Welcome, Guest
Username: Password: Remember me
  • Page:
  • 1

TOPIC: 5.0 MPI 2007 TDC marks ?????

5.0 MPI 2007 TDC marks ????? 11 Jun 2009 17:14 #1

  • boblydon
  • boblydon's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 63
  • Thank you received: 0
Does anyone know if the mark on the harmonic ballancer, when it is inline with the marks on the timing chain cover represents TDC...i have scoured the workshop manual but it makes no note of it, i am trying to locate TDC to check my static timing.

Also if the timing is considerably out, would the hall effect sensor in the distributor stop the coil from firing, i have telephoned Mercruiser tech support but got no help whatsoever, so hopefully someone can help me out on this.

Thanks in advance for any help.

bob

Please Log in or Create an account to join the conversation.

5.0 MPI 2007 TDC marks ????? 11 Jun 2009 17:35 #2

  • Rick Kenyon
  • Rick Kenyon's Avatar
  • Away
  • Premium Member
  • Premium Member
  • Posts: 332
  • Thank you received: 6
On the older GM automotive blocks, when the balancer mark and the timing chain guage mark were lined up, that meant that the #1 cylinder was at TDC. ( I assume marine blocks would be the same) The only problem is that you still had to figure out whether the engine was in the compression stroke, or the exhaust stroke. (4 cycle engine the piston travels up and down twice to complete the process.) If you line up the marks and your rotor is pointing to the #1 spark plug wire contact position on the distributor cap, you are probably at TDC for the compression stroke and the appropriate timing mark. If it's 180 degrees opposite, then you are at the end of the exhaust stroke. By "static timing" I assume you mean that you just want to verify that the rotor is close to the correct ignition location to fire the #1 cylinder at the correct time. Checking the timing this way is pretty crude, but if you've removed the distributor, this is the starting point for getting things back to normal. Don't know about this sensor you refer to, but I've put distributors back into equipment engines, cars, etc in the past and if you get them backwards (180 degress off), they won't run. If the distributor became loose somehow and rotated a few degrees, the engine probably would run poorly or not at all. You could rotate the distributor enough at this point to get it back to near normal by making sure the ignition module and rotor were lined up, and the rotor was lined up with the #1 cylinder wire contact on the distributor cap. After you get it running, use a timing light to fine tune it.

Please Log in or Create an account to join the conversation.

1990 2755 - sold
2005 275 current vessel

5.0 MPI 2007 TDC marks ????? 11 Jun 2009 17:50 #3

  • joeydiver
  • joeydiver's Avatar
  • Offline
  • Elite Member
  • Elite Member
  • Posts: 715
  • Thank you received: 0
Bob,

As a side note, if you havent replaced the distributor cap and rotor: a mechanic told me yesterday the distributor caps and rotors on previous 5.0L's had bad condensation problems which would cause missifires, something about them being old automotive caps. Suppossedly Merc has since rectified it.

Just something to keep an eye out for.

Joey

Please Log in or Create an account to join the conversation.

2007 Discovery 246
5.0L MPI BRAVO III
The "BAY-BEA"

5.0 MPI 2007 TDC marks ????? 11 Jun 2009 20:41 #4

  • boblydon
  • boblydon's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 63
  • Thank you received: 0
Rick,

Thanks for the quick reply, i am trying to make sure the timing is correct ( approx ), i am sure i read somewhere that if the timing is a long way out, then the hall sensor in the distributer does not send a pulse to the ECM, which in turn does not tell the coil to spark....my problem is i cant get the coil to spark so am trying everything and checking everything possible..then begging for help and advice on what else to look for.

Joey,

Thanks as allways for your advice, am getting desparate now to start it, will have to start throwing new bits at it soon

Please Log in or Create an account to join the conversation.

5.0 MPI 2007 TDC marks ????? 11 Jun 2009 21:00 #5

  • Rick Kenyon
  • Rick Kenyon's Avatar
  • Away
  • Premium Member
  • Premium Member
  • Posts: 332
  • Thank you received: 6
Well, if you line up the timing marks, rotor to dist cap wire #1 contact position and the rotor is also lined up with the ignition module contact, it should be close enough to fire the engine at least. Perhaps that sensor you are referring to is bad? Does the manual tell you how to test that? Just another thought.

