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Engine quits after running for hours

R

rugburn

Member
Yesterday, went out in my brother-in-laws 1999 Bayliner Ciera 2655. It has a 1999 Mercruiser Bravo closed cooled EFI engine. Boat ran great for 1.5 hours, tied up to a mooring to have lunch for 45 minutes, started right up and ran it for another 1.5 hours. Ran at many different RPMs but mostly trolling. We went up river to get gasoline, and as we were approaching the fuel dock to set lines and bumpers we slowed downed, and the engine quit. We could only get it re-started in a "dieseling" mode. No power, barely running, but severely struggling to get gas or air?

Gas tank read about 1/4, and after we got towed to the fuel dock, we put 45 gallons of fresh gasoline in a 75 gallon tank, so gauge is about right. After fueling, engine would start, but quit as the throttle was brought back below 50% or so. Tried several times, all with the same result (run for 10 - 20 seconds and die). Took the filler cap off, same result. Dumped the fuel/water separartor, and after priming, got the same result. I'm heading back to try it today, and I'm hoping it does not start, as I'll never figure it out if it is an intermittent gremlin.

Any ideas?

P.S. I did replace one battery and the alternator last week on this bird, as it had an old battery that was internally shorting (2 volts and heating up) and I'm thinking that it may have affected the old alternator's regulator (ammeter was showing nothing when running). Both batteries read 12.85 or higher now, and ammeter was reading 13 -14 volts all day yesterday when cruising. Internal engine temp all day yesterday was 175 F. When it was running, it seemed to run great, but I don't know if this is an EFI electronics issue, fuel, or air at this point?
 
One new battery one old battery the old one will drag down the new one.

You got a clogged filter, or anti-syphin vavle or fuel pickup tube.
 
I did go back out tonight and encoutered the same problem (start, run for 5-15 seconds @ 2000+ rpms and die). Forgot to mention that the engine is a 5.7L.

I'm not very familiar with this boat, but it seems that the only filter is the water/fuel separator cannister, which I emptied (maybe I should replace?). The 2 foot hose from the tank goes directly (slightly uphill) to this filter. Would there be an anti-siphon valve, if the tank is completely below the engine level? I didn't see one.

I suppose that I should remove the tank elbow and inspect the pick-up tube, as last year on my own boat (twin crusader inboards - after similar problems) I literally "discovered" a "pencil" filter in the top of my pick-up tubes, (before the anti-siphon valve) that were completely packed with tank crud from the ethanol E10 tank "cleaning". Once I threw them away, I had no further problems.
 
I checked both batteries (isolated via a battery selector switch) tonight before cranking, one read 12.86 volts, the other 12.94 volts. I quite sure this is not the problem. I checked each, cranked, and started the engine from both separately. Engine dies after about 10 seconds.
 
No, engine starts at 1/3 - 1/2 throttle and as the throttle is brought back toward idle, it dies. I tried to set throttle at 2000 rpm, but it still quit.
 
For over 3 hours, up until failure, it had run fine all day in all positions. We did alot of trolling at idle (800 rpms). But just before we encountered the situation, we were cruising at 2500 rpm for about 25 minutes.
 
Also check item #10, TPS, throttle position sensor. Disconnect it and check it w/a digital ohmmeter on the lowest setting. There should be no loss of resistance as it is moved end to end. Also check it w/the key on for a voltage drop. Use the low scale.
 
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