Absolutely frustrated with this Mercruiser engine

[Hoplite808]

Whose injectors did you replace with? Did you put a noid light on the injector plugs to check for a signal?

Just finished checking it all again and swapped the old injectors back onto it. Since I found the wiring schematic for the injectors I decided to verify them and found the previous owner had reversed the connections for cylinder 8 & 6 injectors. I corrected that now. It runs again but still won’t go over 2000 rpm under load.

Upon closer inspection there are actually three wires near where the ECU and relays mount that I can’t identify. One is the large 12 gauge wire which it turns out I remembered the color wrong. It’s black and when tested it appears to be a ground but if I connect it to ground the console alarms go off. The other is a solid white wire and the last is a white wire with a pink stripe that someone spliced to lengthen at some point. Neither of these wires test to seem to have any sort of DC + or - connection. Also both have a similar connector as the temp sender wire has. These wires appear to be taped into the same part of the harness that goes down to the alternator.

I connected my continuity tester and counted the beeps. The ECU only is throwing code 12 which means it’s working and there are no fault codes stored. I am completely at a loss as to what is wrong here.

 

[Lazy Daze]

Since the old injectors got it running again, we now know there is an issue with the "new" ones. So... do the old injectors still have an issue? Just not as bad as the new ones? Possibly.

Are you referring to the black wire in the middle of your picture with the electricle tape on it? Are you sure it's white? It would make much more sense if it was tan (based on the connector). Those tan wires are used for various sensors - water temp, oil pressure, etc. They sound the alarm by completing a path to ground... hence the reason your unconnected wire sounds the alarm when shorted to ground. What sensors aren't hooked up? It appears you have at least two sensors not hooked up.

 

[Bill Curtis]

Looking at that harness, I would first correct all those misgivings, including butt spices that aren't sealed. One alarm wire has a slice in the insulation. At the top, there appears to be another "splice" that is taped up.

Perhaps she can't go over 2k rpm because it's in limp mode, due to a wiring and / or sensor problem.

 

[jmauld]

You might need to rip that harness out and see what all is damaged inside of it. I see a couple of repaired areas and there’s what looks to be damaged insulation on of the leads.

 

[PlayDate]

Upon closer inspection there are actually three wires near where the ECU and relays mount that I can’t identify. One is the large 12 gauge wire which it turns out I remembered the color wrong. It’s black and when tested it appears to be a ground but if I connect it to ground the console alarms go off. The other is a solid white wire and the last is a white wire with a pink stripe that someone spliced to lengthen at some point. Neither of these wires test to seem to have any sort of DC + or - connection. Also both have a similar connector as the temp sender wire has. These wires appear to be taped into the same part of the harness that goes down to the alternator.

The 12 gauge spliced wire goes to a sensor. Depending on the console alarm it may tell you which one is missing/alarming. By grounding it you complete the circuit.

The other two I will look at tonight when I can have a drink and look at the wiring diagrams.

 

[Lazy Daze]

The 12 gauge spliced wire goes to a sensor. Depending on the console alarm it may tell you which one is missing/alarming. By grounding it you complete the circuit.

The other two I will look at tonight when I can have a drink and look at the wiring diagrams.

John, I don't believe his boat has a console alarm indicator like the bigger boats have. However, most likely, the only things that the alarm would sound for is water temp and oil pressure. Gear lube as well (if his '96 has that) - but that's a moot point here and those are also not the correct connectors for the reservoir bottle. It shouldn't be hard to figure out which connector goes to which pressure switch (even without a wiring diagram) based on their orientation/length/etc.

Being disconnected, though, won't cause the issue - the ECM simply thinks everything is OK since these are a one-wire sensor.

But... by all means, still have that drink... I'm planning on it, too

 

[Hoplite808]

The wire that was “repaired” is definitely white with a pink or faded red stripe. The other is plain white. The 12 gauge black wire is under the mess in the photo.

I can’t find reference to them on any of my schematics. The temp, oil pressure, drive oil, and knock sensor wires are all accounted for and working.

 

[Lazy Daze]

The wire that was “repaired” is definitely white with a pink or faded red stripe. The other is plain white. The 12 gauge black wire is under the mess in the photo.

I can’t find reference to them on any of my schematics. The temp, oil pressure, drive oil, and knock sensor wires are all accounted for and working.

Those connectors are absolutely for the temp and oil sensors. Those are always tan wires. If it truly is white, then someone else has been in there messing around. Unfortunately, that doesn't help you nor does it help us help you

 

[scoflaw]

View attachment 140485
Well, good news, I guess. The shop got back to me today about the injector tests. 3 of the injectors have a short when cold and another 4 of the 8 have a short when they are hot. So I gotta go find 8 new injectors. Anyone know where I can find a set that won’t break the bank?

