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Engine Surging

R

rugburn

Member
"I have twin 1986 Crusader 270

"I have twin 1986 Crusader 270s that have run great for several years. This year after running them trouble-free for about 5 hours (covering all rpm ranges), I was forced to intoduce E10 into my tanks. I added the appropriate additive (Marine Stabil), but next trip out, the port engine started surging. I cross-feed it from the starboard tank, and surging went away.

Next day, when returning, with both engines still running from starboard tank, the starboard engine started surging, and eventually stalled; it restatred easily. This continued all day (only on starboard engine) through various feed configurations. Port engine ran fine.

Checked both filters (pre-pump cannister, and post-pump carburator), nothing special discovered. Consulted various sources and was persuaded to add Racor fuel/water separators (one for each tank). While installing the separators, I blew out (with compressed air) all fuel lines tank to pump) for obstructions - nothing discovered.

Fired them up, and they ran fine for 25 minutes at 3000 rpm, then starboard engine started surging again. Eventally (after another hour of trouble-shooting), starboard engine stalled and could not be restarted. Removed fuel pump; while awaiting a new one to arrive (tomorrow), took old one apart, and unfortunately, the diaphram is intact and seems to be in good shape for a 20+ year old pump.

It seems like a fuel contamination issue, but from frequently checking filters, gas smells and looks O.K.

Help - I'm stumped

P.S. Already checked tank vent. Surging continued with filler cap off."
 
".."Checked both filters &

".."Checked both filters (pre-pump cannister, and post-pump carburetor), nothing special discovered. "

And how did you do this, by eyeballing them? You're not about to encounter anything large enough to actually see, but it can be hiding inside there never the less. The bottom line: don't check 'em, change 'em,

You need to change and keep changing the filters until the crud coming out of your tanks (thanks "evil-nol") stops coming through. It took took big filters on mine.

Jeff"
 
"In spite of the move to ethan

"In spite of the move to ethanol, I'm thinking ignition related. coil or ignitor. Did you check spark when the engine quit?"
 
"Well, I better buy Parker sto

"Well, I better buy Parker stock, as these Racor separators (10 micron) are rated for 90 gallons/hr, cost $35, and if I am not "seeing" water or "gunk" and I'm changing them everytime the engine surges, I'm going broke fast.

Don't think it is spark, as the problems seem to follow the starboard tank at this point. Occassionally, the port engine will surge off the starboard tank as well.

After I get my new fuel pump in, I'm gonna try SeaFoam-ing the carbs. Is it possible that the 20+ year old 3/8" fuel line (rubberized) is "swelling" or deteriorating as it goes from the tank to the filters (again, can't "see" anything obvious)? If I need to change them should I go to hard-line (3/8" tubing)?

Is it possible that this ethanol/water ladden fuel is reducing my octane rating to a point that the engines just balk? Would enriching the fuel mixture help, or would I be better off adding an octane booster (like 100LL from the local airport) or an additive?"
 
better off removing the 'o

better off removing the 'old' fuel and replacing it with new fuel...no additive will 'cure' old fuel.
 
"I am almost positive if origi

"I am almost positive if original the are aluminum and 23 yrs old . My tanks are similar in vintage but I am SOOOO thankful I have not yet run into any difficulties with ethanol problems. I keep reading Pete's note and it sounds like this may be the first fill up with ethanol but I do find that hard to believe given its' totally wide spread distribution and probable govt. mandate.

In speaking to a local tank maker for a major boat manufacturer, they had told me to expect 50 years from my tank.... I thought that would be ok ...so I bought the boat."
 
"Yes, the tanks are origial al

"Yes, the tanks are origial aluminum 100 gallon tanks. Last Nov. the state of Maine required all gas stations to go to E10. As I have always kept my tanks full over the winter, I did not introduce E10 into my tanks until a few weeks ago. Shortly there after is when my troubles began."
 
"Tanks ae over 20 years old, b

"Tanks ae over 20 years old, but have never leaked, or had any problems. Transducers work fine. Is there a special method or pump that I should use to pump them out if necessary? The transducer hole is about 3" in diameter."
 
