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94 evinrude 150

9

94evin150

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I have a problem with rough idol and lack of power. I can hammer down and it takes off good but lose power shortly after hole shot. Once on plain and full throttle you can hear and feel the motor give more then back off and fyi the primmer buld never gets hard and stays hard and line is whether checked and a little wet. Could it be fuel related due to bulb
 
The bulb must go hard.----If not find the issue.----Leaking carburetors.----Bad fuel pump.---Air leaks on fuel hose.----Primer bulb does not need to be hard once motor is running.----Check float bowls as they are known to warp.
 
I did just rebuild all 6 carbs but not bowls and i do remeber a carb or two being wet and the fuel line after the bulb is dry rotted and wet in spots
 
Everybody seems to jump on the carburetors as step #1 in motor repairs.-----What other trouble shooting was done if any?
 
Ive put new plugs in and ran it for about 20 min out of water and rechecked plugs and they all looked like thay where burning the same i checked the timing at idol and that was normal . It runs alot better out of the water for some reason most problems are under a load
 
Exactly.------They all run great / sound great on a hose.----Will run very well on 5 of 6 cylinders..-----The prop does not need to do any " real work " spinning in air !!----Time for some real trouble shooting.
 
When in the water on the hole shot for the first 10sec it has full power but then dies back off like its starving for fuel and running top end you can feel the motor surge like it gets full power for a sec
 
Racerone is correct, it's time to start gathering some basic info to find the real problem. I always suggest doing all the free, easy things first then move on from there.

1) Use an inline spark tester. Remove all 6 plugs and test each lead 1 by 1 and verify each coil can jump a 7/16" gap while cranking.
2) Measure compression values on all 6 cylinders. You should see 100PSI on each and no more than 10% variation.
3) Confirm integrity of all your fuel lines. Make sure the tank vents are open and there are no air leaks in any hose or connection
4) Verify your primer bulb is good and the check valve is working.
5) Look for leaks around the carb fuel chambers. Any weeping around the gasket is an air leak
6) Check around your fuel pump and make sure there are no leaks at the fittings or cracks in the pump body
7) Look around the gasket on the VST and check for leaks
8) Look at the sides of the float chambers for a small BB pressed inside one of the holes. These are notorious for leaking as the plastic ages.

Do you still have the factory OMS fuel pump? Does the engine seem to smoke excessively? If yes, it's possible you have a bad diaphragm on teh fuel side which will cause decreased fuel flow and excess oil delivery and bogging at high throttle settings. My '96 Intruder 150 had similar symptoms 2 years ago and I decided to install a new OMS pump which along with replacing leaking fuel chambers gave me an engine that runs just as well as it did when new. There are kits to rebuild the fuel side only, but I chose to do a full replacement.

KJ
 
All cyl read 97 to 100 psi and i checked spark on all plugs didint test the jump gap but had strong spark. vst? Oms? Sorry not shure what those are and im going to need a cuple cans of carb clean to dry the intake side of motor due to being saturated with gas and oil over the years to determine fuel / oil leaks
 
94evin150 said:
All cyl read 97 to 100 psi and i checked spark on all plugs didint test the jump gap but had strong spark. vst? Oms? Sorry not shure what those are and im going to need a cuple cans of carb clean to dry the intake side of motor due to being saturated with gas and oil over the years to determine fuel / oil leaks
Click to expand...
OMS = Fuel Pump. Originally called the VRO (Variable Rate Oiling) it was later renamed Oil Monitoring System.
VST = Vapor Separator Tank. It's meant to keep fuel available at the engine even if you get bubble formation in the lines from the fuel tank.
All fuel system parts can be found here: 1994 150 Fuel Parts Diagram

Compression looks good. You need to test spark with a gap tester because the presence of spark just grounding against the block doesn't mean it's strong enough under high load. You need to know the coils can deliver enough voltage to give the spark plugs a full charge.

Another place to look for fuel leaks is at the cone shaped fuel filter that inserts into the VST. There are 2 O-rings on that fitting which can distort over time and not seal properly. Actually, I forgot to list that filter as a simple check. It's entirely possible you have a bunch of gunk blocking flow through that filter so it's worth removing it and making sure the screen is clean and you can check the integrity of those O-rings while it's off.

KJ
 
Ok ill check those and i did have a leak at gas filter at one time but the new filters dont come with orings i assume standard oring will work
 
You have looked at / replaced the water pump impeller ?----There is a safety system that kicks in on overheat.-----Test run with a portable fuel tank and hose.
 
94evin150 said:
Ok ill check those and i did have a leak at gas filter at one time but the new filters dont come with orings i assume standard oring will work
Click to expand...
Orings need to be gas/oil resistant. The OEM are brown colored Buna Nitrile material, so if you source some locally be sure they are compatible.
 
Think i found the problem the plastic part that seperates the oil and fuel line going into the cowel leeks a steady stream when priming the bulb so my question is can i delete that part and run strait Pieces.
 
94evin150 said:
Think i found the problem the plastic part that seperates the oil and fuel line going into the cowel leeks a steady stream when priming the bulb so my question is can i delete that part and run strait Pieces.
Click to expand...
Yes, you should be able to use double ended brass hose mending fittings to eliminate the plastic coupling. You'll need 1/4" for the oil line and 3/8" for the fuel line.
 
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