intermittent idle

after oil · Post by **after oil** » Sun Nov 16, 2008 9:55 am

when on WVO the rpms rise and lower while idling. is this a problem?

konadog · Post by **konadog** » Sun Nov 16, 2008 4:52 pm

I'm no expert, but I'm pretty sure any motor should idle at a steady rpm. Fuel delivery issue, maybe...

Post by **BCDelica** » Sun Nov 16, 2008 5:02 pm

First guess would be you do have a fuel restricten problem.

Second guess would be somethings up with your IP.

after oil · Post by **after oil** » Sun Nov 16, 2008 8:51 pm

theres still some 5/16" line, ill change that to 3/8"
theres also 1/4" return but slavko says should be okay. ill change that to 5/16"

that should address all the fuel restriction problems

mararmeisto · Post by **mararmeisto** » Sun Nov 16, 2008 9:41 pm

after oil wrote:theres still some 5/16" line, ill change that to 3/8"
theres also 1/4" return but slavko says should be okay. ill change that to 5/16"

that should address all the fuel restriction problems

Sounds like you've used two different-sized fuel lines along the supply side of the pump - bad idea, for it changes the flow rate when the piping gets smaller. Return side won't matter as much, because it just 'dumps' into the tank.

Other than that, does it do this surging when the engine is warm or just when cold? If only when cold, maybe your inline heater is not functioning properly.

Otherwise, it could be the injection pump.

after oil · Post by **after oil** » Sun Nov 16, 2008 11:04 pm

mararmeisto wrote: Sounds like you've used two different-sized fuel lines along the supply side of the pump - bad idea, for it changes the flow rate when the piping gets smaller. Return side won't matter as much, because it just 'dumps' into the tank.

Other than that, does it do this surging when the engine is warm or just when cold? If only when cold, maybe your inline heater is not functioning properly.

Otherwise, it could be the injection pump.

thats right, the line into the filter is 3/8" and from the filter to the heat exchanger, 5/16" but 5/16" is the nipple on the heat exchanger and on the IP
remember theres an assist pump 7 psi or close to that

it idles inconsistently when warm too

it better not be my IP... but it idles fine on petro-diesel

mararmeisto · Post by **mararmeisto** » Mon Nov 17, 2008 7:06 am

after oil wrote:
mararmeisto wrote: Sounds like you've used two different-sized fuel lines along the supply side of the pump - bad idea, for it changes the flow rate when the piping gets smaller. Return side won't matter as much, because it just 'dumps' into the tank.

Other than that, does it do this surging when the engine is warm or just when cold? If only when cold, maybe your inline heater is not functioning properly.

Otherwise, it could be the injection pump.
thats right, the line into the filter is 3/8" and from the filter to the heat exchanger, 5/16" but 5/16" is the nipple on the heat exchanger and on the IP
remember theres an assist pump 7 psi or close to that

it idles inconsistently when warm too

it better not be my IP... but it idles fine on petro-diesel

Okay, no longer worried about the line size, but it still sounds like there is a problem on the WVO-side of your system. Did you check that other filter? Is it a paper one or a mechanical one (i.e. one you can clean)? I'd check that next.

after oil · Post by **after oil** » Mon Nov 17, 2008 7:36 am

mararmeisto wrote: Okay, no longer worried about the line size, but it still sounds like there is a problem on the WVO-side of your system. Did you check that other filter? Is it a paper one or a mechanical one (i.e. one you can clean)? I'd check that next.

the main filter is a spin on hydraulic oil filter, brand new, the other is a glass sight filter, that can open up and be cleaned. the element inside is a metal screen i believe. i can see the odd bit of debris on there

i still gotta post photos of that filter and there are still no photos of the control switch

oceaneer77 · Post by **oceaneer77** » Mon Nov 17, 2008 10:57 am

If you have constant pressure (7+) psi at the ip inlet
then.. sounds like the viscosity of the fuel in your IP is to thick and is starving to fill the plungers.
can you heat the WVO any higher?

heavy fuel engines have the same symptoms when running bunker c and not hot enough.

oceaneer77

jessef · Post by **jessef** » Mon Nov 17, 2008 11:03 am

You can try running a small 12v inline fuel pump.

after oil · Post by **after oil** » Mon Nov 17, 2008 9:55 pm

oceaneer77 wrote:If you have constant pressure (7+) psi at the ip inlet
then.. sounds like the viscosity of the fuel in your IP is to thick and is starving to fill the plungers.
can you heat the WVO any higher?

heavy fuel engines have the same symptoms when running bunker c and not hot enough.

oceaneer77

two things possible regarding you thoughts oceaneer77
could be the oil isnt heating enough because i presently have mostly water in the cooling system. i didnt want to leak coolant, but now im sure it wont leak (it never did) tomorrow i will put the correct ratio of coolant to water

number 2: my fuel is heated first by the engine coolant, then by a glow plug to 75c before entering the IP. the engine never gets warm enough for the thermocouple to tell the glow plug to shut off. maybe ill need a hotter thermostat for the cooling system, so i can run a little hotter...

jfarsang wrote:You can try running a small 12v inline fuel pump.

got that

oceaneer77 · Post by **oceaneer77** » Mon Nov 17, 2008 10:03 pm

Hi After oil

On #1 water and coolant will hold the same amount of BTUs just the coolant raises the boiling point so #1 is out in my books.

#2 seems to make the most sence.. if i had a viscosity meter we could check the WVO at 75C and compare to #2 diesel but the mere is on the ship and its on the way to panama now.

Can you try to thin the wvo sith some diesel and see what happens at 75C?

thanks
Oceaneer

after oil · Post by **after oil** » Tue Nov 25, 2008 8:51 am

sorry about waiting so long to post results....

i replaced some of the 5/16" line with 3/8", but its still 5/16" from the wvo filter to the heat exchanger and IP

i was in at ccauto to get ip timing and valve clearance set in advance of my trip to mexico.

yesterday i was all over town on WVO and the idle seems steady at around 750 in D and 1000 in P

jrman · Post by **jrman** » Wed Nov 26, 2008 12:00 am

I'm almost having the same issue.
Just had IP fully rebuilt.
Idle set at 750 in D, comes slighting in P or N - maybe 800.
But occasionally I'll go to park and it comes up to 1000. Back to drive, and she's at 750. Doesn't do it every time - and appears to be only after driving for a while. But once it starts doing this - nothing will change till I shut the engine off. Fire it up right away - and it idles normally (ie, 750 in D / 800 or slightly less in P or N).
Funny behaviour!

BTW - didn't do this prior to IP rebuild - solid at 750, ever slightly higher in P or N.

I believe its related to the throttle position sensor (black unit with wire sticking out on top of IP - two flat head screws holding it in place)....but just guessing.
Mardy has 6 mo warranty so may have to go back to check it out, but will tamper with the TPS first and see if that changes things at all.

AndrewH · Post by **AndrewH** » Wed Nov 26, 2008 12:14 am

mararmeisto wrote: Sounds like you've used two different-sized fuel lines along the supply side of the pump - bad idea, for it changes the flow rate

nope, the flow stays the same but pressure changes...

basic hydraulics

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