mercruiser will not plane 220HP chevy v8 305

[lihartke]

1. stored boat over winter without filling tank and with having ethanol. mechanic winterized it not sure if he added fuel stabilizer.
2. redid upholstry and weight of sidewall was hanging on throttle cables and other wires that ran through there. Also drilled into sidewall for wingnuts to be placed in. Near top rail in front middle and back of sidewall. Tried to take shifter lever off(quick silver throttle with square button on bottom to push in to release for neutral) things fell on floor(brass coat hanger looking""z"shaped bar in front of throttle lever), didn't know it, butalso the brass metal bar with 2 prongs that attatch shifter( to throttle cables?) to allow for forward and reverse speeds on back of shifter plate. Replaced brass bar myself and took to mechanic because throttle was racing and I did not know why. He put brass bar with prongs back on and motor ran great.
3.went to reservation to get (ethanol) gas and pumps were running very very slowly(they were replacing top pumps) got 15 gallons of gas in tank to fill boat.
4. went boating in calm water for 20 mins one way. Boat ran fine(did not open her up too much, but did go reasonably fast (15-20MPH)for a couple of minutes. Stopped for an hour to eat and went back to campground boat still ran fine
5. boated for 20 mins (very choppy waters)and hit a wave and stalled within 2 mins.
6. started right back up and went tubing for 20 mins.
6. boat was hesitating and stalled when going faster
7. started back up and ran for a few mins and stalled
8. got towed off water to mechanic(boat would not start)
9. mechanic said boat started right up when he turned her over after sitting 10 mins
10. mechanic changed water/oil separator and said we had bad gas/ added stabilizer enzyme and said we would need a carburator rebuild(carbon fouled plugs) when we get home, he ran engine for 15 mins and we left doc to boat
11.drove boat for 1500 ft and she stalled just cut out
12. started her and ran and was hesitating and stalled within a couple mins
13, started and ran and stalled and restarted
14. got back to mechanic and he checked and said we need a tune up.
15. put on new rotors,distributor cap, plugs and ran boat for 15 mins at dock
16. we took off and within 600ft she started to hesitate and was acting like she was going to stall so we put her on trailor to bring home
17. started engine in driveway on muffs and heard an arching sound and found coil top arching from under wire cap. Also noticed motor trying to turn over when key was just pushed in and not turned over
18. bought new spark plug wires(one new one was bad so we had to used an old one.) and new coil.
19. took her to parts store and tried to start her(was going to work on her there so parts were available. replaced the ignition switch she ran for 8 mins and stalled
18. gave her to mechanic and they changed the ignition sensor, spark plugs, and water oil separator and said we needed carburetor rebuild and to drain the gas.
19. drained gas completely out and refilled tank with premium ethanol free gas
19. bought rebuild kit and new float for carb and new spark plugs
20. mechanic rebuilt carb said ran great on muffs
21. took her to canal (5 mph) she ran great at low idle 40 mins no more stalling Got to no boat dock area and decided to open her up and she had no power to plane and started to sputter/hesitate went back down to 5mph and she ran a bit off but did't hesitate. Husband said he heard a "popping" sound when she was accelerated.
22. took her home and checked (new) spark plugs (after carb rebuild) and they were completly charcoal (chalky-dry-pitch-black)
23. removed fuel pump and extra air valve for emergency spillage was completely clogged with sediment debree)
24. going to buy new fuel pump and then take back to mechanic to check carb
any ideas please advise. thanks! by the way $400 at 1000 Islands, $400 at West marine $100 carb rebuild and on and on ......

 

[pckeen]

Wow.

What boat do you have?

You have had at least two mechanics/visits to mechanics where bad gas was diagnosed, along with a report that the fuel pump was clogged. It's possible you have sediment in your tank. Replace the fuel filter. If you don't have a fuel filter, install one.

 

[Rick Stephens]

What a way to mess up a vacation. That's horrid story.

I agree with pckeen's thoughts, the fuel system sounds like it still isn't clean. And depending on your motor and fuel system setup, you may have components that no one has thought to verify aren't clogged up. (anti siphon valve, vent, fuel filter on pump). I hate buying and installing parts as a method of diagnosis. Buying a pump without checking output pressure seems less than optimum path. Seems that all the mechanics have been doing so far is taking a WAG and screwing on new parts.

