Timing and gap

[clasavi]

Good evening,

I am in need of the following info: timing procedures and spark plug gap. I purchased ac delco plugs ( mr43lts)

I have a 1998 mercuries 350 EFI MPI
Engine Serial OL067176
Sterndrive OL153367

Thanks

Claudio

 

[Bt Doctur]

Re: Timing and gap

I give up, what type of spark plugs did you buy? your manual is here using that serial number, http://www.atlanticmobilemarine.com/service manual 5&57.pdf

 

[clasavi]

Re: Timing and gap

Thank you bt doctur. I read the manual but it doesn't tell me the specific gap nor timing instructions

 

[Bt Doctur]

Re: Timing and gap

re-read page 1B-37 for timing instructions and page 4B-4 for engine specs. You read what manual, the one in the posted link?

 

[clasavi]

Re: Timing and gap

Thank you for the help. Here's my new problem. When I went to hook up the timing tool to the harness I noticed 2 of the wires had been spliced (pink and brown). At this point the tool does me no good. Can anyone tell me which two worse I need to jump in order for it to go into idle mode?

Any help will be great

 

[Bt Doctur]

Re: Timing and gap

4B-5 is for Thunderbolt, 4B-6 is EFI,MPI. nothing mentions cutting or splicing any wires. Checking the mpi wiring diagram there is no listing for those colored wires. Brown can be used for an alt feed up to 5 amps I think.

 

[clasavi]

Re: Timing and gap

Thanks for the prompt reply. Sorry, who ever worked on it before me spliced the wires.

Which two color wires need to be jumped?

That's always my luck, nothing is ever easy!! But it worth it

 

[Bt Doctur]

Re: Timing and gap

 

[Bt Doctur]

Re: Timing and gap

with efi/mpi there is nothing to jump. T-Bolt V needs to be put in base mode by grounding the purple/white lead at the dist.

 

[clasavi]

Re: Timing and gap

Ok, timing is set.

Went for a ride and it started knocking under load. Any suggestion? Could I have not set the timing right or I have another issue?

 

[Bt Doctur]

Re: Timing and gap

poor fuel, incorrect timing

 

[Fun Times]

Re: Timing and gap

with efi/mpi there is nothing to jump.

Since the OP has an MERCRUISER 350 MAG BRAVO MPI (GEN+) he'll have to set it in to service mode. To do that you would need a scan tool, or a Winky Blinky tool from Rinda Technologies, or to cheat the system, carefully jump pins A and B at the data link connector. #6 in the diagram above.

If you did not put the system into service mode, you did not set the timing correctly and it is way off thus making your engine knock under load.

http://www.google.com/url?sa=t&rct=...IRrEJXF-gFpJJDs6bD9wreA&bvm=bv.63316862,d.cGU

Search Results - Crowley Marine

 

[clasavi]

Re: Timing and gap

Thank you. I had the mechanic try to set the timing but on the test run the boat didn't run right.

If I may add my boat is EFI. Does it make a difference?

However, I did notice that when he hooked up the timing tool, the engine speed did not increase. Why would that be? I'm tempted to jump the wires myself, what u happen to know the colors of wire a and wire b?

Also, how can I find 8 degree on the harmonic balancer? It's been painted and I can't see it

 

[Fun Times]

Re: Timing and gap

Some of the early models like yours still called the MPI's EFI before going fully with the MPI name change, so that could be the most of confusion. Running your serial number (if correct?) shows MPI. Typically with these engines the EFI is more thought to be of a throttle body design vs multi port fuel injection.

For example in 96 and 97 they called the 350 MAGNUM BRAVO (EFI-MP GEN+) but in 98 it went to 350 MAGNUM MPI ALPHA/BRAVO (GEN+) ENGINE but the 1997 5.7LX TBI BRAV0 350 TBI MAG ALPHA they call it EFI. So anything is possible.

If the engine did/does not rev up automatically when put into service mode then you have to do it for it is all. Go to 1800 RPM then put it into service mode and set timing. Your engine model year was right around some big changes so the S-B link above may not apply.

The DLC should have the letters on it. The wires should be black/white and Black. They are next to each other.

The easiest way to set this timing would be to have a advance timing light with a dial indicator and line up the two marks in the V (0*) with your light set at 8. Xenon Timing Light with Advance

 

[clasavi]

Re: Timing and gap

Great Thank you.
Everything is set correctly however the knocking/firing still takes places under load. Anything else I should check?

 

[Fun Times]

Re: Timing and gap

Fuel pressure and check fuel condition. Try an external fuel tank. Watch the advance with the timing light to be sure it's going up to 25+ degrees under load.

 

[clasavi]

Re: Timing and gap

I will check all of it tomorrow and advise.

Meanwhile, assuming it's not the gas and the fuel pressure is good what else could it be?

The reason I'm asking is because I'm ready to either change everything that could be wrong with it before the mechanic gets to it at $100/hr. I know it may seem crazy but I'm tired of playing around with it. changing what could be wrong with it is cheaper than a new engine and assures me less breakdown in the future.

Should I replace what next?

 

[Walt T]

Re: Timing and gap

Hiring a tech can be way cheaper than throwing parts at it. A good tech can diagnose a problem within an hour. The problem is finding a tech that doesn't throw parts at it also in which case you are right, you can throw parts at it perfectly well too.

Knocking/pinging:
Ignition timing is wrong.
Knock sensor bad/ wiring/ plug/ pins at main connector
Balancer spun or wrong balancer causing mark to be off. Usually a spun balancer tends to retard timing mark. I've seen this quite a few times. Have to set timing by "ear" which means going out on the lake with the timing light and resetting timing right up until it stops knocking. Helps a great deal to have marking tape on the balancer to keep track of where you're setting it. If you set it to where knocking stops and the boat has lost all kinds of power, something else is causing it.
Wrong or damaged, cracked spark plugs
Combustion temperatures too high engine is overheating or hotter than gauge says / compression too high for gas used. Run compression test and check actual temperature with rectal thermometer.
Running lean causing higher combustion temps. Map sensor. Unlikely with your MPI system but check fuel pressure. Can't hurt and you'll look like you know what you're doing.
Fuel octane too low/incorrect gas type (more than 15% ethanol)
Misfiring for other ignition reasons, 5 & 7 plug wires crossfire, fuel cooler not cooling.
Damage on piston, valves, or head causing hot spot which ignites fuel early
It's not pinging or ignition related at all, its something else, coupler, flywheel, U joints, bearing knock, Tiny man in bilge beating on engine with hammer
Cam jumped a tooth, tooth fought back and beat up cam. Cam no longer jumps those dang teeth cause they tough bastids
Neighbor is dumping his Coleman fuel in your boats tank (actually had a customer that had this one) or something is in the tank or gas you don't know about. Maybe that tiny guy and his hammer in there.
Trailer still attached to boat. Hey we all heard about that blonde and her Bayliner
Sell boat to unsuspecting buyer who then fixes it right there in front of you in 3 minutes. Waves at you every time he zips by you on the lake. Your new boat develops a suspicious knocking noise.
Environists (I leave the 'mental' out) have gotten to the refineries and the entire nation is now knocking but the young kids with buds in their ears can't hear it, old people can't hear it, middle age people hear it, don't care and turn up stereo. Environists gnash teeth. Dentists rejoice.
I was just kidding about the rectal thermometer hopefully you didn't open the package and can still return it. They tend to not want those back if they appear to have been used.
Get out of boating all together and hang out here teaming up with me giving wrong advice that sinks peoples boats n stuff.