Ok folks, help if you can…
I’ve got a 2003 140 hp 4stroke Johnson and it’s been slowly losing rpm’s/thrust the past couple of times I’ve taken it out. It cranks and idles like it should, but it’s not accelerating and reaching full throttle anymore (not even close). It will accelerate to about 4600 rpms ( about 1/2 throttle )and when I push the throttle further to where it normally would reach about 5600 rpms’s, nothing happens. The throttle seems to move the same throughout it’s range, but there is no further acceleration/thrust past 1/2 way. I noticed time before last that it wouldn’t pass 5200 rpm’s and last week it wouldn’t pass 4600 rpm’s.???
Any thoughts or ideas that I could look into myself before I take it to Chris V? He has always done the maintenance on this motor and it’s run fine, but this has kinda has come out of left field.
LW,
I changed the fuel filter outside of the motor (between tank and motor) a couple of months ago and I changed the one that I know about inside the motor about a year ago (it’s a small plastic filter with two stems on it). It had been accelerating fine, running about 60 seconds, and then almost completely cut off. I’d restart the motor and it might not happen again the rest of the day. I changed the filter inside the motor and started using 100% non-ethanol fuel. That hasn’t happened since then. Maybe this is a different symptom of the same issue with the filter?
There is two filters on my 175’s, the plastic low pressure one and also a metal high pressure filter…kinda hidden" mine stopped up 1st of this year limiting rpm’s
Check the fuel pump on the back of the motor mounted on the valve cover. sometimes the vest for the valve cover gets clogged or pinched somehow and build pressure up inside the valve cover keeping the diapham inside the fuel pump from contracting all the way and not picking up enough fuel. ive only seen this a couple of times but its something easy to check. on top of the valve cover is a vent hose. next time your out and want to check it. run the engine till it acts up, then pull that vent hose off and try it again. if it still does it then its probably a fuel problem.
I have an 08 suzuki 150 4 stroke and when a filter is clogged I know it… Yesterday my fuel water separator was bad and I could only get 2500RPM’s… changed it out back to normal… Also I’m with cpt ed IF you haven’t changed your high pressure fuel filter (black metal filter, top transom side of the motor) I’d look at that first, also there is a screen filter that can sometime’s cause a problem inside the vapor saparation tank, use a little carb cleaner to spray it out (don’t use water because it’ll rust)… This is all speaking from experience and alot of Thank’s go to Chris V for not making me put my boat in the shop for weeks just to find out it’s a filter issue… Also those High pressure filters are around $100, a little expensive but I almost garontee it’s your problem
“The Wet Dream”
20’ Pioneer 197
150hp Suzuki 4-Stroke
Jackson make sure you didn’t suck part of a bird nest into the intake.I did and spent a lot of money and time at local dealers before someone from Beaufort posted about the same problem.
Thanks Al and SCM84… Gonna attempt everyone’s advice from simple to complex and see if it remedies the problem this weekend. Will probably change those/that fuel filter at the top of the motor that I’ve never changed anyway.
