skydiveD30571
Lieutenant Junior Grade
- Joined
- Feb 13, 2012
- Messages
- 1,042
New issue so bear with me on this one. A little background first.
VP 5.0GL-H mfg 9/06 carbed, no prior maintenance history except evidence that it was not taken care of (interior issues, no tune ups, etc)
Ran perfect last year with no issues, put it up over the winter then got it out in march, changed plugs and tried spraying the carb with carb cleaner since there was black residue on the choke plate. That's when problems began:
boggy idle, irratic idle speed, excessive drop in rpm when shifting into gear
No starting issues whatsoever. Always cold started fantastic, and hot started great as well. Performs flawless throughout the rpm range with no hesitation or stumbling at all. The only performance issues I have ever had have been at idle.
Put in new cap/rotor/wires since it had never been done. The coil-to-cap wire in my kit was too short so I had to keep the old one on there. Have not checked timing but plan on it next week.
The mechanic didn't have time to really adjust the carb, but I fired it up for him before he left and he said my idle issues were from having a mixture that was too lean. He looked into the compartment real quick and noticed that the starboard idle mixture cap is removed, and that screw had been adjusted. The port screw cap was still in place so it had never been moved. Also, the 4 bolts on the fuel bowl have the red paint stripped off indicating someone has gotten in there before. Seems like someone previously tried fixing (or covering up) a carb problem.
He backed out the exposed idle mixture screw and it really seemed to help the idle characteristics. He said to see how that works, and if it still needs work we can do a more proper adjustment later. Once on the water i gave the speed screw a little adjustment and it idled really well all weekend, right at 700rpm in neutral and 600-650rpm in gear. It'll idle all day right there.
But a new problem started this weekend. The first start (cold) was normal and we headed out to a cove. I might mention that it was windy and we had some big swells we were running with all the way there. Anchored down and hung out for 3-4 hours. When tried to start, it would not catch. I tried the cold starting procedure and it would also not start. Eventually it started only if I placed the throttle wide open (much like clearing a flood). We came back to camp, and an hour later I tried again. Same thing. The next day, same deal. I tried pumping it while cranking to see if it just needed some gas. Negative. Once again, if I put it at wot it would start up after 7 or 8 seconds of cranking. If I shut the engine off, then immediately cranked it, it starts right up no problem. That evening, starting issues took less time to show up. What I mean by that is, if the engine had to be off for an hour during the day to have trouble starting, that evening it would have trouble if left off for 10-15 minutes. During the day it was 100+ degrees, and during the evening I'd say was around 80-85. During these starts, it would turn over, and idle would bog down from 700rpm to about 400rpm, then over the next 15 seconds it would steady out at 700 and have no problems staying there. Otherwise it ran great.
The first thing I checked at home was the choke. It has never been touched and is set at the factory setting of 5 notches lean. I do notice a smell of gas in the engine compartment, strongest right around the carb. There is no liquid of any kind leaking anywhere. Before messing with the carb, I decided to check the ignition components. New cap is still clean, plug wires all connected. I started pulling the plugs, which are about 3 months old now with few hours on them. They are ngk tr55gp "G-Power" plugs which an autozone guy apparently cross matched to the originals but I can't confirm that is actually true. I know these have a heat rating of 5 and the ac delcos that I believe were original had a heat rating of 4. Pulled all 8 plugs, and every one of them had a film of oil on the threads....only the threads....the electrodes were dry but blackish colored. The old plugs that were pulled in march had no liquid on them, but were black on the threads and electrodes.
So my question is, being that only the idle mixture in 1 jet was adjusted prior to starting issues showing up, are the two related in any way, or is it just coincidence? Like I mentioned, someone has removed the fuel bowl before, but since it runs great all the time now except startup, and has never had issues outside of idle, I find it hard to believe it could be a bowl problem. As for the bogging idle only on a semi-cold start, does that sound flooding related? Like when the engine is off, the carb is slowly flooding so after a few hours I have to clear it out, but after 15 minutes its not bad enough to keep from starting, but it idles irratic and unstable until that fuel exits the carb? Just throwing out guesses here. Every mechanic around is atleast 3 weeks out, so I'm trying to go thru the list and check things myself. But some guidance on what to check would be very helpful.
