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  1. #1
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    Mar 2019
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    Default 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Picked up a bass boat that was under a tree for a couple years. Restored the boat, engine ran but struggling with the alarm system.

    Been down countless troubleshooting threads. Engine runs great but what I think is the restriction alarm goes off after a short bit of running and not even WOT. All detail chronicled below but my confusion lies in the description of the alarms. I am getting an alarm that goes off about every 1 sec. ( ear piercing BTW ). Some say that is VRO and that restriction and overtemp are solid tone. If my VRO harness is unplugged and alarm wire is not connected. How could it be anything other than restriction?

    Here's what's been done -
    VRO disconnected. harness unplugged - did this right from the get go.
    pumped the tank out - owner said only ever used 93. Pumped about 11 gal out.
    on first run, took it to the river, ran about 25-30mph for just a few min. stopped to fish a bit, returned to the dock.
    2nd run - idled around in a marina, listened to liven music then when for a run out in the open river - less than 5 min running about 35 or so, alarm. Shut it down, tried to just idle back but kept alarming after running 30 sec to 1 min.

    from there - put in new t-stats and poppet valves, took my infrared gun along and ran until alarm. Temps are perfect. unplugged sensor wires one at a time. each head then fuel vacuum switch. didn't stop until vacuum switch.

    figured it was something in the lines or air. replaced fuel filter and lines in engine compartment. inspected fuel pump diaphrams, looked good but ordered a new set anyway.

    someone suggested running on a portable tank to isolate. borrowed a 6 gal tank, took to river, ran like a champ.
    ordered new pickup tube for tank, installed tube, new hose and new primer bulb - test run - same damn alarm.

    ran out of time so took the portable take w me to NY on vacation. Ran off that tank for a solid 10-15 min at 40mph. No alarm.
    noticed that new primer bulb wasn't holding the fuel in the engine bay.

    back home, out to river, run another portable tank test just to be sure all ok, damn alarm comes on. Could barely idle back to dock w/out alarm

    FYI - when alarm comes on, NO performance change is noted, just scared of burning a piston if it's really actually running lean.

    The only two components that are not rebuilt or new are the vacuum switch ( no longer available ) and the pulse dampener.

    I thought I read an article but cannot find it on how much vacuum it takes to trigger the switch. I could then use a vac pump/guage to test the internal switching. Anyone know how many PSI triggers it?

    Anything else I might be missing? Like I said, might be just an alarm issue but I didn't want to take any chances with killing the motor. This was a swinging deal and two lakes that I fish are electric only so I've gotten good use from the boat but want to get out on the upper chesapeake bay to fish and for that, I need this engine to run.

    Thanks!

  2. #2
    Join Date
    Sep 2010
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    20,229

    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    How long is your fuel hose on the boat and what size is the hose ?-------V-6 motors need 3/8" I.D. hose or bigger.
    Last edited by racerone; 08-06-2020 at 06:50 PM.

  3. #3
    Join Date
    Mar 2019
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    Maryland
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Quote Originally Posted by racerone View Post
    How long is your fuel hose on the boat and what size is the hose ?-------V-6 motors need 3/8" I.D. hose or bigger.
    It's 3/8, even did 3/8 fuel filter even though it appears 5/16 inside the engine area was factory. Prob 10' or so. That's a thought, the hose was routed from the center down the starboard side but has to come back across to go through the access hole in the tray which is on the port side. I might be able to take quite a bit of length out of it but routing the other way. It's a real PITA. No wonder this builder was out of biz after 5 years. After everything was installed they spray foamed the hell out of the boat. I can't even get to my vent line without digging out a bunch of foam. same for things like the bilge line.

  4. #4

    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    In answer to your question,the vacuum switch closes at seven inches
    You could use swith #586544 if needed.
    Last edited by Rwbutler; 08-07-2020 at 08:21 AM.

  5. #5
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    Maryland
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Quote Originally Posted by Rwbutler View Post
    In answer to your question,the vacuum switch closes at seven inches
    You could use swith #586544 if needed.
    Awesome - thanks for the info. Gotta do some testing and also look up that P/N

  6. #6
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    Mar 2019
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    I tested my switch and it's working properly. opening at 6" vs the spec of 7" but I don't think the alarm is giving a faulty warning at this point.

    The engine is definitely having issues getting fuel. I replaced the fuel filter with a much larger element Attwood filter ( still 3/8 ) and again, it ran great for about 20 min or so. Then it started again. This was the first time I wasn't on the boat alone so I could work the primer. All the way back to the dock I fought with it. If I didn't squeeze the bulb, the alarm would be on and it would start to stumble, was only running about 6mph at this point. I ended up laying on the deck pumping the bulb while my wife drove. By the time we got near the dock, I couldn't keep the alarm off in gear and I had the bulb rock hard. My wife and I had gone out to watch the sunset so we were battling daylight and so I didn't attempt to swap out the fuel filter on the water.

    This boat sat for almost 3 years with ~ 12 gal of 93 octane in it. I pumped it out but I'm sure I didn't get it all. It's an aluminum tank. The filter doesn't look gummed up but thinking that maybe there's no way to tell? Anyone else run across this symptom and have it be something else? I have a 3/8 fuel water separator with a spin on and clear bowl at the bottom coming today. Is there anything else I should be looking at?