It is HARD to clean fuel tanks. Even if access is there, it still takes a lot of work to get everything out of it. I have seen posts from those I respect who recommend the only way to do it is to pull it out. Very well could be that replacing the fuel lines is part of the process to get it right. Pulling a fuel tank out is also usually quite difficult process depending on how the manufacturer installed it.

Systematic, front to back inspection and cleaning of the fuel system is the only way to get this right. It is not all that complex of a system.

Good luck! Hope you find the problem quickly.

Rick

 

[Rick Stephens]

I would add one more thought. One of the common diagnosis methods is to use a fuel can with known clean fuel and go directly to carb. Bypass everything suspect and see if the boat runs right. No purpose in this unless you know the carb is clean first.

Rick

 

[bobkat1864]

Ditto on what Rick said about the fuel supply...I've got a small portable outboard type tank that I got at Wallyworld (cheap), and whenever I suspect a fuel system issue, I hook that right up to the water sep filter, bypassing everything upstream, making sure I have the filters nice and clean too. I'll use brand new gas, and a healthy dose of seafoam...some call it snake oil, but I've had good luck with it. Then run the boat. If it runs good, look at the fuel system. Or, sometimes the seafoam will flush out whatever is messing up the carb. If it still runs like crap, at least you know it's not the boats fuel lines, tank, vent, etc. With that being said, however, your sooty looking spark plugs are pointing you toward the carb, rich condition.
Good luck, and let us know what ya find...Bob.

 

[bobkat1864]

Just an afterthought...once you get her running with known good clean fuel, look at the line that comes from the fuel pump, to the base of the carb. If there is fuel in it, that would mean the pump is dumping raw fuel right down the intake. That would cause a rich condition as well. (I'm assuming a mechanical fuel pump here.)

 

[lihartke]

When I drained the tank I actually took the float out and saw the tank bottom. It looked brand new for a 1988. There was very minor sedment if any. I bought an electric pump and lowered the bow of the boat to pump it out. I got all but maybe 7 ounces out. We are going to replace the mechanical fuel pump on thursday and we have done 2 new water/oil separators. I'm thinking the carburator is not adjusted properly but when we replaced the spark plug wires one was bad so we used 1 old one and 7 new ones. I have read that can throw things off soark wise with conductivity or something so we are going to get a new set and put them on and see if that helps. The darn nut was stuck on the fuel line that runs from the water/gas separator to the fuel pump so we had to remove it at the carb and the unscrew the fuel pump off the line. Not sure it's going to go back together so nice! God help me. Anyone want a new old boat that runs pretty great at 5 mph? Oh, yeah one other thing. It seemed as if it would pick up speed better if I gradually increased the throttle instead of trying to go from 0 to 60 in 5 seconds. If that is of any more use. on a separate note the uphosltry came out pretty good for sewing 15 hours in my life

 

[lihartke]

No Title

 

[Rick Stephens]

Mighty nice interior. I can see why you want to get her running to match.

Sure sounds like you have a clean tank. Next is fuel pump. Not hard to tee a line and stick a pressure gauge in to check against realities. Getting the carb rebuilt sounds like it needs be on the list. Carb rebuilds are the most screwed up job of any. Common for them to get done haphazardly and need doing again to get them right.

 

[harleyman1975]

Just to supplement Rick on the carb. Do your research on a good carb rebuilder. Find someone with lots of experience. Does not need to be a marine mechanic. I have rebuilt several carbs and have had a success rate of around 60% so I know how exacting carb rebuilds can be. Maybe try to find someone who is into racing "late model" or "modified" stock cars...chances are they know carbs...or know someone that does.

 

[alldodge]

It seemed as if it would pick up speed better if I gradually increased the throttle instead of trying to go from 0 to 60 in 5 seconds.

Two so called mechanics worked on the carb and it still will stall, but will increase speed if done gradually. Its not the fuel filter unless its the one inside the inlet of the carb (item 2), guessing you have a 4 bbl Q-jet
http://www.mercruiserparts.com/bam/subassembly/31835/1014/140

There good carbs but once messed up, hard to get running good without someone that knows how to clean them correctly and adjust. With installing an electric full pump, there should be no issue with checking pressure right now.

