Engine Dies after long run/ won't start back up

[270sundancer]

If anyone can help or give hints I would greatly appreciate it! I have a 1998 Sea Ray 270 Sundancer Cruiser with a Mercruiser 454 7.4L (I believe this is correct Liter displacement) Single Screw I/O, Bravo III drive. Sometimes after extended runs (1-2 hours) the engine dies abruptly at cruising speed and sometimes won't start back up for more than 1 hour. Sometimes it starts right back up! I thought at first it was an overheating issue (however no alarms) but temp. gauge occasionally climbs to 185-195 F. It seems when temp climbs over 175F this is when the problem is most likely to rear it's head. We have replaced thermostat, fuel pump, fuel pump relay, impeller, risers and intake lines, anything we could think of to take care of the heat problem. Once I had hydrilla (seaweed) clogged around the drive and heard the temp. alarm so I know it works. Temp never gets above 200 however. I have tapped on the fuel seperator/filter and the engine has started but I think this is a fluke and coincidence as it has NOT started after hitting the hell outta it. It has also re-started after tapping on the fuel pump relay but again I think coincidence. It seems to start back up after it sits with the engine hatch up for about 20-45 minutes. At first I was thinking vapor lock (another thing this boat does is spurt ALOT of fuel out of the filler when filling with fuel, even when filling slowly). The boat does not sputter when it cuts off it just dies and it sounds like it takes one last GASP of air while it is dying (like it is "sucking air"). Immeadiately after dying it will usually start right back up but won't stay running for more than 5-10 seconds and dies again. A local Mercruiser mechanic told me he believes it sounds like electrical (maybe the main engine electrical plug) since it doesn't sputter. I have heard of an "anti-siphoning" valve that prevents fuel from spilling if a boat flips and possibly a "screen"? at this valve. Where is this valve located and can I remove it (I don't plan on flipping the boat and if I do, there are bigger problems then than fuel spilling out in the water). Could this explain the sudden shut-off of the engine, the "anti-siphoning" valve or screen. I have checked the fuel filler line for kinks as well as the rubber fuel line coming from the fuel tank, everything looks straight. Is there some sort of "diaphragm" inside the unit that the fuel filter/seperator screws on to that could be stuck or have trash in it? No fuel attendant at ANY dock has EVER seen as much fuel "spurt" out of a fill hole as on my boat (sometimes 2"-3" high for 10 seconds). There is no fuel vent on the hull of my boat below the filler hole like I have seen on other boats (ie. clamshell vent cover). How does the tank vent itself? I operate this boat in "slightly" brackish water, sometimes in salt but always return within 24-48 hours to the slightly brackish water of the Potomac River in Virginia. I have replaced NUMEROUS fuel filters/seperators and studied the fuel that has come out of the used ones and have ALWAYS found CLEAN and DRY fuel with not a speck of dirt in it. Since this problem started, I have replaced probably 15 fuel filters just in case I had some BAD FUEL. I have went through 400 gallons of fuel from different places, even places NOT on the water. I have noticed that this cutting off NEVER happens on short trips (1 hour or less). This weekend the boat ran GREAT at approx. 3200 RPM at 29 MPH for about 1 hr 30 minutes before in "died" within sight of our slip and WOULD NOT start back up and stay running for ANYTHING this time after trying for over an hour. Even after towed to our slip and docked for 2 hours, would not start and stay running. Sometimes it will start and run for 5 seconds and sometimes it will not start at all (engine turns can't tell if it is not firing or just starved of fuel). Any suggestions would be GREATLY appreciated! At this point, after replacing everything we have replaced, I'LL TRY ANYTHING!! Thanks Guys!

 

[chiefalen]

Re: Engine Dies after long run/ won't start back up

there has to be a fuel vent.the gas tank must have a hatch u can open to view the gas pickup.find that hatch open it should see a round recessed cover on tank where the fuel pickup is.electric wire goes to it for gage has the rubber hose that goes to the fuel pump.there is a valve on top that is the check valve.there should be about 5 screws that hold on that cover.take off the hose unscrew the valve blow thru it.is it clogged or not working?pull that cover on the tank there is a long tube metal in there a screen should be at the bottom clogged up?ok can do 2 things here put back on the cover and hook back everything or try to suck the water thats in the tank out.if u want to try to suck the water in the tank out before u take eveyrthing off go to the nearest auto parts store buy the cheapest electric fuel pump u can get get some fuel hose and 2 clamps to hold the fuel hose on the pump.about 3 feet of hose for the side that goes in the tank and about four feet for the side that goes in a bucket .put the hose down to the bottom of the tank other side in a clean bucket hook up the electric puel pump to the battery and suck away the water will be on the bottom of the fuel cause water is heavier than fuel.when u start sucking fuel up the hose youll see the difference in the bucket and stop pumping than put everything back together.now there has to be a vent on that tank youll see where the fat fill hose enters the tank but there must be another hose that goes to the vent.maybe clogged with spiders i dont know has to be one find it and clean it out.post how it runs after.good luck

 

[270sundancer]

