1989 Bogs and shuts off after WOT

[vince champion]

Hello all i am fairly new on this forum so bare with me. I have a 1989 Mercury black max. It starts up fine and idle fine but once i go wot it will bog and shut off unless i pull the throttle back and stroll only 10mph. Anything above it seems like the motor is not getting enough gas. The weird thing is that my primer bulb wont get hard when it is connected to the motor. What is the cause of this? When i bought this boat, the recent only just got the carbs and fuel pump repaired. The mechanic said i need a new stater but i do not want to invest 500 on it just yet. I did a search but i could not find any answer about why the bulb wont stay hard when im going WOT. I also have a thumbsize white filter on my fuel line is it that? can i take it off? Any help would be greatly appreciated. Thanks in advance.vince.

 

[flabum]

Re: 1989 Bogs and shuts off after WOT

Check all your filters first. There may be a water seperating fuel filter inside the boat somewhere that looks like an oil filter. The white filter you described should be replaced too. If the filters are clean and free of water, then you have a restriction or leak somewhere in the fuel system. Put a vacuum gauge between the primer and engine and look at the readings at full throttle. It should be 2 - 3 inches in mercury. anything more means a restriction, anything less means a leak.

 

[j_martin]

Re: 1989 Bogs and shuts off after WOT

Been there with an 88 XR4 (Black Max).

The thumb sized filter is about a 100 mesh screen with only about 2 sq inches of area. ANY little snot at all in the fuel will plug it up. Don't throw it out unless you put in a good (RACOR) 60 GPH water seperating filter in the line from the tank. The same chit that plugs your filter and stalls the engine will plug up one carb and blow a piston.

The fuel pump went from rubber to a plastic for the valves some years back. If there's any rubber valves in it, bet is they look like bacon from the alcohol.

On a V6, the fuel connector bayonet bore size is critical. The plastic aftermarket crap will stall it out or lean it at WOT causing major engine damage. Same goes for the primer bulb/hose assembly. Make it Mercury for sure.

I bought an old boat with a little water and chit in the tank. Stalled at WOT just like you describe.

Final fix included
1. Cleaning the tank
2. Replacing aftermarket fuel hose with Mercury
3. Installing a RACOR water seperating suction side fuel filter
4. Cleaning the carbs.
5. Rebuilding the fuel pump
6. Discarding the undersized fuel filter. Accompanied by removing the fuel connector bayonet and routing the hose direct to the oil mixer.

Keep at it. When that bad boy gets enough gas, it'll blow your hat off.

hope it helps
John

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

thx for your replies. Can someone please explain to me what is a bayonet and where is it located at? Also can any vacuum gauge work to test out my fuel pressure?

I will clean or replace the white filter this weekend and check my spark plugs. I will also change my fuel hose and primer bulb since it is after market. I heard the after market use plastic so its thicker which blocks fuel from your motor, and the OEM part is made out of metal? is that true? thanks for your help.

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

Also someone told me about my Gas tank not able to breathe and i should open the vent. Well i tried looking for it but i couldnt find any slot to open up. I have a 1989 Champion bass boat. Can someone please tell me where this is located or how to do it. thx again

 

[gss036]

Re: 1989 Bogs and shuts off after WOT

1st, what horsepower engine do you have? If you do not an on board fuel/water seperation type filter installed, please do so. It will save lots of headaches.
The bayonet type fitting refered to is used to connect the fuel line to the engine, not all have them as some folks will connect directly.
If you have a built in fuel tank in the boat hull, it will/or should already be vented.
There is a possibilty that the diaphram in the fuel pump has small hole in it and asnther issuse could be with the floats in the carbs not seating, you just keep pumping gas into the engine. The floats act as shutoff when the carbs fill up, the floats rise and shut off the flow of gas.

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

It is a 1989 Mercury 175hp black max v6. I do not have a fuel water seperater, but i will look into getting one. Also i will check the floater in the carb, But can this is a problem since i recently got the carb and fuel pump rebuilt? Thx in advance vince.