 

[lihartke]

So we had the carburetor completely rebuilt with a new float too. I bought the kit and the new float and our boat mechanic did the rebuild. I can't guarantee he did the whole rebuild but he said he did. He said it wasn't that bad inside. we put a new fuel pump on and the vent that holds the plastic line from the pump to the carb was completely clogged and the plastic line was also clogged for a solid 1/2 inch. No liquid just crud. The spring under the top(under the rubber plunger) was really rusted so I figured why not get a new one it's a matter of time before the spring probably breaks anyway. Plus, if something needed to go through for safety reasons it couldn't. We had power before the carb rebuild and after the distributor cap/rotor install so I am thinking that the carb may be the problem. A different mechanic saw fouled plugs after carb rebuild and said it's the carb. I am wondering if the thing attached to the carb that controls the choke is maybe sticking? The plugs are really dry jet black fouled. But it doesn't stall at all when running at slow speeds Could it be the distributor wasn't set properly? We did have power after the distributor install. Does anyone know what the mechanism that controls the choke in the carb that attaches to it is called? We have a carter m60600 fuel pump and a 1983-1997 and a chevy 220HP 305 small block V8 mercruiser 1988 Larson lazer dc200 Just another day 'till paradise :::::::::

 

[harleyman1975]

That is called the choke thermostadt or choke stadt. It is either electric or it may have a small tube running down into the intake manifold? (should be electric but one never knows as the parts are so interchangeable...this engine has been around since 1955). If electric choke is working properly when cold it should close when throttle lever is moved all the way fwd and then back to center, then if key is turned on it should open completely in about 2 minutes or so. You do not need to start engine just turn key to on and it should start moving within 15 secs and open fully in about 2 minutes.

 

[alldodge]

The plugs are really dry jet black fouled.

Dark plugs means either your flooding the motor or your compression is low. Since the boat ran fine for the first trip I don't see compression being the issue. IMO you still have a carb problem and the folks working on the carb are not doing something correct. You could double check compression to make sure

Could it be the distributor wasn't set properly?

The timing could cause some of your issue but not all. That said, again the boat was running fine until it stopped.

Does anyone know what the mechanism that controls the choke in the carb that attaches to it is called?

harleyman has the choke working provided. Just make sure the choke plate is full open (plate straight up and down) when you try to run the boat

 

[Pete104]

Wet dark plugs are flooding. Dry black plugs are lean or incorrect timing.
If nobody has put a remote tank on this engine, I bet lihartke is looking for a volunteer. You have looked in the and it's clean from what you can see. But you cannot see the anti-siphon valve any more than you can see what fuel line looks like inside.

 

[jimmbo]

When you had the float out of the fuel tank. do you take a look at the fuel pickup? There is often a filter on the end of it. Maybe it is clogged

 

[lihartke]

Anti siphon valve is our next swap out. But not until mechanic reevaluates the carb. He has it now so time will tell. It is dry and not flooding. The hose from the valve siphoned well when I drained the tank. We have a non electric choke as far as I know. Engine was completely rebuilt 2 yrs ago after I watched a video online showing how to winterize your boat and it neglected to say that the amount of anti freeze you use depends on the size of your engine and I cracked my block. They put a different engine in that was completely overhauled. It did run well before the bad gas and the ignition sensor being broke. But ee did know the carb was needing to be rebuilt

 

[R055]

Anti siphon valve is our next swap out. But not until mechanic reevaluates the carb. He has it now so time will tell. It is dry and not flooding. The hose from the valve siphoned well when I drained the tank. We have a non electric choke as far as I know. Engine was completely rebuilt 2 yrs ago after I watched a video online showing how to winterize your boat and it neglected to say that the amount of anti freeze you use depends on the size of your engine and I cracked my block. They put a different engine in that was completely overhauled. It did run well before the bad gas and the ignition sensor being broke. But ee did know the carb was needing to be rebuilt

For the future, drain all you water and no anti freeze needed. If you still want to do antifreeze drain all the water first.

 

[mbhoag]

Just my 2 cents worth...many years ago I had a Datsun 510....ran kind of like your boat, seemed to work OK if I accellerated slowly, but if I tried to give it gas, it would sputter and die out... tried everything I could to find issue, tune up, plugs, wires, etc, fuel pump, fuel filters, rebuild carb etc,just like you have been doing... it turned out it was a simple piece of fuel line that would compress from inside when I tried to give it the gas. Fuel line would not hold shape, causing it to choke off the carb under pressure (but you could not see this from the outside).

As a simple elimination, have you changed all your fuel lines from the tank to the engine, and also any short lines on the engine?

 

[NHGuy]

Which carburetor does your engine have?
We may have specific advice for your car guy.
BTW, it is wise to rebuild the factory carb because it is set up for your engine.
Replacements are suspect and tough to verify.