"Pete,
Where in Maine are you

"Pete,
Where in Maine are you located? I am down in Dresden. What I do to pump the tank out is take an electric fuel pump and attach it to the hose going to the tank. What you may be running into is that wonderful e-10 loosening all the crap up in the tank that has developed over the last 20 years."
 
"You may be right, however, I

"You may be right, however, I would think that I would be able to see some of this stuff. The filters show no sign of particles or sediment. Strange. I am in Georgteown, do you have an electric fuel pump I could borrow?

I just came back from putting in a new mechanical fuel pump. Once I got it started, it ran O.K. at elevated rpm, but once I brought it down to idle, it would stall. I put in some seafoam and it sounded smoother, however, after a while it just quit. I'm home now getting some starter fluid to see if I can get it restarted."
 
"Well, it wouldn't re-star

"Well, it wouldn't re-start with ether, so I replaced the condenser, coil, and ballast resistor. Zoom, it started right up and ran great. Took it out for a spin, and after 15 minutes at 3000 rpm squared, starboard engine started surging again. So Dive Dave was partially right, but I still got water? or something in my starboard tank.

After talking to a friend, he mentioned that his aluminum tank has a screen (filter) at the bottom of his pick-up tube. Is this common? Matbe that is what is plugging up on mine? It seems to occur after running 20+ knots with my bow up 15-20 degrees. This would settle the water? at the lowest point of my tank. Makes sense, however, my tanks only have an opening for the transducer. I guess I'm gonna have to pump it out. Is there an easy (cheap but safe) way? Looking for suggestions."
 
"I have a Gibson 50 foot with

"I have a Gibson 50 foot with two 454 CID engines. I seldom get the bow up because I normally run at 7 knots. However when I do, accumulated water moves to the back of the tank (the low spot). I have huge water separators that takes care of the problem. I have put up with this problem for a few years. There is only one opening into the tank; the fill nozzle (which is flush with the deck). I have replaced the "O" ring but it still leaks water into the tank. Replacing the deck fitting will be a real problem so I just don't worry about it. We don't have ethanol in our fuel at Aqua Yacht Harbor yet so it doesn't seem to be a problem.

I suggest you get a water separator with more capacity or fix the source of water if that is the problem.

Chuck Hanson"
 
"The screens are pretty stand

"The screens are pretty standard, on the pickup tubes, but removing them won't help with water in the tank or with ethanol.

You could always take a sample of whats inside the fuel bowl of the carb. As the entire primary and idle system is fed from the main jets (at the bottom of the bowl), any crud that may settle out winds up right there, restricting fuel flow.

You can also hook up a vacuum gauge to the spin on filters. This will help assess not only the filter loading up but any possible collapsing of the fuel supply hose(s). You don't need the $90 racor one but a liquid filled one is most durable."
 
"Pete,
Give me a call Monday

"Pete,
Give me a call Monday I am in the book. I am off that day. I do have a pump you can borrow. How much fuel do you have in the tank and what do you plan to do with it?"
 
"Pete; the next time the engi

"Pete; the next time the engine quits, see if the accelerator pump will squirt fuel into the carb. The statement (runs fine for 15 to 20 minutes) leads me to think of a air leak in the fuel supply that eventually drys the carb."
 
"Well, I think that I have fin

"Well, I think that I have finally come to the end of this journey. I decided to pump out the starboard tank, so I bought an electric fuel pump. I had already previously removed the tank pick-up tube and noticed that there was NOT a filter at the end of the tube. After installing the pump on the pick-up tube, I turned it on and pumped it into a white bucket so that I could observe the fuel. I was surprised that it pumped so slowly for an 8 psi pump. After a while, as the hose in the bucket went "undergas", I noticed that there was more air coming out than gas. I expected the air to stop (being immersed), but it didn't, so I checked the fittings, and the pump, but there were NO air leaks. That left the only place where the air could be coming from was where the tube screwed into the 90 degree elbow that screwed into the tank. So I took the pickup tube out, and holding my finger over the elbow fitting I tried blowing air through the end of the tube. To my surprise, I was able to blow air out where the tube screwed into the elbow. At this point I tried unscrewng the tube from the elbow, and it quickly parted. Inside was a pencil filter that was totally clogged with crap! No wonder my Racors were clean, and no wonder my engine was starving for gas underway! I had NO idea that these pickup tubes had filters in them. Guess what, with the Racors, they won't have filters any more! It looked like "ant dust" or cornmeal everywhere on the filter.

