Mercruiser ECM replacement?

Lou C

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Lou cleaned it up, it's the intake bolt pattern. 8 vs 12. I'm quite sure he has Tbi heads but one never knows. And vortec heads vs tbi heads is a big deal in programming a file.

Again a picture of the intake/valve covers will define things so you can move move forward. Or just count the bolts holding down the intake.

8/vortec
12/ tbi
The pre-vortec engines also had center bolts holding down the valve covers, my pre-vortec V6 does, GM started using the center bolt design way before Vortec came on line. In that first pic I see one manifold bolt at the lower right side of the pic, and it is at an angle, this suggests to me that is is a pre-vortec engine. Vortec intakes had the bolts going straight down, pre-vortecs had them at an angle. Now it is possible to have a pre-vortec engine with a roller cam at least with the 4.3 V6s, mine has the roller cam, pre-vortec manifold and heads, and center bolt valve covers. In this pic you can see the center bolt valve covers, and intake bolts going in at an angle, this is a 1988 pre-vortec roller cam 4.3 V6.

PS
I looked at the pix and its hard to see where the bolts are but judging by the shape of it, the intake looks like a Pre-Vortec, should have 12 bolts holding it down....
 

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Lou C

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PPS
looked again and I saw the tin cover over the area where the choke stove would have been if it was a carbed engine, definitely a pre-vortec. The vortec manifolds do not have an exhaust cross-over so there would be no place to mount a thermostat choke spring as on the pre-vortecs (used on the Quadrajet carbs like mine).
Why not post up your block casting #?
I'm not sure of the timing of when the V8s went from the pre-vortec to vortec and flat tappet to roller tappet, but on the V6s I can tell you for sure they went to roller tappets in 87/88 but did not go to vortec heads till '96 as far as I know.

Looking further and checking Merc parts diagrams best I can determine is that up to 1995 the engines had pre-vortec heads (judging by the intake gaskets listed) but in 1996 what they called the Gen+ engines had vortec heads, again judging by the intake gaskets.

now when they changed from the flat tappet to the roller tappet cams....this seemed to have happened in the 1987/1988 time frame as for these years blocks with either cams were listed in the parts catalog. So it seems more or less the same as the 4.3 V6s....
so 1987/1988 for roller tappets
1996 for Vortec cyl heads & intake manifold
that's all I got....
 

Tail_Gunner

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Below are pics of intakes, the 8 bolt pattern is true vortec. Speaking to why that is important, the vortec head improved engine performance enough a new tune was required. That is at the heart of this conversation.
 

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Ferrarakias

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I will, but currently away from the boat! Will go on Saturday and let you all know.
Many thanks.
 

Lou C

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Below are pics of intakes, the 8 bolt pattern is true vortec. Speaking to why that is important, the vortec head improved engine performance enough a new tune was required. That is at the heart of this conversation.
Looking over the pix I'm pretty sure that this is a pre-vortec TBI engine. The intake looks more to me like the pre-vortec style so that puts it as 1995 or older. Can't answer the question of flat tappet or roller cam without the casting # or seeing a pic with the intake removed, if that tin lifter locater piece is there in the cam valley its a roller cam, if not its a flat tappet.

Here's a pic of my roller cam 4.3 with the heads installed but the intake off, you can see the lifter locater for the roller tappet cam....
First pic is from when I was taking it apart after the blown HGs second pic is after I installed the new cyl heads.
 

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Tail_Gunner

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These are the injectors that I bought almost a year ago...


Looks like you have matching part numbers. Now on to your serial number. With that being said was that engine rebuilt? It look pristine, a big issue can be the coolant temperature sending unit. There are many types and only one for tbi.

I see your reply below, besides the coolant sender you want to thourghly clean all the electrical contact points, efi does not play well with corrosion. I see another point of worry, the knock sensor in the pic below. That sensor can picks up unwanted vibrations and retards the timimg...think very low preformance.It must be clean and functional....on the bottom of the block near the oil pan..That shiny round sensor

Again you really need a code reader for a old tbi unit, it will save you a lot of headaches. I have a suspicion your engine will not rev do to being in protect mode. That mode prevents the engine from revving past 2900 rpm. And your fuel pressure needs to be 28/ 32 psi... not to much or less. It is read at the gas line coining into the tbi...At all rpm levels it needs to be constantly at least 28 psi.


MerCruiser Set of 2 Flow Matched 4.3L 5.0L 5.7L TBI Injectors "852956A1"
 

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Ferrarakias

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Looks like you have matching part numbers. Now on to your serial number. With that being said was that engine rebuilt? It look pristine.

MerCruiser Set of 2 Flow Matched 4.3L 5.0L 5.7L TBI Injectors "852956A1"

Just a good wash was enough for the old layer of wax to be removed. The engine only has 235 hours since new...
 

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alldodge

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The MEFI 1 didn't have a protection mode, and not many codes. Codes can be read if any with a register led and paper clip as mentioned previous
 

Lou C

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Just a good wash was enough for the old layer of wax to be removed. The engine only has 235 hours since new...
when you say only 235 hrs since new, is this engine original to the boat? Then what year is the boat? To me the boat looks too old to have a TBI system, it looks mid to late 80s.
BTW I like a clean engine but I'd never use a pressure washer around a wiring harness! you don't want to be forcing water into places where it can cause corrosion....
 

alldodge

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Yes I have it. It says 93-95 does but no one I have ever discussed says it will actually do it
 

Ferrarakias

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when you say only 235 hrs since new, is this engine original to the boat? Then what year is the boat? To me the boat looks too old to have a TBI system, it looks mid to late 80s.
BTW I like a clean engine but I'd never use a pressure washer around a wiring harness! you don't want to be forcing water into places where it can cause corrosion....
No, this is not the original to the boat engine. The boat is 1984, the previous owner replaced only the engine (Mercruiser 225hp) around 1997-1998 with this new one (left the original alpha one sterndrive).
I'm wondering whether the pressure washing is the cause of the problem I have!
 
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Tail_Gunner

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No, this is not the original to the boat engine. The boat is 1984, the previous owner replaced only the engine (Mercruiser 225hp) around 1997-1998 with this new one (left the original alpha one sterndrive).
I'm wondering whether the pressure washing is the cause of the problem I have!
Which is why I wanted to see the intake manifold...smiles its all telling. Now that you bring up this new engine..the serial number is quite relevant. It is eye opening to see how European country's approach US made boats and Rv's. Lots of hands on fabrications...

A question is that stern drive a left or right hand rotation?
 

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Lou C

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No, this is not the original to the boat engine. The boat is 1984, the previous owner replaced only the engine (Mercruiser 225hp) around 1997-1998 with this new one (left the original alpha one sterndrive).
I'm wondering whether the pressure washing is the cause of the problem I have!
Well I might want to open up those connections and see if there is any corrosion!
 

Tail_Gunner

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Ive found the timing protocols, to the original poster the below procedures are used to time your engine..Do not vary.

The DLC is simply the Data Link Connector located near the MEFI 1. You can jumper the A / B ports to get the ECM into base timing mode. You can do this with a paper clip.

Start the motor, bring the rpm up just a little (1000-1200), jumper the A / B pin outs on the DLC connector and you will be in base timing mode. Put a timing light on the balancer and adjust the distributor until you get 8 deg BTDC. Lock down the distributor and remove the DLC jumper. Base timing is now set.
 

Tail_Gunner

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Well I might want to open up those connections and see if there is any corrosion!

Below is a product that excells, just be sure to test it on any plastics.

 

Lou C

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Yep and when they are all dried out I like to coat the outside of the connector with dielectric grease.
 
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