VP 5.0GL-H mfg 9/06 carbed, no prior maintenance history except evidence that it was not taken care of (interior issues, no tune ups, etc)
Ran perfect last year with no issues, put it up over the winter then got it out in march, changed plugs and tried spraying the carb with carb cleaner since there was black residue on the choke plate. That's when problems began:
boggy idle, irratic idle speed, excessive drop in rpm when shifting into gear
No starting issues whatsoever. Always cold started fantastic, and hot started great as well. Performs flawless throughout the rpm range with no hesitation or stumbling at all. The only performance issues I have ever had have been at idle.
Put in new cap/rotor/wires since it had never been done. The coil-to-cap wire in my kit was too short so I had to keep the old one on there. Have not checked timing but plan on it next week.
The mechanic didn't have time to really adjust the carb, but I fired it up for him before he left and he said my idle issues were from having a mixture that was too lean. He looked into the compartment real quick and noticed that the starboard idle mixture cap is removed, and that screw had been adjusted. The port screw cap was still in place so it had never been moved. Also, the 4 bolts on the fuel bowl have the red paint stripped off indicating someone has gotten in there before. Seems like someone previously tried fixing (or covering up) a carb problem.
He backed out the exposed idle mixture screw and it really seemed to help the idle characteristics. He said to see how that works, and if it still needs work we can do a more proper adjustment later. Once on the water i gave the speed screw a little adjustment and it idled really well all weekend, right at 700rpm in neutral and 600-650rpm in gear. It'll idle all day right there.
But a new problem started this weekend. The first start (cold) was normal and we headed out to a cove. I might mention that it was windy and we had some big swells we were running with all the way there. Anchored down and hung out for 3-4 hours. When tried to start, it would not catch. I tried the cold starting procedure and it would also not start. Eventually it started only if I placed the throttle wide open (much like clearing a flood). We came back to camp, and an hour later I tried again. Same thing. The next day, same deal. I tried pumping it while cranking to see if it just needed some gas. Negative. Once again, if I put it at wot it would start up after 7 or 8 seconds of cranking. If I shut the engine off, then immediately cranked it, it starts right up no problem. That evening, starting issues took less time to show up. What I mean by that is, if the engine had to be off for an hour during the day to have trouble starting, that evening it would have trouble if left off for 10-15 minutes. During the day it was 100+ degrees, and during the evening I'd say was around 80-85. During these starts, it would turn over, and idle would bog down from 700rpm to about 400rpm, then over the next 15 seconds it would steady out at 700 and have no problems staying there. Otherwise it ran great.
The first thing I checked at home was the choke. It has never been touched and is set at the factory setting of 5 notches lean. I do notice a smell of gas in the engine compartment, strongest right around the carb. There is no liquid of any kind leaking anywhere. Before messing with the carb, I decided to check the ignition components. New cap is still clean, plug wires all connected. I started pulling the plugs, which are about 3 months old now with few hours on them. They are ngk tr55gp "G-Power" plugs which an autozone guy apparently cross matched to the originals but I can't confirm that is actually true. I know these have a heat rating of 5 and the ac delcos that I believe were original had a heat rating of 4. Pulled all 8 plugs, and every one of them had a film of oil on the threads....only the threads....the electrodes were dry but blackish colored. The old plugs that were pulled in march had no liquid on them, but were black on the threads and electrodes.
So my question is, being that only the idle mixture in 1 jet was adjusted prior to starting issues showing up, are the two related in any way, or is it just coincidence? Like I mentioned, someone has removed the fuel bowl before, but since it runs great all the time now except startup, and has never had issues outside of idle, I find it hard to believe it could be a bowl problem. As for the bogging idle only on a semi-cold start, does that sound flooding related? Like when the engine is off, the carb is slowly flooding so after a few hours I have to clear it out, but after 15 minutes its not bad enough to keep from starting, but it idles irratic and unstable until that fuel exits the carb? Just throwing out guesses here. Every mechanic around is atleast 3 weeks out, so I'm trying to go thru the list and check things myself. But some guidance on what to check would be very helpful.
