2003 ZR6 in 226 shuts off after 30 minutes of runtime

[reggiemtbk]

My ZR6 shuts down after about thirty minutes of runtime. If I let the engine cool down for about 20 minutes the engine will refire. I then have about 5 minutes of run time before it shuts off again. This procees seems to continue until I get back to the dock or until 'm towed in. This has happened twice ( two tows). My local dealer replaced the low pressure fuel pump the last time it happened. The plugs were relaced last week also.

The the boat was under load both times the issue started. First time pulling the kids on an inflatable the second time wakeboarding.

Any suggestions would be greatly appreciated! I have no faith in taking the boat out at this time.

[j2nh]

ZR6 is closed cooling but there is an impeller for fresh water cooling of the radiator and exhaust manifolds.
What is the condition of the fresh water impeller?
Does the engine give an alarm?
Engine temps normal?

[DanielC]

Check your fuel pressure. Get back to us.

[reggiemtbk]

The boat has 130 hours on it and the impeller was changed at 100 hours. The boat started acting up last summer and was immediately taken in for service. No alarm has went off. The boat was used sparingly last year one time after I recieved it back from the few pump being replaced. When I took the boat off the lift to take it in for service the motor ran very ruff. We have since had the batteries and plugs changed. The boat semed to run well until we put it under load (wakeboarding) Once again no alarm. When the motor refired it ran very ruff including backfiring for 5 minutes then it shut off again and another ski boat towed us in. The motor refired after about 20 minutes of being towed and we idled it into the slip.

How would I check the fuel pressure?

[AirTool]

When you say "shut down" do you mean die or go into limp mode. I assume die becuase later you say "refire". You need to confirm this and any alarms.

Can you take a timing light with you to check for spark after it "shuts down". It has the symptoms of bad ignition module on an auto...not sure if the ignition module is separate from the ECM on these marine engines...I'll have to look at my manual tonight....after you confirm die or limp.

[reggiemtbk]

I failed to answer the motor temperture question. The temp runs between 157 and 175.

[reggiemtbk]

The engine is not going into limp mode. The engine did go into limp mode at 100 hrs when the impellar wore out.

Total shut down. refires after 20 minutes. no alarms.

thanks

[jaybird]

Is engine turning over? If it is then narrow it down to lack of fuel or lack of ignition (spark).
Check pressure at fuel rail while attempting to start.
Check for ignition spark while attempting to starting.

What about the obvious kill switch connection?

[CradGen2]

When you say the impeller went bad. Did you check to make sure pieces of the impeller aren't stuck? Could still have a heating issue.

[Onevw2go]

you said boat was used sparingly. Just curious How often do you use your boat? a 2003 w only 130 hrs. If the answer is not very often, how long has the gas been in the tank? What you are describing as I read it, sounds like bad gas. If the tank is low, fill it with fresh gas, if the tank is full, might want to think about pumping it out and refilling with good (new) gas. Just my observation.

[reggiemtbk]

The dealer replaced the impeller and the boat ran fine for 30 hours. The fuel was topped off (93octane) before being winterized by my dealer in November of last year.

if it was bad gas why would the engine have to cool down/wait +/- 20 minutes before refiring? Still could be bad gas or water in the gas?

I tend to think think that it is either not firing (spark) when it gets hot or the fuel pumps or not getting fuel to the chambers?

The kill switch is connected. I made that mistake the first year I owned the boat my buddies at the dealership had a good laugh on me.

Of course on Tuesday the boat will be sent to the dealer again for another review.
I look forwrd to all replies and thank you all for your input.

It is truly a terrible filling when you are stranded on the lake.

[SkiTundra]

Was your boat with a full tank of gas ever in freezing weather over the winter? Wonder if you've got condensation in your fuel and lines. A couple of cans of Heet (Isopropyl Alcohol) in the tank and a very small amount into the fuel line wouldn't hurt I don't think. Many of your symptoms, particularly it needing to cool down sounds like vapor lock, but this engine shouldn't have any problems with that so my next guess would be the fuel as mentioned earlier.

[reggiemtbk]

i have no problem putting heet in the fuel. why would it take 20 +/- minutes for the engine to refire with bad fuel? Would it not fire instantly and just run bad? Also why does the ZR6 not vapor lock. I had thoght that vapor lock might be the problem?

Thanks in the advance for the reply.

[SkiTundra]

Thinking out loud... Well, I suppose it could be vapor lock, but it's extremely rare on non-carborated engines. Do you have a single or dual fuel pumps? How close is the first one to the engine? Close enough that the intake side could get hot enough to vaporize the fuel? On injected engines I wouldn't think it could vaporize after the pump since it's high pressure (vs carborated that are low pressure or even negative pressure).

A guess on the fuel is that if water got through to the engine could the water have vaporized causing ignition problems and when the engine cools the water goes back to liquid allowing the boat to run again? On second thought though, wouldn't the fuel filter prevent water from getting even to the pump? If you do have water in your fuel could it be vaporizing pre pump and causing lock?

[DanielC]

Compression, proper timing, and proper air fuel ratio, you engine will run.
Millions of gas engines prove that every day.
If you are asking how to check the fuel pressure, I am guessing your area of expertise is not in diagnosing internal combustion engines. That is OK.
Your fuel system works like this. There are two fuel pumps. The low pressure fuel pump job is to keep the FCC full of fuel, and vent any vapor back to the gas tank. It recirculates about two or three times more fuel than your engine could possibly use at wide open throttle, and max RPM.
The high pressure pump also can pump more fuel than the engine can ever use, and the excess fuel is bled back into the FCC, to maintain the proper fuel pressure. This fuel system is almost impossible to vapor lock. I have had my boat running in the middle of the day, at Lake Shasta, in over 115 degree heat without vapor locking.
How did the dealer arrive at the decision that the low pressure fuel was bad?
Do you know how to drain the FCC, and check for water in the fuel?