10 Pts to Answer 5.7 4100 WOT

[jeremyhuston]

Re: 10 Pts to Answer 5.7 4100 WOT

I soaked everything in my parts washer. Then sprayed down well with carb cleaner. Lastly I blew everything with my air compressor. Im going to test tonight. I will be back with results fixed or not simply so there is an answer to the issue

 

[jeremyhuston]

Re: 10 Pts to Answer 5.7 4100 WOT

Also. I have a 12 bolt intake.. non vortec heads. Therefore no knock. I am at maybe 800'im elev. (Indiana) the premium was to help clean. I am running 89 last fill up. Will see tonight

 

[John_S]

Re: 10 Pts to Answer 5.7 4100 WOT

Also. I have a 12 bolt intake.. non vortec heads. Therefore no knock. I am at maybe 800'im elev. (Indiana) the premium was to help clean. I am running 89 last fill up. Will see tonight

If it is not advancing, outside of a wiring/connection issue, the ICM is the prime suspect. Your engine may have the old style T5 module (one connector) and not the newer (two squarish connectors). The early has been discontinued, and will need the retrofit kit with new connectors. The price of the module will make you consider an alternative marine ignition. Let's hope it was the carb.

You should be able to hit mid to upper 40's mph with that engine/boat. Are you triming it out, like what was asked above?

 

[jeremyhuston]

Re: 10 Pts to Answer 5.7 4100 WOT

Ok, so got the boat out today.. Carb ran great.. BUT.. even with trim barely touching 4150 RPM? SO.. I looked through manual 24 and I think my engine does in deed have a knock sensor? Tomorrow I am going to test to see if the circuit is ok. (meter hooked up to purple/white, tap engine look for voltage reduction? ) Could a bad knock sensor stop the engine from Advancing? BTW mine is the T5, it has the one connector which I messed with and didnt do anything. SO.. If no one disagrees knock sensor, then bite the bulledt and maybe put a GM TBI system on this thing before I spend $400 on ignition module. Wouldnt the knock sensor from a say 94 Pickup with 350 SBC work on this application?

When I looked at the engine revved to 3k the spark advance was irratic unlike a car engine that I work on.

 

[fossill]

Re: 10 Pts to Answer 5.7 4100 WOT

What's the mechanical condition of the engine? Flame arrestor clean?
What about the prop, Is it a quality model and undamaged?
Is the hull clean?
Verify speed with a gps and rpm with a shop tach.
That engine/boat combo should twist a 21 pitch prop with ease.

 

[John_S]

Re: 10 Pts to Answer 5.7 4100 WOT

BTW mine is the T5, it has the one connector which I messed with and didnt do anything. SO..
When I looked at the engine revved to 3k the spark advance was irratic unlike a car engine that I work on.

While your boat is a '98, engine is '97 vintage, and the manual for that is #17. #24 only covers vortec sbc. Per #17 this is only a 210hp engine, and wot range is 4200 - 4600. I have the same engine in my 20' bowrider, with same drive ratio. While I have modified engine since then, the right prop was a merc black max 19"P, which I got 4500 rpms with my normal family load.

If you had a knock sensor, a knock module would have been piggybacked over the ICM. ie it looks like a slighly smaller ICM.

T5 can look erratic because it has adaptive functions. If it was erratic under load, engine would be surging. What is the advance with engine held at 3K rpms at the dock? Also, put it in base mode and do the same test. You don't want to do an expensive shotgun approach to the ICM.

You mentioned reading engine vacuum in an earlier post. What was the results at idle and doing rev tests?


PS: Since you were using #24, did you replace the plugs with the non-extended version for standard heads? Also, since you replaced wires, reverify the firing order. Prior owner might have had it wrong too. Anyway, need to systematically go through the provided list.

 

[jeremyhuston]

Re: 10 Pts to Answer 5.7 4100 WOT

Ok. So I had a chance to take boat out tonight. On the way home I picked up a working ignition module (which ended up being the wrong one). I did look and can confirm I have no knock sensor or module. So. I also looked at advance and it does appear the engine is advancing. On the water I ran wot and the boat ran the same. 4100. As I trimmed up I got a little high and the engine revved up to 4600. But the boat slowed down. What's going on. There? No load? Where do I go from here?

To recap. New plugs. Wires. Cap rotor. Rebuilt carb. I have confirmed base time at 10 degrees. And it does seem that the timing is advancing. Where to now?

 

[180shabah]

Re: 10 Pts to Answer 5.7 4100 WOT

... As I trimmed up I got a little high and the engine revved up to 4600. But the boat slowed down. What's going on. There?

You ventilated the prop - no biggie, just don't make a habit of it

Have you done a compression test yet?

 

[jeremyhuston]

Re: 10 Pts to Answer 5.7 4100 WOT

150 every cylinder

 

[QC]

Re: 10 Pts to Answer 5.7 4100 WOT

Verify speed with a gps and rpm with a shop tach.

What he said . . .

 

[John_S]

Re: 10 Pts to Answer 5.7 4100 WOT

What he said . . .

While your speed seems reasonable for rpms you are reaching, for that boat and drive ratio, it is best to make sure you are not chasing your tail. An auto gps battery should last long enough to get a speed verification.

Do you have the factory boat weight and deadrise specs?



List of possible causes of low WOT (Wide Open Throttle) rpm.

In no particular order

Engine Won't Reach Operating RPM. Check

2. Propeller pitch or diameter, damaged blades (As noted 14.5 x 19.. Should be under propped)
That is probably the right prop for boat/motor/drive ratio. What brand/type prop? and does it look like new? A prop such as a Hustler may explain lower rpms, but think speed would have been higher than you reported. Do you have a 17P or could borrow one to test? That should get you into the "good" range while you continue to pursue issue.


