Fuel delivery issue

[Marian Claire]

On my last trip the A-4 ran like a champ for the first few weeks. Instant start, steady PRM and consistent 8 hr days of running. Then on a day with following seas I noticed a slight RPM variation. Hard to pick up on the tach but I could hear/sense it. I, ever the optimist or maybe just lazy, blamed it on the conditions loading and unloading the prop. Wrong. The next day I had the same thing on flat water. I decided to adjust the main jet, I have the early model carb. I no more than touched the packing nut and she ran smooth as could be?????. Every few days for the next week or so the problem would return. After a few more attempts at adjusting in place I removed the assembly and cleaned it, no sign of gunk, and shot carb cleaner thru the main jet. This did the trick for about a week as I worked my way back down the St Johns River thru Jax and turned N for the trip back to NC. A day or two later as I approached St Andrew Sound she started dropping the RPM again but this time I could see it on the tach. I was heading down the Cumberland River with a helpful SW 15-20 but fighting the flood current. Not the best conditions for St Andrew. So I am running thru my options when the A-4 stumbles/catches/stumbles and dies. I swing over to some shallower water under sail and drop the hook. Very bouncy but I could see that my inline filter just before the carb was dry. Must be getting air in some where or the pump has died or the OPSS is shot?? I tightened all the hose clamps, bypassed the OPSS, and she primed just fine. Fired up and off I go. The next hr was a tense, rough battle thru the most confused seas I have ever been in. To top it all off the CG had removed the R-32 marker since the last time I was thru here two weeks before. Being a couple hundred miles S and not really listening I had missed the info on the NTM. My mistake. Thank goodness for my chartplotter and the fact that this was my forth time thru in as many weeks. I made the turn and flew up to the anchorage behind Jekyll Island. This was the start of the most frustrating week I have ever spent on a boat. Everyday she would shut down with little warning. The inline filter would be empty but if I "messed" with things and jumped the OPSS she would refill. I thought it was my carb when I made the mistake of removing the plug in the bottom of the throat, remember earlys do not have the external scavenge tube, instead of the bowl to check for gas. No gas! Well dahh. This led to a "needless" carb cleaning as I sat at anchor. Switched to my spare fuel pump no change. I thought it might have been my petcock clogging because I spun it 180 deg from open and a blob of crud showed up in my inline filter. After the petcock deal I made it thru Elliot Cut, Wappoo Cr, Charleston Harbor and as I started to pass thru Ben Sawyer bridge she shut down. I had the jib ready and raised it and sailed thru. At this point I had been fighting for four days and 200 miles. I did some more cleaning, tightening etc that night but the next day near Mc Clellanville SC she shut down. I decided to strip the fuel system down to the bare bones. Hose in main tank to eliminate the pickup tube and possible crack/air leak, bypass petcock and water separater filter and noticed that it sounded empty but was in fact half full, jump OPSS. SHE RUNS. After two days of no shut downs I have to start adding things back or I will never know what the problem was. I added back the petcock filter assembly and the next day after running fine for hrs she shut down. I must give the Marian Claire credit because she did this just before I entered the area known as the Rockpile. A rock lined section of the ICW and no place to have problems. I dropped the hook removed the petcock/filter and away we go. It has now been a week of constant tension and long days due to stops and late nights for repairs. I am exhausted. I know I could have stopped but what could I learn from sitting. The constant SW wind also played into it. Over the next few days I slowly, one at a time replaced/returned to normal the fuel system. Except for the petcock/filter. She ran great and I made it back to Matthews Point. I set up the boat for slip life and made sure I disconnected and plugged the fuel line at the top of the tank. With no petcock I did not want to risk a flooded carb/boat.
I brought the P/F assembly home and pressure tested it for leaks. I made the mistake of disassembling/cleaning and greasing the petcock before I pressure tested. No leaks.
My theory is that given that the P/F was the highest point in my fuel system any air leak may have allowed air to build up in the filter. This could take hours and when enough air built up the Facet pump would have to pump a "large" amount of air thru the carb to re-prime. This would cause the shut down. I plan to reinstall the P/F at a point lower than the carb. This way if there is a small air leak the air will pass thru the filter and not build up.

Advice is welcome. Dan S/V Marian Claire
Edit: P/F stands for petcock/filter

[joe_db]

Hate to be obvious, but is the OPSS going bad?

[JOHN COOKSON]

This is so obvious that I hesitate to post it but here goes anyway.
Is there an in line anti siphon valve at the fuel tank whose function was comprised by a pressure leak in the "P\F assembly"?

