merc 350 5.7 Loss of power

Loss of power about 2k rpm. Electrical items that have been replaced. ignition coil, ignition amplifier that connects to manifold. ignition module that fits inside of the distributor. mechanical fuel pump changed.

engine is out of boat for trouble shooting. I have done a cold compression test per advice from members here. results
1. 180 3. 180 5. 170 7. 179
2. 180 4. 170 6. 180 8. 180

danthemancarolina said:

engine is out of boat for trouble shooting.

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I don't see how you can troubleshoot a power problem with the engine out of the boat.
Suppose you could check your timing advance with a light capable of showing dynamic advance.
comp looks good.

Check the anti siphon valve at the fuel tank connection. clean the flame arrester. check fuel pressure.

providing the year and drive model/type will help for getting some suggestions.

Dan, glad to see a fresh thread. I think it will be beneficial.

Let's begin with ALL information.

You mention module inside of the ignition distributor.
Can we be clear that this is a Mercruiser TB EST Ignition system? There are several TB systems!

Can you mention what year model for us?
Can you mention which module is being used?
(different modules provide a different advance curve/limit...... also, a malfuntioning module may not be offering the necessary advance)
No, or Inadequate, Ignition Spark Advance..... and NO Power! Simple as that!

If Merc TB, are you aware that the ignition coil is specific for this system?

Can you bring us up to speed on your Ignition timing procedure that you used?
Did you use the OEM procedure for setting BASE or Initial Advance?
Did you use a marked off balancer and strobe light for dynamic timing?
Did you record any advance data? (you can actually plot out a curve on paper)

How about carburetion? Which type/make/model?

Which boat.... hull length, etc?

The more info.... the better!

I agree, the true test will be with the engine installed and under load. But the ducks must all be in a row prior!

.

If the compression is good, is there any need to do a leakdown test. Or does this tell that the valves are working properly??

If these compression readings (if in psi) are good!
They actually appear to be a tad better than what I'd expect for a full dished piston SBC Merc.
I'd say yes...... most all should be A-OK.

1. 180
2. 180
3. 180
4. 170
5. 170
6. 180
7. 179
8. 180

.

I have entered the answer to the questions by underlining the answers. thank you again

RicardoMarine said:

Dan, glad to see a fresh thread. I think it will be beneficial.

Let's begin with ALL information.

You mention module inside of the ignition distributor.
Can we be clear that this is a Mercruiser TB EST Ignition system? There are several TB systems! est no points outside dis cap #J1171, ordered from merc dealer).

Can you mention what year model for us? 1986 wellcraft 200 classic
Can you mention which module is being used? merc dealer ordered and i cant find receipt, will open dist cap and look. will also look at the top cap and make sure there is no wear in the cap leads.
(different modules provide a different advance curve/limit...... also, a malfuntioning module may not be offering the necessary advance)
No, or Inadequate, Ignition Spark Advance..... and NO Power! Simple as that!

If Merc TB, are you aware that the ignition coil is specific for this system? Hmm, ordered from napa coil #1103 could be the culprit

Can you bring us up to speed on your Ignition timing procedure that you used?
Did you use the OEM procedure for setting BASE or Initial Advance? did the base 8btdc and curve 32 btdc
Did you use a marked off balancer and strobe light for dynamic timing? yes
Did you record any advance data? (you can actually plot out a curve on paper)

How about carburetion? Which type/make/model? rochester 4bbl reman

Which boat.... hull length, etc? wellcraft classic 200 20ft open bow. merc 5.7 350 ramanufactured, installed 2006 with reman carb, new heads, new manifold (vortec)and a new alpha 1 reman outdrive

The more info.... the better!

I agree, the true test will be with the engine installed and under load. But the ducks must all be in a row prior! took engine out to replace oil pan gasket. want it running right before installation

.

Click to expand...

I think that you are getting the module and triggering device confused with on another.
If this is a M/C TB EST, it will be Photo Eye triggering within the actual distributor. (a rotor wheel makes/breaks a infrared light beam that is sensed by a pick up unit)
The Ignition Module will be bolted onto the engine somewhere.
The rotor wheel triggers ONLY..... the Module does the actual advance control.
Each module # offers a different advance curve for different engines. So you can see why the correct module must be used.
I do not care for these systems!

