FUEL PUMP WOES

[walkers2rad]

It might help to add what is called a flashback diode between the coil of the relay and or the fuel pump. Maybe someone with a little bit more electrical knowledge than I can explain this better but I will give it a try. When you apply voltage to a relay to energize it, you are charging a coil that magneticly pulls in the main contacts, the trouble happens when you remove the power to that magnetic field, you basically have a minature version of the coil that fires your spark plugs. Think about it, a ignition coil fires when you remove the voltage to it. It can make a little backwards spike in your electrical system or it could make the relay ring (switch the contacts on and off quickly) and when you are running something with a high current draw like a fuel pump it can weld the contacts together eventually because you are making an arc when you open and close the contacts. Circuts do not like to be broken, that is what the condencer in a points sysem does.
What you would do is hook up a small diode between the two coil leads on the relay. You would point the arrow on the diode so that you do not create a direct short, ie; arrow flowing from neg to pos and blocked. This gives the coil a path to harmlessly collapse into. The same thing can be happening on the other side in fact it may be more likely that when you shut off the fuel pump it also has a magnetic field that needs to go somewhere, otherwise it turns into somewhat of a generator for a split second and becomes a mini welder trying to fuse the contacts together on the relay. I dont know for sure but there is probably a diode in the harness somewhere and it has opened up. You would just do the same thing and put a diode between the two wires going to the fuel pump, just be carefull and put the blocked arrow in the right direction or you create a direct short and wires will suffer.
Let me know if this helps.
Ray

[Domsz06]

Now the problem is that my impeller shreaded. To make matters worse, i had bought a new one from the dealer to put in the day before, just didn't get to it. I brought it with me and said, hey lets just put it in no the lake, no big deal. long story short, THEY SOLD ME THE WRONG ONE!! I'm so pissed, I mean they have it on a computer, how come they just can't look it up right.

now i'm off to deal with them. I just hope this is the end of the problems. The boat didn't run for crap when i was trying to drive, that's when I Noticed the temp was getting warm so I shut it off. I hope it was just a hot sensor and not allowing the boat to go to full throttle.

Dom

[raythompson]

You are probably right about the temperature not allowing the boat to reach full RPM. I was using a friends pontoon boat and toward the end of the day the engine was loosing power and would not reach full RPM. Originally thought it was the fuel pump (again). Noticed the temperature was very high for the engine. Took the boat out of the water and replaced the lower unit pump (it was an I/O). After that the engine ran fine.

[Domsz06]

well i hope it's the case. I can't belive the way they design the impellers. I know that they are so tight a fit and the fins are bent so much they are designed to fail. Kinga makes me mad. They are supposed to last three years or 300 hours, mine didn't even make two years or 140 hours.

Dom

oh yeah, if anyone has a direct drive boat, and needs help changing the impeller on the seawater pump, let me know, the article does a good job giving you a knowledge, but there is an easier way, on and off you can do it in thirty minutes.

[raythompson]

The impellers have not changed in 20+ years and current impellers look the same as what my 20 year old Mercruiser used.

I used to get about 2 years of fairly good use from the impellers. Changing one in an I/O was not an easy task simply because of the bulk of the lower unit that had to be removed. I could do it in about an hour. I also always put silicone lube on the impeller when reassembling. The engine was never started without water.

A lot of the durability depends on what type of water you boat in and how much sediment you pick up. Brown water is harder on the impeller than clear water. Also being careful to not run the engine until the bottom of the lake/river has enough clearance so that sediment is not sucked into the enginer.

It would seem that V and direct drive would suffer less from sucking from the bottom as the inlet in in the hull. On an I/O the water inlet is in the outdrive and closer to the bottom of the water.

[Tige M.D.]

ray, mercruiser did change their impellers in 02'. they changed the housing to brass and changed the hub in the impeller. the old hub had a flat spot and the new ones are splined.

[Domsz06]

well that would make some sense ray, I only use my boat in brown water(no clear lakes around Oklahoma.) Maybe thats why it only lasted 130 hours.

Dom

[raythompson]

Originally posted by Tige M.D.
ray, mercruiser did change their impellers in 02'. they changed the housing to brass and changed the hub in the impeller. the old hub had a flat spot and the new ones are splined.

OK. I have not changed an impeller on a boat (I/O) that has been newer than about 1992.

Did they change the basic fin design?

I never had any problem with the steel housing (actually steel lined plastic) or with the way the impellers attached. The little ridged key was fine, until you dropped it.

Biggest problem with my old boat was muscling that lower unit up while lining up the drive shaft, shift coupler, and the water pump tube. Newer units such as my friend had on his boat improved on the tube and made life much easier. Plus you had to drain the oil, and watch for the little o-rings.

I did like the four cylinder engine in that boat as it was very easy to work on. Change the plugs, fuel filter, points, condenser, set the gap, dwell, change the oil and filter, and Bob's your uncle. Never had a problem with that engine in 20+ year and hundreds of hours of boating.

Hopefully changing the impeller on my 22V will be easier although I may not be doing it for awhile. Probably have the dealer do it when it I have it serviced for the summer, at least until the warranty has long passed.

[Domsz06]

Well it looks like i have the same problem ray has. My relay goes out everytime I turn the boat off after it's warmed up. Not quite sure why. All I do is unplug the fuel pump relay, plug it back in and it works fine. So now I just don't turn the boat off when I'm picking up skiers and boarders, just make sure to tell them the motor is still on. I know the prop isn't supposed to be running, but still. Kinda pisses me off. I don't feel like waiting a month though to have the dealer fix it, or attempt to fix it. If anyone has any ideas, they would be much appreciated.

Dom

[Tige M.D.]

you can always call mercruiser yourself, see what they say.
405/743-6555 tech support. i'm sure they would hate to here that you can't shut down your engine with people near the prop.

[Domsz06]

calling now different number though 405-743-6566

dom

[Domsz06]

worthless, they don't have a tech dept. They can't trouble shoot anything, have to take it to the dealer, and I"m not leaving my boat up there for a month. Any dealers down in dallas that have no wait?

Dom

[Tige M.D.]

the words worthless and mercruiser in the same sentence, doesn't suprise me a bit.

[Domsz06]

I'm finding that out Tige M.D. really pisses me off!! I mean everyone has told me, that boat stands for (Bring Out Another Thousand) granted mine has not been that bad, just pisses me off that they don't do something about it, I mean you have these problems on a car and people throw fits, but boat dealers and motorcycle dealers all have a monopoly on the market and pretty much do as they feel

Dom

P.S. I pmed you a question if you have time to answer it would be great!

[jeffro]

update on my buddies boat....

they changed out the ECM this time, so far it's working. But we haven't had much time to board on it since the new ECM was installed. if it happens again, i'll be sure and post back. just for counting, this was ECM #1 and relay #8. let's hope it lasts!