Update to my bogging/stalling 3.7L

[Beefer]

Catch-up; When I 1st got the boat (almost 2 mos. ago), would bog and immediately stall if given throttle. Idle speed was 'ok'. Changed a bunch of stuff, which could be said as throwing parts at it, but most were regular tune-up items. Emptied fuel, and refilled with non-ethanol. Changed the anti-siphon with a new one, and then (last night) removed anti-siphon completely. Vent tube appears to be clear and free-flowing. New gas cap. New filters. New USCG fuel lines where there was (what appears to be) automotive fuel lines. That's where I'm at.

After each 'improvement', I saw improvement, and thought I was getting close. Last weekend, I started to see a correlation between bogging/stalling and less-then-smooth water. If I hit wakes, or got out to the Gulf, it would bog some, but not necessarily stall. As the FWS filter is new, I hadn't been checking it much. Last weekend when I stalled, I opened the valve, and air sucked in, then fuel came out. Then the boat would start and run fine for another 'x' period of time.

Last night, after removing the anti-siphon valve, it ran like a champ for 2 hours, and I got to play 5 miles out in the Gulf without the slightest hiccup. I figured I had it fixed. AAAAAAAAAARRRRRRRRRGGGGGGGGHHHHHHH.

Just as I got into the inlet where the speed goes down to min. wake, it hiccuped. Then, when I got to the next speed zone, it stalled once given throttle. Sure enough, opened up the FWS, let air in, closed it back up, and on my way I went.

What could be causing this? One mechanic thought maybe electrical. Another thought that there is residual water in the bottom of the carb that could be getting stirred up. Do either of these sound logical? I like the water in carb, as that would eventually work its way out, and a little seafoam never hurts.

I feel I'm soooo close to getting this corrected.

 

[Adirondack]

Re: Update to my bogging/stalling 3.7L

Have you checked the fuel tank vent? Does it suck air in if you run it then open the fuel fill? Sorry I wasn't following your other thread so I don't know if this was mentioned.

 

[Beefer]

Re: Update to my bogging/stalling 3.7L

Have you checked the fuel tank vent? Does it suck air in if you run it then open the fuel fill? Sorry I wasn't following your other thread so I don't know if this was mentioned.

Yeah the vent is clear. It was actually the first thing I checked when it happened the first time, and I've checked it multiple times since.

It really acts like an obstructed vent, but I'm 99.99999% sure it's not a vent issue.

 

[LAC_STS]

Re: Update to my bogging/stalling 3.7L

What kind of IGN system do you have? Points?

 

[dubs283]

Re: Update to my bogging/stalling 3.7L

if you remove the vent hose from the tank, can you blow air out through the hose??

also, check the barb where the vent hose attaches to the tank, make sure it is free of obstruction

the vent hose should be routed upwards from the vent on the side of the boat, this will prevent any water from getting in the hose and settling in a low spot blocking air flow

 

[Adirondack]

Re: Update to my bogging/stalling 3.7L

Yeah the vent is clear. It was actually the first thing I checked when it happened the first time, and I've checked it multiple times since.

It really acts like an obstructed vent, but I'm 99.99999% sure it's not a vent issue.

That's a pretty good level of confidence. It sounds like you have really gone thru everything. What I would do is rig up a small gas can to feed right to your fuel pump. see how it runs. If the problem is gone something is restricting flow from the tank. I have seen things get down into automotive tanks that clog the intake once in a while, then not. A rag someone was using as a gas cap comes to mind. Rode around harmless most of the time till the gas sloshed just right and it got sucked up on the pickup tube. Car shut down, suction went away, rag fell off, and off you went again. Sometimes it didn't clog it all the way and the car just ran crummy till you shut it off and restarted it.

I would look for a clog of some sort upstream of your WFS. I don't think there should be suction there on a non running engine.

 

[Beefer]

Re: Update to my bogging/stalling 3.7L

That's a pretty good level of confidence. It sounds like you have really gone thru everything. What I would do is rig up a small gas can to feed right to your fuel pump. see how it runs. If the problem is gone something is restricting flow from the tank. I have seen things get down into automotive tanks that clog the intake once in a while, then not. A rag someone was using as a gas cap comes to mind. Rode around harmless most of the time till the gas sloshed just right and it got sucked up on the pickup tube. Car shut down, suction went away, rag fell off, and off you went again. Sometimes it didn't clog it all the way and the car just ran crummy till you shut it off and restarted it.

I would look for a clog of some sort upstream of your WFS. I don't think there should be suction there on a non running engine.

I did the topside tank a while back. Used up all 6 gals without a hiccup. That's when I decided to remove the 40 gals that were in the main tank.

Garbage in the tank makes lots of sense. Only problem is, I didn't see anything when I emptied the tank (mirrors and a flashlight), and now I've got 60+ gals in the tank... I wonder if there is something I can put in the tank through the sending unit, and see if I can catch something in there, like a small net or something.

 

[Beefer]

Re: Update to my bogging/stalling 3.7L

What kind of IGN system do you have? Points?