Just to be clear..... you actually watched as the ignition advance climbed to 32* , but @ what RPM?
More specifically..... where was the advance (in crankshaft degrees) at/near 3,200 rpm?

TA numbers are worthless without an accompanying RPM.
Example: If a TA of 32* did not reach Full-In until 4,400 RPM, it would do almost ZERO for any power at 3,200 RPM.
So we must have an accompanying RPM for this figure to be of any real value.

.

Have not done the timing after the intial base timing. I thought the ignition module takes care of that. I have pics of the ignition module and the dist base and cap for review. just cant figure how to post a pic. It will be nice tommorow and I will take the engine out and get her running.

If your boat is a 1986 and the ignition is correct it is a thunderbolt IV (four).

Yes the timing module does the advance. You should get ~ 28 degress and it should be fully advanced by 2400-2800 rpm ( I forget the exact number). Add that to the 8 initial and it should be 32 TOTAL.

Typically on the module is a stamped number and the last two digits represent the modules total advance and the application, (V6 or V8) (the module only).

I am not sure if they still do this but they use to.

fuel pump is giving between 4-7 psi ?

You can when the motor is re-installed run it on a external tank of fresh clean fuel, no fuel water separator.

Then if the problem is still there i would do a vacuum test.

Please post the result of the vacuum test.

See the compression numbers are surprising good, great actually. So that leaves out overly tight valves.

click on the link

On Fire vacuum gage

danthemancarolina said:

1. Have not done the timing after the intial base timing.
2. I thought the ignition module takes care of that.

Click to expand...

1. You'll want to check this. I have explained how to do it. If unclear, please post back, and one of us will explain it differently..... sometimes that helps! There are no dumb questions..... so don't hesitate to ask.
2. True...... it does! However, until you strobe this, you will not know whether it is working correctly! You will be guessing ONLY!

Again, if the advance is not doing what it should be doing....., the engine will not provide the power that it is capable of producing, Period!
Not a chance in Hell!

kghost said:

If your boat is a 1986 and the ignition is correct it is a thunderbolt IV (four).

1. Yes the timing module does the advance. You should get ~ 28 degress and it should be fully advanced by 2400-2800 rpm ( I forget the exact number). Add that to the 8 initial and it should be 32 TOTAL.
2. Typically on the module is a stamped number and the last two digits represent the modules total advance and the application, (V6 or V8) (the module only).

I am not sure if they still do this but they use to.

Click to expand...

1. 32* by 2.4K rpm is definitely too much/too early if this is a typical Mercruiser SBC w/ full dished pistons, IMO. This engine will suffer Detonation with those numbers. Use Caution!
2. To be clear, and if memory serves me......, the module number represents the amout of added advance beyond BASE advance... NOT Total Advance! Do not confuse the two.

Kghost, double check me on that last one........ but I believe that is correct!

Dan, you may want to find an OEM ignition curve for your engine by model number. Use this data when checking your ignition advance.
I can't emphasize enough as to the importance of correct ignition timing! Both for performance, and to protect against Detonation damage.

There was a fairly recent thread whereby a member literally had the tops of several new pistons burn, due to a very similar issue.
He timed this engine by ear!
Not a pretty sight!

.

Rick,

I feel that some of the language used to describe things here for many people is a bit too elevated.

I would venture to say MOST do not have a grasp on the technical terms or english language that you may.

Maybe a step back to more basic words and terminologies may be taken into consideration.

OK I do not have much acess to stuff here at work, I do have one elec ignition pdf that contains info for TB IV V6 and TB V V8 only.
Both show the module advance (not including the initial timing) a max advance by ~ 2500 rpms.

The older point ignitions I believe came in later ie: 4000 rpms.

I do not have a manual at hand right now but i will when I get home tonight. I will double check this and repost for TB IV V8

Here is a pic from the MERC pdf for V8 engines. It has other stuff relating to the knock sensor and such but the point is WHEN the BOLD dark line reaches max value at what rpm.




