Mercruiser 3.0 1997 bogging at 1500 rpm

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I have a 1997 Sea Ray 3.0lx that runs great except it has a couple of minor issues. I hope someone can give me advice on working out these issues.

1st issue
If I throttle up slowly, when I get to about 1500 rpms (my tach is probably not correct but it's a point of reference) the engine starts to "bog". It feels like it's getting too much gas. If I accelerate past 1600 it smooths out and runs flawless. If I accelerate quickly (like pulling a wake board) it doesn't miss a beat and I never feel the "bog" at all. I will describe what I've done below....

2nd issue (maybe related to 1st issue)
It runs a little rough at idle after the boat is warmed up. I have to give it a little gas after it starts up and pump the accelerator a few times to hold idle without conking out.

New plugs (gap to specs), wires, distributor cap, rotor
Timed in "base timing mode" to 1% Top dead center (to specs)
- Base timing seemed to do exactly what the manual said it would do
- Timing verified at reputable boat repair shop
Removed all gas and ran about four tanks of fresh gas (fishing and playing)
Tried all three positions on the carb accelerator pump
Had carb rebuilt at a very reputable boat repair shop (new pump, needle, etc..)
 

fat fanny

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

Well if you trust all the work performed by your shop to be accurate the 1st thing I would do is check all electrical connetions clean and tighten, Then verify that your anti siphon valve is working correctly and is not sticking,also verify that you are getting the correct fuel pressure to the carb, Make sure your flame arrestor isn't clogged (clean it) after that go to the stickies section at the top of this forum and use the posted info for the issues your experiencing. I would lean more toward the choke and or the accelerator pump in your carb if it were me. I had a similar issue w/ my 95 LX and it turned out to be the timming wasn't advancing corrrectlly and I had to replace the ignition module but in any case go through the inexspensive items 1st and always by GM replacement electrical components or your just wasting your time! Good Luck!!!!
 
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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

Good advice on all accounts. I did the tune up myself with some help and ran through the check list with the shop. They verified my work, river tested the boat, then rebuilt the carb. The problem was less noticable, but it still isn't perfect. I don't know for sure that the IM is working perfect, but it did seem to go into base timing mode properly and actually ran better after timing it to 1%ATDC. Once out of base timing, the timing read around 12%ATDC. It's been a month or two so I don't remember the exact number, but it was what the manual said it would be.

I'll go through the electrical as you suggest and also look at the pickup coil. It's an inexpensive part to replace if it's not working properly. The shop changed the fuel filter on the fuel pump and at the carb by the way. Flame arrester is very clean (did that during tune up). I'll also test the accelerator pump setting now that the carb has been rebuilt. Couldn't hurt.

I'm new to this site. What are the "stickies sections". Thank you for your help, it's much appreciated.
 

fat fanny

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

It's @ the top of this I/O forum (ADULYS ONLY STICKIES) it has a wealth of usefull info for general repair and frequently asked questions. A couple of other issues you may want to consider is a compression test and the carb if it's a mercarb it may just be worn on the shafts to the butterflies?? Once again Good Luck! and report back w/ your solutions.
 
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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

I'll spend a little more time tracking down the issue. Hopefully I find out what's causing this. Thanks again.
 
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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

Haven't had time to do work on boat lately but I was having a battery issue so I had it tested yesterday. Every time I started the boat, my stereo and GPS would turn off. Additionally, my GPS would not immediately report the depth. Turns out, it was registering 12 volts but the amperage was very low. Had it replaced, problem with battery solved and.... the bogging seemed to be barely noticeable last night. It still bogs, but it's very slight now (as of last night). Not sure it's completely fixed, but it certainly seems better now.
 

smartwork

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

Did you by chance also have your alternator tested?
 
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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

No, I didn't have the alternator tested but I was told that the battery probably had a bad cell and it wasn't putting out the recommended amps. The new battery solved the GPS related issues and it seems to have diminished my bogging problem although it still has a "soft" spot. Probably not a bad idea to check the alternator too. I've never had a problem with the battery going so low it wouldn't start the boat so I assumed it was charging.
 

smartwork

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

The only reason I asked about the alternator is because you indicated that the new battery perked up your "bogging spot". With the engine running off the alternator's power, I was surprised to read the battery affected the engine's performance, so that made me wonder if your alternator wasn't performing at 100% and your engine was partially sucking off the battery while running.
 
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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

That's a good point and I need to take the boat out again the weekend to verify that there really was a change in performance. As I said, the problem is still there but it seems to be diminished to a degree. I can probably find a method to test the alternator in my shop manual. Certainly, the GPS shutting off when I started the boat indicated that there wasn't much reserve in the battery. The sonar (depth indicator) would display 60 feet until the boat got up and running and I was told that it probably wasn't getting enough amps. That turned out to be correct. With the new battery, I registered the correct depth immediately upon starting the boat at the boat ramp. I wonder if the ignition control module needed more current than the battery was able to supply. As the boat gets higher revs, the alternator is capable of supplying more current and therefore, the ICM would advance the timing properly? Just a thought.
 

fat fanny

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

As smartwork stated have the alternator tested and keep in mind that every little gaget you add that draws power will diminish the life of the battery that much faster especially if the alternator isn't up to snuff. good luck
 

Bob1958

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

I have the same boat - '97 175 series. I've always noticed a slight bogging down at 1500 but that's usually when the boat hasn't reached its plane yet, so I attibute that to normal drag. So far I've replaced the battery, the starter solenoid and the water pump. Have you replaced anything? I inspect everything every spring and fall, and the belts and bellows still look perfect.
 
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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

On my original post I specified everything I've done. Most important, a full tune up, new battery, and a carb rebuild. If I put the boat at around 1500 rpm, it does a surg/bog on and off until I either reduce the throttle or increase the throttle. At that point, the motor runs very smooth.
 

RAGS702

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

I see this thread is almost a year old now. While searching the internet for solutions to the same problem, I'm curious if anyone found a solution for this bogging or hesitation problem? I had a mechanic adjust the timing, raplaced the distributor cap and new plugs/wires. It seemed to run slightly better but not much. No I still have the problem and now it sounds like the timing chain is slapping or making noise. After reading these forums the "timing chain noise" may be an exhaust valve. Any information is appreciated.
Thanks
 

axxe

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

I have the same problem except my boats stalls between 1200 and 2000. It runs perfect at cruising speed. I have replaced the fuel filters, plugs, wires, cap and rotor. There is no improvement. Sometimes, however, it will just start runing fine.
 

T140E

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

I own a 03 17' glastron bowrider that has a 3.0 merc. I just had the carb rebuilt today and it still bogs down at around 1500 rpm when I'm taking off. This has been a problem since day one and no one has been able to fix it. My electricals seem fine, just installed a merc water separator to see if it will help. Open to suggestions that could fix the problem.
 

dmotl

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

Check the main wiring harness on the right side of your engine.

Make sure the wiring has not rubbed and is shorting on the block
 

rbevis

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Re: Mercruiser 3.0 1997 bogging at 1500 rpm

Exact same problem here guys. '97 3.0L bogging in the 1k-2k range. Runs great above that but will try to stall on hard accel.

I've perfected timing, plugs, dist. cap/rotor, fuel filters. I used a handheld tach because my dash tach is off by a little, keep this in mind. Plan to adjust mixture with a vacuum gauge if I can find a port to hook to.
 

Nate Haught

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I just bought a 96 SeaRay 175 w 3.0 mercruiser . Sounds like same problem bogs at 1800 rpm. Anyone find a solution?
 
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