1998 3.0L stumbles/bogs on acceleration

[Jmunk]

I picked up a 1998 Sea Ray 180 with the 3.0L back around February. Today I changed out the impeller and gear lube in the lower unit to get it ready for the season. After the impeller change I put the muffs on and started it up. It started with no issues, and let it idle till the temp gauge moved to 150 and held. I gave it some throttle and it stumbled and stalled. Restarted right away and it seems that if I gave it 1/3 throttle it would bog and stumble. If I gave it 2/3 throttle it would hesitate then get to where it should be and sounded good.

Gas tank is full, previous owner stated they put marine Stabil in when they winterized it. When I started it right before I bought it I don't recall it stumbling in the lower RPM, but if it did I'm sure I chalked it up to "It's cold". I checked the plugs which are Champions (junk) they looked good a little white (lean). Plug wires look to be original as was the cap and rotor. The contacts inside the cap were completely crusty and I cleaned them up. Ran little better, but still stumbled. It will start right up with no throttle after warm and idle with no issues. I'm going to put new cap, rotors, and plugs. I think my last 3.0L I put NGK's in, anyone have any other preference. Boat is in excellent shape and had original impeller which wasn't too bad.

Anyone have any other ideas as what to check to fix the bog/stumble ?

 

[fishrdan]

Re: 1998 3.0L stumbles/bogs on acceleration

Sound like a bad accelerator pump in the carb, time to rebuild the carb.

Engine off, pop the flame arrestor off the carb, have someone else push the throttle from idle to WOT while you look down the carb's bores. There should be 2 stead streams of fuel that shoot into the bores. No fuel or a weak stream and you found the problem.

 

[Jmunk]

Re: 1998 3.0L stumbles/bogs on acceleration

Thanks for the advice. I will do that tomorrow when I have a helper. I have rebuilt atv carbs, but I think a rebuild on this is probably better left to the professionals.

 

[Bondo]

Re: 1998 3.0L stumbles/bogs on acceleration

I checked the plugs which are Champions (junk) they looked good a little white (lean).

Ayuh,... Have ya changed the fuel Filters,..??

If ya don't have a cannister type spin-on filter,...
It's always a Great idea to add 1, before the fuelpump...

 

[Jmunk]

Re: 1998 3.0L stumbles/bogs on acceleration

No, I have not yet checked the filters. No, it does not have any type of canister filter. I need to pull the feed line off the carb and see how the filter looks. Correct me if I'm wrong but should be another filter to the feed on the fuel pump ? If it does turn out the carb needs rebuilt what should I expect to pay if I take the carb to them?

 

[infideltarget]

Re: 1998 3.0L stumbles/bogs on acceleration

Sound like a bad accelerator pump in the carb, time to rebuild the carb.

Engine off, pop the flame arrestor off the carb, have someone else push the throttle from idle to WOT while you look down the carb's bores. There should be 2 stead streams of fuel that shoot into the bores. No fuel or a weak stream and you found the problem.

DO yourself a favor...do this with a mirror, and not with your head and face over the carb looking down into it. Trust me on this.

 

[Bondo]

Re: 1998 3.0L stumbles/bogs on acceleration

Correct me if I'm wrong but should be another filter to the feed on the fuel pump ? If it does turn out the carb needs rebuilt what should I expect to pay if I take the carb to them?

Ayuh,... The 3.0ls used to have a filter Inside the fuelpump...

Donno what it might cost,... I don't pay folks to do what I do...

DO yourself a favor...do this with a mirror, and not with your head and face over the carb looking down into it. Trust me on this.

Aaawww,... come on,... At worst, ya won't havta shave the next day, 'n probably won't need to go to the Barbershop for awhile either....

 

[Jmunk]

Re: 1998 3.0L stumbles/bogs on acceleration

Alright I had a helper push the throttle while I watched to see if the accelerator pump worked. I got two steady streams of fuel when throttle is pushed. I started it up and the stumbling was less pronounced when it was cold. After it got warm stumbled every time at 1/4 to 3/4 throttle. I pulled out the fuel filter inline with the carb inlet feed. The filter did have a fair amount of brown/black particles. I cleaned the filter out and put it back in to see what it would do, same thing. The arm in the accelerator pump lever is in the middle. If I kept the throttle at a constant rpm above idle it seemed to slowly come down and run rough. Leads me to believe the carb needs rebuilt, but i'm going to hold off with that till I do a tune up on the ignition side of things.

 

[Jmunk]

Re: 1998 3.0L stumbles/bogs on acceleration

Would adjusting the idle fuel mixture screw have any effect on this issue?

 

[earlandamys180]

Re: 1998 3.0L stumbles/bogs on acceleration

I have the same boat and engine as you do and mine was doing the same thing and a lot of build up in the filter at the carb. Your fuel pump has the old stone type filter in it as mine did, I replaced it with the new paper type filter and replaced the one in the carb and took her out yesterday and she ran like a champ. Give that a try.

 

[ont/ohana]

Re: 1998 3.0L stumbles/bogs on acceleration

I have the same boat and engine as you do and mine was doing the same thing and a lot of build up in the filter at the carb. Your fuel pump has the old stone type filter in it as mine did, I replaced it with the new paper type filter and replaced the one in the carb and took her out yesterday and she ran like a champ. Give that a try.

