Electrical Troubleshooting Help Needed

kap2 said:
What engines do you have?

If they are the 7.4L (454cid) or 8.2L (502cid) the timing needs to be set to 8 degrees BTDC while in "Service Mode".

To get into Service mode you'll need a Scan Tool or what MerCruiser refers to a Timing Tool, part number 91-805747A1. The Timing Tool is a connector with two pins jumpered together. It plugs into the same port as a Scan Tool - Data Link Connector.

With the engine in Service Mode the ignition advance is held steady and the RPMs will jump up to 1800rpm. The RPM increase will only happen on MEFI-2 and MEFI-3 revision ECMs. If yours is an MEFI-1 you need to manually adjust the throttle to 1800rpms. Now your ready for the timing light.
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Good info. I had no idea.
 
kap2 said:
What engines do you have?

If they are the 7.4L (454cid) or 8.2L (502cid) the timing needs to be set to 8 degrees BTDC while in "Service Mode".

To get into Service mode you'll need a Scan Tool or what MerCruiser refers to a Timing Tool, part number 91-805747A1. The Timing Tool is a connector with two pins jumpered together. It plugs into the same port as a Scan Tool - Data Link Connector.

With the engine in Service Mode the ignition advance is held steady and the RPMs will jump up to 1800rpm. The RPM increase will only happen on MEFI-2 and MEFI-3 revision ECMs. If yours is an MEFI-1 you need to manually adjust the throttle to 1800rpms. Now your ready for the timing light.
Click to expand...

They are 7.4’s in a 1998 400 Sea Ray
 
you jump pins A & B on the DTC connector for base timing...set to 8 degrees and you're done.Terminal (A) will be a black wire with a white stripe on it. Terminal (A) is going to ground.

Terminal (B) will be a white wire with a black stripe on it. Terminal (B) is going to ECM.
 
Bt Doctur said:
you jump pins A & B on the DTC connector for base timing...set to 8 degrees and you're done.Terminal (A) will be a black wire with a white stripe on it. Terminal (A) is going to ground.

Terminal (B) will be a white wire with a black stripe on it. Terminal (B) is going to ECM.
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How do you know this stuff? I love this forum. Smart SOBs on here.
 
Should be sticker on the intake cover with some basic specs (wot range, spark plugs, timing).
 
hd2002hd said:
It is fuel injected. It started and ran fine. The timing was adjusted and off we went. I ran it a couple of weekends before I noticed the engine that had the new distributor wouldn't run up to the RPM's I expected. I typically only run about 3200 rpm. When I bought the boat in 2012, both engines ran about 4300 rpm WOT. Now, the engine with the new distributor only runs about 3200 rpm WOT while the other one runs about 3900 rpm WOT. I have never ran either of them WOT since my initial test run. So, what would prevent the engine with the new distributor from running on up? Is it possible the wrong distributor is in it or would it not run at all in that case?
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further to my last, if the rpm is not going up on one engine ,this slower motor will cause a lot of extra drag on the boat and not allow the "good" engine to develop max rpm. I believe that once you get the motors timed correctly rpm should increase more easily on both engines hopefully giving you the proper power //rpm//indications on both motors.
 
Thanks for all of the info. I tried to locate the serial numbers but still haven’t found them. The cover plate over the electrical connections has a spot labeled “serial number”. It it is blank. I looked around the spark arrestor and the top cover on the engine and didn’t see anything. I assume it will be stamped in the casting some where but no luck finding it yet.
 
hd2002hd said:
Thanks for all of the info. I tried to locate the serial numbers but still haven’t found them. The cover plate over the electrical connections has a spot labeled “serial number”. It it is blank. I looked around the spark arrestor and the top cover on the engine and didn’t see anything. I assume it will be stamped in the casting some where but no luck finding it yet.
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On my 350 mag/mpi, there is a small mercruiser plate riveted to the engine block on the rear,right side of the block below where the heads attach to the block. Mine was not stamped into the block.
 
The marina should be checking the timing on both motors later this week. Hopefully, this corrects the issues. With Playdate's suggestion, I dug up the survey and looked through it. I bought the boat in 2013 and at the time of the survey the RPM's on both motors at WOT was listed at 4800. Seems like a t lot to make up with the timing adjustment, but maybe it is possible. The engines seem to run good although the RPM's are so low. I suppose there are numerous things that could rob the RPM's.
 
If you had a compression test done in 2013....doing that again would tell you if anything internal has changed. It is easy to do and a good reason to change the plugs at the same time.
 
Got a call from the marina today. After checking the timing, the starboard was definitely off. Will take a run tomorrow to see how much difference it made.
 
Well, much better the starboard hit 4500 at WOT. However, port was only at 4300. Not sure what is going on there.
 
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