5.0L EFI Question

alldodge

alldodge

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boatguya1 said:


If no spark with spark gap tester follow this troubleshooting tree.
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You sure about that?
He does not have a TBV ignition module, he has a MEFI-3. While it may or may not be able to see if the coil and the distributor sensor may be bad, have seen no info to determine IF this works with the MEFI
 
Fun Times

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boatguya1 said:
I've been doing this since 92 and had never seen one do this til now. It's the sensor the "teeth" on the rotor pass through. Try a spark gap tester to see if getting good spark.

Fun Times I don't know if Jim is still in the Hayward area, Merc. closed the school there. He is a good guy, hope he is still with Mercury.
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Started in 93 for me but no longer professionally...I'm sure we've probably met once or twice over the early years out there with Jim.:encouragement:

One question for Rickochet service guy would be is the tachometer moving while cranking the engine over?? If he has the Merc type sensor in stock, it could still be worth a try knowing what boatguy went through. Lightning does some odd things to electrical components.
 
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AllDodge said:
You sure about that?
He does not have a TBV ignition module, he has a MEFI-3. While it may or may not be able to see if the coil and the distributor sensor may be bad, have seen no info to determine IF this works with the MEFI
Click to expand...
10-4 my friend. Now that we know Rickochet has the merc sensor and not the GM sensor (Can't believe I missed that:confused:) When Merc went to this ignition system in the late 90's/early 2000's they provided new info (which looks close to but not exactly the same as a carbed engine like shown in the link above) about how they suggest checking the TB-5 / MEFI ignition system of this design. Here's that info if interested, V6 and V8 305/350 cid Engines with MEFI-3

Take note of the ignition sensor color too as guided here, Sensor Failures in MEFI-3 Mercury Distributors Used on V6 and V8 305/350 cid Engines
 
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Rickochet

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Fun Times said:
Started in 93 for me but no longer professionally...I'm sure we've probably met once or twice over the early years out there with Jim.:encouragement:

One question for Rickochet service guy would be is the tachometer moving while cranking the engine over?? If he has the Merc type sensor in stock, it could still be worth a try knowing what boatguy went through. Lightning does some odd things to electrical components.
Click to expand...
The big puzzler here is that two engines are doing the same thing. I don't recall seeing what the port engine did on the tach but the starboard tach did operate when it fired with some starting fluid. Will check the port engine next weekend.
 
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Sounds dumb but be sure that the mercruiser lanyard ignition kill switches are physically moved up and down or in and out depending on style a few times while making sure they are in the run position. These switches do tend to fail sometimes.

Good luck.
 
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Fun Times said:
Sounds dumb but be sure that the mercruiser lanyard ignition kill switches are physically moved up and down or in and out depending on style a few times while making sure they are in the run position. These switches do tend to fail sometimes.

Good luck.
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This is a 55' houseboat with MMC controls. No kill lanyards.
 
alldodge

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You know we could actually be chasing our tails. The fuel pump has been replaced but we don't know what the fuel pressure is, or if there is ANY fuel pressure.
 
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Looking at the ODB website, replacement MEFI-3 ecm's for my motor are listed at $1,695 each. Why are these so expensive?
 
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AllDodge said:
You know we could actually be chasing our tails. The fuel pump has been replaced but we don't know what the fuel pressure is, or if there is ANY fuel pressure.
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Both fuel pumps were replaced. What is the chance of neither pump working properly?
 
alldodge

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Rickochet said:
Both fuel pumps were replaced. What is the chance of neither pump working properly?
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Don't think its the pump, but maybe its something in the pump circuit, line, reg, something. If it is not tested, we don't know, were just assuming there is no issue
 
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If the fuel pumps turn on with key on and run for 3 to 10 seconds then turn off is this an indication they are pumping up to desired pressure and cutting off?

Edited: Got a txt from my bud who said both motors had good fuel pressure at the throttle body.
 
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Rickochet

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Saga continues. Sent both ECM's off to Bob at Obd. Great customer service as he called me next day and told me the ECM's are OK, sort of. He told me that for my issue the ECM might still have an ignition coil issue within the ECM that he can't diagnose. It can only be done with a diagnoses with the ECM's on the engine. How nice. I spent $200 for nothing. The only Mercruiser dealer who is willing to come look at my boat already told me that he doesn't know of any dealer who has the diagnostic equipment to read issues. So, why did Mercruiser even put a diagnostic plug on the engine if nobody can use it? I am really disappointed in what OBD did. So I have limited options at this point. Gee, maybe buy a $1700 ECM to test on both engines which has no guarantee and is not returnable. This is my last dealing with Mercruiser ever.
 
alldodge

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This is my last dealing with Mercruiser ever.
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I would never say never but understand your sentiment. Indmar and VP use the same PCM/ECM and all have issues. Change to points or other electronic ignition

As for the dealer not having the equipment would have me worry about the dealer.

Also your bud says everything is OK so I to don't know which way to go next
 
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AllDodge said:
I would never say never but understand your sentiment. Indmar and VP use the same PCM/ECM and all have issues. Change to points or other electronic ignition

As for the dealer not having the equipment would have me worry about the dealer.

Also your bud says everything is OK so I to don't know which way to go next
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Ignition change over won't happen. I don't know how to do it and don't know anyone who can. Isn't this all tied into the EFI? The "Merc tech" is not the one who built the boat. It is the only one who will come to the lake to check on it. If you check back it is a 55' houseboat that stays in the lake 365. And not sure what you meant about my bud (the mechanic). His last idea was that was both ECM's were bad so I sent them off to OBD who gave me a "Maybe" diagnosis.
 
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