4.3 running problem, bogs and goes bogs and goes ???

[zark72]

I have a 1990 stratos open bow with a 4.3. The boat was sitting for about 4 years due to a bad motor. I bought the boat and put a new long block in it .installed new fuel filter and drained all old gas out of it and took her out and ran great. Used the boat for several weekends and even pulled tubes with no power problems.
Now all of a sudden it starts to bog down like its running out of fuel and then goes and bogs and keeps doing this. It idels great and is fine at 1000 to about 1500 rpm and anything above that the problem starts. It seemed like a fuel problem so I changed the fuel filter and took it out and same thing. Replaced the fuel pump, same thing. I had a new set of points and condenser so I put them in, same problem./ Its like its running out of fuel and then picks up and rpm just keeps going up and down. It seems like the problem started after I was out on the lake when the lake was real rough and the boat was hitting the water pretty hard. Could this be a fuel tank pick up problem ???
I think tomorrow Im going to take a fuel hose and put it into a gas can and run it off the gas can to see if this fixes the problem. If not, where do I start next. Like I said it idels fine and runs up to about 1500 rmp fine so I dont think its the interuper switch ????? Any thoughts would be great and thanks in advance

 

[willwade]

Re: 4.3 running problem, bogs and goes bogs and goes ???

my 5.7 was acting up similiar to your problem so i replaced fuel pump, didnt help next i replaced ignition coil and that solved my problem. good luck

 

[Maclin]

Re: 4.3 running problem, bogs and goes bogs and goes ???

One thing at a time, try the separate tank and then report back if problems persist or new ones pop up.

 

[ryendube]

Re: 4.3 running problem, bogs and goes bogs and goes ???

you could pull the plugs and checked to see if its a lack of fuel or lack of spark. hold on let me spin my wheel of diagnosis and see where it lands. throwing parts at an engine isnt going to fix it.

 

[Rocky_Road]

Re: 4.3 running problem, bogs and goes bogs and goes ???

Loosen (crack) your gas tank cap...if things improve, then your tank vent has some sort of blockage.

In North Florida, the wasps love to build their nests in the gas tank vent outlet...this creates a vacuum in the tank, after running for awhile!

 

[CharlieB]

Re: 4.3 running problem, bogs and goes bogs and goes ???

With the engine turned OFF

Remove the spark arrester, disconnect the throttle cable, and while opening the throttle to WOT observe the fuel pump shot, it should be solid streams squirting into the throats lasting the duration of the throttle opening. If NOT, then R&R the carb with a kit, if your ordering a kit from a dealer then be sure it contains an accelerater pump plunger, factory kits leave this out and must be ordered separately, most aftermarket kits contain this part.

When you pumped out all the old fuel from the tank did you remove the pick-up tube or the sender and suck out any trash/water accumulation from the bottom of the tank?

Rough water can stir up this crud and clog your filter again, the factory filter is NOT a water separating filter, it doesn't take much water in a carb to make them run strange. Install a water separating filter before the fuel pump to prevent this from future occurances. Change annually.

Next, remove the distributor cap and rotor and check the flyweights (mechanical advance) to ensure that it is operating smoothly and not sticking in one position, rusted. R&R if needed to clean up, ONE DROP of oil is plenty to lube the pivot points.

 

[zark72]

Re: 4.3 running problem, bogs and goes bogs and goes ???

Boat is up and running again !! Ran it on a seperate gas tank, ran great, pulled pick up tube, was clean and all intact, checked fuel check valve and found valve wasnt opening all the way and caused the engine to starve for fuel at full throttle, replace check valve and all is good to go.
Thanks everyone for your advice.

 

[Maclin]

Re: 4.3 running problem, bogs and goes bogs and goes ???

good job

 

[1993 celebrity 4.3L]

Re: 4.3 running problem, bogs and goes bogs and goes ???

I'm in the early stages of trouble shooting what sounds like the exact same symptoms that has been discussed in this thread. I might just jump right into checking for the same problem. where is this fuel check valve located? Mine is a 1993 4.3 instead of a 1990.

 

[Maclin]

Re: 4.3 running problem, bogs and goes bogs and goes ???

If your boat has one it will be the fitting at the top of the fuel tank that the hose to the fuel pump connects to. It looks like a 90 degree fitting but will have a check ball type valve inside. Be sure that is the problem first, it may be hard to unscrew and you could booger up the threads it goes into, hate to see that happen and the valve was actually ok!

If you want to continue getting help for your issue it would be best to start a new topic