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-   -   Replaced filter, engine no longer revs high. Why? (http://www.cruisersforum.com/forums/f54/replaced-filter-engine-no-longer-revs-high-why-149710.html)

antoha 19-07-2015 10:23

Replaced filter, engine no longer revs high. Why?
 
i just replaced my old racor 200 with a racor 500. the engine is a westerbeke 35c-three, with under 300 hrs on it. have been having fuel delivery problems with it ever since we got the boat (burnt out 3 lift pumps), tank is deep in the bilge so i have close to 5-6 feet of lift from bottom of tank to lift pump. so i decided to change to a filter which restricts flow less.

so all is good, dockside the diesel runs fine, both at high rpm (2500) and at idle (<900), doesn't choke, no fuel leaks. but put the load on - and it doesn't go above 2000 rpm. what could be going on?

compared to last year all that's different is: i added more fuel (a couple of 5 gal jerry cans, bought at a local car gas station; the mixture is no longer deep red but light orange - still has pigment though); i tightened the packing gland just a little so it drips less (but it still drips when shaft is spinning); i replaced the fuel filter as described above. primary filter is 10 micron 2010 element, brand new. i did not change the secondary filter.

any advice or suggestions will be greatly appreciated!
thank you!
Anton

zeehag 19-07-2015 10:30

Re: Replaced filter, engine no longer revs high. Why?
 
keep filter and add a nice low flow electric assist pump. when engine running, turn that electric pump off unless you bypass lift pump..first filter should be 30 microns. engine filter should be 10 microns. just add larger cannister to be a 30 micron filter.
keep the 10 micron filter on engine. dont need 2 same size.
will restrict flow of fuel, yes

Cheechako 19-07-2015 10:33

Re: Replaced filter, engine no longer revs high. Why?
 
A vacuum gauge on your filter might help. Maybe there is some restriction, pickup tube etc.
You could also add an electric fuel pump between the tank and the filter, this is handy for when you change filters anyway to fill the system. If it runs fine with that in there you know you are starved for fuel.

antoha 19-07-2015 10:40

Re: Replaced filter, engine no longer revs high. Why?
 
Zeehag, sorry not sure i understand: engine runs, starts with no problem, gets in gear with no problem. it's when i start giving it throttle, it stops at 2000 rpm and doesn't go higher as i open the throttle more. how would lift pump help if you suggest i switch it off once engine is running?

also: my racor 200 elements were 10 micron as well. so i thought i was changing like for like - but bigger canister (500 vs 200) should provide less of a restriction. am i wrong?

thanks again!

antoha 19-07-2015 10:44

Re: Replaced filter, engine no longer revs high. Why?
 
Cheechako: thank you, vacuum gauge is next on my list. i didn't want to put it in the t-handle, so i'm now trying to find the fittings to put it inline downstream after the 500 canister.

Cheechako 19-07-2015 10:57

Re: Replaced filter, engine no longer revs high. Why?
 
1 Attachment(s)
Quote:

Originally Posted by antoha (Post 1872325)
Cheechako: thank you, vacuum gauge is next on my list. i didn't want to put it in the t-handle, so i'm now trying to find the fittings to put it inline downstream after the 500 canister.

like this. But some racors have different threads than others....

antoha 19-07-2015 11:07

Re: Replaced filter, engine no longer revs high. Why?
 
Cheechako: yes, this is the filter i have and the t-fitting i want for the gauge (except my gauge is the racor 1669 or whatever it is called, with 3 needles; probably the same 1/4" thread - so all my threads are now 1/4" after the racor, i am using the old fuel lines). where to buy this?

thanks again!

antoha 19-07-2015 11:26

Re: Replaced filter, engine no longer revs high. Why?
 
7 Attachment(s)
Here are some photos of the install:
Old Racor 200:
Attachment 105614
Fittings (old and adapter for new):
Attachment 105615
New Racor 500:
Attachment 105616Attachment 105617Attachment 105618Attachment 105619Attachment 105620


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Cheechako 19-07-2015 11:43

Re: Replaced filter, engine no longer revs high. Why?
 