View attachment 1819

kghost said:

Rick, I feel that some of the language used to describe things here for many people is a bit too elevated. I would venture to say MOST do not have a grasp on the technical terms or english language that you may.
Maybe a step back to more basic words and terminologies may be taken into consideration.

Click to expand...

That may be true, and I do understand and appreciate what you are suggesting. However, here's my take on this, while on the subject;

If the language is too elevated (as you nicely put it), then the actual task may be also!
If we were to use a more basic language and terminology, we may risk mis-comunication.... not only with the OP, but with anyone else chiming in as well.
I think that I'd much rather create a scenario whereby someone may need to ask what a Zoomfroid Valve is, rather than them NOT asking, and then going on to make an installation or application error.

Kghost, I guess what I'm saying is........, if we man-up to the task, we may as well man-up to the language! Should it prove to be somewhat over one's abillity, then they'll likely seek the assistance of a Marine Mechanic anyway.
I'm certainly willing to tone it down if the general consensus agrees. The goal is to help here... not to confuse!

What say all of yee to that?

.

The ignition module is 5j2-9a-v824. My manual says 8* btdc and 32* btdc at 3700 rpm. So ricardo If I understand your experience, then you want to see a total advance of 24* @ what rpm?? I mean the module has an advance of 24* btdc correct?? I am also going to call napa and get the specs for the ign coil in case they gave me a standard coil. that would make it run wrong according to the book.

Kghost you are correct the ignition system is a thunderbolt iv breakerless.

about the language, its fine, alot cleaner than the (thingy) language I use LOL

Dan, the last four digits are what I was refering to V824
That would be the correct module for a v8 and with a MODULE advance of 24 degrees. Add in the 8 initial and a total of 32. Some say V8 26 or more, typically for high performance motors and some big block 454/502...

So you are good for that.

If you were to point the timing light at the marker on the balancer and the tab on the timing cover at idle you should see 8" before top dead center. BTDC

as you give the motor throttle the mark should advance. Now you will not know how much unless you have a timing light with some kind of advance ability (a turn knob or push button) If you do not You basically will have to take a guess.

The timimg tab may give you some ability to judge this. eyeball the ZERO point on the tab and visually measure the distance to 12 degrees, four more than initial. Now as the rpms increase the mark should be moving in a C'clockwise = advance direction. the module will allow for 24 degrees BUT when you add in the 8 initial the total you should see at "say" 3000-3500 rpms is 32 degrees before top dead center BTDC.

If your initial was set to ZERO then all you would see is 24 total advance from the module. BTDC

This exersize is to confirm the timing advance module is doing what it is supose to be doing, Advancing the timing and doing it when it is supose to (by 3500 rpms).

Simple as that......................I hope!!

lanquage..........all good.........lol

Dan, put the red thingy in the round what-cha-ma-bob, and turn the other thing to the left..... opps, I mean to the right. Be sure that the metal thing is locked down. That should work!

Dan, on a serious note, according to what I decode, your TB IV module offers an advance of 24*.
This is NOT total advance..... this is Module advance ONLY!
BASE or Initial advance will be added to this once up and running.
So, in essence, your math is incorrect!
You will want to add BASE (8* btdc) to the module advance (24* btdc)
This totals 32*....... 32* will be your TA... but ONLY if the module is working correctly.

As you strobe the timing marks, you can't help but read the sum of both BASE and Total.
This does NOT mean that your IV module is offering what the specs suggests that it will.
It will......., but ONLY if it is working correctly....... hence the reason for strobing your timing marks as rpm is increased to the point of NO MORE Advance.
This is your means of varifying TA. Jot these numbers down on paper.

If your balance is not marked off, Mr. Gasket offers a decal that can be place on the balancer. Balancer diameter must be known, in order to purchase the correct decal.
I think that these run about $7.


It's nothing more than a progressive advancing system.... all related to engine rpm and crankshaft angle (i.e., degrees of crankshaft position, relative to TDC for each cylinder).


Dan, unfortunately, I do not know if your TB IV must go into BASE mode to set "Initial" timing. You'll need to see an OEM manual for this.
Perhaps Kghost knows this........ I'm a Volvo Penta schmuck!