TRUE GRIT

[hanleyclifford]

Dan - I like the idea of moving the valve and filter off the tank. The part of the system where the pump has to maintain, in effect, a syphon (and airtight at that) is the Achilles heel of the fuel system. I have nothing on the tanks themselves except the actual pick up tube. BTW, do you have that low pressure fuel gauge right at the carb fuel intake? BTW, have you ever tried the back way thru St Andrew's via Umbrella Creek; thought I might try it next time just for fun.

[Marian Claire]

Joe. Is there a way to test an OPSS. I know at least once during all this that the engine shut down but the fuel pump was still clicking as the OP dropped. Then at 5+- psi the OPSS kicked in and shut down the pump as it should. That would indicate normal function, but if it is intermitant how can I tell?

John. No inline anti siphon valve.

HC. My set up is tank, 20"+- of line, petcock, attached to the feed side of the water/fuel filter, 15+- of line, Facet pump, 8" of line, inline filter, 2" of line and then carb. I had the water/fuel filter mounted high to make it easier to change. I do not have a fuel pressure gauge installed. I tried installing one a year or so ago but it never worked so I removed it. Maybe I can try it again.
I did use the alternate route several years ago. I would have to check my log for the exact spot but I touched at mid tide. Many have reported very shallow water.

Thanks for all the replies. I know my post is a bit scattered and I think I may have had two seperate issues. Is it possable for air to collect in the filter if it is at a high spot? Just want to know if what I am thinking makes any sense.
Dan S/V Marian Claire

[Marian Claire]

I plan to be on the boat over the next day or two. This may be the only chance I have to work on her before a trip in early June. So let the ideas fly. Is there a goop that would help seal the barb to hose connection? Some permatex?? I noticed that the barb leading into the petcock has a scratch running the lenght of the barb. My guess is from cutting a hose to remove it. I will try and remove and replace that barb but it has been togeather since before I got the boat and I am worried about breaking something. Would lightly sanding the scratch help?
Do not worry about obvious answers/suggestions. What kind of readings are normal on your fuel pressure gauge? Does it vary? My inline filter fills, empties, trickles, fills and repeats when running at cruise RPM.
Thanks again. Dan S/V Marian Claire

[67c&ccorv]

Originally Posted by Marian Claire

I plan to be on the boat over the next day or two. This may be the only chance I have to work on her before a trip in early June. So let the ideas fly. Is there a goop that would help seal the barb to hose connection? Some permatex?? I noticed that the barb leading into the petcock has a scratch running the lenght of the barb. My guess is from cutting a hose to remove it. I will try and remove and replace that barb but it has been togeather since before I got the boat and I am worried about breaking something. Would lightly sanding the scratch help?
Do not worry about obvious answers/suggestions. What kind of readings are normal on your fuel pressure gauge? Does it vary? My inline filter fills, empties, trickles, fills and repeats when running at cruise RPM.
Thanks again. Dan S/V Marian Claire

That doesn't sound like normal operation...should stay filled.

From FAQ's;

1. Our engine starts and runs fine for about an hour. Then suddenly stops. It can be re-started immediately and runs fine for another hour or so. The only thing we have done mechanically is add an electric fuel pump.
My first three guesses are all the same; i.e., the fuel pump you installed probably has too low a pressure rating.

The normal fuel pump pressure for an Atomic 4 powered boat is a nominal 3 psi. Boats (like Catalina 30's), with fuel tanks lower than the engine and 6 to 8 feet away, will need a nominal 4 psi pump. If your tank is high and close, there may be a partial restriction somewhere in the system which your old pump was handling, but the new electric pump cannot. Updated: May 15, 2009

[Marian Claire]

"That doesn't sound like normal operation...should stay filled."
67. Thats what I thought but it ran great like that for hundreds of hours of hard use. My pumps are Facets from MMI and switching to the spare did not seem to help with the shut downs. Could be the "stuck ball" low flow, issue but what are the chances of both pumps having that? Will try and check them when I get to the boat. IIFC. My carb is the lowest point in my system. I used longer than needed pieces of hose so if the ends got messed up I could just cut them off and reuse the hose. That may have been a mistake as it made some dips, low/high spots in the system.
Thanks for the help. Dan S/V Marian Claire

[JOHN COOKSON]

Originally Posted by Marian Claire

My inline filter fills, empties, trickles, fills and repeats when running at cruise RPM.
Thanks again. Dan S/V Marian Claire

I think there is a clue here.
My inline filter does just the opposite. It fills partially but not all the way and maintains that level always. The diameter of my (illegal, plastic) filter is greater than the diameter of the fuel line so this is to be expected. I consider it normal operation.
There is a way to figure your shut down problem out but it's the long way around. Start with an auxiliary tank to the fuel pump bypassing the boat's fuel system. When you get this much working correctly add in parts of the boats fuel system until you find the problem area.

