Johnson 150 smokes like h**l...primer bulb never solid...do i need a new fuel pump?

Question

Hi...I have a 1988 Johnson 150 VRO outboard. The guy I bought the boat/engine from disconnected the oil part of the vro and I'm mixing fuel:oil at 50:1.

A few things:

1) when i prime the fuel, the bulb never gets solid...i can keep squeezing and squeezing.

2) I just cleaned the carbs, replaced the fuel filter, and put all new spark plugs in

3) when i prime the fuel, I can now see that the fuel filter never becomes full (it's a clear filter)...it always looks just half full of fuel

4) as i prime the fuel bulb, i can see fuel seeping out of the vro pump.

5) the engine starts fine, but smokes a lot...looks like more smoke than there should be...like a huge cloud

6) the engine runs fine out of the water when i run it on a hose and, in dle, i can rev it like crazy without a problem

7) when in the water, the engine starts and put put puts along in gear at low rpm's (@1500)...no problem

8) once i give it gas and try to open it up, the engine stalls out.

Question...if I replace my VRO pump, will this fix my issue? my theory is that the fuel pump is blown and that's letting air into the fuel line...causing excessive smoke when it's buring fuel and also not giving the engine the fuel it needs to run under load at high rpm's.

my plan is to get a new vro pump and just replace it, keeping the set up exactly the same (aka, keep the oil pump disconnected and continue to run on the 50:1 fuel ratio). another question...do i need to stay with the same pump if this is my plan or can i get a strictly fuel pump (no VRO)...if so, what fuel pump should I be looking at buying??? The vro pump for this engine costs about $300 new...I'd like a cheaper option if possible...the money isn't the issue here though (in other words, i'll buy the vro if that's my best option)...just want to get this thing running like a ussain bolt.

all advice is greatly appreciated!

Answer 1

I think Cal 45 is on to something.  Did someone rebuild the power head on this engine?  Sure sounds like no power. Good luck!

Answer 2

Did you check the compression on all cylinders> If the vro pump leaks> That's the high speed stall> The smoke is over fueling> Or incorrect oil gas mixture> Use a remote with 16oz per 6 gal>Make sure the timing advance is correct if not it will smoke excessive>

Answer 3

OK....lets start off simple....get a portable gas tank and hook up to your engine. Run it on the portable tank and see if your problem goes away....if it does your problem is on your boat and not your engine. Start checking out all your fuel lines, primer bulb  and pick up tube in your tank.

  If the problem does not go away, then you have a problem at the engine...start traceing out all of the fuel hoses and check for leaks. Also...you said you cleaned your carbs....did you replace any parts? Carb mounting gaskets should not be reused...they will leak. When you pulled the carbs....did you do a sync and link after reassembly?  This is also something that almost always needs to be done when the carbs come off. The engine revs up fine when on a hose, but under load in the lake it stalls when you rev it up.....that may be a timing issue or a carb issue. Back to the sync and link. But that tells me the fuel(VRO) pump is working. if it runs at all it is getting fuel from the vro and if you can rev it up in nuetral, it is getting fuel. How did you clean the carbs.....spraying carb cleaner in them while running will only do so much....they may need to be completely rebuilt and dipped in a tank of solvent. As far as the smoking.....do a compression test on the engine.....you may have a stuck ring or a bad cylinder. Excessive air will not cause the engine to smoke. Too much oil in your fuel will cause it to smoke. 50:1 is the correct ratio.

a couple of notes on this stuff

1. the primer bulb has a check valve in it...it may be bad, and this could be why it is not getting hard.

2. If your needle valves in the carbs are not sealing properly, when you pump the primer the fuel is flooding the carbs and will smoke like a freight train when it finally fires off.

3. Sucking air into the fuel system is very common on an outboard engine, pay close attention to all of your fuel hoses outside the engine as well as inside the cover.

4. There are tests that be run on your engine to check fuel flow and volume, you will need a service manual and some test equipment....may want to take it in to a dealer for these.

5. Another thing is reed valves.....they can cause you all kinds of problems on an outboard.....especially one that is 20 years old...if they are not working properly nothing you do will correct this problem.

6. If you need more help, reply to this and maybe we can e-mail each other.