CTboater78
Cadet
- Joined
- Mar 21, 2013
- Messages
- 16
Stumbles & stalls at idle & when shifting but runs perfect when PCV valve is removed?
Hi Everyone...just some quick background info, I had a bad U-Joint bellow so I did a transom rebuild this past Spring and after some difficulty with the new shift cable, I watched Chris' cable adjustment video and all was good (Thank you Chris!). About half way through the Summer I noticed some stumbling while under way that seemed to go away after a few trips. Then the problem got worse quickly. I started to notice rough starts, poor idling and when shifting into reverse out of the dock the engine would stall. About 50% of the time it would also stall when I would float away a bit and restart and try to shift into forward. I could only get it to fire if I gave it a fairly decent amount of throttle but then when I would slow down as I approached the dock later on, it would consistently stall. The gas was stabilized and fresh enough to not make me concerned about bad fuel but I replaced the fuel filter/water separator anyway. I was hoping to find particles in there but all I saw when I emptied the filter into a clear glass was clear gas. I replaced the filter and gave it a Sea Foam shock treatment....I know there's mixed reviews on the procedure but I thought it might help if I had a clogged injector(s) but that didn't work at all. Now I'm in the process of winterizing and can't give up on investigating this problem. It fired right up today but had a horrible idle. What's odd, to me, is that the RPM needle was at a steady 600RPM but the boat was shaking like it was going to bounce off the trailer. I gave it some throttle up to about 1500RPM and it did smooth out considerably but not enough to be considered "normal". The RPM needle was jumping all over the place for some reason but the engine was steady. This may have been a senseless move but I re-checked the upper and lower shift cable adjustments thinking that the new cable may have possibly stretched over the Summer but everything was accurate so I sprayed some carb/fuel injector cleaner down the throttle body hoping for the best, but nothing. That's when I noticed a PCV valve just behind the throttle body with a 3/4" or so short vent line running over to another PCV valve on the top of the port-side valve cover. I decided to remove the valve behind the throttle body with the boat running and the boat instantly ran like it was brand new. No stumbling, no issues at idle, no problems shifting and no stalling (at least on land). I shut the boat off and she started right up and, again, everything was perfect. The second I put that valve back on, all of the problems came back again. I should note, and I'm sure many of you know, that these are really elbows and not traditional PCV valves that you would find in a car that rattle when you shake them and don't when they're clogged. The hose was completely clear and so were the 2 elbows. I don't know if this was a coincidence or not, but removing that elbow from behind the throttle body instantly solved my problem. Now, I doubt the permanent fix is to leave this disconnected, but does anyone have any suggestions on what could be the cause behind this or what I should be looking for? As always, your help is much appreciated!!! - Gary
Hi Everyone...just some quick background info, I had a bad U-Joint bellow so I did a transom rebuild this past Spring and after some difficulty with the new shift cable, I watched Chris' cable adjustment video and all was good (Thank you Chris!). About half way through the Summer I noticed some stumbling while under way that seemed to go away after a few trips. Then the problem got worse quickly. I started to notice rough starts, poor idling and when shifting into reverse out of the dock the engine would stall. About 50% of the time it would also stall when I would float away a bit and restart and try to shift into forward. I could only get it to fire if I gave it a fairly decent amount of throttle but then when I would slow down as I approached the dock later on, it would consistently stall. The gas was stabilized and fresh enough to not make me concerned about bad fuel but I replaced the fuel filter/water separator anyway. I was hoping to find particles in there but all I saw when I emptied the filter into a clear glass was clear gas. I replaced the filter and gave it a Sea Foam shock treatment....I know there's mixed reviews on the procedure but I thought it might help if I had a clogged injector(s) but that didn't work at all. Now I'm in the process of winterizing and can't give up on investigating this problem. It fired right up today but had a horrible idle. What's odd, to me, is that the RPM needle was at a steady 600RPM but the boat was shaking like it was going to bounce off the trailer. I gave it some throttle up to about 1500RPM and it did smooth out considerably but not enough to be considered "normal". The RPM needle was jumping all over the place for some reason but the engine was steady. This may have been a senseless move but I re-checked the upper and lower shift cable adjustments thinking that the new cable may have possibly stretched over the Summer but everything was accurate so I sprayed some carb/fuel injector cleaner down the throttle body hoping for the best, but nothing. That's when I noticed a PCV valve just behind the throttle body with a 3/4" or so short vent line running over to another PCV valve on the top of the port-side valve cover. I decided to remove the valve behind the throttle body with the boat running and the boat instantly ran like it was brand new. No stumbling, no issues at idle, no problems shifting and no stalling (at least on land). I shut the boat off and she started right up and, again, everything was perfect. The second I put that valve back on, all of the problems came back again. I should note, and I'm sure many of you know, that these are really elbows and not traditional PCV valves that you would find in a car that rattle when you shake them and don't when they're clogged. The hose was completely clear and so were the 2 elbows. I don't know if this was a coincidence or not, but removing that elbow from behind the throttle body instantly solved my problem. Now, I doubt the permanent fix is to leave this disconnected, but does anyone have any suggestions on what could be the cause behind this or what I should be looking for? As always, your help is much appreciated!!! - Gary
