Help Please 1988 50HP Johnson OB 15" prop

[mspencer512]

Ebay
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Good running 50 hp Johnson Outboard Motor this motor has 125 compression on both cylindars & new water pump. The motor runs well shifts good has only been used in fresh water. The skeg (below the prop) is missing a small piece which can be welded or will not be noticible on small horsepower motor. This motor has a clean Missouri title.
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D&D Marine Started motor shifted gears from forward to reverse disconnected fuel line until engine died. Never load tested. Paid cash

Purchased motor

Installed on boat. Controls already on boat.

Steps taken to resolve throttling issue.
Started engine backed off trailer idled to dock to pick up other engineer.
Drove across the lake about 50 yards then motor kicked back to about half throttle or 1200 rpm squeezed fuel bulb engine picked back up to 3000 rpm
another 25 yards same thing. drove this way back to the dock.
Purchased new 3/8 inch fuel line and primer bulb $30.00 and 1 can sea foam
poured 6 oz sea foam into tank that had 6 gal with valvoline TCW3 pint oil. for 50/1 mix after installed new hose and primer bulb started engine while tied to dock, shifted to half throttle in forward and engine ran for a minute or 2
then cut back and still remains faulty. untightened the fuel cap for ventilation to see if fuel in line was suctioned tight. still faulty removed the carburetor cover started engine sprayed Gummout into top carb engine picked back up rpm's sprayed bottom carb and engine died. Gravity flow fuel in carbs so top carb uses fuel as needed and releases the rest of fuel to lower carb.
Engine will continue to run across the lake at 3000 rpm as long as someone continues to squeeze primer bulb, if you quit squeezing
the boat will run about 25-50 yards and cut back throttle even with control handle in full throttle position.

Please any suggestions.

Thanks buddavid that's what I thought so I looked up a fuel pump rebuild kit on the net and it 14.00-18.00 however a mechanic told me that I would need to buy a new fuel pump cause you cannot rebuild this type of fuell pump. The vro is not in use on the engine so it currently has a vro fuel pump on it which I being told $200.00 for new non-vro fuel pump. Model # J50TLCCS Ser # G7733251

[budddavid]

My first guess would be the fuel pump diaphram, this engine uses crankcase pressure to run the fuel pump. The easiest way to diagnose this problem it to continue to prime the fuel hose bulb while running the engine, if the problem goes away as long as the bulb it hard, it is very likely the diaphram, this would be a good thing as it is about the cheapest thing to fix on an outboard, <$10

[gofshn]

fuel pump diaphram, or even possibly the fuel line has a kink in it, had a similar problem with the 90hp on my flats boat, if the bulb sucks in, suggest you look at the fuel line for a kink, or a restriction, otherwise i would recommend replacing the fuel pump since you have already eliminated the check valve possibility with replacing the primer bulb.

[barnacle bills marine]

There are a few kits you can purchase to rebuild your VRO pump. It is best to replace the pump. If you rebuild it be sure to replace the flame arrestor fitting also. This is what damages 95% of VRO pumps.