Engine looses power & surges

[gnrboyd]

I purchased a used boat last fall (1993 50 Hsp Evinrude). The motor had a blown engine and was repaired by Cabelas in 2006. (new pistons/rings - 1 cyl was bored out to .030 over. Also the VRO pump was replaced and was the apparent cause of the motor problem or at least it got the blame. A new water pump was put in but the carbs were not rebuilt going by what the work order said. The owners said they hadn't used it since. (They spent 1,500.00 on the repair and didn't use it? yea right! I bought it cheap enough that if the engine didn't hold, I could still get my money out of the boat/trailer without a loss which is why I took a risk on this motor.)

I took it out for the first time today. Engine starts and idles fine. When I hit the throttle to get on plane, it looses power and the engine surges. Here are some notes I took.

* Compression was checked last fall by a mechanic and in my driveway by me. One set of gauges read 148/150 and the other 128/130.

* Cabelas work order indicated to use double oil for 1st 3 tanks. (18 gallons)

* Using fresh gas mixed 50:1 with Sea Foam (1/3 of bottle to 6 gallons)

* In neutral - 1,200 RPM.

* In gear at first notch, 900 RPM

* Gradual throttle increase - When it hits 3,000-3,500 RPM, it starts to surge from 2700-3500 RPM with no change in throttle setting. This is the point where it feels like the boat is just starting to breakover on plane.

* When I hit throttle down full, it bogs down at 3,000 RPM and has no power.

* Primer bulb is soft and pliable but does not stay 100% firm. (seems about 1/2 - 2/3 as firm as it should) Pumping bulb while driving seemed to help only a minimal amount. RPMs got a slight bit higher before surging began but it was minimal enough that it could have just been my imagination wanting the primer bulb to be the only problem.

I was planning to run the double oil through the break-in period and then have the carb rebuilt. I'm now wondering if I should go ahead and do it now. Could just a primer bulb cause this? It really doesn't seem like this bulb is all that bad to me.

Any help would be appreciated. Thanks

 

[jbjennings]

Re: Engine looses power & surges

SOunds to me like your fuel pump is o.k. When I hear SURGING, I start thinking about one cylinder losing spark. Could be a coil, a powerpack, etc. You need to check your spark by pulling a plug wire when it starts that surging stuff and see if it kills the engine. Then try the other plug wire and see if it has any effect. I'll bet pulling one wire doesn't have much of an effect, but pulling the other will kill the engine. That will tell you if you're losing spark on one cylinder. try to ground the wire you pull on the block if you can. Running it without it being grounded isn't good for the ignition system, but I don't think a couple of seconds will hurt. You might want to use some rubber gloves or it might give you a jolt when you pull it. Your compression sounds good to me if both gauges show very little difference in cylinder pressure. I'll bet it's just an ignition problem which shouldn't be THAT high priced to fix.
Just an idea,
JBJ

 

[tashasdaddy]

Re: Engine looses power & surges

that of a link n sinc problem. check the throttle linkage. there is a little plastic bushing that is known to crack and fall out. clik to enlarge

 

[gnrboyd]

Re: Engine looses power & surges

TD... I assume you are referring to the bushing with the red mark on it from your photo. I checked mine and it appears to be in place. Here is a photo in case you can see something else wrong.

 

[tashasdaddy]

Re: Engine looses power & surges

looks fine to me, yes the bushing.

 

[ondarvr]

Re: Engine looses power & surges

Your problem may be electrical, but there's agood chance it's a plugged up carb too since they said they weren't rebuilt. A motor that needed to be rebuilt due to the type of failure this motor experianced needs to have the carbs rebuilt before it gets started or you may have it back in the shop for another rebuild very soon. Don't run it until you make sure the carbs are clean.

 

[Ranger 330V]

Re: Engine looses power & surges

this is off the subject of your problem but when you check your link and sync I think you should idle her down some....1200 rpm is pretty high to be putting her into gear...really hard on clutch dogs and gears. I like mine as LOW as I can get it before she stumbles and dies...must remember that prop isn't moving when we go into gear. I'd say right under a thousand rpm in neutral at the most. Good luck on the surge...don't you hate gremlins?

 

[tashasdaddy]

Re: Engine looses power & surges

actually idle should be 650-750 IN GEAR IN THE WATER.

 

[billybones]

Re: Engine looses power & surges

I don't know a lot about boat motors. But I do know that boring out 1 cyl and not the other will cause an imbalance to the HP. I would never do that to a car motor and expect it to be smooth. But this situation may be a normal repair to OB motors.. Though I would never do it. Just a bystanders thought.

 

[iwombat]

Re: Engine looses power & surges

Replacement oversize pistons are the same weight as standard size. One hole is done all the time in outboards. It's probably even the normal procedure as opposed to doing them all.

