Oh Oh, is this a problem?
 

I'm running a 2000 454 MAG with EMI exhaust, K&N filter, reprogramed ECU. After dumping in some fresh gas and stabil for a last season dip I noticed that after I would idle a bit I'm getting either a small fuel or oil slick from out of the thru hull exhaust. (Captains Call) Not much of a gear head so I thought I'd ask the experts here!:cool: I put about 80 hours on the boat this summer but cannot ever recall seeing this before, but then maybe I never payed that much attention to the chit behind my boat! :D My fuel pressure show 39-40 at idle if this helps...

Any suggestions or ideas or do I have a two stroke wannabe? :rolleyes:

Thanks in advance for any suggestions or info!

You maybe running a little rich(typical at idle). You can check plugs and oil for excess fuel. You may notice your transom gets sooty too. Usually not a problem.

One thing I can for sure say is your fuel pressure gauge is not right. Do you mean oil pressure??

I'm with hotbeek, rich idle. My motor does the same thing, infact sometimes I see clusters of carbon floating in the water. This is fine, much better than a lean condition.

hotbeek,
The transom was a little sooty. Normally I have very little accumulating during the summer months. I assume your suggesting to pull the plugs after a idle period? Will I be looking to see if they are overly wet or ??

Now Allan4, I may not be a gear head but I do know the diff between a oil and fuel pressue gauge! :D :D It's a Auto meter brand fuel pressure guage that is mounted on the engine. I'm almost positive that it was bouncing between 39-40 at idle but I'll check it again yet this weekend sometime and let you know for sure when I change the oil out. Where should I be at idle?:confused: I just assumed the fuel pressure stayed the same throughtout the RPM range.

Thanks for the encourgement so far! :D

Mine runs at about 3-4 psi at idle. I would assume your autometer is using a two digit scale as opposed to a one digit scale like my grafrig guage. BTW, are you sure the slick os coming out of the exhaust? Either way, sounds to me like a no big deal thing, you want to be a little rich if given the option.

You might want to check the lower unit for any signs of water. The slick could be drive oil. Easy to check and way cheaper than not checking it.

That fuel pressure is correct for an EFI engine.

ZP'D

E.F.I. fuel pressure is supposed to be 43 p.s.i. Yours is right.

Allan4

3-4 p.s.i. can't be right for fuel pressure, even if you are running a carb. Do you mean that your Gaffrig guage only has 1 digit, so you really have between 30-40 p.s.i.?

Hmmmmmmmmmmm..........
 

Okay, I am sitting here wondering if I have my head up my a$$. What is the normal operating range for a BBC?

C454, yes, I have single digits on my Gaffrig. I'm having a brainfart here trying to think if that means abbreviated or is the actual numbers. I have always refered to it as and had it refered to as 3 or 4 or 5 psi....etc......I'm confused.:(

Zp'd, to answer an earlier question you had, the fuel pressure will rise with an increase in RPM. However, that is coming from a guy who doesn't seem to know how much pressure you should have.....I'm still sitting here scratching my head, about ready to get on the phone and see what the hell is going on:D :D ;)

Allan4;

Mercruiser rates their fuel pressure regulators at 43 p.s.i. Your guage must mean 3-4 times 10. That would make sense.

ZP'd,

As long as you're not fouling plugs(motor will "load up" ((run rough till opened up again)) or washing your cylinders down with fuel (watch for raising oil level or decreased oil pressure from oil thinning). I imagine whomever reprogrammed your ECU probably programmed to the safe side (rich).

Thanks Everyone!

I'm sure it's out of the exhaust and did change the oil and gear lube this past weekend. Both looked good (other then the motor oil looked awefully dirty for 30 hours on it) with no sign of water or fuel in either.

hotbeek, I have had the motor load up before after extended idle periods but the transom very seldom was what I'd call sooty, which would make me think it's not running all that rich. I'm going to fog the cylinders this week sometime so I'll be pulling the plugs to see what they look like. (last at a idle, so is it hard to get a read the plugs now?) I'm also curious as to how often you all reccomend 454Mags plugs should be changed out and what plugs you guys reccomend for my set-up. You guys say the fuel pressure rises with the RPM correct? I'm curious as to what to expect next spring when I have the Mrs. open it up a bit while I peer under the sundeck!

Thanks again Gentlemen, I may learn something yet! :D

ZP'd you'd better hold on to that sundeck. Better yet, why don't you climb inside and have her close the deck. (LOL)

Hey, C454, you'd never guess that I built, dynoed and rigged this 509 motor for my boat last year.....:confused: :confused: :confused: .....One of lifes little chuckles...:D :D