Johnson 88spl no fuel to carbs.

1990 88Spl., created a fuel leak(dry rotted line repaired) this is when I was asked to fix. Previously this leak caused a flash fire. Motor ran decent when I got to it, ran it to check for leaks. Found recirc. lines melted and inlet nipple on bottom carb melted. Replaced, all good. Superceded bowl was slightly different but all seemed good w/ clearance and float chamber. Started motor and ran flat at higher rpm's. Pulled plug wires and bottom cyl. dead. Sprayed fuel into carbs, and motor cleared up. Pulled carb back off and found nothing. Tried starting, wouldn't fire. Good spark and 115psi comp. on all 4 cyl. Checked fuel to pump, good, nothing coming out. Replaced fuel pump, still no fuel exiting fuel pump. Sprayed fuel directly into carbs and motor will fire.???? Am I not getting pulse pressure to operate fuel pump or please help w/ any other thoughts.

Re: Johnson 88spl no fuel to carbs.

Start at the gas tank and work your way back, checking the fuel flow.
Try pumping the primer bulb until hard and look for leaks.
Fuel pump pulse comes from the intake manifold. Take off fuel pump and make sure the port for the pulse port clear and fuel pump base gasket is in good shape.

So all fuel and recirc lines have been replaced? Any damage to the plastic fuel rail?

Re: Johnson 88spl no fuel to carbs.

Try a simple fuel pump test. Constantly prime the fuel hose bulb. This should/will flow extra fuel into the carb bowls, through the fuel pump. The bowls should fill and you should be able to start/run the engine normally through all rpm ranges. If the engine runs normally while constantly priming the fuel hose bulb, the problem is with the pump or it's setup. If it won't run with all that extra fuel in the bowls, you may have an issue internal to the carbs. Any chance the carbs have plastic fuel bowls on this engine? Have you done a test for water in the fuel?

Re: Johnson 88spl no fuel to carbs.

As far as bowls, upper carb still has plastic bowl(oem). Lower carb is the one which had melted elbow and I ordered part and recieved alum. bowl. Was told this is the superseded part. Been working on boats 15 years. 10 in dealership and 5 on the side. Never had one get at me like this. Seeing double, afraid I'm overlooking the obvious. Man do I need a beer!!!

Re: Johnson 88spl no fuel to carbs.

Yes, upper still has plastic bowl, was there a problem with them. Unaware. I did check for water.

Re: Johnson 88spl no fuel to carbs.

If there is no pulse (pressure/vacuum) on the pulse line then there is NO carburetor problem Is there a pulse limiter in the port on the engine. If the pulse limiter is bad the pump can't work. If you have a vacuum gauge, pull the hose off the pulse limiter (or the hose barb) if there is no pulse limiter. Attach a vaccum/pressure gauge (vacuum/fuel pump tester). Pump the primer bulb and fire the engine. The needle should pulse between pressure and vacuum. If not, there is an internal seal issue. If there is, the pump is either not plumbed correctly or it's bad.

Re: Johnson 88spl no fuel to carbs.

Those plastic fuel bowls are a real problem. It's not so much a matter of if-but when they warp. When they warp, the mating surface of the top of the bowl won't lie flat against the bottom of the carb body. No matter how hard you screw the 4 gasket screws. You can have gas leaks, and worse-if it warps in the wrong area, you can suck air into the carb throats, causing a lean condition on one or more cyls. I'd replace the other carb bowl with the aluminum bowl also.