892's what is the proper pressure?

[Nightingale]

Just did a complete racor rebuild on the port engine, changed the racors from 2020PM 30 Micron to 2020TM 10 Micron filters. The housing is a 1000MA

Put everything back together and the port engine wouldn't stay running or idle above 510 Rpm. Messed around a bit making sure it was primed, ended up changing the secondary filter out to the same one that was in there (AC TP540X) and it still wouldn't run. Finally I shut off the outboard side racor filter and the boat came back to life after a few caughs, I then opened the outboard filter and everything was fine still. Ran the boat at the dock for about 25 min and everything was still fine.

I then noticed that the port engine was now idling at 620, prior to messing with anything it ran at 580+/- and the starboard still idles at 580 (I have not touched the filters on that motor yet).

I took a loot at the pressure gauges on the racors and I'm not sure what I'm reading here, any interpretation on all of this?

Port engine at idle:


Port engine shut down:


Starboard engine at idle:


Starboard shut down:


Are these readings correct? Please remember the starboard has not been changed and the boat has run perfectly, I was doing some preventative maintenance since who knows what the prior owner did. All help greatly appreciated!

Ray

 

[Nightingale]

Anyone have any thoughts here? Heading to the boat in a few.

 

[rsmith]

Did you turn the fuel valves back on fully?

 

[34Hatt]

Did you turn the fuel valves back on fully?

Same exact thing I thought

 

[Nightingale]

They are fully on, the engine is running perfectly and possibly better than it ever has at least from a sound and feel standpoint.

 

[seasalt]

I think that you have an obstruction somewhere up stream from the Racor. It could be anywhere from the fuel pick up tube to a piece of debris that has gotten into the fuel line.

That vacuum gauge should read "0" at idle. With everything clean and on the same page my gauges stay at "0" even at cruising speed.

 

[Nightingale]

None of the racor gauges on the boat have ever read anything below -8 even when shut down. If you completely open the racors at either engine or gen set it will never go below that -8 mark.

Is it possibly that the gauges all are reading incorrectly or the same?

 

[SKYCHENEY]

I think you're fine. Take it for a spin and run them up under load. Then you'll know for sure.

 

[seasalt]

My Racor gauges have small rubber plugs that you can take out to relieve the vacuum which will set them back to "0". I think that they are filled with a dampening fluid so be careful not to spill any.

Since yours are flush mounted you will have to get behind the panel to do this...if yours have the plugs.

Then you push the rubber plug back in.

 

[MikeP]

"That vacuum gauge should read "0" at idle. With everything clean and on the same page my gauges stay at "0" even at cruising speed."

That's only physically possible if the engine fuel pump is at the same level as the fuel in the tank and the fuel system is completely without obstruction. Otherwise there will be SOME amount of vacuum involved in drawing fuel from the tank. It is impossible for there to be NO vacuum (0) if the fuel has to be lifted from the tank by the engine-driven fuel pump.

6-8 inches of vacuum is pretty common at idle but again, that totally depends on the lift involved. Different installations/same engines can have different vacuum at the same RPM.

As noted, some gauges tend to hold the vacuum readings so that even with the engines off, they show the vacuum from when the engine was running.

 

[Red Hatt]

Did you say you changed the R-filter from a 30 m to a 10 m if so change it back . the 10 m is not letting enough fuel by.

 

[Nightingale]

Changed it back to the 30 mic filters and it is still just like the starboard engine. I ran the boat on the lake and all is well, still pulls a lot more vacuum than 0 but the boat runs just like it should. Hit 2345 rpm - 25.4 mph.

 

[MikeP]

I agree with Red; if it used to be lower and now it's higher and the only thing you did was change the filters to a finer porosity, that's the reason the vacuum is higher. As far as the actual vacuum, if the engine will pull full RPM at WOT under load, then that's all that matters. You can note that vacuum and monitor the filter based on that. Of course, at some point, depending on the type of fuel line that runs from the filter to the fuel pump, the fuel pump could collapse the hose if the vacuum is too high. You can't really put a figure on the "correct vacuum" because it will change depending on the application.