Quote:

Originally Posted by antoha (Post 1872337)
Cheechako: yes, this is the filter i have and the t-fitting i want for the gauge (except my gauge is the racor 1669 or whatever it is called, with 3 needles; probably the same 1/4" thread - so all my threads are now 1/4" after the racor, i am using the old fuel lines). where to buy this?

thanks again!

If yours is 1/4 pipe thread you should be able to get a bronze T at most hardware stores.... nothing wrong with machined brass either.

DrivinSteve 19-07-2015 11:56

Re: Replaced filter, engine no longer revs high. Why?
 
"burning out" 3 lift pumps may suggest that delivery from the tank may be an issue.
What does the exhaust look like under load?
Prop clean?

antoha 19-07-2015 12:18

Re: Replaced filter, engine no longer revs high. Why?
 
not sure what the prop look like now. it's a feathering prop (autoprop), pitched correctly, cleaned irregularly (not since last year).

the lift pump on engine is not rated for 6 feet of lift, most of them are good for up to 36" of lift (you can buy others from automotive stores, but those are for some reason not recommended by westerbeke).

my question is not so much "what's wrong with the fuel delivery system design and how to fix it once and for all" (i think i know the answer to this qn: get a day tank located at or above engine level, with all new fuel lines - but that's not a project for this year). rather, it's: "why was it working before (with racor 200) and not anymore (with the 500 model), i thought the new setup should provide less restriction to the fuel delivery".

first time the lift pump burned out after only 20 hrs on the engine; then another couple of times when the engine was still under 100 hrs. we bought the boat with new engine (8 hrs), never were told what necessitated the replacement, didn't look like a red flag at the time (boat was well kept, winters in a shed, belonged to a reasonably wealthy man who took good care of his toy until 2008 when you know what hit the fan).

i looked at the insides of the fittings i removed from the old racor 200, and found a lot of corrosion (when they replaced the engine, they chose to keep the fittings, i believe); given they were steel and whatever went into them, bronze - the steel had a lot of what looked like rust shavings still attached - but could break loose any time. if these were to go through the secondary filter (since the corroded fitting was downstream of the racor), they would certainly damage the lift pump.

exhaust looks fine, no black or white smoke, no oily residue in the exhaust water, from what i can tell. what should i be looking for?

it's possible the fuel filter change is just incidental, and the culprit is a dirty prop. thank you for this suggestion, i didn't think about that, will look into it.

Cheechako 19-07-2015 12:28

Re: Replaced filter, engine no longer revs high. Why?
 
1 Attachment(s)
Quote:

Originally Posted by Cheechako (Post 1872357)
If yours is 1/4 pipe thread you should be able to get a bronze T at most hardware stores.... nothing wrong with machined brass either.

Picture. Auto parts or smaller hardware stores

antoha 19-07-2015 12:33

Re: Replaced filter, engine no longer revs high. Why?
 
1 Attachment(s)
Cheechako, thank you!

Here's a photo of an old corroded Racor fitting off the 200 unit:

Attachment 105633

Especially inside, you can see the almost loose bits.


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DeepFrz 19-07-2015 19:03

Re: Replaced filter, engine no longer revs high. Why?
 
It sounds more like a fouled prop. What is the temp. of the stuffing box since you tightened it upÉ

transmitterdan 19-07-2015 20:16

Re: Replaced filter, engine no longer revs high. Why?
 
Quote:

Originally Posted by antoha (Post 1872378)
my question is not so much "what's wrong with the fuel delivery system design and how to fix it once and for all" (i think i know the answer to this qn: get a day tank located at or above engine level, with all new fuel lines - but that's not a project for this year). rather, it's: "why was it working before (with racor 200) and not anymore (with the 500 model), i thought the new setup should provide less restriction to the fuel delivery".

My guess is that the new filter install is letting a tiny amount of air in and causing the RPM problem. It appears your system pulls significant vacuum just to lift the fuel from the tank. So the plumbing must be absolutely air tight. Look again at all the fittings you installed and any rubber hose connections. One of them may have a microscopic air leak. What "goop" did you use on the threaded fittings?


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