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Johnson 1996 150 hp Starving after 20 seconds. VRO?

T

treefish

New member
My engine idles just fine and runs just fine. After about 20 to 30 seconds of running at mid-range throttle the engine bogs down, but give it about 10 to 15 more seconds and I will get another surge out of it for a few seconds before it bogs down again. I can keep it running by pumping the bulb every 20 seconds or so.
I tested a separate fuel tank this morning and had the same problem. I bypassed all fuel lines and the fuel/water separator this morning and hooked the separate tank straight to the small fuel filter next to my VRO pump (where the main fuel line comes in). The other tank is off of a smaller boat I have which runs fine. I used it's fuel line and primer bulb.
I recently rebuilt the VRO. I did so because I was having the same problem before the rebuild. One of the old diaphragms had a hole in it and the silver dollar sized gasket was ripped in half. I was certain the rebuild kit would fix the issue, but it didn't.
It appears as if plastic parts of the VRO have warped slightly. The warped areas are where the VRO comes apart to access both the oil diaphragm and fuel diaphragm. I'm wondering if this will cause my problem. I figure it is a possibility.
I don't see any fuel leaking anywhere.
I'd really like to avoid purchasing a new pump.


Any suggestions are greatly appreciated?
 
If there are internal engine problems then the VRO will not work properly.-------Poor crankcase compression will result in poor operation of the pump.---------What about the pulse limiter ?----I do not believe that slightly warped housings will cause failure.-----Have you verified that the 2 check valves in the rectagular housing part of the pump are working properly ?
 
What will I need to test poor crankcase compression? and if it is poor, what do I need to do to correct that?

Is the rectangular part of the housing the part that is on the bottom of the pump as it sits in the engine? I think that's gotta be it. What is needed to check that portion out?
 
The rectangular portion is at the bottom of the pump.---Part of what they call the air motor.-----Remove the pulse limiter , have someone crank over the motor and see if there are strong pulses from that cylinder.------A cylinder compression test MAY also help in determining the condition of the crankcase that drives the pump
 
I removed the hose from the blue pulse limiter and cranked the engine. It does shoot pulses out at me. I should have used my compression tester, but I didn't have it with me tonight.
I can't say for sure that the check valves on the bottom of the VRO are working properly, but I took the pump off and tried to blow and suck on that hole, but was unable to pass air through it. I then took apart the VRO and was able to kind of see how the check valve works by covering a hole inside and blowing on the bottom of the rectangle then covering another hole and either blowing or sucking. I forget. Anyway, it seemed to be working by allowing air to pass one way through one hole and another way through the other hole.

O yeah, so I put it all back together, and I replaced the hose from the blue fitting to the bottom of the rectangle (just in case).
I took it out again and I experienced the same problem as stated in my first post.
Any thoughts, besides the fact that my methods for testing are sub-par?
 
This is my fourth year running this engine on my boat. I use it at least every 2 to 3 weeks, as I live in jacksonville, fl and there is plenty of water and warm weather.
It all started when the motor was eating way too much oil. I may be the cause for the problem. I read online that I could premix oil if I capped off the oil inlet into the VRO and unplugged the electrical plug coming into the VRO and the other plug running from the oil tank. So I did that and got about 3 or 4 weekends out of it. Then one day it just bogged down on me and died. I started right back up after pumping the bulb and in order to get back to the ramp, I had to pump the bulb about every 20 seconds.
When I got home from that trip I took apart the fuel pump to find the silver dollar gasket was cut in half and one of the diaphragms has a hole in it.
After rebuilding the fuel pump it worked alright for a trip or 2, but my problem came back. I'd used a bolt to plug the oil line and noticed a bit of a leak, so I wrapped Teflon tape around the bold and hose clamped it back on, which fixed the problem for about a day.
I then decided to hook things back up the right way to see if my problem would go away, but it didn't.

So that's where I sit with the situation now.
 
This will sound funny, but do a spark gap test right after it bogs down, could be a powerpack starting to fail, mine would run fine, then for no reason bog down and sometimes die, it would crank up again and idle, but wouldnt go to power. The spark gap would test fine when the engine was cold, but as soon as it warmed up it would start failing. I thought mine was a fuel issue as well at first. Good Luck
 
J150EXEDB. I Bought a new VRO. Replaced it this morning and everything works great again.

Earlier in this post I said something about the pump housing being slightly warped and that may be why it was giving me issues. Who knows what the real reason for my problem was, but getting up off of my wallet was well worth it. I actually purchased the part from MarineEngine.com. And it arrived in about 4 days.

I am now using the VRO system as it was intended to be used (pumping both oil and fuel), but I would never have had any of these issues if there was a normal fuel pump in this motor to begin with. I would have only had to rebuild the pump. My wallet would have liked that option.
 
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