, could it be possable for the first filter to trap some air in the top and to still get fuel all the way up to the injectors?
This is me clutching at straws.

Sorry about the bad spelling.
Oh yeh, can someone explain why the water should be closed/off why trying to bleed the engine?
Jeff
Low engine RPM was the original problem and the "Injector No1 (thanks Bob) still dribbling " and "The accelerator lever is clearly being obstructed by something internal." would be explained by a faulty fuel injection pump. Pull the pump and also the injectors since they need periodic maintenance anyway and take it all to a specialized shop for diesel fuel injection pumps. If you do not want to deal with setting the timing on the fuel pump, get a mechanic to do it and reinstall the injectors. Since the air in the system happened after changing filters, you need to check O rings and filter installation. The mechanic could check for air leaks while he is there for the fuel injection pump timing and injectors
__________________
westwinds is offline   Reply With Quote
Old 24-02-2014, 12:52   #188
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Re: 50hp Perkins won't rev past 1900rpm

The likely hood that air is leaking into the system is very slim to none. After the lift pump the system is under pressure. Fuel could leak out but air cannot "leak" in.

There will be a slight vacuum between the lift pump and tank. It is possible for air to be sucked in there but would also leak fuel when not under a vacuum.

The raw water pump needs the water for lubricity or your impeller will be destroyed.
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 24-02-2014, 13:00   #189
Registered User

Join Date: May 2012
Location: Western Wisconsin
Boat: O’Day Daysailer II, 17'
Posts: 572
Re: 50hp Perkins won't rev past 1900rpm

Quote:
Originally Posted by Cap Erict3 View Post
The likely hood that air is leaking into the system is very slim to none. After the lift pump the system is under pressure. Fuel could leak out but air cannot "leak" in.

There will be a slight vacuum between the lift pump and tank. It is possible for air to be sucked in there but would also leak fuel when not under a vacuum.

The raw water pump needs the water for lubricity or your impeller will be destroyed.
You could be right. It just depends on where the lift pump is located. If it is in the fuel tank, then yes, there is no chance of air getting into the fuel system.
__________________
westwinds is offline   Reply With Quote
Old 24-02-2014, 13:23   #190
Registered User

Join Date: Feb 2014
Location: Auckland
Boat: Crowther, buccaneer, 33'
Posts: 14
Re: 50hp Perkins won't rev past 1900rpm

had sometyhing similar in a BMC engine and found the cut off valve used to stop the engine was staying slightly open - we could start the engine run it up to 1400 or so but no further. When hot it was fine.

It turned out to be that the cable which operated the valve was old and the sheath was gripping the wire and holding the valve ever so slightly open. The heat of the engine would eventually expand the sheath, free the wire enough to allow the valve to close, but when cold it would shrink again and grip. We replaced the cable and all was well.

Sorry if this has been suggested earlier but didnt have time to read all posts
__________________
threes_company is offline   Reply With Quote
Old 24-02-2014, 18:32   #191
Registered User

Join Date: Apr 2013
Posts: 227
Re: 50hp Perkins won't rev past 1900rpm

Quote:
Originally Posted by Cap Erict3 View Post
The likely hood that air is leaking into the system is very slim to none. After the lift pump the system is under pressure. Fuel could leak out but air cannot "leak" in.

There will be a slight vacuum between the lift pump and tank. It is possible for air to be sucked in there but would also leak fuel when not under a vacuum.
Sorry but this simply isn't the case. Air leaking into the system between tank and lift pump - with no diesel leaking out - is so common that the greenest apprentice diesel mechanic is aware of the phenomenon.
__________________
bornyesterday is offline   Reply With Quote
Old 24-02-2014, 18:42   #192
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Re: 50hp Perkins won't rev past 1900rpm

6 posts here and used one to try to insult me.

Thanks
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 24-02-2014, 20:08   #193
Registered User

Join Date: Apr 2013
Posts: 227
Re: 50hp Perkins won't rev past 1900rpm

I believe the quoted part of your post is unhelpful and it's certainly wrong.

I also believe that "put the wrench down, step back from the engine and call a mechanic" was unhelpful.

Now I have six posts.

You're welcome.
__________________
bornyesterday is offline   Reply With Quote
Old 24-02-2014, 20:36   #194
Senior Cruiser
 
SkiprJohn's Avatar

Cruisers Forum Supporter

Join Date: May 2006
Location: Kea'au, Big Island, Hawaii
Boat: Cascade, Sloop, 42 - "Casual"
Posts: 14,192
Re: 50hp Perkins won't rev past 1900rpm

It's been a couple days since he posted so maybe he's taking a break from the engine and us. He's got a lot of information to play with in order to sort out his engine starting problem.

Once he gets it started again then there are some tests he can do. I wish there was an experienced diesel guy there to help but he's kind of solo on that.
__________________
John
SkiprJohn is offline   Reply With Quote
Old 24-02-2014, 21:07   #195
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,815
Re: 50hp Perkins won't rev past 1900rpm

Have not read every response, But a clogged mixing elbow will cause the low rev issue for sure.
__________________

__________________
sailorchic34 is offline   Reply With Quote
Reply

Tags
perkins, rpm

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 11:55.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.