My Mercruser has a Chevey S10 4.3L engine in it

Technoid

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Hello I got this boat for free. Its a 1991 Maxum 2100SC. Someone installed a 4.3 motor from an S10 Pick up truck. He added the marine cooling system parts. My problem is they tried to use an inline fuel pump with no way to regulate and control the fuel supply. From reading about the S10's they used a TBI carb, A submersible pump controlled by a throttle sensor. And this motor just does not run right with this current set up.. How can I modify this so that it runs correctly? What do I need to do? The engine is in good condition. Good compression. Thanks.
 

alldodge

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Hello I got this boat for free. Its a 1991 Maxum 2100SC. Someone installed a 4.3 motor from an S10 Pick up truck. He added the marine cooling system parts. My problem is they tried to use an inline fuel pump with no way to regulate and control the fuel supply. From reading about the S10's they used a TBI carb, A submersible pump controlled by a throttle sensor. And this motor just does not run right with this current set up.. How can I modify this so that it runs correctly? What do I need to do? The engine is in good condition. Good compression. Thanks.

:welcome: to iboats

My guess is the computer controlling the TBI requires input from the exhaust sensors which are not there.
Remove the TBI and install a carb with low pressure fuel pump (reasonable price)
Replace with a Holley or FAST EFI system (expensive)
Replace with Mercruiser cool fuel, TBI and ECU setup (very expensive, unless you can find one on ebay)
 

Technoid

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:welcome: to iboats

My guess is the computer controlling the TBI requires input from the exhaust sensors which are not there.
Remove the TBI and install a carb with low pressure fuel pump (reasonable price)
Replace with a Holley or FAST EFI system (expensive)
Replace with Mercruiser cool fuel, TBI and ECU setup (very expensive, unless you can find one on ebay)

What standard make carb do you suggest? I can get a generic low pressure fuel pump at USA auto.
 

thumpar

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Make sure the externals are marine rated. Things like starter, alternator, etc Need to be marine rated for the spark protection. If they used the parts off the S10 motor they don't have that protection.
 

NHGuy

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Sure, just get a carb type electric fuel pump, they make only around 7 psi, Holley's red pump will fill the bill nicely. I'd get an Edelbrock 1409 marine carb with the V6 jet kit. It will also need an intake manifold, and you will need to wire the pump to shut off when the engine isn't running.
 

Technoid

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Make sure the externals are marine rated. Things like starter, alternator, etc Need to be marine rated for the spark protection. If they used the parts off the S10 motor they don't have that protection.

Thank Thumpar. How do I know if the starter and other parts are Marine or just auto?
 

Technoid

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Sure, just get a carb type electric fuel pump, they make only around 7 psi, Holley's red pump will fill the bill nicely. I'd get an Edelbrock 1409 marine carb with the V6 jet kit. It will also need an intake manifold, and you will need to wire the pump to shut off when the engine isn't running.

Thank you NHguy. I'll call Holly today.
 

Technoid

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Thank Thumpar. How do I know if the starter and other parts are Marine or just auto?

I also read that the Vortex engines in the S10 had poor intakes gaskets. So I'll ask Holly about that and see if they have an upgrade gasket
 

achris

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Thank Thumpar. How do I know if the starter and other parts are Marine or just auto?

They should have a sticker on them that says "SAE-J1171" No sticker, not marine rated (that's what SAE-J1171 is, a marine rating, not a part number)...

Chris.....
 

thumpar

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I also read that the Vortex engines in the S10 had poor intakes gaskets. So I'll ask Holly about that and see if they have an upgrade gasket
The intake gasket on my 1994 that was in my Safari van went out. I wouldn't call it common but that is a weak point.
 

alldodge

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What standard make carb do you suggest? I can get a generic low pressure fuel pump at USA auto.

I think you have a 2 brl TBI setup so a Merc carb should fill the bill. It's item 7 in the link below, part number 3310-807764A1
http://www.mercruiserparts.com/Show_...%282+BARREL%29

Or the Holly 0-80320-1 which is a 300CFM carb
http://www.amazon.com/Holley-0-80320.../dp/B000CMFP6A

Now there are some sharper dudes here which may be able to find a better replacement carb and give them some time to see if they respond

On the fuel pump, You must use a marine fuel pump as others mentioned. Don't go to the auto store and pick up one for a car. We just met ya and don't want to be reading about you in the papers about a boat blowing up. We got a lot more teasing to do :rolleyes: There are several manufactures, Carter, Holley, Merc, Airtex
 
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Technoid

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Update: I just came back from a Marine mechanic shop. An automotive engine from a Chevy S10 can not be used for Marine purposes. First of all he told me that a Marine engine tolerances are not the same. That GM 4.3 from the truck is not made to go above 2700 for long duration. He told me it would seize up half way across the lake at cruise speed. I would have wasted a ton of money on a new Holly carb and manifold. And there are laws about inboards and their fuel systems. Mine would have landed me a big fine! He also looked over everything. Some one who owned the boat before me did not winterize it. And the exhaust manifolds had been cracked. They brazed it to repair. But my mechanic said they fixed the outside but it might also cracked where you could not repair. And if I used them water would get into the engine. He also told me to have the impeller changed since its been sitting a long time. All good advice So anyway it was an educational day. I am having him replace the motor with the correct Mercury long block. Its going to cost me about $4000 for everything. But its piece of mind. I am 62 years old and really don't feel like pulling on wrenches anymore. So if anyone plans the cheap way out using an automotive engine and parts, DON'T. Save your money. Or pay the price. If you can't afford to maintain it, don't own it. That was advise to self as well, LOL.
 