This is where your at, You need to buy 8 good injectors and they can be had for a about $800 for 8. OEM double that. Very primitive electrical system on the gen 5, no limp mode

 

[Hoplite808]

This is where your at, You need to buy 8 good injectors and they can be had for a about $800 for 8. OEM double that. Very primitive electrical system on the gen 5, no limp mode

Where are you seeing 8 injectors for $800?

This is the injector my engine needs: Mercruiser part number 805225A1 https://www.mercruiserparts.com/805225a1-injector-kit-fuel
They are on sale there for $288.87 each, $288.87 x 8 = $2310.96. I can't afford spending that much unless I know for a fact that is the issue. I don't believe I can trust the company that tested the injectors for me as the set they set tested as working properly obviously don't after I installed them. I don't know of anywhere else that could test them for me.

 

[jmauld]

There are a lot of companies on the internet setup to test & clean injectors. Here’s one example: https://theinjectorshop.com/collect...ng/products/fuel-injector-clean-and-flow-test

*I haven’t used these guys, just did a web search. You can probably find a local company offering the same service.

 

[Bill Curtis]

There are a lot of companies on the internet setup to test & clean injectors. Here’s one example: https://theinjectorshop.com/collect...ng/products/fuel-injector-clean-and-flow-test

*I haven’t used these guys, just did a web search. You can probably find a local company offering the same service.

Heck, even Amazon sells some injector cleaner / testers with an ultrasonic cleaner attached for around $600.

Injector maintenance set up and a Rinda tester could be a revenue stream for him, after he uses on his boat, since he said HI is sorely lacking folks to do that.

 

[ttmott]

Where are you seeing 8 injectors for $800?

This is the injector my engine needs: Mercruiser part number 805225A1 https://www.mercruiserparts.com/805225a1-injector-kit-fuel
They are on sale there for $288.87 each, $288.87 x 8 = $2310.96. I can't afford spending that much unless I know for a fact that is the issue. I don't believe I can trust the company that tested the injectors for me as the set they set tested as working properly obviously don't after I installed them. I don't know of anywhere else that could test them for me.

But you said that you installed NEW injectors (Post #66). Then the engine wouldn't start at all. Then reinstalled the old injectors. Then the engine would run but not over 2000 RPM. Now issues with the company that tested the injectors and how they tested apparently something used.... Didn't you also say the old injectors were tested and electrically shorted or something???

 

[jmauld]

But you said that you installed NEW injectors (Post #66). Then the engine wouldn't start at all. Then reinstalled the old injectors. Then the engine would run but not over 2000 RPM. Now issues with the company that tested the injectors and how they tested apparently something used.... Didn't you also say the old injectors were tested and electrically shorted or something???

This is why I suspect the harness is the issue. I’m curious if the injectors in the engine are the right injectors or if the previous owner tried hacking some cheaper alternatives in and possibly switched the wires around. Do injectors have a standardized pin layout per connector type? Ie is the positive pin always pin #1?

 

[ttmott]

This is why I suspect the harness is the issue. I’m curious if the injectors in the engine are the right injectors or if the previous owner tried hacking some cheaper alternatives in and possibly switched the wires around. Do injectors have a standardized pin layout per connector type? Ie is the positive pin always pin #1?

Fuel injectors do require the correct polarity so the pintal inside of the injector is correctly actuated and held. There were at least a couple of post from members on the electrical to the injectors but no response from the OP. Yet, the OP moves forward with a path that seems inconsistent with what he posts and his issues compound. It seems many are trying to help but falls on deaf ears.
Isn't this the same engine the valve train was hosed up and required aftermarket adjustable parts? That was a posting debacle also.

 

[scoflaw]

I've had good results from these 2 companies. They will test and repair your old ones or sell you new for the price I mentioned.
Southbay Injectors. New York
Parts Unlimited. Texas 817-658-7721

 

[KevinC]

I've had good results from these 2 companies. They will test and repair your old ones or sell you new for the price I mentioned.
Southbay Injectors. New York
Parts Unlimited. Texas 817-658-7721

We used South Bay here on Long Island for my friends boat that I mentioned above. Not only did they Diag the problems they affordably rebuilt the injectors. After installation my friend no longer had the RPM issues he was experiencing before.

@Hoplite808: I would suggest you contact them (SouthBay Fuel Injectors, 516-442-4707). While I know your in Hawaii you can easily send these out USPS Priority and get them there and back affordably and quickly.