Please Log in or Create an account to join the conversation.

1990 2755 - sold
2005 275 current vessel

5.0 MPI 2007 TDC marks ????? 11 Jun 2009 22:39 #6

  • boblydon
  • boblydon's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 63
  • Thank you received: 0
The mercruiser manual tells you nothing about the MPI and how to test the various components, which is a big shame as it costs a small fortune to buy....i think it wrongly presumes we all own or have access to a diagnostic tool, as i said before, no where does it mention the mark on the harmonic ballancer, you dont even get wiring diagram never mind a flow chart of what gives what a signal to start.

If i could find out what gives ECM it signals, i might have a small chance in fixing it...have even tried to buy diagnostic tool, but cant even seem to do that at the minute...once i can get it started on base timing i will then be able to set it correctly with the timing light.

When i go to sleep at night i keep dreaming the tooth fairy will have left the answer as to why the coil wont spark under my pillow....here's hoping!!

Please Log in or Create an account to join the conversation.

5.0 MPI 2007 TDC marks ????? 12 Jun 2009 13:06 #7

  • Rick Kenyon
  • Rick Kenyon's Avatar
  • Away
  • Premium Member
  • Premium Member
  • Posts: 332
  • Thank you received: 6
Probably not going to be an issue for you since the engine is so new, but have you looked at the shift assist switch to make sure it's in the neutral position? I had a starting problem one time and it happened because the shift assist switch was not returning to the neutral position when shifting out of gear. I fooled with that thing for a day, changed the distributor cap, rotor, ignition module, still could not get the thing to start. A mechanic told me to check the switch and sure enough, it was hanging up still partially in the interrupt position, not the neutral position. The real culprit was the lower unit shift cable being worn out and not sliding freely enough to allow the switch to return to the neutral position when shifting from reverse to neutral. It took me over a day to figure that one out and only because an experienced mechanic told me where to look next. Just another thing to check.

Please Log in or Create an account to join the conversation.

1990 2755 - sold
2005 275 current vessel

5.0 MPI 2007 TDC marks ????? 12 Jun 2009 14:14 #8

  • 2850Bounty
  • 2850Bounty's Avatar
  • Offline
  • Platinum Member
  • Platinum Member
  • Posts: 24478
  • Thank you received: 1121
I believe that these are a photo eye triggering system ignition..... many manufacturers have had their issues with these over the years. Since you mention that you are not getting any spark, it may be possible that this photo unit is bad. Hopefully there is a trouble shooting section in your OEM manual that will address this.

Now, is this system using a flywheel sensor unit at the rear of the engine?
Again, see if there is a trouble shooting section for this in your OEM manual.

Once you do get it running, you can strobe the timing marks and see what it is doing.

Check Rick's idea of the shift interrupt if this is an Alpha drive.
5.0L engine...... very likely it is!

Please Log in or Create an account to join the conversation.

Rick E. Portland, Oregon
2850 Bounty Sedan Flybridge model
Twin 270 HP 5.7's w/ Closed Cooling
Volvo Penta DuoProp Drives
Kohler 4 CZ Gen Set

5.0 MPI 2007 TDC marks ????? 14 Jun 2009 20:35 #9

  • boblydon
  • boblydon's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 63
  • Thank you received: 0
Thanks for the replys, sorry for the delay in replying but just got back from a 2 day boat delivery job.

My drive unit is a bravo 3, which as far as i am lead to believe does not have the shift interrupter ( unless it was removed by the salvage company who recovered her ), however it does have a plug which is in that vicinty but not connected to anything....this may be something for me to look at as this plug does not have cover on it...maybe it did have something on it ( cover ) which was linked out for a open or closed curcuit.

I have found the manufactuers workshop manual very poor when it comes to the ignition system for testing and fault findings on components...has anybody else found this?

Please Log in or Create an account to join the conversation.