3. Restricted fuel pickup tube or anti siphon valve Fuel System Test (will check, but doesn't seem logical)
Easiest to test this with a portable fuel tank and hose feeding fuel pump.


7. Restricted carburetor air intake (clogged flame arrestor) (cleaned)
Choke oppened fully? I'm betting yes, but didn't see it mentioned.

8. Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive (help here? doesnt overheat.. what else to check)
Need to pull the exhaust hoses to see if they are there. If not there, pull the drive, you will probably find them.


11. Fuel pump pressure and vacuum (Again, runs?)
Running doesn't mean you can eliminate the test. I think you have a mech pump. If so any fuel in the tube going to carb?


12. Boat overloaded, improperly loaded, or improperly trimmed. (nope. Me and wife)
That is a lite load, and I know you think boat is light, but watterlogged foam is still not out of the question.


13. Engine Overheating (stays at 180)
While that is not overheating, it is on the high side. May be just gauge or sensor. Mine is 175, and 180 would indicat a problem for me. Even if accurate, I wouldn't believe that would hold the speed back. Alarm should go off in the 185-190 degree range.

14. Engine timing and ignition system operation (checked as noted above, 10 advanced base timing, new tuneup)
"Seems to be advancing" Does that mean you saw approximatly 25 BTDC at 3K rpms?

 

[z1nonlyone]

Re: 10 Pts to Answer 5.7 4100 WOT

I know someone asked, but I did not see the answer,,,,what altitude are you running the boat at? I have a 19.5 foot chapparal w/ a 5.7 EFI and I can get almost 5 grand on the tach at sea level. At lake powell at 3600 feet elevation, I can only get about 4400 rpm with a 19" pitch prop. Switching to a 17" pitch this year to get back into the proper rpm range.

 

[John_S]

Re: 10 Pts to Answer 5.7 4100 WOT

I know someone asked, but I did not see the answer,,,,what altitude are you running the boat at? I have a 19.5 foot chapparal w/ a 5.7 EFI and I can get almost 5 grand on the tach at sea level. At lake powell at 3600 feet elevation, I can only get about 4400 rpm with a 19" pitch prop. Switching to a 17" pitch this year to get back into the proper rpm range.

I think it is buried in one of his posts. 800ft, which is almost half the elevation I boat at. Unless that maxxum has allot more weight, more deadrise, or other significant hull differences, I would think his performance should be near what I had with same motor/drive. My hull would not be considered a "fast" hull by any means. If his speed and tach are verified, I think there is an issue somewhere.

 

[AZSenza]

Re: 10 Pts to Answer 5.7 4100 WOT

On a side note, my '97 NON Vortec 5.7 is Fuel Injected, has T5 ignition, a knock sensor and pushes my 22' Boat with a Bravo III and 26p props to 4800 RPM and 55 MPH at 1600 feet ASL, lightly loaded, full fuel. When I got her, plugs were original and worn, only did 4200 RPM and 50 MPH, changed to correct plugs and off she went.

 

[jeremyhuston]

Re: 10 Pts to Answer 5.7 4100 WOT

I think I used the delco mr 34t plugs gapped at. 045.

I don't think my boat has foam to be water logged?

How can I check exhaust. What do I take apart.where and what to look for?

 

[John_S]

Re: 10 Pts to Answer 5.7 4100 WOT

I think I used the delco mr 34t plugs gapped at. 045.

I don't think my boat has foam to be water logged?

How can I check exhaust. What do I take apart.where and what to look for?

AC MR43T

I would guess there is foam, but it is going to be under the floor and in other areas where you can't visually see it. It is sometime easier to scale you boat/motor/trailer, and then subtract the weight of the trailer, and compare to mfg spec. Could email maxum with your model # and they should tell you for sure. Also won't hurt to ask about specific boat model/motor/prop expected performance numbers.

The shutters are item #7. The elbows(#3) and hose (#5) usually have to come off to inspect to see if the shutters are there.

 

[jeremyhuston]

Re: 10 Pts to Answer 5.7 4100 WOT

Boat is a 1998 maxum 2000 sf

I will check the "flappers" tonight. Only connection to the 4100space rpm is if it is restricting the exhaust correct?

 

[John_S]

Re: 10 Pts to Answer 5.7 4100 WOT

Boat is a 1998 maxum 2000 sf

I will check the "flappers" tonight. Only connection to the 4100space rpm is if it is restricting the exhaust correct?

Yes, they fall down and usually lodge in the exhaust on the shift rod.

From a Maxum parts manual for your boat, it came with a 62587 PROP 15 1/2 X 18 X 3 AL RH I didn't find any hull specs. If you have them, please post. My stock prop was a 15" X 19" X 3 AL. With no other data, that may indicate you do have a heavier and/or more deadrise than mine.

 

[jeremyhuston]

Re: 10 Pts to Answer 5.7 4100 WOT

Where would I find that info? This is my first boat. And I've only had it 3is weeks... the current prop is a 14.5 x 19

 

[John_S]

Re: 10 Pts to Answer 5.7 4100 WOT

Where would I find that info? This is my first boat. And I've only had it 3is weeks... the current prop is a 14.5 x 19

http://www.maxumcustomercare.com/

Go to part manuals, year, sport boat, 2000sf

This is your engine pkg:

210 M C/A1 5.7L (EK5)
ENGINE SYSTEMS
Ref. # Part # Description Quantity
* 62234 5.7L A1 1.47:1 SD 1.0 EA
* 62587 PROP 15 1/2 X 18 X 3 AL RH 1.0 EA
* 36315 3" RISER KIT 1.0 EA
* 64560 5.7 EXHAUST ELBOW,3" 2.0 EA

The difference between that prop and what you are running is neglegable. A bit more stearn lift and bite on acceleration, but wot rpm would probably be about same.