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Crusader 6.0 losing power

J

jimw

Member
I am guessing fuel pump problem.

Port side Crusader 6.0 MPI on my Pursuit 3100 overheated couple of weeks ago. Took it to the shop to have that problem booked at among other maintenance things that I thought need to be done, including changing both raw and fresh water impellers on both engine pumps. They did find a water leak on the port engine and fixed that. Service manager said Techs ran the boat for about 45 minutes and everything checked out OK. Went to pick up the boat today and drive it home to its slip behind our house. It is about a 40 minute run.

Little more than halfway home, cruising along just enjoying the ride, I noticed that the boat seemed to be slowing down. Check the gauges on both engines and all indications, temperature, volts, oil pressure were normal. But the port engine rpm had fallen off from 3000 to 2800 rpm. Engine didn't to respond to advancing the throttle. Left it alone for a while and watched the rpm continue to fall off, still playing with the throttle with no response. Finally shut the engine down at around 2000 rpm and limped home on the starboard engine.

I did keep watching the exhaust for any signs of internal problems. No smoke of any color coming from exhaust.

Normal gauge indications (including no check engine light), no signs of internal damage, leads me to maybe fuel problems.

What do you think, fuel pump maybe?
 
Changed fuel filter and ran the boat about 20 minutes this afternoon with not problems. Have my fingers crossed that we have solved the problem.
Thanks for the inputs.
 
+1 on Mark's comment. You now believe that you had high rpm fuel starvation that was fixed (or improved) by a filter change. A pressure check will tell you if you really solved the problem or just made it a little better. It is important because lean running can lead to burnt exhaust valves (and overheating...sound familiar?). Then you have loss of compression and even more power reduction leading to needing a valve job. You were wise to shut the engine down when you did.

The fuel rail pressure gauge is an automotive one, and can often be borrowed from an auto parts store, and of course they also sell them. Or you can pick one up pretty cheap at Harbor Freight. Or order over the internet. Or, do what I did, stop by the local A/C service shop and get an old charging hose (they have the right fitting) and add a $10 gauge head. You will have to look up the specs for your engine, likely somewhere between 50 and 60 lbs, and increasing gradually all the way to WOT.

And on a similar subject, these MPI engines that sit idle for many months of the year have a tendency to get some clogged injectors. That is unlikely to be your issue right now, but it does lead to the same lean running/burnt valve but only on the affected cylinders. Since this lean condition is present at all rpms (but the power loss may not be evident) the plug in the affected cylinder will look a lot different. Inspection of the plugs after some early commission runs is a good thing to do.
 
johnnygjr said:
If u have a water/fuel separator, dump contents into clear container and inspect for contaminants.
Click to expand...
The ethanol in the gas will cause the water to be absorbed into the gas making it hard to see. Add some fresh gas to your sample, let it sit overnight. You will see a clear line between the new and old fuel if its contaminated. I would take a sample both before and after the filter.
 
The fuel pressure gauge is a must have for fuel injected engines. Mine stays on the boat. I added a tee at the gauge with a petcock that can be used bleed air out. I also carry an outboard priming bulb with a short hose. If you run out of gas,forget to switch tanks or clog a filter, It can be extremely hard to get restarted if you get air in the system. The electric fuel pumps do not prime very well and only run for a few seconds. Just temporally insert the priming bulb before the filter to prime the system.
 
Thanks for all the responses. I really appreciate them and reading all of them carefully. What I am up against is seemingly an intermittent problem. Seems that I would have to catch it when the problem occurs to have a pressure gauge tell me anything??
So I am about to pull the trigger and replace the high pressure fuel pump. What do you guys think?

Here is the latest:
1. Replaced fuel filter, ran the boat for 10 to 15 minutes, around 2800 rpm. No power loss.
2. Ran boat both Saturday and Sunday (two weeks ago). Ran 10 minutes or so at 2800 rpm, but most of the time spent running at low rpms. No problem.
3. Ran the boat on a short fishing trip. Spend twenty minutes or so at 2800 rpm, cruising around 19 knots. Slowed down and spent couple of hours at trolling speeds, 4 to 6 knots, 1200 rpm or so. No problem yet.
4. On way home, running again at 2800 rpm. After 10 minutes or so, began to loose power again. Slowed down to low rpm and things seemed ok. But shut down that engine anyway, limping home on the starboard engine. After slugging along on one engine, I decided to crank the port engine to see if it would respond. Cranked fine, slowly and carefully pushed up the rpm on both engines to 2800 rpm. Ran for about 15 to 20 minutes to my dock and not problems.
 
If you have the returnless fuel system be sure you have water flowing thru the fuel cell cooling hoses. It should be cool to the touch.
 
Recommend checking the pump pressure first. If the pressure is dropping off check the pump supply voltage next. Pressure loss due to voltage loss is a common problem usually caused by a bad connection, wiring, or failing circuit breaker, relay, or oil pressure switch (if equipped). Best not to drop $$ on a new pump until you can be sure it is the problem. Good Luck.
FL Panhandle
 
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