OMC 115-bogging down-HELP

[katlin10]

Bought this '97 Four Winns Fling in the spring. It's a jet drive with an OMC 115 powerhead to run it. Had it out a couple of times and it seemed to run OK. The last time out when I went to accelerate it would only get about 1/3 power at full throttle setting. I limped back to the dock pulled it onto the trailer a went home. It seemed like it was missing on a couple of cylinders so I changed the plugs. (oem champions-they were already new plugs with about 2 hours on them)
I went back to the lake and the same thing. I took it home again (25 miles) and changed the fuel filter, it seemed quite hard to blow through so I figured I had the problem. Same thing at the lake. Dragged it home again. Took the top cannister off the VRO pump and fuel spilled out! The fuel out line to the engine had a slice in it. Replaced the line and checked the other lines well. Back to the lake. Same thing again. I don't know if the VRO pump is no good or maybe the powerpack. Any suggestions. (compression is good in all cyl.)

 

[SKEETR]

Re: OMC 115-bogging down-HELP

What do you mean by "seemed to be running on two cylinders" was it running rough as well or just lacking power?

 

[SKEETR]

Re: OMC 115-bogging down-HELP

Was the split in the hose on a line after the fuel filter? Small pcs. of hose can block jets. Assuming it idles ok you may just have clogged high speed jets or a blockage in the float valve. There are two screws on the bottom sides of your carbs. Drain the bowls there and inside the holes are the jets. You need a flat screw driver that will just fit into the hole without scoring the threads. Best to make one or grind the sides down on one that is close. They also sell them. Remove the jets and soak them in carb cleaner. If you have a primer bulb inline force some gas thru the carbs to hopefully wash any other debris out of the carb bowls. Reinstall the jets and give it a go. If it still runs poorly rebuild the carbs. While you are in the carbs look inside the throttles at the buterflys. Disconnect the throttle cable and operate the carbs manually. Do they open fully together? If not you will need to adjust the linkage.

 

[ezeke]

Re: OMC 115-bogging down-HELP

You should not have a primer bulb on an inboard setup.

The first check to make, if the compression is good, is the spark test to be sure that you have a hot blue 7/16" spark on each hole.

If that is OK, get a inductive timing light to see if the spark is consistant at the higher range.

Watch the spark advance lever as someone advances the throttle arm at the control to be sure that the timer base is functioning properly.

If you have had a rectifier problem, check the stator for drips.

If someone has had the flywheel off, check the torque.

 

[katlin10]

Re: OMC 115-bogging down-HELP

What do you mean by "seemed to be running on two cylinders" was it running rough as well or just lacking power?

It wasn't running rough, it just seemed to lack power. I was thinking of replacing the powerpack to see if that helped. Then I was going to replace the VRO pump. Hopefully one of those will be the culprit. Thanks for all the post- great site for info!!-

 

[iwombat]

Re: OMC 115-bogging down-HELP

If you want to throw money around blindly, I'll PM you with my home address.

If you want to properly diagnose the problem before opening up the wallet, let's start with compression and spark checks.

 

[BHFG]

Re: OMC 115-bogging down-HELP

Are you idling ok and the engine is not missing when at throttle? If the answer is yes, then your problem sounds VERY similar to the problem I have had with my 130. The Factory Service Manual troublehooting chart all points to fuel system and dirty carb issues.

The compression and spark test are easy to do and help rule out other things as well, Do these tests first. But if they look good, I would definitely look at cleaning the carb jets next.

The way I was told to do it by the mechanic at the dealer's engine shop is to pull them out as suggested above, soak them for a couple of hours in full strength Sea Foam carb cleaner. Wash out the bowls as suggested or spray them out with a can of regular carb/choke cleaner. Get the running again then and run a tank of some Sea Foam treated gas at 1 oz per gallon of gas to wash out the fuel system and injectors.

Good luck.

 

[BHFG]

Re: OMC 115-bogging down-HELP

By the way, listen to "ezeke". He knows what he is talking about and has been a huge help to me with my 130. Definitely take what he says as sage advice, and my suggestion as just that.

Good luck, I'll be watching to see how you come out.

 

[jonesg]

Re: OMC 115-bogging down-HELP

I haven't needed a lot of help so far but I read a lot of posts,

if I were one of the marine engine experts here I would get frustrated .

 

[katlin10]

Re: OMC 115-bogging down-HELP

The spark is good, the compression is good. I have a primer pump between the tank and fuel filter and I took the hose off the line to the tank and blew air into the tank (5 psi) and could hear bubbleing and air coming out the vent.
I checked the timer base when the throttle is advance and it does turn (about 1 1/2"). I bought a powerpack and used VRO pump on ebay ($100 for both) because I'm going up to a cottage I rented in a couple of weeks and don't want to end up having to replace one of these items and no time to get it. The other problem is to test the boat in the water I've got to trailer it about 25 miles to the lake and pay $10 to launch it. I've never had a rectifier problem or had the flywheel off but I've only owned the boat a few months and only had a few hours of running before this problem. Not sure what you mean by "stator drips". Anyway I'm taking the carbs into work and going to clean them. Maybe I'll find a bunch of crap in there.
I'll keep you posted. Thanks for all the suggestion--priceless. (lol)

 

[SKEETR]

Re: OMC 115-bogging down-HELP

Since you have had some issues with your fuel lines it wouldn't hurt to check/replace the small sections feeding the carbs and primer. I have read a few posts noting deterioration and blockages at the brass "t"s.

 

[katlin10]

Re: OMC 115-bogging down-HELP

Had the carbs apart tonight-they were very clean.

 

[SKEETR]

Re: OMC 115-bogging down-HELP

check the faq page for carb cleaning instructions.

 

[SKEETR]

Re: OMC 115-bogging down-HELP

I happened upon a post on a whaler site noting the 'U' shaped exhaust hose as a potential cause of power loss. Apparently they can collapse internally and choke off the exhaust. Worth a look.

 

[katlin10]

Re: OMC 115-bogging down-HELP

After installing my "clean" carbs it wouldn't even idle on the hose. It would run for a second and then die. Tried several times and the same, wouldn't run.
So I pulled the carbs off again figuring that I must have done something wrong. I pulled the carbs apart again and there it was...actually there they were. Under the float seat was a bunch of gunk on both carbs. The float needle wouldn't even seat completely so I took SKEETR's advice and changed all the hose sections and line after the pump and blew out the 't' fittings. I haven't had a chance to run it yet but I'm confident that that was the problem. Thanks to all for your help...awesome.
I'll post again when I get it in the water.

 

[katlin10]

Re: OMC 115-bogging down-HELP

Problem solved--runs great now.