5.0 MPI 2007 TDC marks ????? 15 Jun 2009 01:45 #10

  • bkaltec
  • bkaltec's Avatar
  • Offline
  • Junior Member
  • Junior Member
  • Posts: 71
  • Thank you received: 1
Im not sure of how Mercruiser sets up their engine control modules. But if its anything like the GM ecm's, you wont be able to adjust the timing without a scanner/programmer. As far as positioning, all you can do is get it as close to #1 firing position on the cap/rotor.

Cam retard (timing) is adjusted with a scanner once the engine is running. From what i can remember, gm uses the crank position sensor to run spark timing and the cam position sensor to run fuel timing on sequential multiport injection.

You should find out if youre getting any spark at all, uplug a plug wire, stick a screw driver in it and position the screwdriver close to the block, within 1/4 inch, turn it over and watch/listen for spark.
If you are, then take out #1 plug, bump youre engine over to compression stroke, hand crank it to tdc. Youll need a ratchet for this, theres a bolt in the center of the crank pully you can use. Then take off the distributor cap and make sure the rotor is pointing to #1 plug wire. Again, timing should have to be reset with a scan tool, you might need to check with mercruiser on that.

If youre not getting spark. Make sure your coil is getting power, should be 12guage +pos in run/start. Make sure the knock sensor is plugged in tight, crank sensor is tight, as well as the coil and distributor.


Other than that, id say you need a scan tool.

Please Log in or Create an account to join the conversation.

5.0 MPI 2007 TDC marks ????? 16 Jun 2009 18:08 #11

  • boblydon
  • boblydon's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 63
  • Thank you received: 0
Well have just bit the bullet and order a rinda scan tool, looks like the only way i am going to be able to get this engine problem sorted...has anyone used one of these before, are they easy enough to ubderstand?

Please Log in or Create an account to join the conversation.

5.0 MPI 2007 TDC marks ????? 16 Jun 2009 19:27 #12

  • Merlin
  • Merlin's Avatar
  • Offline
  • New Member
  • New Member
  • Posts: 17
  • Thank you received: 0
Congrats Bob!!

Looks like you could be the new Hi-Tech Tri-Tech Merc guy down the marina in future! :cool:

Hope it helps sort the problem out. :)

Please Log in or Create an account to join the conversation.

Ian S.
'89 5.0L Merc LX/OMC Cobra (Don't Ask! Please!!)
'88 Trophy HardTop (Dunno Model Tho!)
6 YEARS BOATING, AND STILL LEARNING!!
AN OLD BOAT IS THE BEST THING TO GET
YOUR WORST ENEMY!!! ;) :D

5.0 MPI 2007 TDC marks ????? 17 Jun 2009 07:08 #13

  • boblydon
  • boblydon's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 63
  • Thank you received: 0
Not with out your help i wont be

Please Log in or Create an account to join the conversation.

5.0 MPI 2007 TDC marks ????? 17 Jun 2009 15:27 #14

  • bhawes
  • bhawes's Avatar
  • Away
  • Platinum Member
  • Platinum Member
  • Posts: 1952
  • Thank you received: 82
I just went through a similar scenario with my 4.3 l GM.
On the 4.3 there are 2 wires coming out of the ECM (mounted on the port exhaust manifold). These 2 wires have bullet connectors on them, and run behind the carb to the coil. One of them had become disconnected, and hence no spark to the coil.
It is not necessary to have a scanner to time these engines. What is necessary is to have a timing light with an advance/retard function. On my 4.3 the spec'd timing is 10 degrees btdc. By setting the timing light to a 10 degree advance, when the mark on the timing chain cover and the harmonic balancer line up, you are timed correctly (of course you have to get the thing running first).On this particular motor as well, you have to bypass the "knock sensing unit" by grounding a provided wire while doing the timing. I'm sure that the 5.0 is the same. The manual should tell you which wire this is and where to find it. Mine is on the starboard side of the intake manifold, just forward of the carb (purple and white I think, with a rubber stopper in the female bullet connector).
Good luck.

Please Log in or Create an account to join the conversation.

Bob Hawes.
Kelowna, B.C.
1998 Trophy 2052 WA
4.3 Vortec, A1 G2
  • Page:
  • 1
Moderators: Jim GandeeRuffryder
Time to create page: 0.110 seconds
Powered by Kunena Forum