Cougar235

I had my 84' Evinrude 235hp completely rebuilt in 09'. Since this and prior to, I've had poor low end take off having to choke it because it starts to bog. Even after choking, it doesn't have the get up and go I think it should have for that size of motor. At idle it runs fine for a few minutes then will stall. When reaching around 3500rpm's the motor winds out and takes off like a bat out of !@#$%. I'm at roughly 4000ft should I try rejetting low end jets to a bigger gauge. Any suggestions would be greatly appreciated.

Re: Cougar235

And why was the rebuild done? If the reason wasn't found and corrected, you will be in for another rebuild.

I suspect lean running. I would rebuild and properly clean the carbs. See OEM shop manual.

Re: Cougar235

Thanks for the reply - wilde1j

When I bought the boat (frist boat purshased) I didn't take it out for a test drive. Sounded good w/ the muffs on but when I took it out to the lake it ran like !@#$, no power what soever. I brought it into the marine shop and they checked it out and found that the compression was low and proceeded to tare it apart. Found that the rings were shot, cylinders had scoring and a pin hole in one of the cylinder sleeves. Options were to replace it with a similar engine @ 14-15000.00 (not knowing what problems it would have) or rebuild this one. After the rebuild (3-4 months after) I had the mechanic out on the lake to see if he could diagnose the problem and he said this was normal. Full of !@#@$ I think. Does run alot better but definately not the low end take off it should have. I brought it to a mechanic down the street had the carbs cleaned out and still did the same thing. He suggested getting another set of jets (keeping the old ones) for the low end and with trial and error drilling them out in stages to see if that would rectify the problem.

Julien

Re: Cougar235

I wouldn't drill out the jets. That's a brute force method which avoids finding the cause of poor running and just treats the symptom. Do a complete carb teardown and rebuild. Make sure all core plugs are removed, the carb bodies soaked over night in carb cleaner, then blown dry with compressed air, new jets installed, etc. The OEM shop manual provides guidance. Make sure to check the block for air leaks. BTW, does squeezing the primer bulb or activating the primer/choke change anything while at speed? You may have a fuel delivery problem. Has anyone checked the fuel pump output pressure or checked the fuel system for air leaks (cracked tank pickup tube, lose connections/clamp, bad anti-siphon valve, etc. ?

Sorry, just reread your initial post. Yes, 4000 ' MSL is enough for rejetting if you routinely run at that altitude or higher. See the OEM shop manual for the right jets. BTW, jet size is smaller, not bigger at altitude, so one of your 'mechanics' had is backwards. If you rejet, you shouldn't use the motor at sea level or close to it with the same high altitude jets installed.

If you're not going to do it this yourself, sounds like a new mechanic may be needed.

Re: Cougar235

I'll check the manual to see what gauge they call for for this specific alt. Can't remember what's in there now. Anyway I'll try that and wait for the lakes to thaw and see how it goes.

Thanks again - wilde1j
Julien

Re: Cougar235

If you can find the right Evinrude dlr there is a service bulletin out there that recommends the correct jet sizes for different altitudes.

Re: Cougar235

You might want to check the compression yourself. I don't know your mechanic, but I've heard lotsa stories about unneccesary labor charges for work that wasn't ever done. If he's not a friend of yours, try to find an auto mechanic with a compression tester. At least he/she won't have a personal gain by finding problems that don't exist, & should be able to give ya some compression numbers that you can post here to find out if the rebuild was really done & done right. Also, buy the repair manual even if you aren't workin on it, or maybe check with the local library! Lotsa great info in 'em!

Re: Cougar235

Thanks guys,

Had everything checked out at the beginning of last season and all checked good. Do have a Clymer shop manual for 73' - 90' and the manual doesn't have any info regarding the 84' 235. Stops at 82'. Anybody know about the 84'? Also, can someone enlighten me on which jet is the intermediate, idle air bleed and I've figured out the high speed, the lower plug on the side of the carb. The manual says to change high speed from 62C to 59C (this is on the 82' model) and the ones on there presently are 62C. Is the 59C a bigger orifice? If someone out there can help me out, I would appreciate it.

Thanks, Julien

Re: Cougar235

If you run a stock engine at high altitudes, it will overfuel which is probably what you are dealing with. Yes, you would want to rejet the engine with smaller jets. Don't drill any out, as the factory twist drills them for optimum fuel flow. Re-drilling destroys the factory flow. Jet sizes are measured in thousandths. The 62 jet is .062 size, the 59's are smaller .059. You may be able to get someone at the factory to talk to you from Bombardier in Waukegan, Ill. They may be able to give you some rejet guidelines regarding altitude adjustments. Try their consumer line at 847-689-7090. Your 235 is a high port engine with low compression heads. This is a problem for hole shot-esp on a heavy boat. Since these high port engines rev higher than basic engines, you have the option to go down one prop size and rev it up 5700-5900 without any problem. My 200 high port was always a dog out of the hole, but would really haul at top end. You might be able to find a set of used early big bore high compression heads which will help the situation (325638/639.)

Re: Cougar235

If you plan to do any serious work on your motor, get an OEM shop manual.

Re: Cougar235

Thanks emdsapmgr,

If I'm going to a smaller size jet why then would I have to choke the motor at take off. Taking off, I hammer the throtle and it starts to bog to the point of stalling if I don't choke it. Curious, I was reading the manual and it mentions possibly changing the fuel pump from standard to high performance enabling the carbs to get more fuel. HMMMM. Thanks for the suggestions, I know it's going to be a while untill I can actually test these ideas out on the water. I'll start with the less costly ideas first then go from there. Is the OEM manual alot more detailed than the Clymer?
Julien

Re: Cougar235

Most of us have a poor opinion of Clymer and Seloc. I've used both and they aren't even close to useful compared to the OEM book.

Re: Cougar235

You are correct, if the engine pics up when you choke it, it is running lean. That could be a symptom of the idle/mid jets. You could have a fuel restriction in the idle/mid passageways. It still could be overfueling on top end with the stock (sea level) high speed jets. If you have a concern about the original VRO pump, have a friend constantly prime the hose bulb on the fuel hose. This will force extra fuel into the carbs. If the engine runs fine while you constantly prime the hose bulb, you may have a weak fuel pump. You would foremost be looking to rejet the high speed jets down a size or two-depending on a factory recommendation.

Re: Cougar235

Thanks emdsapmgr,

Went into town today to see the mechanic that rebuilt the engine and he suggested the same as you in regards to having someone pump the primer bulb while in idle and accelerating. This, to eliminate possibilities of a defective pump . He advised this before rejetting. If this doesn't rectify the problem, then we'll go to the rejetting.

Julien