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thumpar

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Find a new mechanic. He is full of crap. The blocks are all the same. The only real difference is brass core plugs. The cam is slightly different but so close it won't make a different. The externals are really the only main difference.
 

funk6294

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What concerns me over putting in a new long block is that a long block typically does not include the marine accessories which would leave you still purchasing intake, carb, starter, alternator, water pump ect. If he is installing a whole new motor accessories and all that's another story. If that's running 4k and includes all new stuff it maybe worth it for piece of mind.
 
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achris

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Update: I just came back from a Marine mechanic shop. An automotive engine from a Chevy S10 can not be used for Marine purposes. First of all he told me that a Marine engine tolerances are not the same. That GM 4.3 from the truck is not made to go above 2700 for long duration. He told me it would seize up half way across the lake at cruise speed......

First up, this ^ is complete and utter BS.When I was a Merc dealer we went to the annual conferences. One of the facts that came out of one of the conferences was that all of the marine manufacturers GM engine requirements, put together, are less than one days production run. GM don't re-tool and re-spec for 6 different base engines (3 litre, 4.3, 305, 350, 6.2, 8.1) just for 0.5% of their sales...

What IS different about a marine base engine is the core plugs and head gaskets, THAT'S ALL. The cam is the same as a truck, for a near-flat torque curve... After that, yes, huge differences, especially the electrical and fuel systems, but the base block... your 'mechanic' is full of **IT!

Chris.........
 
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DaveG55

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Congratulations, you have found a mechanic who has given you something for free, a huge load of "let's scare the newbie crap". He has done this in the hope of sticking you with a several thousand dollar invoice for a new engine.
Listen to achris and AllDodge, the won't steer you wrong.
 

Watermann

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I would be more worried about sinking that kind of cash into a 23 year old boat that could be and most likely is rotten. Unless cared for the wooden stringers, transom and floors rot out of those older glass boats.
 

zealer

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Yes either the mechanic is lying to you to make a $4000 sale, or he just doesn't know any better. A lot of these 'marine' mechanics' are spoon fed the same misinformation when they start out and then blindly spread it. The 'marine' inboard/outboard world is pretty interesting. Finding parts for them is a lot of fun. I was looking for a new intake manifold a couple of weeks ago. Out of 5 marinas/repair places, only one person understood what a Vortec 8-bolt manifold was... everyone else kept asking for a serial number! The serial numbers do make lookup very easy, but I honestly just think that system is there to confuse people (owners and mechanics alike) and prevent people from cross-referencing to the same GM part. (Of course, some parts ARE specialized).
 

Technoid

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I would be more worried about sinking that kind of cash into a 23 year old boat that could be and most likely is rotten. Unless cared for the wooden stringers, transom and floors rot out of those older glass boats.

The boat is a 91. Its 13 years old. The Boat is not rotten. And the transom is solid. But I will print out all from this page and bring it to my Mechanic. I really don't know what was done to this engine. But since the manifolds were welded I suspect trouble. A long block installed was $3,000. Another $1,000 for the manifolds. And if any of the other parts are not marine I will have to purchase them. The wiring was a mess from someone who does not know how to wire. I am a retired electrical tech. I have been in Aviation mechanics, Plumbing, Air conditioning, Generators, Diesels, Building trade, and retired from a public water utility. But not in the marine field. I understand the workings, problems and theory of an internal combustion engine. And with my Aviation experience have done some overhauls. What he told me about RPM's and tolerances made some sense in the terms of engine heat and expansion. But I'm not in this field so I will talk with him about this. And I'd rather have a new engine to start with that I am maintaining from scratch. Thanks guys for all the come back. And God bless.
 

H20Rat

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Out of 5 marinas/repair places, only one person understood what a Vortec 8-bolt manifold was... everyone else kept asking for a serial number! The serial numbers do make lookup very easy, but I honestly just think that system is there to confuse people (owners and mechanics alike) and prevent people from cross-referencing to the same GM part. (Of course, some parts ARE specialized).

Having worked parts before, you have to look at that from the other side. Standing on the other side of the counter, 99% of the backyard mechanics think they know what they are talking about, and then order the wrong part. That is cost and headache to the parts guy. Hence, the serial number to verify it. What you think of as an 8 bolt manifold might actually be 3 different sku's that even might look identical but have different material properties.
 
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