 

[mrmossman]

Re: 1989 Bogs and shuts off after WOT

It is a 1989 Mercury 175hp black max v6. I do not have a fuel water seperater, but i will look into getting one. Also i will check the floater in the carb, But can this is a problem since i recently got the carb and fuel pump rebuilt? Thx in advance vince.

I'm no outboard mechanic but as an auto mechanic, the first question I would ask was "what was the last thing done to it?" more often than not, I ended up fixing what was supposedly fixed by the last guy. I'd check it again.

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

Thx for your replies. I was reading the other post about a situation similiar to mine and he fixed the problem by cleaning his carb and repairing his fuel pump. I just had those 2 parts fix by a mechanic but i think i am going to clean and repair them again. On Saturday i took the boat to try to eliminate some possibilities by Me driving at wot and a assisstant constantly pump the primer bulb to feed it gas. This actually worked. I went wot as long as i want and boy this boat is fast!!! I recently bought this boat and never had a chance to WOT it before. So i am excited about getting this fixed! so what i will do is change the carb and fuel pump and hope this fix it. Stupid mechanics, i sometimes think they dont do a correct job just so you will go back to them. The mechanic even wanted me to change the stator and said theres no way i can fix the boat and laughed. what an ***! anyways thx again

 

[gss036]

Re: 1989 Bogs and shuts off after WOT

With the test you just did, the first thing to do is rebuild the fue lpump and try again. Either you were sucking air or bad diaphram in the pump.
Check the connections on the fuel line. If you don't have OEM primer bulb, get one.

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

With the test you just did, the first thing to do is rebuild the fue lpump and try again. Either you were sucking air or bad diaphram in the pump.
Check the connections on the fuel line. If you don't have OEM primer bulb, get one.

Thanks for help. Quick question when the bulb isnt connected to the motor 3 squeeze and its hard, but once i connect it to the motor it would never get hard. So does that mean my bulb is bad? Another thing i notice on the test run is when im going about 10 mph for 10 mins my motor will slowly shake and bog as it has no gas, once squeeze and it will fix it right up and i can go for another 5 mins or so. So for sure i know it aint getting enough fuel am i correct?

Can someone link me direction how to clean and take apart the carb and fuel pump please. thanks in advance

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

Another question i had is that if i fill up a trash can full of water and use it for a pool for my motor is that sufficient enough so my motor wont over heat? I live over 1 hour away from a lake so its troublesome for me to do these test run. Thanks again. Vince.

 

[j_martin]

Re: 1989 Bogs and shuts off after WOT

Thanks for help. Quick question when the bulb isnt connected to the motor 3 squeeze and its hard, but once i connect it to the motor it would never get hard. So does that mean my bulb is bad? Another thing i notice on the test run is when im going about 10 mph for 10 mins my motor will slowly shake and bog as it has no gas, once squeeze and it will fix it right up and i can go for another 5 mins or so. So for sure i know it aint getting enough fuel am i correct?

Can someone link me direction how to clean and take apart the carb and fuel pump please. thanks in advance

You can develop 10 lbs or more of pressure with the primer bulb. 7 or so will overpower the floats in the carbs, and flood them. You should be able to see that with the air cover off. If it isn't going there, you have a hole in the fuel pump diaphragm. From your symptoms, it's either that or a hole in the fuel line before the pump (most likely right at the primer bulb) or a plugged tank vent.

The fuel pump kit comes with directions. 4 screws and about 8 other parts. You can do it. Be sure the pulse line between the fuel pump and the crankcase (or reed plate) is stock and in good shape. A tygon, or mushy rubber line will absorb the pulses and make the fuel pump very weak. While you're at it, make sure the crankcase fitting isn't plugged. You should be able to wrap a lip lock on the pulse line and blow freely into it.