Re: Engine Dies after long run/ won't start back up

Thanks Chief Alan, so you think it is WATER in the fuel? Can I do away with the check valve so that I don't keep having problems with it? I would think if it is water in the fuel, A) It would show up in the filter/seperator and B) It would sputter before it dies and not just abruptly shut down. Thanks for the info on the check valve. I will try all of that one evening this week and post a reply after I try another long run. Do you know of a "V" shaped kill button located somewhere near the shift cable that sometimes gets stuck or depressed when the shift cable is out of adjustment or something. I read a post on here about it but can't find the post now. The owner sprayed the button with WD40 and unstuck it and had his shift cable re-adjusted. This problem with my boat DID NOT happen until we had the shift cable replaced after it broke leaving the boat stuck in forward gear. It happened the NEXT day after we picked it up from the shop, we called the mechanic and he said our problem had NOTHING to do with the cable replacement which sounds fishy to me! It happened that one time, and did not happen for almost a year after that. It is happening MORE frequently now (maybe also because we are taking longer trips now). NEVER happens on a short 10 mile run to our favorite beach. Thanks again. Any thoughts, just PUT YOUR BRAIN ON SPEAKERPHONE!!!!!

 

[TommyA]

Re: Engine Dies after long run/ won't start back up

From everything you said I believe that there are two separate problems. Engines can ingest water along with fuel and still continue to run. At lower RPM you may experience a stall but at a higher settings the engine would simply sputter a Little until the water passed through. The mechanic was correct that it sounds electrical. The Ignition system will cause the engine to just stop as you are explaining. More than likely one of the modules is breaking down. I'm not familiar with your engine but there are probable two ignition modules each with four wires leading to the spark plugs. The next time it stalls pull one of the wires off of the plug end from each module and insert a screw driver (Phillips head) into the wire end to make contact with the plug attachment inside. Holding the screw driver next to a metal surface on the engine and not touching the metal yourself have someone try to start the motor. If you see or hear the spark arcing then replace plug wire and try another from the other module. I'm guessing that you will find one module not working. What happens is they(module) heat open and develop an opening. When they cool down they may return to normal. This is why the hour cool down period. Try this and let us know what you find.

 

[chiefalen]

Re: Engine Dies after long run/ won't start back up

you cant do away with the valve very important.this is what i would do i would beg borrow or steal a portable gas tank like they use on outboards holds 6 gallons hook that up to your fuel hose bypassing the water separator and just the fuel pump.now make sure its clean and fresh gas.fresh gas i said it twice run the hell out of the boat see if the problem persists.now it wouldnt hurt to disconnect the main plug and see what it looks like clean it out with sand paper spray some corrosion pro in it and rehook it up.i think u have a vacume condition.the vent is plugged up.i keep reading your post over and over.y is it over heating could be riser is plugged up.u have 2 when u run it have someone else drive and put your hand on the risers one hotter than the other?manifolds when was they checked last.u have a engine mounted impeller and water pump i believe no impeller in the outdrive if i can remember correctly.check them.u have power steering.if yes u have power steering cooler maybe just maybe thats clogged up typical of them.that could be giving u the over heating condition.i would check the power steering cooler more i think about it that could be it.good luck keep us posted better minds here than me maybe the'll chirp in

 

[bruceb58]

Re: Engine Dies after long run/ won't start back up

Next time this happens, check for spark to see if it is an ignition problem. You are focussing in on the fuel and ignoring the electrical and it is the easiest thing to quickly check.

 

[bruceb58]

Re: Engine Dies after long run/ won't start back up

Do you know of a "V" shaped kill button located somewhere near the shift cable that sometimes gets stuck or depressed when the shift cable is out of adjustment or something. I read a post on here about it but can't find the post now. The owner sprayed the button with WD40 and unstuck it and had his shift cable re-adjusted. This problem with my boat DID NOT happen until we had the shift cable replaced after it broke leaving the boat stuck in forward gear.

Not only should you check this but you should check your "man overboard" kill switch up near the helm. It could possibly be intermittent.

Again...check for spark when this happens.

 

[270sundancer]

Re: Engine Dies after long run/ won't start back up

You guys are the BEST!! Thanks so much. I have been reading other posts literally ALL DAY (I'm the medic at a local Cub Scout Camp this week so I have TONS of time on my hands and my laptop.) I have read about 20 pages of similar problems and posts. I am leaning toward something to do with the cable that was replaced last season and something "killing" the engine whenever it feels like it. I can't MAKE it die by doing one specific thing, and it never dies after one specific circumstance. I can almost guarantee NO WATER in the fuel. The fuel pump is NEW, the risers and intakes are NEW, the impeller is NEW, thermostat NEW, water pump NEW. My mechanic friend who is not allowed to work on my boat because of where he works says that 190-200 is not all that uncommon after running for over an hour, says this is typical engine heat build-up. He does admit it may be a little warm, but not hot enough to shut anything down as in factory shut down safeties/kills. NO HEAT ALARM. You guys are right, I focused on FUEL instead of electrical and got tunnel vision on the fuel issue. At least everything fuel and cooling related is BRAND NEW!! I will post a new topic after I try some things and hopefully the next thread I post will be SUCCESS FIGURING OUT KILL/SHUTDOWN ISSUE!!! Thanks again for everything guys! Don't be afraid to keep throwing out speculation on this subject, I'm open to try anything!!! This has puzzled me and everyone I know, AND every mechanic I have taken it to because it runs fine on muffs. No mechanic has ever taken it out for over an hour, and even if they did, it doesn't die EVERY long trip. Thanks again!

 

[chiefalen]

Re: Engine Dies after long run/ won't start back up

190-200 is high.too high.however if u can get away with that so be it.what camp?