Well crap...

[oldmako69]

Port motor took a dump today.

Previously running flawlessly, today it wandered a bit in RPM when I first throttled up. It was hunting and pecking between 3800-4100 RPM but eventually settled down and ran fine. Then, later on, it had a rough idle that seemed to smooth out above 1500. But on the way in it would not turn more than 3900-4100 RPM at WOT. When I added power on the good engine, the RPM on the bad would bump up a tad (1-200) in response to the increased hull speed driving the prop.

I do not have a computer with which I can run the diagnostic program. Any leads on where to start are appreciated.

1. Plugs have less than 100 hours on them. Perhaps one or more have fouled, but why on a computer con*****ed engine?
2. Fuel is super fresh and the other engine is running perfectly. Same tank, different filters.
3. Fuel injectors were cleaned last year. They probably have less than 150 hours of run time on them.
4. Throttles have a stagger now at even RPM's.

I'll pop the cowl and check the first stage fuel filter as well as the pre-stage Racor for water.
I'll check for a loose plug connection and pull and examine plugs for a bum cylinder.

What else?

[99yam40]

always pull the plugs and inspect when a problem shows up, they can show many things.
while they are out do a compression test

and we have no idea what your motors are, my memory is not very good

[robert graham]

What motors?

[oldmako69]

Sorry. 2005 F225TURDs.

[99yam40]

fuel pressures
all filters and screens
stuff plugs up before you know what happened.
oh and since it is a F motor a leakdown instead of a compression test

[oldmako69]

I guess I'll get to bone up on my VST skillset. Might take the opportunity to place a glass inline filter up by the F.

[pstephens46]

If you are planning to take the VST apart and it has not been disassembled recently....go to Harbor Freight and buy an impact driver. Those little screws were stupidly tight. Buy a gasket for tank too.

I had to cut a little jig in a piece of
plywood to hold the vst while I smacked those screws with the impact driver.

[oldmako69]

I was in there last year. It ought to be OK. I will, however, be sure to put AS on those screws. Just take a look at what used VST's are going for on eBay.

[oldmako69]

55821768735__173D652F-95F9-41E5-919A-D2F6C04B45F4.JPG-1.jpeg Gee, I wonder what was wrong with my engine? I sure do wish this thing was easier to access. What a pain in the ass. All the little damn hoses and squeeze clamps, etc etc. And I managed to snap the tip of the top water bib on the fuel cooler. Great.

The first stage filter shows zero crud. That tells me that this is coming from the inside of the fuel lines downstream of the first stage filter and upstream from the VST through the return flow. I'm going to try to put a clear inline filter just short of the VST intake. One that can be accessed without removing all the crap necessary to get to the VST. I just have to find the appropriate filter.

And I guess I need to change out my fuel lines. They are now 13 years old and clearly, the E10 is eating them up. This would have cost me close to 400 bucks had I taken it in, minimum. Two engines and you're almost kissing a grand goodbye for service that ought to be quick and simple. I wonder if Zukes are like this?

How essential is water flow to the fuel cooler? Obviously, it won't cool without it, but its such a TINY diameter I have a hard time to believe that it's actually doing much at all.

[pstephens46]

You snapped the tip or the whole thang...so that a hose cannot be attached? My brain surgeon said he never uses E10.

[oldmako69]

Just the tip. I was able to connect the line, but I don't feel too confident about it. Another stupid design flaw if you ask me.

[pstephens46]

Just the tip. I was able to connect the line, but I don't feel too confident about it. Another stupid design flaw if you ask me.

If it leaks, worry about it then. Bigger issues to deal with.

[oldmako69]

Fuel hose information.

Foot stomp ----------->>>>>>>> CAR STUFF.


https://www.hemmings.com/blog/2014/1...hould-not-use/

[TownsendsFJR1300]

I'd replace that cooler. You won't see it if it starts leaking (fuel or water) under the cowl.

You don't want to suck sea water into the intake or flood the inside of the cowl (or fuel inside that cowl )

As for those screws, I'd put a dab of anti seize compound on the threads before re-installing.
(80% of the generator carbs I work on need the hand held impact tool to remove)


*Just a side note, I'll drain my VST every once in awhile just to check for debris, water, etc.
I've seen some very small spec's come out awhile ago, nothing recently. Doesn't take long and cheap insurance IMO.

[oldmako69]

Found one on eBay for $28/shipped. On its way.

I really need to find out which hose(s) are falling apart and replace it. As mentioned, there is no crud in the first stage filter. So, that crap is sloughing off in the first hose to the LP pump, or any of the other hoses downstream of the HP pump/VST canister.

It makes me wonder how much crap gets delivered to the injectors and gets passed. Up until the day it started running poorly, it was turning 5600 and running great. Perhaps a bunch of junk broke loose all at once. As can be seen in the pics, that screen was loaded.