8v53 fuel problem 41 Hatt 1966

[SeaEric]

I’m having a fuel problem on my 1966 Hatteras 41 Twin Cabin which is powered by the original GM 8v53’s. She still has the original fuel filter set up that came with these engines. It’s a “sock” element in the primary on the suction side and a cartridge filter in the secondary on the pressure side. We change them once a year and really never see much dirt or debris.

Friday a week ago I started up and got underway for a short weekend cruise. About 10 minutes out, running just above idle (no wake zone) the starboard engine started to run a little rough and falter. I gave her a little more throttle and it got worse instead of better. Shortly thereafter the engine died. It would restart, which I did several times but it would not stay running enough to get into gear. It seemed like it was starving for fuel. So I gave up and limped back to the dock on one engine.

My first call was to my diesel guy Tom Hug. I left him a message. The next call was to a local diesel guy who answered the phone and said he would be there in a half hour. About 20 minutes later Tom Hug called back. While he was on the phone, I restarted the engine and it ran fine. Tom immediately questioned the integrity of the tank pick up tube. I figure that it’s probably original, but lacking any problems up to this point, I have never looked at it. I told him that I had a guy on the way to change the filters, which we did. There was a little bit of black crud in the primary, not enough to stop the engine. There was no dirt on the secondary and both filters were full of fuel when we took them apart. We got it back together, started up checked for leaks and all was well. Off I went on my cruise with no problems. I stared up Sunday morning and came home, no problems.

This past Friday morning – same thing happened. I started her up and about 10 minutes out of the slip the starboard engine ran rough, seeming to starve for fuel. This time I kept going on one engine. I attempted restart a number of times. Same scenario. It would start but not run well enough to get into gear. After I cleared a narrow channel, I decided to turn back for the marina. Just as I was approaching a narrow draw bridge, running against a strong tide I tried once more to restart the engine and it started and ran perfectly fine. So I turned around again and continued to my weekend destination. Sunday morning she started right up and ran all the way home with no problems.

So what would make this engine starve after 10 minutes running and then clear itself up after sitting about another 20 minutes? Tom Hug is coming to take a look at this and has suggested that I shut the fuel off at the tank so that we can try to identify where an air leak may be. I think I still have the original copper fuel lines. Anything is possible! If anyone has an idea of what we should be looking at, please chime in. Thanks in advance!

 

[saltshaker]

I had a similar problem on my 46C. Little bit of gunk was fouling the ball check valve in the Racor. Some fuel would siphon back to the tank leaving air in the Racor. Boat would start and run for 5 mins or so then stall out same symptoms as you described. It would take a few attempts to get her running but once she primed herself the engine would run as normal. Problem would pop up again after she sat for more than a couple of days. Open the Racors after she's been sitting for a few days and see if the fuel level is low.

 

[SeaEric]

Sorry Jack, The first part of my post wasn't there where I mention that I have the original old "on engine" filters that came with the boat. I don't have Racors.

 

[bigbill]

eric, maybe you have something in the tank that is clogging the pickup, then falling free after is is shut down and sits for a while. i had this with my genny on my 46sf. i undid the fuel supply and blew air into it until it unclogged. never did figure out what it was, i lost the boat to katrina 3 months later.

 

[Boatsb]

eric, maybe you have something in the tank that is clogging the pickup, then falling free after is is shut down and sits for a while. i had this with my genny on my 46sf. i undid the fuel supply and blew air into it until it unclogged. never did figure out what it was, i lost the boat to katrina 3 months later.

Dan had a bottle cap or something on his too. maybe he can better describe his fix.

 

[DCMY #92]

I have a 1965 DCMY with 6V53s. I replaced the original primary filters with Racors. But, I had the same symptom you describe a few years ago. It turned out to be a small piece of what looked like 3/8" fuel hose in the tank. It got sucked onto the pickup tube intermittently. Who knows why it took 43 years to make its way to the pickup.

It took me a while to get the bronze tank access cover off. There was quite a bit of fiberglass resin slopped over the retaining screws, but with care I got all the screws out OK.

 

[34Hatt]

Dan had a bottle cap or something on his too. maybe he can better describe his fix.

Yup mine was a bottle cap and the fix was get my arm into the tank and find it didn't know what it was until I found it. Man that was 05 when that happened, seems like 2 years ago. It haunted me for a while because it would do it now and them mostly when it was Rough out it would then just clear up.Then one day up in Plymouth Ma it did it after a fill up, couldn't plane port would not turn up. I removed the fuel line from the pickup took my raft inflater and some electrical tape and pump 10 good shots of air into it. Made it all the way back to Long Island cruising along low on fuel port started to stumble. I grab the throttles pulled back fast and when my wake lifted the ass end I hit the throttles hard causing the fuel to slush around made it back to the dock . That's when I knew something was in there and close removed the bronze plate on the top and 2 minutes later I had the cap in my hand
Never had a fuel problem since then and that's when I found out there was no sludge in the tanks actually it was spotless which caused the cap to free up and start floating around.
Mark had weird shit like this happen to him his was a piece of tape trap in the 90 degree fitting above the fuel pickup which acted like a check valve that was backwards
Never know and it a process of elimination.

