View Full Version : 1995 Marine Power 454's running rich

Nick Nicholson
01-05-2011, 04:19 PM
I recently purchased a 1995 Silverton 362 with twin 454's. Both engines seemed to run rich with the starboard running the richest. I mixed a heavy dose of Sea Foam and new fuel and ran the boat at cruise for an hour. It ran great. They now run richer than ever (leaving a sheen on the water at idle, and the starboard engine fuel supply is so rich it is very hard to start and stumbles until warm. 130-138 compression all around, new plugs, etc.
I imagine the two fuel injectors on each throttle body are original. Would that be a good place to start?

01-05-2011, 10:32 PM
yeah. look for drips after the pumps bring the system up to operating pressure. Bad news is that replacement parts for that fuel system are rare. best bet is to find a good fuel injection shop, locally, to rebuild what you have. there's a few places on the www, just use the search function on your browser.

Nick Nicholson
01-06-2011, 11:04 AM
Makomark, Thanks for that feedback. I foolishly thought I could just order four new injectors and move on. Hopefully, I will be able to find a shop that can handle the task.

01-06-2011, 07:13 PM
maybe you will get luck but I wouldn't plan on it.

Those injectors were based on GM's TBI auto systems. They had a very short live so the (insignificant) marine market support started to evaporate soon after.

I haven't had to look but a couple times and wound up getting existing stuff rebuilt.

Nick Nicholson
01-07-2011, 11:17 AM
Thanks again makomark. So far the nearest outfit I have found is in Naples, Florida. I am in Pensacola. In the past I foolishly used a local NAPA outfit to clean and check some MPI injectors off a 6.2 Horizon and they proceeded to pump them up to 250lbs pressure and ended up costing me 8 new injectors at $250 a pop.

I wonder if a GM source might have some product or were these injectors marinized?

01-08-2011, 06:19 PM
I doubt that a GM dealer would have anything but it never hurts to make the inquiry. As far as I know, nothing was done to the injectors to marinize them.

I can't remember who the outfit was we used several years ago (or where they were located) but they specialized in auto based fuel injection and claimed they could rebuilt pretty much any mass produced throttle body injection unit. The MPI parts have a huge base (numbers of units made and number of applications) so they are much easier to source.

Good luck and let us know what you find.

01-09-2011, 05:53 AM
You could also check out Jegs. ( http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&Ntk=all&Jnar=0&Ne=1%2B2%2B3%2B13%2B1147708&searchTerm=injectors )

With a little researching, you could cross your injectors to some found here. As Nick stated, the local shop pumped the injectors to 250 psi, which I could see destroying any electronic injector that normally runs on 45 psi fuel pressure. What were they thinking, the were CAT diesel injectors on an old mechanical injector pump? EESH.

Good luck finding what you need

01-14-2011, 10:24 PM
they have numbers posted on the injectors
i bet the pressure regulator built into the t-body is bad

Nick Nicholson
01-15-2011, 01:27 PM

Thank you for your tip. I have delayed pulling the throttle bodies because it is suddenly winter her in sunny Florida (temps in the 20's). I guess it would not hurt to just replace them both with remans.

01-15-2011, 10:58 PM
ok let us know