  7. #7

    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    What happened between post#1 (no performance change) and now (starts to stumble)?

  8. #8
    Join Date
    Nov 2005
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    Mt. Zion, Illinois,
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    1,108

    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    I don't see any mention of you checking the fuel tank vent hose since you've changed everything on the tank but this part. I"m willing to bet if you could run the boat until you get the alarm/running problem then stop immediately and loosen the fuel filler cap you'd hear a whooshing sound as air gets sucked into the tank.

    You need to trace the vent line from your tank to the fitting on the side of the hull. Little spiders like to make their home in those places and I'll after setting under a tree you have a nice collection in the hose that is restricting air flow. Either remove the vent and blow everything out or just replace the vent and all hose leading to the tank.

    KJ

  9. #9
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Quote Originally Posted by kevinj View Post
    I don't see any mention of you checking the fuel tank vent hose since you've changed everything on the tank but this part. I"m willing to bet if you could run the boat until you get the alarm/running problem then stop immediately and loosen the fuel filler cap you'd hear a whooshing sound as air gets sucked into the tank.

    You need to trace the vent line from your tank to the fitting on the side of the hull. Little spiders like to make their home in those places and I'll after setting under a tree you have a nice collection in the hose that is restricting air flow. Either remove the vent and blow everything out or just replace the vent and all hose leading to the tank.

    KJ
    Sorry, yeah, i failed to metion that I've checked this already. removing the cap has no effect. I also don't have a checkball in the brand new pickup tube and my vent is clear.

  10. #10
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Quote Originally Posted by Rwbutler View Post
    What happened between post#1 (no performance change) and now (starts to stumble)?
    Had more run time. Before, when the alarm went off, I shut it down after maybe 30 sec to 1 min. The longer I ran with the alarm on, the worse it got. this time I had my wife onboard and so I had someone to steer the boat while I checked the bulb and also tried to remedy by squeezing it. In prior runs I was solo out testing it. Last time I had a boat with an outboard, I was in my teens and it was my dads. Old Johnson 70 back in late 70's / early 80's. I never recall us having issues with it and never learned about the 2 strokes. this has been quite a learning adventure. I work on cars all the time but 2 stroke outboards definitely have their nuances.

  11. #11
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    Sep 2010
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Need to know why you keep running with the alarm on ??------Unless you understand / know 100 % what the alarm is telling you you are risking destroying the motor.------If it is a steady continuous alarm it could be overheating.

  12. #12
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Quote Originally Posted by racerone View Post
    Need to know why you keep running with the alarm on ??------Unless you understand / know 100 % what the alarm is telling you you are risking destroying the motor.------If it is a steady continuous alarm it could be overheating.
    It's definitely the fuel restriction. I've been down the "pull one wire at a time route" to ensure it wasn't overheating, I also have brand new impeller, t-stats and poppet valves and taken temps with a IR gun multiple times and my head temps are perfect. VRO is disconnected and I also did pull the off the sender while it was idling and alarming.

  13. #13

    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    If you are getting an alarm with all switches disconnected,you have a wiring or horn issue and the stumbling is another problem.

  14. #14
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Quote Originally Posted by Rwbutler View Post
    If you are getting an alarm with all switches disconnected,you have a wiring or horn issue and the stumbling is another problem.
    sorry if I wasn't clear. I used connect/disconnect one at a time to isolate and confirm the source of the alarm which I isolated to the vacuum switch. I also hooked up a vacuum gauge and a mighty vac with a meter on the terminals to determine how many inches of vacuum it took to open. I tested mutiple times and it always opened at 6" and when running longer and having to squeeze the bulb to keep it running, I'm sure that it's a valid alarm. Now I have to figure out if the only possible contributor is the fuel filter. Brand new in-tank pickup with no screen or anti-siphon, thread sealant, brand new hose, brand new primer bulb. Opened the gas cap while it was alarming with no change.

    I have a 3/8 fuel water separator with a clear bottom and drain arriving today. Planning to mount that in line and put on a fresh filter and head out again. Just wondering if I missed something.

  15. #15
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Guys -
    It looks like I've sourced the issue. It looks like I didn't do a great job in cleaning out this tank given that the boat sat for 2+ years. I inspected the last filter and its got a bunch of gunk, mechanic I know said likely from the ethanol. I siphoned out the fuel but did it from the pickup so I likely left crap in the bottom. I guess I'll be pumping out again and pulling the tank from the boat for a thorough cleanout...

  16. #16

    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    How many rpm is 6mph?
    You dont have a fuel quick disconnect at the lower pan,do you?

  17. #17
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    Sep 2010
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Where was the 6 MPH mentioned ?

  18. #18

    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    Quote Originally Posted by racerone View Post
    Where was the 6 MPH mentioned ?
    Post #6....!

  19. #19
    Join Date
    Nov 2011
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    tennessee
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    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    These havent had disconnects in years...disconnect went away in early 80's
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  20. #20

    Default Re: 1990 GT150 J150STLESB - Sorry, read so many posts and still have a few questions

    I know,but i have seen them added.

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