-Kevin

 

[PlayDate]

Okay....even after having a couple of drinks....trying to sort out the OP wiring without actually seeing it leads me to think I'm wasting my time. This is the standard Mercruiser used to wire the engine harness:

Black Grounds, General
Black/Brown Pump Grounds
Black/Red Voltmeter Grounds
Black/Orange Isolated Accessory Grounds
Black/Yellow Ignition stop
Black/Green Water Level Sender Ground
Black/Blue Lighting Grounds
Black/Gray Nav Light Grounds
Black/White Battery Parallel Solenoid
Brown Pumps, General, Bilge or Sump (Manually Switched)(Also alternator starter to Ign.)
Brown/Red Pumps, Bilge or Sump
Brown/Orange Power feed to Auto Bilge Switches, Pumps, Fuel/Oil Tranfer or Priming
Brown/Yellow Baitwell or Aerator
Brown/Green Fresh Water Pump/Water Maker
Brown/Blue Head Pump
Brown/Violet Washdown Pump
Brown/White Trim pos sender
Red Battery Feeds Unprotected
Red/Violet Misc. Accy. Main Feed Protected (fused) from batt to trim panel.
Pink Fuel Sender
Orange/Black Audio System Feed
Orange/Brown Electric Head, Sanitation System
Orange/Red Wiper Port
Orange Accessories common feed, Dist Panel to Acc switch, Anode Electrode, Mercathode
Orange/Yellow Diesel Preheat
Orange/Green Wiper Stbd
Orange/Blue Communications Equipment
Orange/Violet Navigation Equipment
Orange/White Wiper Center
Yellow/Black Choke Neutral saftey trans mounted
Yellow/Red Start Solenoid (starting circut), Neutral Safety
Yellow/Orange Powered Ventilation, Fans
Yellow Bilge Blowers (also alternator DC output)
Yellow/White Rudder Angle Sender
Green/Red Stop Solenoid/Kill Switch
Green/Yellow AC Grounding
Green Bonding
Green/White Engine Trim in and or tilt down
Green/Orange Engine Independent Trim down
Blue/Black Cabin Lights
Blue/Brown Oil Temp Send
Blue/Red Cabin or Cockpit Lights Port
Blue/Orange Engine Independent Tilt Up
Blue/Yellow Lighting Circuits to Remote Send
Blue/Green Cabin or Cockpit Lights Stbd
Blue Instrument & General Lighting
Blue/Violet Courtesy, Boarding Lighting
Blue/White Engine Trim Outand/or Tilt Up
Light Blue Oil Pressure
Violet/Red Eng. or Generator B+ from Breaker
Violet/Yellow I/O Trim Up (ballast bypass)
Violet/Green I/O Trim Down
Violet 12v Ignition Generator or Engine
Violet/White Trim "Trailer" switch
Gray/Black Mast Light
Gray/Red Spotlight Remote
Gray/Orange Docking Lights
Gray/Green Strobe or Beacon
Gray/Blue Spreader/Flood Lights
Gray/Violet Windlass/Winch
Gray Navigation (running) Lights, Tach. Send
Gray/White Anchor Light
White/Brown Temp. Alarm or Indicator
White/Red Fuel Alarm or Indicator ((Ignition module to Dist.)Mercury Thunderbolt Ignition)
White/Orange Fire Alarm or Indicator
White/Yellow Air Flow Alarm or Indicator
White/Green Water Press/Flow Alarm or Indicator ((Ignition module to Dist.)Mercury Thunderbolt Ignition)
White/Blue Oil Press Alarm or Indicator
White/Violet Voltage Alarm or Indicator
White General Alarm Usage, Yamaha Kill Switch
Tan Water Temp sender
Tan/Blue Warning system sense wire (Audio warning)

As you can see the White with a Red stripe is used for a Fuel Alarm or Indicator on the Mercury Thunderbolt Ignition. IF the wire is original ......it doesn't show up on the EFI or Engine wiring harness diagrams for his engine.....but I have seen the wire before on Thunderbolt distributors.

In any case if the engine starts and runs.....even poorly....my money is still on the fuel system.

Speaking of money......the OP is quite clear that he doesn't want to spend $1,000+ on injectors just because CSR says it is the most reasonable solution.

I get it......I'm guessing he bought the boat for almost nothing after the original owner couldn't make it work and doesn't want to keep throwing money at it.

 

[Lazy Daze]

Hoplite, I completely understand why you don't want to drop a ton of money on the injectors until you know for sure that they're the problem. I get it. It's also a shame that you don't seem to have more mechanics around - but I suspect you actually do... you just don't know where to find them. Ask friends... take a walk to a marina and ask other boaters... you might be surprised.

At this point (and as mentioned above a couple times), you've been replacing things - often without true diagnosis. BUT, from what you've reported, it DOES seem like the injectors (or the wiring/connectors at the injectors) is a PLAUSIBLE cause and it's worthwhile to continue down that track.

For now, forget about the wires - there are sometimes extra wires in harnesses... although the white wire with the sensor connector on it makes no sense. In my opinion, based on what recently happened by swapping the injectors, it makes the most sense to focus on the fuel injectors.

You may have to mail them away as mentioned above... but keep asking around and you might find another local company that can help you. There's lots of boats and cars on that island... there's gotta be some good fuel injector shops.

 

[jmauld]

I would start by pulling the injectors out and making sure they are all the same part number. If so, send them to an injector cleaning service. It’s $20-30 per injector and should be considered 10 yr maintenance anyway. The injectors “should” outlive the engines.