 

[gnrboyd]

Re: Engine looses power & surges

I checked with a guy I know that works in the marine industry. He suggested that I launch the boat and try to hit the key choke when it bogs down. He said if it picks up and comes to life, then it probably is the carbs. If not, he said it sounded electrical. I guess I'll run it just long enough to test that out sometime after work this week. (If the rain stops.)

 

[ondarvr]

Re: Engine looses power & surges

That method will work, just don't run it very long at the problem RPM range.

 

[gnrboyd]

Re: Engine looses power & surges

Update:

I stopped on the way home from work tonight and picked up a primer bulb to try that first. I launched the boat and had the same results. I then tried the key choke trick. It didn't seem to help. I tried just punching it a few times at first and then gradually did it faster and faster. A couple of times while I was punching it, it seemed like it might have picked up just a tad but it was more than likely just a coincidence. It will surge on its own without throttle movement. Then after holding the throttle down all the way, it doesn't surge but has very little power. I even tried the other tank just to see if by chance the pick up tube was clogged up.

I am running double oil due to the break in period. Surely that couldn't be the problem. I can see it acting a little sluggish but not like this.

I have a buddy of mine that is going to try and look at it but he can't get to it for a while. I may have to take it to a shop. I appreciate any and all advice.

Thanks

 

[ondarvr]

Re: Engine looses power & surges

It's very common for the coils to fail under load, resulting a surging, or cutting out as you open up the throttle, it may idle just fine though. Check them over and see if they have cracks (most do when they get old).

 

[wavrider]

Re: Engine looses power & surges

Lets look at ignition first, and eliminate it as a problem

Get a spark tester from auto store, adjustable, around $8.00

Once you get it make sure you remove the paint from the end of the adjustment screw so it wqill have a good path to jump the spark.

Remove spark plugs and ground the one you are not testing, keep any stray sparks from igniting fuel vapor

spark should jump 7/16" gap, bright blue spark, yellow wont cut it as it is weak.

Once both have been tested and they jump good spark then lets see what the fuel loks like.

could be dirty high speed jets or weak fuel pump, or fuel lines.

 

[gnrboyd]

Re: Engine looses power & surges

I checked the coil assembly and I don't see any cracks. In fact, it looks basically brand new new to me.

As far as spark, I had it checked by a marine guy last fall when he gave it a once over and he said it had good spark. That was last fall and all I did was winterize it after that.

The fuel pump/VRO was replaced in fall of 06 when the previous owner had the head re-built. Most of the fuel lines I can see look brand new. The work order does not indicate anything about rebuilding the carbs which from what everyone says, should be done at the same time when major work like this was done. The choke test didn't pan out as indicated above but maybe the carbs are so clogged that it doesn't help. ??

Anyway, I am planning a trip in a couple of weeks and don't really have the time to tinker too much. I'm not really very good with engines, I don't have a manual, and I don't have much time so I'm just going to bite the bullet and take it in to a mechanic. I'm lucky in the fact that a new Bass Pro just opened about 5 miles from my house and they said they could get it looked at pretty quick. I'm a bit nervous since they sell and service primarily Mercurys but I'm hoping that since this engine isn't one of the new advanced motors, they'll be able to get me going.

One thing I would like an opinion on is......Before I knew I had a problem, I was planning to have the carbs rebuilt after I went through the 3 tank break in period of double oil. Now if I find out the problem is not with the carbs, should I go ahead and have them rebuilt anyway while it is in the shop? I just thought it might be better to do after the double oil period was over. I'm just not sure what the norm is. When you buy a new motor, do they rebuild the carbs after break in?

Thanks everyone for your help.

 

[gnrboyd]

Re: Engine looses power & surges

Update:

I dropped the boat off at Bass Pro today. I spoke with them briefly this afternoon and they said so far, they just cleaned the plugs and adjusted the timing a little. They said they need to a lake test to see what is going on. I thought they'd be able to do more than that in the shop. I couldn't talk long since I was at work. I guess I'll have to wait until Friday to find out.

Could timing alone cause a motor to idle ok and sure just before you give it much gas as explained above? I still think it is the carbs. We'll see what they say on Friday.

 

[gnrboyd]

Re: Engine looses power & surges

Update:

The mechanic took the boat to the lake and confirmed what I was telling them about the surging. They recommended that the carbs be rebuilt. When they started taking the carbs apart, they found the real problem. The float on one of the carbs was upside down. My only guess is that when the previous owner had the work done, they must have put it in wrong. The owner said they hadn't taken the boat out since but I would have thought Cabelas would have lake tested a head rebuild and found this. Who knows... The previous owners were not real forthcoming with information so I am mererly trying to piece together the real story and I'm sure they left out a few details. Oh well...now I just need to get it to the lake so I can see for myself that it is fixed. Time to go fishin' !

 

[pcrussell50]

Re: Engine looses power & surges

well? what was the verdict? anyone know how this turned out?

-peter

 

[gnrboyd]

Re: Engine looses power & surges

pcrussell50... the outcome was that the carb rebuild (and correcting the upside down float in the carb) solved the surging problem last year.