When you replaced the stone filter with the paper filter in the fuel pump, does the end with the opening face up or down. I just replaced mine now second guessing myself.

 

[Bondo]

Re: 1998 3.0L stumbles/bogs on acceleration

Would adjusting the idle fuel mixture screw have any effect on this issue?

Ayuh,... Possibly...

 

[Jmunk]

Re: 1998 3.0L stumbles/bogs on acceleration

I already ordered the fuel filter in the pump, be here Monday. Today I put the new cap, rotor, and new MR43lts plugs in, ran about the same. I checked the idle mixture screw and the last owner had it set at 3 turns out. I turned it out at one additional turn and at 4 turns out it ran a lot better when it was given throttle. I know the manual states 1 1/4 turns out, at 1 1/4 it would not idle and was hard to start. I'm going to put the new fuel filter in on Monday or Tuesday and then if that doesn't do it I guess it's time for a carb rebuild.

 

[Bondo]

Re: 1998 3.0L stumbles/bogs on acceleration

I know the manual states 1 1/4 turns out, at 1 1/4 it would not idle and was hard to start. I'm going to put the new fuel filter in on Monday or Tuesday and then if that doesn't do it I guess it's time for a carb rebuild

Ayuh,... The fact that you need to turn the idle screw out 4 turns is SCREAMING that the carb needs to be Rebuilt, or replaced...

 

[Jmunk]

Re: 1998 3.0L stumbles/bogs on acceleration

Thanks for your help Bond-O, I was thinking along the same lines. Suggestions on where to get a kit from the # on the carb is 807504. The date code on the carb indicates it's a 1997. Is it safe to say this uses the accel pump with the 90 bend on the end. Anyone use this kit before http://bpi.ebasicpower.com/mm5/merc...tore_Code=eBasicPower&Product_Code=MAL9-37612

 

[fishrdan]

Re: 1998 3.0L stumbles/bogs on acceleration

I know the manual states 1 1/4 turns out, at 1 1/4 it would not idle and was hard to start.

Ayuh,... The fact that you need to turn the idle screw out 4 turns is SCREAMING that the carb needs to be Rebuilt, or replaced...

^^^YUP

1 1/4 turns out is a ball park setting to get the engine running, then you have to fine tune it from there, turn the screw(s) in/out for smoothest idle. I prefer to do a final fine tune the idle screw(s) when the boat is in the water, engine is warmed up and idling in gear. Adjust the idle mixture and idle speed screws (idle speed, idle mixture, idle speed, idle mixture, etc, etc.) until it's purring along at idle speed.

I don't know if you got the fuel pump filter orientation figured out, but the filter opening faces the pump. If you don't have a water seperating fuel filter, it would be a good idea to add one. With the ethanol in our fuel now, water contaminated fuel is a big concern. Plus,,, the added filtering capacity of the filter isn't a bad thing.

 

[a1nowell]

Re: 1998 3.0L stumbles/bogs on acceleration

I am having my Rochester 2G two barrel rebuilt for the same reason, stumbles on acceleration. National Carburetor was about the least expensive, that really did the proper cleaning and rebuild and engine tune of the carb before returning it. They also have the best price on kits if you want to try the rebuild yourself. I rebuilt mine myself, solved other problems I had but not the stumble so I let the pros do it. www.nationalcarburetors.com

Do a search on this topic, there was someone on this forum about 2 weeks ago that said Mercruiser is now reccomending drilling out the holes in the carb base where the accelerator pump goes to 1/16" because of the less powerful ethanol gas.

I hope to get my carb back from National this week, hope my problem will be solved.

 

[Jmunk]

Re: 1998 3.0L stumbles/bogs on acceleration

Ordered a QuickSilver rebuild kit last night, I'm going to get a gallon of carb cleaner from NAPA and try my luck with rebuilding the carb. I have rebuilt ATV and motorcycle carbs in the past with good results. I will update everyone after I get the carb on and the new fuel filter. Also I wanted to add that if you mash the throttle it is less likely to stumble, if you gradually ease into the throttle it will stumble every time.

 

[Jmunk]

Re: 1998 3.0L stumbles/bogs on acceleration

UPDATE:

Tore the carb down and the bottom of the bowl was completely covered in brown/black particles. Soaked the carb in a gallon can of carb cleaner, rinsed, dried with air. I damaged the power valve removing it as it was stuck in there, got a new one. I put the carb together to the specs in the manual. Mounted the carb and splash some fuel down the butterflys and it ran flawless. The idle mixture screw was about dead on at 1 1/4 out. It was amazing it ran as well as it did for the amount of junk in the carb. Thanks Bond-O for your help.

 

[Ls1camaro2001]

Re: 1998 3.0L stumbles/bogs on acceleration

Sound like a bad accelerator pump in the carb, time to rebuild the carb.

Engine off, pop the flame arrestor off the carb, have someone else push the throttle from idle to WOT while you look down the carb's bores. There should be 2 stead streams of fuel that shoot into the bores. No fuel or a weak stream and you found the problem.

Should it be a steady stream or like a shot every time you accelerate