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Went out this weekend and had to stick close to home - left the marina (about 1/4 mile to clear the no wake zone) motor running fine. Went to throttle up to get on a plane and the motor was slow to rev up then picked up and dropped back - up to about 4500 RPM then fell off. I throttled back and pumped the fuel bulb and tried again and it revved up to about 5000 RPM got on plane and then fell off. At this point I decided to pass on heading out much further - motor idled and ran smooth at low RPM's anchored and fished a bit - motor fired up and made it home without issue, motor even revved up on the way back.

It's done this before and I changed the fuel filter (RACOR) and replaced all the fuel lines and fuel bulb, they needed it - last year. This year it's done a similar slight hesitation and then cleared up and ran fine. Now I need to figure out what's wrong. My first guess is the fuel system - it's been running fine. Put new spark plugs in at beginning of the season.

I guess what I'd like to know if the best order to check - fuel pickup? filter, fuel pump on the engine. This motor has VRO removed with a straight mix in the tank. I've been tempted to add an inline electric fuel pump so I can prime the filter if I need to change it out on the bay - I had a heck of a time getting it primed last time (from the belly tank). Would be worth installing an inline check valve near the pickup tube?

I've just never been comfortable with 2 cycle motors. Thanks in advance - I tried the search and guess I didn't get my criteria right - I'm sure there are some similar posts.

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Interesting. My 1985 Johnson 150, behaves the same way and I've been chasing it for two seasons now. I still have the VRO installed.

Mine runs best when giving it a LONG time to warm up...like 5-10 minutes under 1200 rpm. When I do this, it usually runs fine. If I start from stone cold and give it a more normal 2-3 minutes, then try to accelerate up to 30 mph, it will sometimes bog and fall off plane, pretty much as you describe.

I also thought fuel, but am now starting to think it may be the power pack, as JMARTIN described a similar issue with his 1992(?) 200 that was fixed with replacement of the power pack...about $150 + labour.

I will watch this thread

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I had a very similar problem.

There are 2 power packs. One for each bank.

One of mine was bad.

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Joe,

Was your problem inconsistent like mine, as in, acted up over 50 or more hours, somewhat with regularity, but also allowing the engine to sometimes run just fine for a full days outing?

Thank you

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Yes.

Sometimes it would be just fine.
And then either taking off, or while on plane, it would just cut back.
It always started and idled just fine.

I thought it was a fuel related problem at first.
So, I filled up my 6 gallon portable tank and connected that to the motor.
Still did the same thing.
So, for me, it wasn't fuel related at that point.

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Thanks Joe.

This sounds like the very problem I have. The symptoms sound identical.

I'll confirm my exact engine year, then order one.

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Really appreciate the feedback... mine is very similar to what you describe, sometimes it runs fine and then for no apparent reason some days it just seems to lose power (and may or not get it back). What was confusing me is that it never runs rough or sputters just seems to lose power.

Thanks again, I wanted to run it by the forum before I went to my local outboard shop. Luckily they're pretty tolerant with the local shade tree mechanics.

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If squeezing the primer bulb helps, it can be the sign of a damaged gasket in the fuel pump or the pump itself.

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I have heard of this problem/remedy so often with OMC motors of this vintage I suspect power pack first. And if one goes, the other is probably not far behind.

The older a motor gets, the more expensive replacement parts are. I'd just replace both of them now. At $110 each, they're kinda expensive, but should preempt that ignition stumble for the next 25 years or so.

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Sounds like I've got my list of checks in order.

1) Fuel filter
2) Get some help and see if priming with squeeze bulb helps when power drops (to rule out fuel pump issues)
3) Get with my local mech to check out power pack issues.

Thanks for input, will post any updates...

Found this link searching around the web... the part about the power kicking in without warning is similar to what I've experienced.

http://continuouswave.com/ubb/Forum4/...01597.html

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tothemax.

Yes, that is my post from 2003.

I ended up purchasing 2 power packs and kept one old one (the good one) for a spare.

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Funny, sounds to me like the engine is running lean, probably dirty carb jets.

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Hi Walter. My issue is too abrupt to be the engine going lean...it's like a switch being turned in and off. I'm installing a pair of power packs before I go out this weekend. I will report back next week.

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The good news is that the Power Packs are easily changed.
I did them myself in 15 minutes or so.

Fixed my problems completely.

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Thanks Joe, when I saw that I was wondering if that was your post...

I'll probably do a compression check while I'm at it. The previous owner said that he purchased the motor used a few years back but the powerhead had been replaced and it had low hours. I have no reason to doubt him. But it never hurts to verify.

On adding a check valve, or electric primer pump question...

Has anyone tried that, trying to get a filled RACOR filter primed with the queeze bulb is not easy on this boat. I can't imaging trying to get dry one filled out in open water. I realize that it should be a sealed system - wondering if this might be pointing to an issue with the pickup tube. All hoses and connections from the pickup tube to the motor were replaced last season so they should be good.

Figuring that the engine fuel pump is not that powerful I'm hesitant to add anything inline.

Again, appreciate the feedback...

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I would expect that because the engine's fuel pump pulls fuel from the tank once the engine is running, any fuel pump sitting idle between the tank and the engine would just add unnecessary restriction to the fuel flow. The fuel system isn't complicated, check valves, anti-siphon valves and hose. The primer bulb is just a couple of check valves. My humble opinion is you would have no reason to change the Racor at sea anyway. If your tank has that much debris in it you shouldn't be out on the water anyway until that is corrected.

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If it is filled, it does not need priming.

An empty Racor filter should not be difficult to fill with the primer bulb. It the primer bulb is not accomplishing this, get a new one.

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There may be other issues here... because the primer bulb is only a year old. When I replaced the fuels lines last year I added a glass screen filter ahead of the Racor so I could see if the fuel looked bad or had obvious water - and so far it does not.

Time to methodically check through the systems...

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The primer bulb is a BRP OE primer bulb?

If it's aftermarket, toss it and get the real thing.

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Update: I installed a pair of new Power Packs. Problem solved!

One minor issue I had on the install was that one of the rubber plugs on the new PP was the wrong size. Only the rubber grommet was incorrect, and I found an independent dealer who changed it for me using a special tool for changing the rubber part without cutting the wire

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Mark,

Thanks for letting us know.
Same problem I had.

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Finally got some free time last week and went through my fuel system. Started at the fitting going into the tank and verified all was good to the motor including a new fuel filter. The rubber seal in the bottom of the water seperator was shot so I ended up replacing it to make sure it wasn't a source for an air leak. I did find that the glass inline filter I added had loosened from vibration and think that was most likely the source of the problem.
My fuel bulb is a West Marine after market (new last year), and I remember a post suggesting using the Evinrude OEM model (see last section).

I got out fishing Sunday morning for a few hours the motor ran fine, no lack of power and jumped right up on plane even with a dirty bottom.

The one thing I noticed when going through the fuel system, there does not seem to be a check valve on the pickup tube. If you disconnect the fuel line going to the filter all fuel drains back into the tank. It primes enough to start but I always see an air pocket in the glass inline filter and the squeeze bulb doesn't always get that solid feel like the float valve is closed and the carbs are full. The engine starts fine, so I'm guessing the leak back is on the tank side. I like having the glass filter ahead of my main filter so I can see if crud is coming from the tank and the screen will stop any chunkies - but once the system is primed I would think that air pocket should clear - it doesn't.