Boat Tech

It should be the same

Here's Johnny

If you do find out the GM part number please let us know.... It could come in handy down the road for some of us.....Thanks and good luck with the engine, hope the problem gets solved...........

Steve Zuckerman

These throttle bodies are off a 7.4/454 GM truck motor. Most internals are identical.
Steve

SB

iTrader: (1)

Yup, you guys are correct.

Normal 454 t-body parts will work.

The regulator in the TBI unit is deadheaded by Merc with a solid screw in plug to the return line port on the TBI. Thus, it does not control psi.

Merc uses a different regulator down near the pump, before the TBI. It does have a vacuum line that hooks up to the rear vacuum port on the tbi unit.

Pic #1 - see part#14 - this is the regulator Merc uses to regulate the fuel psi.



And in this pic, see part#4 which is the plug used to plug off the tbi's return line which renders it's built in regulator to be useless other than sealing off fuel of course.

SB

iTrader: (1)

From the pic below, it looks like these 575SC's t-bodies use the base gaskets from the 87-90 454's. So, if looking for gaskets, o-rings, regulator diaphragms, etc,etc I'd get them from local parts store for 87-90 454 truck. Say, K3500 to make parts look-up easier. Or hell, a 90 454SS pick-up truck should be know easily too. LOL.

Note: Don't assume your injectors themselves are the same as these trucks, if you are ever going to replace them. Look at the #'s stamped on the top of the injector in between the injector electrical posts, and I or anyone could probably find out for you how to get outside of $$$$Merc. LOL.

Pesky Varmint

Myself and the local injector shop couldn't make heads
or tails out of the numbers on the injectors. I don't think
anyone can figure out what they are.

If I ever need a new injector I'll take a good one back to
him and have it flow tested at normal GM pressure (either
10 or 14 lbs I think) and then we'll know what they flow.

I don't know that number now because when he cleaned
them I had him flow them at the Merc 28 psi. For what its
worth, 6 year old injectors with 430 hours were on average
7% low on flow across the board (8 injectors).

There is going to come a day when any 575SCi owner is
just going to have to go to all new stuff from manifold up.

Pesky Varmint

lakeman2

Thanks for all the feed back.I talked with CFM and found out the same thing sb is saying.Mercury racing gave me a GM part # 17113192.That part has been gone for 6 years.The regulator i used is GM #17112399.It is for a 1992 5.3 and 7.4 GM motor.They made a 13lb and 30lb regulator.I guess it does not really matter because there is no return line and the fuel is regulated before the tpi.I would really like to find out a good # on the injectors.The # on my injector is 25170301.They are nla from merc.I did find a post from someone taht purchased some a few years back from merc and under mercs sticker on the box was a part #17113305.Still can not find out ant info on that #.I think it was a part # just for merc.Is it worth having my injectors cleaned.the motor has 250 hr on it.Iam going back out to the lake next week.Iam going to install a new thermo sensor,iac and tpi.I also found out they had the wrong spark plugs in the motor.Hopefully that will take care of my rich prob.Thanks.

Boat Tech

merc dealers now have a way too clean injectors while on the engine I have not done it yet but I believe they could also do [TBI] engines also in the past we where always told not to clean the injectors only replace them but now they have changed there minds about that idea.FYI the shop that has the tool to do it in CA is Quality performance marine in corona 951-735-5503.If you had all those problems with the fuel system it looks like it might be worth trying to get them cleaned.wrong plugs and stuck thermostat will make it run rich,bad MAP sensor would be super rich and run real bad in many ways. [IAC] would surge up down, also you should change the IAC muffler in the T/B.I have had many boat oweners tell me the boat is more responsive on acceleration after cleaning T/B and IAC and new muffler. The [TPS] tells the [ECM] how much throttle you want by % and ECM tells other sensor how much fuel curve the engine needs.sorry if you already know about all this info I have a feeling you know a lot about your engine.good luck with it.

SB

iTrader: (1)

I'd do some more digging thru a local AC Delco dealer. 1711305 shows up on this 2008 'Emissions Control' Jobber Price Sheet.
http://66.0.3.26/Specials/AC%20Delco...ets/21A-20.pdf
Go to pg 15. Also, Price shown is near/at what TBI Injectors are sold at thru AC Delco dealers. So, maybe ???

The part#'s on the injectors is what many of us go by, but they are not the same part # on the box.

Again, so maybe you are on to something ????

BTW: I am CFM. LOL. I came to find this thread because you talked about OSO on the phone so I figured I'd check in on this thread. I'm not here much anymore. I can be found by phone during the week or at http://marineperformancetechtalk.com/forum/index.php a good amt of the time, but a little less now since it'm my extremely busy time of year.

Sorry I don't know more about the TBI's used on Merc's/Volvo's. I haven't gotten any of these tbi equipped boats (N/A nor S/C) in my hands.

lakeman2

Thanks for the info boat teak.Iam going to stop by turbo city in orange on monday.They have built a ton of hi flow tbi for street and marine.They also clean and flow injectors.If i have no luck there i will stop by Quality on the way home (live in temecula)I also have a lavey (27 sabre).Great boats.sb,Thanks for setting me straight about the fuel regulator in the tbi.I spent two hours at my GM part dealer yesterday pulling part #s for tbi parts (seal kits ,injectors).no luck.I think i might call AC Delco on mondat and chase the part #.It would be good to know down the road.Iam going to have mine cleaned and flowed and see how that works.Thanks again.Dave