However, if it does require a BASE Mode..... once timed for BASE, it must be taken back out of BASE Mode before checking TA.... or for that matter, when done.

Good luck on this!
We should have this wrapped up by May or June! LOL

.

No base mode for TB IV.
Simply set it and forget it............the same way as done in years past.

The "base" mode issue came about when they added the KNOCK sensor. The knock sensor then adjusted timing on the fly based on sensor feed back to the module. TBIV did not have the knock sensor. Not all TB V did either. there was a split when introduced. Also I think they went to a digital EST type distributor and that one also needed a jumper used to set BASE mode. The 4 cycl had this digital dist back in the early 90's. It required the jumper to achieve base mode.

I may be a bit off on the years but i think you get the idea........

The ignition module is 5j2-9a-v824. My manual says 8* btdc and 32* btdc at 3700 rpm. So ricardo If I understand your experience, then you want to see a total advance of 24* @ what rpm?? I mean the module has an advance of 24* btdc correct?? I am also going to call napa and get the specs for the ign coil in case they gave me a standard coil. that would make it run wrong according to the book.

Kghost you are correct the ignition system is a thunderbolt iv breakerless.

about the language, its fine, alot cleaner than the (thingy) language I use LOL

napa # (SME 185438) v6, v8 HEI marine ignition coil, Replaces merc oem #'s Mercury Marine 392-7803A4, 392-805570A2.

I can not answer if the OEM for your motor is either the numbers above from here.........at work......

You could look at this site for that info and for replacement parts..........including ignition coils.

NAPA # (SME 185433) is the points ignition coil.....

Which one do you have?

Dan, are you having a senior moment? LOL
(your post #20 is same as post #16)

I'd like to reserve the senior moments to myself, if you don't mind.

ok just for the record

Merc Technicians Manual for model year 1995 ( all I feel like looking at right now)

Advance, max timing at a certain RPM per module plus initial.

3.0 with EST ignition. @ 2800 rpm, 22 to 24 degrees BTDC, Initial 1 degree BTDC Total 23 to 25 degrees

V6 262 cid Thunderbolt IV @ 2500 rpm 13 to 15 degrees BTDC, Initial 8 degrees BTDC Total 21 to 23 degrees

V8 305 cid Thunderbolt IV @ 3400 rpm 20 to 24 degrees BTDC, Initial 8 degrees BTDC Total 28 to 32 degrees

V8 350 cid Thunderbolt IV @ 4400 rpm 20 to 24 degrees BTDC, Initial 8 degrees BTDC Total 28 to 32 degrees

There are other specs for SKI magnum 350 and big blocks but this is good enough for our discussion

Dan, are you having a senior moment? LOL
(your post #20 is same as post #16)

I'd like to reserve the senior moments to myself, if you don't mind

(Actually my computer was having a senior moment, as it most always does!!!!)

kghost, about the coil, i looked up one from napa as well and got the same number you did. daughters boyfriend is going to order the coil, rotor cap, new plugs, new plug wires, fuel filter and oil filter. probably wont get these for a couple of days. but we get them at cost!!!! so its worth the wait.

I totally understand the timing, now just need the parts to oil her up and fire the beast.....going to get a tach from hf tommorow to assist in the timing diagnosis prior to placing back in the boat...(kind words from alan "If it was me, id have her timed and purring like a kitten before going in a boat") so thats what I am going to do....ok guys take a break for a couple days. will post back once i get her prettied up....

There is a cure to all of this Mercruiser Thunderbolt IV distributor, module, this/that and the other stuff! It looks like this, and it's called a YLM 624 AV, by Mallory:



Uses VR triggering, mech Advance (No photo eye, No EST module). VR has been in used since the early 70's, it is tried and proven, extremely low failure rate, if any at all. It's the only system that I'll use on an AQ series VP Marine SBC. It will do just as well on the M/C.

E-Bay seller "Chimptoast" is selling these for way below what I can purchase one from my supplier for.......... $170 + shipping.

Pretty darn hard to beat both the YLM and that price, IMO!