Johnson 88 SPL carb problem

westr212 · May 21, 2017

I Just water tested a new to me crestliner phantom 170 with a 1990 Johnson 88 spl.
Engine runs fine at idle. Electric choke works. Fuel lines and primer bulb look to be recent (good flexibility and lack of sun or weathering problems. I pump fuel in with bulb and that works, but I expected to have the bulb get had and difficult to pump once carbs filled. I can keep pumping and the primer bulb never gets hard. Is this normal or should I expect full float bowls and then a really firm primer bulb?
So I get the boat up on plane and it quickly is starved for fuel. I am able to get it to run at high rpm by holding the electric choke in continuously. What should I check to trouble shoot this?
Thanks, Paul

Gamefisherjon · May 21, 2017

If the bulb never gets hard check the float needle and seat valve(inside carb) and also check your fuel pump for a bad diaphragm as that will prevent pressure from building then lastly try a new fuel line

94 xlt 5speed 3.0v6

Pappy · May 21, 2017

Before you start pulling carbs apart and your fuel pump apart to "check" why not check the primer bulb? Let's deal with the primer bulb first.
When pumping the bulb it must be held in a vertical position (outlet up) for the check ball to close. Do that first. If that does not work then pull the bulb out of the system and squeeze the bulb (vertical remember). Once squeezed place your finger over the inlet and release the pressure on the bulb. It should remain flat. This checks for leaks. Second check is to place your finger over the outlet and squeeze the bulb (vertical remember). It should be hard. This tells you the check ball is sealing. If it does then the bulb is good.
Once that is solved you can move on to the running issue. Run the engine at the rpm the issue occurs at and pump the bulb. If it picks up by pumping the bulb you have a possible fuel pump issue (you are replacing or helping out the fuel pump by hand pumping fuel to the engine).
Now...you have an electric primer, not a choke.
If the primer bulb does not help then bump the primer while running. If the engine picks up momentarily then you have a carb issue. If you really want to nail down which carb and which throat you can get a squeeze bottle full of fuel and oil and shoot a bit down each throat at the rpm the issue occurs at and you will find which carb and throat has the problem. I would get two OEM kits and clean and rebuild both carbs just for peace of mind. OEM kits are the only kits that are complete with floats and needle/seats along with all the soft parts. Aftermarket kits are not complete.

Stumpalump · May 21, 2017

Pump some fuel into a clear container and let it sit. Look for ethanol/water separation. I believe that boat has a built in tank so if it's got last years fuel in it then suck it out. You can do it thru your fuel hose or these are great. https://www.tractorsupply.com/tsc/product/liquivac-large-capacity-oil-extractor-8-qt-capacity?cm_vc=-10005
If you have a canister water separator mounted somewhere then start with a new filter or at least remove it and dump the water. I've seen old fuel clog carbs so often it just crazy how bad ethanol is. Water can fool you intermittent as well. It burns some and bogs some when mixed with today's fuel. Now that you actually have fresh clean fuel all the way thru it then troubleshoot it using Pappys post to the letter. That post should be a sticky thread. Another thing is to look for is grey fuel line. That's the kind that disolves then falls apart to clog your fuel system.

westr212 · May 23, 2017

I checked the bulb and it is fine. In checking I could not hold pressure until I took the bulb out of the circuit to test. I noticed some leaking at the connector that clips on to the engine. I changed this connector and the fuel lines connecting the bulb and retested. The boat runs great now and no need to rebuild the carburetors. Thanks, Pappy!