TRUE GRIT

[Marian Claire]

I removed the fuel system from tank to carb. Found a couple of bunged up hose barbs and replaced them. Relocated the water/fuel filter so it is on about the same level as the pump and carb. All are now below half full tank level. This may have been a mistake from what I just read on another thread. I do not like the fact that there is now one connection below 1/2 tank level and before the petcock. I should have added another petcock just after the tank. Purged the line of air by disconnecting the line into the fuel pressure gauge T and ran the pump. Flow was very good. She fired up and ran fine and the amount of fuel in the inline filter stayed constant. A long run is needed to see if it is fixed. I did mount the fuel pressure gauge just before the carb but it either did not read or the needle jumped around at the 1 psi mark. I will get a new gauge.
Dan S/V Marian Claire

[67c&ccorv]

Originally Posted by Marian Claire

I removed the fuel system from tank to carb. Found a couple of bunged up hose barbs and replaced them. Relocated the water/fuel filter so it is on about the same level as the pump and carb. All are now below half full tank level. This may have been a mistake from what I just read on another thread. I do not like the fact that there is now one connection below 1/2 tank level and before the petcock. I should have added another petcock just after the tank. Purged the line of air by disconnecting the line into the fuel pressure gauge T and ran the pump. Flow was very good. She fired up and ran fine and the amount of fuel in the inline filter stayed constant. A long run is needed to see if it is fixed. I did mount the fuel pressure gauge just before the carb but it either did not read or the needle jumped around at the 1 psi mark. I will get a new gauge.
Dan S/V Marian Claire

Originally Posted by 67c&ccorv

That doesn't sound like normal operation...should stay filled.

From FAQ's;

1. Our engine starts and runs fine for about an hour. Then suddenly stops. It can be re-started immediately and runs fine for another hour or so. The only thing we have done mechanically is add an electric fuel pump.
My first three guesses are all the same; i.e., the fuel pump you installed probably has too low a pressure rating.

The normal fuel pump pressure for an Atomic 4 powered boat is a nominal 3 psi. Boats (like Catalina 30's), with fuel tanks lower than the engine and 6 to 8 feet away, will need a nominal 4 psi pump. If your tank is high and close, there may be a partial restriction somewhere in the system which your old pump was handling, but the new electric pump cannot. Updated: May 15, 2009

1psi - you need at least 3psi...something wrong in there mate.

[Marian Claire]

After a short test this past weekend the system seems to be much improved. The new fuel pressure gauge is reading 3 psi and the bubble in the filter seems to stay the same size. I have also come up with a plan to add a second petcock just after the tank. Full update after my next long run.
Dan S/V Marian Claire

[zellerj]

Hi Dan,

For the sake of clarity for others that read this thread, what is P/F? I know when it is posted I will say: Duh??? but I can't figure it out at the moment.

[Dave Neptune]

Jim, its "polishing filter".

Dave Neptune

[Marian Claire]

"I brought the P/F assembly home and pressure tested it for leaks. I made the mistake of disassembling/cleaning and greasing the petcock before I pressure tested. No leaks.
My theory is that given that the P/F was the highest point in my fuel system any air leak may have allowed air to build up in the filter. This could take hours and when enough air built up the Facet pump would have to pump a "large" amount of air thru the carb to re-prime. This would cause the shut down. I plan to reinstall the P/F at a point lower than the carb. This way if there is a small air leak the air will pass thru the filter and not build up."

If this is the P/F you are asking about it stands for petcock and water/fuel separator filter assembly.

Dan S/V Marian Claire

[Marian Claire]

Had a chance to make an extended run on the boat. The new fuel pressure gauge is working. Hanging around 3 PSI most of the time but I did see it drop to around 1.5 then back up. Is that normal? Made the 55 mile run to Ocracoke running at 1700 RPM. Solid as a rock RPM and no issues in 10 hrs of continual use. While at anchor I added the new petcock just after the fuel tank. On the return trip it was 9.5 hrs of 1900 RPM and perfect performance.
I believe she is now safe due to the new/additional petcock, as air tight as I can make her with new lines and fitting and hopefully good to go even if a small air leak occurs with the filter being low allowing any air to pass thru instead of building up. Only time and hrs will tell. Guess I need to go on another trip.
Dan S/V Marian Claire
Now I need to go and check the 256 posts I missed.

[Dave Neptune]

Dan, good to hear. My gage shows between 1.5 and 3 and moves around a bit especially at lower demand settings. Seems steadier as the power increases.
Most pumps have a min/on/pump and a max/off/no pump range and the pound and a half is moot unless it stays there with a big demand on the engine.

Dave Neptune

[joe_db]

Now I fixed the gauge (long story, see thread on liquid filled gauges), my fuel pressure stays between about 3.8 and 4.1.