 

[drburke]

If you system permits it, you might make a crossover of temporary fuel hose so that you are drawing from the starboard while the valve indicates port and vice versa. Probably can leave the returns alone (but switch as necessary).

If you issue shifts to the other engine, it is the tank like others guessed. If not, do the same trip downstream of the filter system for additional elimination.

Just my two cents worth...

DAN

 

[SeaEric]

If you system permits it, you might make a crossover of temporary fuel hose so that you are drawing from the starboard while the valve indicates port and vice versa. Probably can leave the returns alone (but switch as necessary).

If you issue shifts to the other engine, it is the tank like others guessed. If not, do the same trip downstream of the filter system for additional elimination.

Just my two cents worth...

DAN

Thanks Dan, that is pretty much what I plan to do next.

Today I went aboard and started the stbd engine while tied in the slip and let it run at about 1000 RPM's. About 10 minutes in just like last time, it began to starve. It would not stay running for long. I restarted it a number of times and it either ran like crap or died. After about 30 minutes of restarting it and then letting it sit a while - it started up and ran fine. Again, just like previously - although it seems like this problem is getting worse. I can't help but think that it's getting air in the line somewhere. The fail and clear times are almost identical each of the three times I have experienced this. If it was a clog or blockage of the pickup I would think that the symptoms would be more random. On the advice of my mechanic, I shut off the fuel valves at the tank when I shut the engine down. He thinks that this may help us determine if the problem is between the valves and the engine, or between the valves and the tank.

Since each engine is drawing off of and returning to it's own tank and the port engine is not affected, I will next do as Dan suggested above and isolate the stbd tank by opening the crossover so both engines run off the port tank. If the problem goes away then it's most likely the stbd tank pickup.

Does my logic make sense?

 

[bobk]

On the advice of my mechanic, I shut off the fuel valves at the tank when I shut the engine down. He thinks that this may help us determine if the problem is between the valves and the engine, or between the valves and the tank.

Since each engine is drawing off of and returning to it's own tank and the port engine is not affected, I will next do as Dan suggested above and isolate the stbd tank by opening the crossover so both engines run off the port tank. If the problem goes away then it's most likely the stbd tank pickup.

Does my logic make sense?

Eric, Some years ago I had a suspected valve problem because my port engine seemed to fire on less than 6 cylinders when started after it sat a while. The selector valves always wept a bit. I had the seats lapped in with little change, then bit the bullet and got new valves from SAMS and that issue seems gone.

Just an obvious point, when working with twins and selector valves, be sure the return goes to the correct tank. It can make for a big fuel spill or empty tank in a hurry otherwise.

Cheers,
Bobk

 

[rsmith]

Just IMHO with the low usage and hi probability that condensation moisture is likely in not just your tanks but also in the supply chain side not having water seperators with vacuum gauges is asking for trouble. I replaced our sock filters in 1978 when then Cape Island marina left the cap off the underground fuel tanks and half the parking lot drained into them. 30boats were filled with mostly water. Sock filters will not stop water like racors! And the vacuum gauges would determine if you have a blockage in the fuel system

 

[SeaEric]

Today we opened the crossover valves and started the Stbd engine. It is now running off the port tank. No problems in 20 to 25 minutes. So now with the stbd engine's fuel lines open to the port tank, the next test is to leave it for several days and see if it still starts and runs OK. If it does, then the problem is in the line between the aft valve and the stbd tank. If the fuel line leaks down and causes the same old issue, then the fuel line problem is between the valve and the engine. Slow but sure we are isolating the location of the problem. Stay tuned.

 

[SeaEric]

So here we are 4 days later. I started the engines today to run the boat to the lift well for haul out. I'm getting bottom paint and hull wax. So while I waited for the lift guy, I ran the stbd engine at least enough time for the fuel problem to occur. It didn't. So - based upon this I am going to assume (!) that the air/leak problem is on the starboard fuel line somewhere between the shut off at the fuel manifold and the tank, which is only about 2 feet away. My $$ is on the pickup tube being somehow compromised. This is what Tom Hug told me he suspected at my first phone call to him. He is good. For the record: Dr. Rosenthal agreed early on that this was likely the problem. So now we have to take it apart and have a look see.