97 Speedster - RPMs Variable After Fuel Filter Change

[3littlepigs]

I just did some work on my 97 Speedster and now my port engine is acting funny. I took it out the week before and both engines were running great.
I just preformed this work yesterday.
- Both fuel filters changed.
- Both oil filters changed.
- Both jet-pump fluid changed.

Today I took it out and only the port engine had problems holding a set RPM. It would drop down 1000-2000 RPMs for a few seconds and then go back up. It kept doing this for several miles. This then started to go away after a while. By the end of 2-3 hours it was totally gone at full throttle but would pop up occasionally at around 4000-5000 RPMs.
Seems like a fuel starving problem. Air in lines? Any ideas?
Thanks.

 

[3littlepigs]

Posted to wrong forum. How can I move it to the boat forum? Can only an admin do this?
Sorry folks.

 

[Coastiejoe]

I will move it for you.

But,, if the only thing you did was the fuel filter relative the running aspect, I would check it out very well. Could be sucking air.

 

[3littlepigs]

Sucking air at the filter bowl did cross my mind but you'd think it would then leak(at least a little) with the engine off.
Plus, after changing the fuel filters I ran the engines briefly and allowed the bowls fill. I then checked for leaks with the engines running and off.
I guess I'll check it again.
Thanks.

 

[racerxxx]

Did you change the filters in the original filters? If so I would re-check those. The o-ring could be messed up or the body could be cross threaded. And honestly, it's almost cheaper to just buy the entire assembly. The entire deal is like $22, the filter alone is $10 plus the o-ring is an additional $4.50. Does the boat have additional inline filters? If they were replaced did the flow arrow point in the direction of flow?

 

[Coastiejoe]

It is not uncommon to suck air and not leak fuel. A very common spot for that to happen is the water speparator.

 

[3littlepigs]

I was gouged by my local dealer. I paid something like $24 each for just the filters. Then another $3 or so each for the o-rings. I should have looked online but I was there and I didn't know better.

I put very little oil on the starboard o-ring and when I installed it on the bowl it stayed in place. But on the port filter I added a little to much oil to the o-ring and it kept wanting to slip off the seat. This is because the lip on the bowl isn't that high and the new o-rings were a little under-sized and had to be stretched slightly. I thought I had it but maybe I didn't. So it could have popped off again as I was screwing on the bowl. But if that's the case I'm still surprised that it wouldn't have caused a leak.
I'll have to pull it tomorrow and take a look.
Thanks Again.

 

[racerxxx]

Next time, use grease---just like paste to hold it in place. The gas will break it down. Ouch, you got smoked on those filters.

 

[3littlepigs]

Stupid me. I pulled out the starboard bowl. Then I realized my problem is with the port side. So I ended up re-seating both of them.
Well, both o-rings looked fine but I ran into a problem. The new o-rings I bought at the dealer, that were slightly undersized, now were oversized from absorbing gas and now were even more of a pain to attach to the bowl. So I reverted back to the original round profile o-rings I saved. I measured them before I put them back in. They are 1.5" OD with a thickness of .080". They fitted better then the ones I bought. They just laid right in the bowl.
After I was all completed I measured the new o-rings again and they must have dried up and shrunk because they now were 1.5" also. I would think if I waited a day they would dry up more and be back to being undersized again.
I then started the engines and took the opportunity to flush the cooling system. Then I checked for any leaks at the bowls. All was good. I'll see what happens the next time I take it out on the water.
I should add. I also put in new plugs today. They all looked fine. No fowling but lightly oiled. The gaps were larger then the .022" required. But then again, before this RPM problem the boat was running fine.
Thanks.

 

[3littlepigs]

Well after taking it out again my problem looks to have gone away.
Thanks Everyone.