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Johnson 150 alarm activating

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ff92

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"I've got a 99 150 that st

"I've got a 99 150 that starts and runs impeccably. Last time out though, the "check engine" light appears and the audible alarm sounds at WOT (5600 rpm). I bring it down to idle and the light and alarm quit. Try again at WOT and same result. My manual quotes "fuel restriction" as the cause. I've checked and cleaned the fuel filter, checked all fuel lines I could get at, lots of gas in the tank, oil bulb is primed, tell tale nozzle is spraying fine. Any ideas what my problem could be?"
 
Two more likely options:
-Fue

Two more likely options:
-Fuel tank vent - try running with fuel cap open.
-Anti Siphon valve on tank-top stuck.(Spring loaded ball valve)
 
"Thanks Morten. The boat is a

"Thanks Morten. The boat is a Stratos Vindicator, I just attempted to get at the Anti siphon valve on the built in tank but I haven't found a way to get at it yet, and darkness has set in. The tank seems to vent properly though, the vent is beside the tank filler and it hisses when I fill the tank. I'll chase this lead and post any findings. I just don't understand how the motor doesn't skip or stutter if it has a fuel restriction, is it smart enough to know it's not getting the required amount of fuel at WOT?"
 
"That is why that engine is eq

"That is why that engine is equipped with a vacuum switch, the engine itself is not smart enough!! The engineers however knows that at a certain vacuum in the suction line, the engine will not only run lean, but Your VRO pump might be damaged as well."
 
"Had it out today and it runs

"Had it out today and it runs great, kept rpm's at 5000 and didn't set off any alarms at all. I'll try and get at the tank valve tomorrow."
 
Well I just inspected the anti

Well I just inspected the anti-siphon valve and it seems to move freely. What is my next move? I've got a few people interested in purchasing this boat but I can't sell it knowing there could be an issue with this motor.
 
"I registered just to assure t

"I registered just to assure this for you it's quite simple !
Your Max RPM = 4500-5500 RPM !

You have to much pitch on your prop if you turning 5600 as stated !

My Pop has a 1999 Johnson 150 !

I noted the rpm range on www.IBoats.com prop finder section !"
 
"Hi Roy. I considered that. I&

"Hi Roy. I considered that. I've got a Raker 14.5 X 24p that I've been running for two years at WOT and haven't heard the alarm, so it seems strange it would alert now. I'm thinking I might have been trimmed up too high. What's your dad running for a prop and on what vessel?"
 
"kelly,....u have,a fuel restr

"kelly,....u have,a fuel restriction...chg all filters,repl anti syphon valve,w/plain nipple..5600,is not setting off ur vacuum sw...in fact,thats not even a problem,itself."
 
"Hi there jwb. It's a J150

"Hi there jwb. It's a J150PLEE if that gives you more info, is there only the one cone shaped filter on the engine itself or could there be more upstream in the line somewhere, because I've inspected that one and it's clear. Would I be wise to remove all fuel lines and blow compressed air back through the lines? The fuel primer bulb appears to be functioning properly because I removed the filter on the inlet of the VRO and had to reprime upon reinstallation. I've also removed the anti-siphon valve and the ball and spring move freely. Is the restriction definitely the only cause or could the VRO pump be questionable? Sorry for the questions but I'm starting to get frustrated with this problem."
 
"u can pull a vacuum test,on v

"u can pull a vacuum test,on vacuum switch,to verify,it wks properly...i dont know the spec of hand."
 
"The Clymer says to place a va

"The Clymer says to place a vacuum gauge inline at the fuel pump and look for a reading of less than 4 in. hg, anything more and there's a restriction. Does that sound right to you."
 
"Alarm should sound when vacuu

"Alarm should sound when vacuum on the switch is either within 6.5 to 7.5 in. Hg or 5 to 6 in. Hg depending on the color of the housing, according to Clymer. Now I've got to find a vacuum gauge or a mechanic with one."
 
"Assuming the vacuum gauge tur

"Assuming the vacuum gauge turns out to be okay, something is causing the vacuum to rise, and this can lead to serious trouble. Frequently the culprit is a fuel hose that is collapsing as the vacuum increases. A slight kink in a hose can cause this. Some fuel hoses have an inner core that can become detatched and thereby restrict flow."
 
I've managed to find a nic

I've managed to find a nice Snap-on vacuum/pressure gauge that will work nicely. Hopefully have time tomorrow to test. Do you recommend I vacuum test the fuel hoses and then the vacuum switch?
 
Just stumbled on this site. L

Just stumbled on this site. Like it already. I'm new here in more ways than one. Got new/used boat and might be over my skis on this. Don't know hardly anything about outboards. Spending more time troublshooting than boating right now. I'll be on here probably every time after I'm working on the boat. Appreciate any advice I can get. Thanks!!
 
"I've tested the vacuum sw

"I've tested the vacuum switch with a hand pump, the 'check engine' light came on but the audible alarm didn't activate at 6.5 in hg. What does this result mean?"
 
"the overheat...wont operate,o

"the overheat...wont operate,on a system ck...system,unless eng is running,..i suspect,that,may be the case,w/the vacuum sw also..not 100% on that tho."
 
"So the audible alarm only wor

"So the audible alarm only works w/ engine running- makes sense, gotta overcome engine noise. I can assume the switch is functional then?"
 
"i would say so,...u might ck,

"i would say so,...u might ck,w/eng running.....i hardly ever,..see a prob w/vacuum switches."
 
"OK, thats good enough for me.

"OK, thats good enough for me. I'll move on to vac testing the fuel lines once I find a 3/8 tee."
 
A question. Why does the vacuu

A question. Why does the vacuum switch reach 6.5-7.5 in. Hg before activating when the acceptable vacuum at the pump is 4 in. Hg or less?
 
"Well just got back from the l

"Well just got back from the lake. Motor ran great, no alarms set off at WOT, hopefully problem is fixed. I had full intention of measuring vacuum at the fuel inlet, I had a tee built, a nice vacuum gauge, and changed the anti-siphon valve to a straight through nipple. On the water I primed the fuel line bulb and must have sucked fuel into the gauge rendering it useless. I assumed since it's a combo vacuum/pressure gauge it could handle fuel? What could I do but reassemble the fuel lines and try some wide open running. I guess the siphon valve was the culprit after all. On a lighter note does anyone care to teach an idiot how a vacuum gauge works and is it possible to replace the needle spring? Thanks for the quick responses to this problem all."
 
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