Yep. Most of the ignition system is new. New: plugs, cap, rotor, points, condenser, and coil. I have new wires, but haven't put them on yet.

 

[Adirondack]

Re: Update to my bogging/stalling 3.7L

Next time around, (if you can do it without getting water down the fill) try running with the gas cap loose. If it still acts up then you are 100% sure the vent isn't clogged.

 

[dubs283]

Re: Update to my bogging/stalling 3.7L

if you had no issues with a shop tank in place of the boat fuel tank...AND...there were 2 hours of awesome run time - the odds of an ignition issue are pretty slim

it sure sounds like it is a fuel delivery issue, especially since the fuel filter sucked air when you unscrewed it - that means there is built up vacuum in the fuel line and you are relieving it by unscrewing the filter

i know you have gone through the fuel tank and vent lines but that is most likely where the issue is

you can also try routing a temporary vent line from the tank and keeping the end inside the cockpit - that way you know no water is getting into it

if it continues to act up, check the tank for debris

 

[Beefer]

Re: Update to my bogging/stalling 3.7L

Ok, I went to change out the tank vent line as a cheap precaution, but couldn't get the line out without tearing out a bunch of flotation foam below the deck. I am now 100% certain that the vent line had/has no obstructions in it. I did, however, notice that where it connects to the tank it looked like it was split at some point (possibly during original construction), and 'patched' with some silicon. Hmm. Cut about a foot off the line, and spliced in a new section to attach to the tank.

So now I'm thinking debris in the tank. Possibly a chunk of the silicon stuff fell in? In any case, how do I now see into the tank, and if there is something in there, how do I get it out? Through the sending unit access I can only see a very small section (and it's dark in there), and what do I use to remove the debris? I've got my fuel down to about 20 gals., and once I get to 10, I can siphon it out without having to lose any of it (2 5 gal cans).

Anyone ever have to get debris out of a tank? How'd you do it?

 

[hooks1]

Re: Update to my bogging/stalling 3.7L

I haven't cleaned out a boat tank (yet) but I expect I will have to so I've been cruising the forum for tips. It sounds like almost all boat tanks use an open pick-up tube - i.e., no sock filter - so any debris that would plug it up would have to be fairly large. One post discussed using the fuel pick-up tube by putting the boat on the trailer (I presume out of doors), disconnecting the flexible tube from the fuel pump, and connecting that tube to a hose small enough to fit thru the transom drain. If it won't start draining on its own use a bulb pump to get it started and note the flow. If it stops before emptying then you at least know where the debris are (is) - in the end of the pickup tube. You might be able to get at it by removing the fill line - this is where I would probably just remove the tank (mine is held in by four small pieces of aluminum angle) and try to slosh the debris around until it is near the fill or sender port and fish it out with a tea strainer or similar. I'm interested in your progress - good luck!

 

[Beefer]

Re: Update to my bogging/stalling 3.7L

It's an 80 gallon tank, and the distance from the sending unit access to the pickup is about 2.5 feet. When it clogs (assuming that it is clogging), There wouldn't be a way for me to 'reach' the pickup from the sending unit. I think whatever it is that's causing the clog is too big to be pulled into the pick up, because once I release the vacuum, I believe it falls away from the pickup. Also, the boat is in the water. I think I may have to call in a professional tank cleaner ($240) to take care of this.

 

[hooks1]

Re: Update to my bogging/stalling 3.7L

Bummer! My filler neck is only about 10 inches from the pickup (they are both at the very rear of the tank). For $240 I would probably look for a used CG-approved transfer pump with a large pickup tube and do it myself - but then I look for excuses to buy toys.

 

[Beefer]

Re: Update to my bogging/stalling 3.7L - 12/5/10

Re: Update to my bogging/stalling 3.7L - 12/5/10

Five months. That's how long I've been trying to solve this problem, and I think I finally got it.

I did end up having the tank professionally cleaned, and was sure my problem was solved, but alas, it wasn't. Put on a brand new FWS filter this morning, and took her out, hoping that the filter was just clogged from pre-tank cleaning debris. Went out, and she bogged and died like she had been. When I got back, and told my wife, she about lost it, and said we should sell it.

The only thing I hadn't done to this point, was disassemble the FWS, and make sure something wasn't plugging up the inlet to it. Of course, as my luck would have it, it looked brand new, and there were no obstructions. Would have been an easy fix.

Then I decided to (once again) check the pick up tube. Blew through it, and it felt a bit obstructed. Jammed a wire coat hanger in there, and it came out with gunk! In my ignorance, I hadn't realized that the pickup tube assembly came apart. Figured I'd see if it did, nothing to lose. When I did, lo and behold, there is a screen at the top of the tube! Everybody I had spoken to previously had asked about the screen at the bottom of the tube, of which there wasn't one. Nobody ever said anything about one at the top.

Well, the screen was caked with gunk, so I cleaned it out. I have to guess that that was my problem. I'll be sea trialling on Tuesday, and have my fingers crossed.

So for all of you, you may not see a screen in your pick up tube, but that doesn't mean there isn't one!!!