When I was trouble shooting mine, I teed a line into the fuel line just before the carbs and put a pressure gauge right in my lap. When it failed, fuel pressure would go to zero.

That engine needs about 18 GPH at WOT. An aftermarket bayonet (plastic) will not pass that amount of fuel period. I just chit canned mine and hooked it up direct to the oil mixer.

Cheep, aftermarket fuel line also will not deliver that much fuel. At that flow rate, a rough finish on the hose inner tube will cause it to starve. Use Mercury line.

RACOR 60 gph water seperating fuel filter; worth it weight in gold.

If you install the RACOR filter and bypass the bayonet, you can safely chit can the internal thumb sized filter eliminating another common trouble spot.

Find the little fuel vent fitting, usually on one of the gunwales. Check it for a mud dauber nest.

I put a RACOR vent check valve in my vent line. Now I can run a full tank without splashing gas out the vent. It was hard to get in with the limited elevation, but it went in and works well.

When you get it all figured out, be sure you wear a life vest and use the kill switch. It'll go past fast to wild.

hope it helps
John

 

[j_martin]

Re: 1989 Bogs and shuts off after WOT

One more thought.

A common place for a suction side leak is inside the fuel tank, in the pickup tube. Often they are just plastic and often don't even have a clamp. some also have a troublesome check valve built in, though you don't usually find one in a boat that old.

A piece of clear vinyl tubing (from the hardware store) temporarily installed in the fuel line just before the engine will show any leaks as air bubbles in the fuel. If normal, it should be clear with no bubbles.

hope it helps
John

 

[j_martin]

Re: 1989 Bogs and shuts off after WOT

BTW, don't try to run it hard until you are sure that fuel delivery is good. You can burn a piston in seconds if it's lean.

John

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

Thx for your reply j martin. I do have some questions tho.

1) Is having a big bucket full of water sufficient enough to keep your motor cool? I live too far from a lake to do the tests.

2) I have a problem looking for parts for my boat. I found the serial # on the bracket of my motor but it doesnt match the products on iboats. Can someone help me find a fuel pump repair kit, carb cleaner kit, and a OEM primber bulb fuel line. Thanks alot the serial is "0B363651"

 

[j_martin]

Re: 1989 Bogs and shuts off after WOT

1. Can you run it at WOT in the bucket?

2. Your motor has 3 possible fuel pump setups. Google mercury parts express home page. I'd post the link but the forum prohibits that. Enter your serial number (the first digit is a zero), your zip code, and look at the 3 different fuel pump diagrams listed.

I'd get a genuine mercury kit. they changed the check valves so they don't wrinkle up like bacon with the alcohol in the fuel.

hope it helps
John

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

lol Sorry i meant if i use a big trash can that is big enough for the motor to wot will that be sufficient enough? and also can you just pm me the link or how do find the correct parts with the serial # thanks alot. Youve been alot of help.

 

[Don S]

Re: 1989 Bogs and shuts off after WOT

You can't run WOT in neutral or you will damage the engine. You must be in the water and under load to get max fuel flow.

Here is the link to Mercury parts express. Just copy and paste. Remove the " " at each end or it won't work.

"http://www.mercurypartsexpress.com/PartsExpress/HomePage/homepage.asp"

 

[j_martin]

Re: 1989 Bogs and shuts off after WOT

lol Sorry i meant if i use a big trash can that is big enough for the motor to wot will that be sufficient enough? and also can you just pm me the link or how do find the correct parts with the serial # thanks alot. Youve been alot of help.

Some dealers have a really big test tank, and test wheels (worthless power wasting props) for wot testing. It's still noisy and wet, and it's all expensive.

You need to rig up so you can test while underway. The fuel pressure gauge is the primary tool needed. If it craps out and you have over 2 lbs of fuel pressure, it's something else, like ignition. Fuel is the prime suspect in this case.

The link in the previous message is good. go to "parts for Mercury Engines."

hope it helps
John.