Mercruiser 4.3L TKS -Carb or Injection

[Chris Bruff]

Hi again All,

The purchase process of the 2005 Maxum 2900 SE I am looking at is ongoing. Full survey booked for this weekend so am looking forward to that. Now looking at local berths and pondering whether a 180 mile trip down the coast is wise on a boat I don't know yet. Anyhow.....

In the sales advert for this boat the Owner stated 2x fuel injected 4.3L V6 engines. I thought I'd do a bit more reading on these engines and get up to speed. I looked the pictures the Owner sent and noticed it has 4.3L TKS on the air filter housing of one engine and 4.3L Turn Key Start on the other.

I'm aware that these filter housings may not be original but am now concerned that they may actually have carburetors. It's hard to tell from the pictures alone.

Can anybody assist? Was there a specific year they changed from carb to fuel injection.

Thanks in advance for your help.

[The Pirate]

The photo on the right looks exactly like the 4.3 V6 in my '06 1800 SR3. Mine is definitely carborated and has a flame arrestor for that reason. These are rated at 190 hp.
Not sure when they went with fuel inj. on these, but their 210 hp would be a nice upgrade.

[mmwjr]

These are TKS which is a carburetor that doesn’t have a choke but instead uses an enrichment circuit to add more fuel when the engine is cold. Some folks love them others hate them. Main problem that arises is the enrichment jet gets clogged. This can be cleared with carb cleaner.

The TKS engines and EFI were available at the same time it was a matter of cost and additional HP for the EFI. This was available on the 4.3, 5.0 and 5.7.

While I prefer the EFI most entry level boats such as Maxum seldom have it until the single power 2000’s.

[shrew]

I love the non-ignition protected electric space heater in the engine compartment. Where is the boat located? Did the owner winterize the engines?

[mmwjr]

Originally Posted by shrew

I love the non-ignition protected electric space heater in the engine compartment. Where is the boat located? Did the owner winterize the engines?

Funny I saw it but wasn’t sure what it was, guess it’s because I’m not feeling well.

[Chris Bruff]

Hi Gents,

Shrew, are you saying it should be an intrinsically safe heater due to the risk of explosive gas build up? If so, I agree.

Ok, so the pre-purchase survey has come back. A few minor issues - anchor winch foot pedals not working, fire suppression system requires service, aft bilge pump not working on switch. Nothing too drastic.

But, back to the engine identification issue. The report states the engines are Mercruiser MCM 4.3 (300hp)? I can't find much useful info on these, does that sound correct? Is there anyway to confirm the exact types using the serial numbers?

Port S/N: IA339715
Stbd S/N: OW346526

Secondly, the report stated Bravo 3 drives, but to me they look like Bravo 2.

Thirdly, the report also stated a maximum of 4200 rpm was reached. I'm hoping to confirm at what speed the boat planed.

As always, any comments/opinions are appreciated

Many thanks,

Chris

[mmwjr]

Chris - Is this a surveyor you picked and are paying? If so they are clueless. If it's the sell picked person or the marinas this person is looking out for the seller and not you.

Clearly these are Bravo 2 drives. No way to confuse these with Bravo 3 which have counter rotating props.

300HP 4.3! lol.

The 4.3 MPI is rated at 220HP and the Carburetor version of the 4.3 is 190HP.

[mmwjr]

The first serial number comes back as invalid.

The second comes back as follows which clearly states carb. BTY its a TKS carb.

[donald]

The starboard drive has been repainted and the port side drive has not, it shows some corrosion on it.
Just for your info I would ask about it.
Don

P.S
I also agree with Mike as the surveyor is not looking out for you!
Hire your own surveyor it is money well spent.

[Chris Bruff]

Thanks Guys, this was my surveyor believe it nor not. Came recommended.....

I have gone back to him with some further questions and he has rectified his mistakes (I think he has a template report that he changes per customer). I was quite harsh with him and he's promised to give a more detailed report, with pictures, and no mistakes. We shall see.

Yes, the picture I provided was one previously provided to me by the current owner, not one taken yesterday by the surveyor. Both drives we stripped, treated, primed and painted.

The first serial number should show a '1' rather than an 'I'. My mistake. What site do you use to find engine type/parts etc.?

Once again, many thanks. I'll await this next report and then start negotiations with the Owner...

[Chris Bruff]

The 4200rpm WOT is a concerning as from all I have read, it should be between 4400 and 4800rpm correct?

Am I able to tell which ratio drive I have and then which prop is correct for the boat/engine/drive? I've seen somewhere a company mentioned who are good at specifying the correct props.

Engine serials: 1A339715 and OW346526

Drive serials: ON434443 and ON420041

I'm assuming it might be over-propped but if I can specify the correct prop, I will check with the current Owner to hopefully either confirm or negate this.

[mmwjr]

What site do you use to find engine type/parts etc.?

https://www.marineengine.com/parts/m...r-stern-drive/

The 1A339715 also comes up as a TKS 4.3. but I could tell they weren't MPI just by looking at them.

Regarding you surveyor, template or not these are basic mistakes that there is no excuse for. Just a sloppy job and makes me concerned what else he missed.

BTY the serial numbers for the drives are coming up not valid.