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Author Topic:   Power loss at WOT
cmarques posted 09-18-2003 10:02 PM ET (US)   Profile for cmarques   Send Email to cmarques  
2 times in the last couple months I've run my Dauntless 160 wide open and had the rpm's drop about 5-600 rpm or more like bucking or starving for fuel. It will happen every second or two for a few minutes and then clear and be fine- 1 time hot with 4 people in boat and 1 time cold with just me. I have a 2002 Mercury Saltwater 90 2 stroke. Both times have been running about 5200-5400 rpm and trimmed up pretty high. Any ideas???? Since this happened I've just installed new NGK plugs $14.00 a pop thank you! a new fuel water seperator filter and new gearlube but have yet to be back on the water to test. 1 thing I noticed was a clamp or zip tie missing off a fuel line fitting about 2" from engine cowling that dripped some gas when I wiggled it around. Could air be sucked in and cause a drop like mentioned or is fuel pressure too low or make a diff. with bowls on carbs like it could with fuel injection? I did not notice any water in filter when removed and plugs looked o.k.. I have been using Pennzoil semi synthetic 2stroke oil and usually mid grade gas.
Dick posted 09-18-2003 10:25 PM ET (US)     Profile for Dick  Send Email to Dick     
Any place that fuel can leak out air can go in, this could be your problem.

I doubt that using Pennzoil is the problem, if it were you would have fried the engine by now.
Being a Merc/J&E dealer and service facility I wouldn't run anything but a major motor manufacturers 2 stroke oil. Merc, Bom, Yam & Suz are all good oils and are interchangable except when you get into the high tech motors like Opti and Ficht.

cmarques posted 09-18-2003 10:37 PM ET (US)     Profile for cmarques  Send Email to cmarques     
Thanks for help- I think that may be the problem- probably got worse when trimmed if fuel line stressed the right way. Gonna be out this sunday and will hopefully know. For the pennzoil- have used almost 1 year and runs great (just wanted to give as much info as possible). Broke engine in with Quicksilver premium + but at $18 a gallon locally gets a little expensive 52 weekends a year. I stock up on the other stuff when Bass Pro Shops puts on sale about $10 a gallon. I ran the engine 5-10 minutes on earmuffs the other day and started right up better than before after new parts in.
Sal DiMercurio posted 09-19-2003 12:59 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
The way to check & see if your engine is sucking air in the fuel line is.
Use a clear plastic fuel line from the fuel pump to the carbs & with the coweling off run the engine at WOT & have someone sit back there watching to see if any air bubbles are going through the line, then you know for sure if it's pulling air.
I totally agree with Dick on the oil.
Never fails to make me shake my head when someone posts says they use the cheapest oil they can find in their $12,000 engine....."DUH".
Saving $4.00 . .......$5.00 on a gallon of oil because it's cheaper then the recommended, aint the sharpest knife in the drawer.
Cmarques, i'm not talking about you, just people in general that own very expensive engines then skimp on the fluids, including lower unit grease, will come back & bite you on the a$$.
Bigshot posted 09-19-2003 10:46 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Being the semi-synthetic oil, I would not worry about it, probably better than OEM non synthetic.

$14 a plug? You had to buy the wrong plugs. Too late now but standard NGK are like $2-5 depending on where you get them.

cmarques posted 09-19-2003 09:00 PM ET (US)     Profile for cmarques  Send Email to cmarques     
yeah..$14 a plug- same that came out they were NGK buzhw-2 went to 5 places searching for them- west marine,boat u.s., boaters world, and another dealer did not stock plugs-found at local whaler dealer and he had 3- checked list at like $13.90 each!
I agree should use oem oil when possible but staying with a name brand I trust has been o.k.. Working as an auto service advisor we'e sparked many debates about oils and whats better in cars. Everyone will swear by their favorites and I guess if it works for you then its good. Same with gas- when I can its always amoco silver used in the boat unless on the road then any good mid grade gas- no circle k's or race tracs.
I have used the Quicksilver prem + the last 2 years in my 2002 8hp Merc due the fact that it is still the same gallon I bought with the motor. I have better than 12 tanks of gas run through that engine- I can take 2-3 outings on the 3 gallon tank with my 12 ft john boat.

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