Carb and Temp Gauge Probs

[AaronWhitt82]

Hey guys... I know this is my first post, but I just bought a 99' Outback about a month ago. It has the Indmar 350 (310H.P.) DD in it.
I had the boat out the other day for the 2nd time and all was running fine until right around sunset the boat decides to die in the middle of the lake and it wouldn't start back up. Had to get her towed in to the trailer.
Well the next day took a bunch of stuff apart and put the water pickup hose in a 5 gallon bucket and turned the hose on and started it up....
Well come to find out for some reason the choke was staying closed and wouldn't open. I'm not good with carbs (Holley 4150 or 4160/ Not sure which one), but did some researching and think I may have fixed it, but aren't sure at all, and I got it to stay open and it ran good and wouldn't flood itself out.
Well today took her out to see how it ran under a load.... Seemed to run fine, but from a dead stop I would hammer the throttle and after it would just about get to plane and speed up the motor would backfire and spit and lose acceleration. If I just eased into it everything seemed fine, but it also didn't seem like it was reaching top speed either. The boat also idles no prob and runs smooth. I'm pretty much lost now and don't want to take her into the dealer.
Just wondering if any of you guys might know off the top of your heads what it might need? Rebuild kit?, Accelerator Pump?, Power Valve? Idle/ Air mixture screw?; I'm clueless.
Also I've noticed the Temp. gauge is only reaching to around 125 degrees, but if I shut the boat off and turn the key on then it goes back up to near operating temp. then as soon as I start the boat and take off it drops right back down again. I'm not sure if its the gauge or maybe the thermostat...
Any help would be much appreciated.
Thanks in advance,
Aaron

[JesseC]

I am not much help with Carbs either, but it sounds like someone may have removed the thermostat all together or it is stuck open.

[Buttafewcoe]

Get the engine temp up to normal. That may help with the fuel prob. Make sure your plugs do not have any build-up on them. Check the distibutor cap. Some fuel problems turn out to be combustion issues and the fuel thing is a symptom.
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Hope this helps
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B

[AaronWhitt82]

Thanks guys. I'll check that stuff out when I get a chance.

Also does anyone know the correct plug for this motor? It had the AC MR43LTS in it and I took them out then checked the owners manual and it reccomended an AC MR43T. So I went to the parts store and got those and put them in and I'm not sure which is the right plug.
Thanks

[JesseC]

We need Larry (Engine_nut at Indmar) to chime in on the correct plug. This may be the cause of the unburnt fuel. The plug you removed was a
MR43LTS L "Long", T "Tapered", S "Stainless"
and you replaced it with a
MR43T T "Tapered" this plug should have a shorter shank (threaded part) as well as not being stainless. The stainless part will not matter, but the different shank on the plug will affect the burn in the cylinder. Hopefully Larry will read this one soon and give you the correct plug to use.

You could always call Indmar and ask. They are VERY helpful.

[AaronWhitt82]

Hey thanks alot for the reply Jesse. I called the local Moomba dealer that is about 4 hours away unfortunately. They said to use the NGK TR5 plug. He also said that is the only brand they use and that they don't use the AC or Autolite or whatever else. Fortunately the local CarQuest has them in stock for $2.86 a plug. I'm going to head on over there now and pick them up and get em installed in the boat. Not sure when I will be able to get on the water again, but hopefully this might resolve my problem. I'm also going to check cap and rotor to make sure there is no moisture in them. If this doesn't fix it then I'm assuming the damn Holley Carb needs some work.....

[AaronWhitt82]

Alright so I just got back from taking the boat for a test drive.
With the new NGK plugs she seems to run better, buttt at or around 3,000R's and over when I hammer the throttle after about 10-15 seconds the boat completely cuts out then when I back the throttle down it will cut in and out. So then I pulled it all the way to neutral and the boat comes back to an idle. I then hammer it down again and it runs fine for 15 seconds maybe longer then does the same thing all over. Almost seems like it's not getting enough fuel or something in the carb?
If I just cruise below 3,000R's it runs fine and doesn't cut out at all so I dunno....
Thanks

[Brian Raymond]

Aaron, hope all is well. I would stay with the o.e.m. spark plugs (MR43LTS), and gap them @ .030. They can be purchased and drop shipped from your dealer, or purchase them from Indmar (901.953.3350). The carb. issue at hand can be several things, it sounds to me like the secondaries are not opening. You will visually have to verify this. There are a few factors that may be involved, if the fuel has not properly been stabilized over the years during winterization, there may be some varnish build up on the primary needle and seat (which effects the float level), which will not let enough fuel in the primary bowl to deliver the proper flow to build up the r.p.m.'s for the secondaries to open. There may also be residual varnish on the secondary butterfly shaft, which may restrict them from opening. The other thought is, the secondary vac. diaphragm may be dry rotted or ruptured, this will not let the secondaries open at all, and can create a lean "pop" when the primary is emptied. One adjustment to look at, is the accelerator pump spring. There should be zero clearence between the pump hammer and the spring nut at w.o.t. This should be checked with the key off, and the throttle in the w.o.t. position. If there is a gap, use (2) 3/8" wrenches to adj.(open the spring). I would order and replace the thermostat and gasket set to, just for the piece of mind. Hope this helps, keep us posted. Brian Raymond

[AaronWhitt82]

Hey thank you very much for the reply Brian!
As far as the history on the boat goes.... The guy hardly used it and it sat for a few years or more and he maybe took it out once or twice a season, but it was still serviced in spring and fall of every year at the local marina.
As far as the fuel goes I'm not sure if it was stabilized or if he had put anything in the tank. When I bought it there was about 3/4 of a tank in it which he said had been in there a while, but stabilized.
If there is parts of the carb that are varnished up is it possible to just run some carb cleaner through the gas or do I have to take the carb apart and clean everything with some carb cleaner? Also if I do take the carb apart will I need to replace any gaskets? It does seem as there is a lack of fuel going to the secondary though. I will check the acc. pump spring adj. today and see what that looks like and also take a look at the secondary vac. diaphragm.
Thanks a bunch Brian. Aaron

[JesseC]

I would also change the fuel filter. It is real easy and inexpensive. It may not be able to handle the high flow of the higher RPMs.