Fuel filter change

[Viper]

When you replaced the fuel filter, did you check the contents? Was there water in there? Not doubting the suspicion of water in tank but there should have been some in the water separators if that was the case.

[cpoint]

Source of the post When you replaced the fuel filter, did you check the contents? Was there water in there? Not doubting the suspicion of water in tank but there should have been some in the water separators if that was the case.

I did not, the mechanic had, but I don't know his findings and can't get a hold of him. But tomorrow we will find out, I will place the results here.

[cpoint]

I had the fuel extracted Friday, all 60 gallons. Switch to aux tank to head out to fuel up with clean fuel. Have not yet switched back to port tank as I figure I should replace the fuel filter. The engine did fail once or twice on aux tank. Again I have no idea the shape gas is in in the aux tank and also if there is water in the fuel filter. The gas that was removed showed mix of water, old fuel and new fuel. So it was in bad shape. I was going to switch to new filter, but previous mechanic must have over tightened it, could not get it off. I will try again tomorrow with better wrench.

[cpoint]

Fuel filter was tight, but managed to get it off and replaced with a new one and switch from aux to port tank. started and seems to be OK on neutral. I will take it out this weekend and hope that was the problem and do not have engine problems. Will keep you posted.

[cpoint]

Update on this issue. Port side tank completely emptied, re-fueled with new fuel, replaced fuel filter. Took it out for about 45 minutes. No erratic movements on port side RPM indicator. Engine did not cut out as before. I believe the problem was bad fuel after all. If I find otherwise in future outing I will update here, but for now I believe the issue is resolved. They have not billed me yet, but service call was $300 + $x per gallons (I do not know what the x is yet). They did pump out 60 gallons from port tank.

[cpoint]

Another update, Well I am now $420 lighter for emptying the port tank + about $150 new fuel. Took her out today for about1.5 hours. Everything great. went up to 20k rpm gradually and everything perfect, no RPM fluctuations, no engine cutting off. Finally we turned back to dock, as we approached had to drop speed to 6 knot (speed limit in the harbor), noticed slight RPM movements on the port side, no engine cut off or drastic RPM changes though. So compared to the run before fuel change big difference. But still I do not like the RPM indicator to fluctuate (very minor). Any ideas, suggestions? I think I will try one more time to see if there are any issues, if so see the mechanic. Again the starboard side has no RPM fluctuation.

[Viper]

CP, do you have 7.4 MPI?
during the fluctuations, does the engine rpm actually sound like it's fluctuating or is it just an instrument indication issue?

There are several things that will cause both engine rpm fluctuations and tach fluctuations.

If it's just a tach indication and the engine rpm is actually steady, it could be a faulty tach, wiring issue, regulator, not applicable to yours but points could cause the same, etc. You could try swapping the tachs to see if the fault follows the tach. Also, at the back of the tach, there is a cylinder selector switch. These tend to get corroded internal contacts that eventually make poor connections and cause erratic readings. Note the position of the switch, then turn it back and forth several times in hopes of cleaning the contacts while sweeping the switch back and forth. Return the switch to its original position and test.

If engine rpm is actually fluctuating, it could be a fuel delivery issue, ignition, EFI system sensor, voltage issue, etc. At lower rpm, the IAC is suspect, IAC port filter, etc.

[cpoint]

viper, thanks for the info, i will check as you suggest.

[After Taxes]

I changed my engine spin-on fuel water separator filters last summer. I never filled the new filters with fuel prior to spinning them on, and experienced no issues on start up. However, an old salt boater told me that he always fills his new filters with fuel before installing them, as he is preventing an air lock or issues with the fuel pump.

Does anyone have comments or experience in this?

Cheers all,
Steve

[cpoint]

Since it was suggested, I did fill the filter with fuel first. Unfortunately after I had the fuel extracted, I thought it was good with new fuel and new filter, but July 4th weekend we tried going out RPM starting to shoot up and down again, and engine was also going up and down, so it was not just RPM indicator after all. Any case, I dropped off the keys at boatyard, we'll see what they come up with. I will post here once we know the cause and cost