Fuel filter change

[Viper]

Go to the back of the tach and you'll see a cylinder selector switch. It's common for the internal contacts on these to corrode and give you the symptom you're having. Take note of the position the switch is in and then turn it to the left and right several times. This sweeping actions helps clean the contacts. Then return it to the proper position and test. Some of these require that you push the switch in before you can turn it. Don't force anything. If that doesn't solve the issue and you've checked wiring, connections, etc. replace the unit. If it still happens with the new unit, let us know.

There are a couple of other things that will cause this. It doesn't take much for this to happen such as an engine runability issue or an electrical cause. If you want to dig deeper before replacing the unit, a bad alternator and regulator can cause this as well, wiring from engine to tach, and the engine itself (you may not hear it in the way the engine runs)

[cpoint]

viper, thanks. I will try as you suggest. The mechanic said the engines were running smooth, there was no fluctuation. he said most likely it was the gauge. I don't mind buying new one, hard to find exact match. meaning I have to find closest one to match and replace both. rather get these to say stable if I can. You think still can be gauge issue, because it is stable upto about 2000 rpm, then it's moving around about 100-400 rpm.

[Viper]

It's a simple thing to try so worth a shot before you replace, especially when you may not find the same ones. They'll need to be replaced one day but maybe not just yet!

[cpoint]

Source of the post It's a simple thing to try so worth a shot before you replace, especially when you may not find the same ones. They'll need to be replaced one day but maybe not just yet!

At this point I am convinced its not the gauge. I still have port engine problems. 2 weeks ago I was told everything was fine after port side fuel pump changed. But was not successfully sea trialed. I was told under hull needed cleaning. made sense as it was not used for 4 months due to engine issues. Had it cleaned Thursday. Friday I took it out, everything started out fine. Took up to max, but it would only go up to 12 knots top and drop back to around 11+ knots went at that speed for a little while, then fire alarms started going off and smoke started come out of port side exhaust. I think it was oil burning. I stopped the engine and anchored and waited to be towed. Engine was overheated according to temp gauge. There was no smell or smoke in engine compartment though. Not sure why fire alarm went off. So Monday I need to call them back to check it out. I am assuming I should not try to take her out before than as I do not want to be towed back in.

[cpoint]

Overheating was caused by disintegrated water pump impeller on port side. Was replaced, engine compression test was performed with perfect output. timing checked perfect. replaced spark plugs. Finally took her our successfully, but kept it around 8 knots until we get the injectors pulled out and cleaned up next week. Because that seems to be the only issue left that's holding back the port engine from going at max power, so we think It is scheduled for Next week. But meantime we can use it finally

[cpoint]

Final update on my issues with port side engine. Finally engine is in great shape, with injectors replaced, sensors, etc. Took her out did 21 knots for an hour. Docked next day RPM started moving around again, performance down to 12 knots. Called the mechanic. He checked sparks, were fine. he checked fuel filter and said there was particles in it and replaced the filter, and took her out again, rpm is good, 21 knots. So week after before taking her out replaced the fuel filter myself, and checked the contents (I can't attach video here) there was brown matter in it. But it performed well for about 2 hours on new filter, and rpm started going crazy again after 2 hours. So called the fuel cleaners (for third time, they said they will clean for free this time), and they cleaned the tank, this time they used chemicals and cleaned the walls and all of tank and sucked everything out while tank was agitated. I am hoping tank is finally clean. But at this point I am getting ready to winterize, so will not try it out till next season. Conclusion, fuel issue was my enemy since the engine was fixed up. At least now I know engine is in good shape and I know when problem re-occurs (if it re-occurs) it is the gas issue, and I can deal with that. I think I have 25 micron filter now, if anyone can recommend a better fuel filter please let me know. Maybe a better filter would be good. so if anyone is using a better filter for carver 356 (mercur gas engines) please let me know. But I think its safe to put this issue to rest now. You can see the video here: https://www.dropbox.com/s/1jwnb12l8b8qb9h/20161107_213618.mp4?dl=0

[bud37]

Wow seems like you have been thru just about all the problems one could run into. Check out Racor spin on gas filters, maybe one of them will fit your current filter head and some of these go to 10 microns. If not maybe you could fit a Racor gas filter in line before the filter you have on the engine now.....just make sure you get the one with the metal bottom bowl that is drainable, the see thru is for diesel or non engine room situations.

[Viper]

Source of the post..... maybe you could fit a Racor gas filter in line before the filter you have on the engine now.....

I know your intentions are in the right place but I wouldn't recommend the extra filter. The more restriction you have on that side, the better the chances of getting vapour lock. Under the right conditions such as a hot engine compartment while running, it doesn't take much for things like fittings, elbows, fuel flow senders, fuel filter, etc. in the fuel line to add up to enough of a restriction to cause enough vacuum for this phenomenon. Adding another filter would increase your chances of this happening. You only need one filter.

I do agree that the Racor is a better choice as long as the original equipment is removed.

Again, we must focus on correcting the root problem and not add more band aids. Band aids in the mechanical sense don't remedy the fault and they often cause additional problems.

[bud37]

I was not suggesting adding multiple filters just the racor, sorry if it reads that way. thanks for catching that....he asked if there were better filters.....I have had very good success with them on previous boats, just a little pricey.

[cpoint]

Source of the post I was not suggesting adding multiple filters just the racor, sorry if it reads that way. thanks for catching that....he asked if there were better filters.....I have had very good success with them on previous boats, just a little pricey.

I understood as replacement to one on the engine now, not as an add-on. I was just wondering if I replaced the 25 micron with 10 micron, if that would be ok to catch more particals if any. Aggree with viper, base problem needs to be fixed, and do not want to add bandaid. I am not sure the 25 micron was the original fuel filter. I am not sure what the original filter was, thats my problem. if it was suppose to be 25 micron, than thats fine. The fuel cleaning tech gave me a small sample after it was cleaned up, and I did not see any particals in it, but I guess I have to try and see that it really is cleaned up this time around. Got my fingers crossed.