Took the port one out and was able to coax it out and removed the filter properly. This was also plugged, but more so along the whole length of the filter as opposed to jamming up at the top (like the starboard one).

Anyone know where I can get an aluminum pipe elbow with an outside thread for the tank, and an inside thread for the pickup tube?

Thanks for everyone's help, really appreciate all your advice. Hope that this tread will save someone else lots of time (and money), as that's what this is all about."
 
"Excellent find. I agree, fil

"Excellent find. I agree, filters and plastic dip tubes don't belong in marine Al fuel tanks. I've bought SS tank fittings here: www.mscdirect.com

Finding Al fittings are tough, but avoid brass."
 
Pete:
Glad you stuck with it

Pete:
Glad you stuck with it and found the problem. Any good local hardware store or plumbing supply house should be able to hook you up with the pipe fittings.

Paul:
You want to avoid the brass fittings in an aluminum tank as they will set up a galvanic cell and corrode big time. The recommended practice is to use a 300 series stainless fitting if you need to go to another metal in the fuel system.
 
"Thank's Makomark, I forgo

"Thank's Makomark, I forgot what his tank was made of.

Pete, If you have no luck getting the fitting you need get ahold of Jim Begin in Richmond, 737-2888. he has a small machine shop and does great work at fair prices. He worked as a machinist at the yard and at Maine Yankee. I'll bet he could whip something up for you in no time."
 
Good job. It is great that yo

Good job. It is great that you found the problem and it is equally great that you reported it. I will add this one to the book.

Chuck Hanson
 
"Well, thought you might like

"Well, thought you might like to see my secret filter. Image it completely jammed up with crap, and you'll understand my problem. While I was power testing today (no surging, all systems GO), I got to thinking why these filters were in the pickup tubes, and came to the conclusion that they were there to protect the anti-siphon valve. Without the filters, am I setting myself up for clogging up the anti-siphon devices? Do I really need an anti-siphon valve?
291592.jpg
Pickup Tube Filter (3/8")
 
"Pete:

Pretty good thought

"Pete:

Pretty good thought processes there. Glad the surge is really gone and you shared your findings.

In addition to protecting the anti-syphon valve, they also function as a coarse strainer for the rest of the fuel system.

On the anti-syphon valves and the need for them...I'll leave that up to you. They are there to mitigate the resulting 'spill' that could exist if your fuel supply system developed a leak. Some have called them automatic shutoff valves. If your tanks are higher than your filters or pumps, their use has merit. If you tank is lower than the filters and pumps, they really have little benefit.

My tank sits on the centerline, back under the fighting chair. I eliminated the anti-syphon valves years ago (with the screens) and haven't had any problems since."
 
"I wonder if that filter scree

"I wonder if that filter screen was the cause of your Al corrosion. It looks like yellow metal, perhaps. In any case, the other approved option to ASV are manual shut-off valves at the tank. Myself, I do run ASV's without screens, but a piece of Al swarf did lodge in one ASV after I installed a new Al tank. For 5 years now, no more issue."
 
"Reminds me of a short story:

"Reminds me of a short story: an engineer had been proudly boasting of his new clutch design and how great it really was, until they later found out after 10's of thousands of production units, ...YOU COULD NOT easily get the transmission back into neutral. One year later...another new design.

Makes you wonder why things need improvement at times"
 
"I believe Diver Dave is corre

"I believe Diver Dave is correct again. The corrosion of particle buildup at the pickup tube/filter elbow over time, weakened the aluminum tube at the thinner threaded area which eventually caused a crack in the tube. This allowed air in, which exaserbated the corrosion cycle.

After thinking it through, I'm going to make up a spare "straight" (no ASV) fitting that I'll use as a replacement should my ASV ever get plugged up while underway. Depending on how often this happens (if ever), I'll go from there.

I may not have any more problems, as my thinking is that the more demand for gasoline through the ASV (higher engine rpm) there is, the larger the ASV orifice will open for gas to pass through, which should prevent sediment build-up at the ASV, I'll just have to keep an eye on my Racors (which I have installed vaccuum gauges on)."
 
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