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1997 Evinrude 150 OceanPro surge

R

rssteph

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"1st time poster but have reli

"1st time poster but have relied on board advice previously. So, rebuilt both sides of the fuel pump (air motor and fuel diaphragm) couple of weeks ago. Oil feed disconnected and just running pre-mix. Here is my problem and the recent history:

1. After fuel pmp rebuild, was producing a lot of white smoke. Thought it was steam but:
2. Was able to run the boat on the lake today (gorgeous here in New Orleans). Boat ran great for 5 minutes at about 3,500 rpm. After 5 minutes or so, I opened it a bit more say 4,500 - 5,000 rpm. After a couple of minutes the RPM started to drop 500 rpm then jump back up, then down then up.
Got scared of being stranded so backed down to 3,500 and headed to the dock. Ran pretty good.
Noticed excessive fuel in lower cowling and discovered cracked fuel fitting where fuel hose connects to front of cowling. Fixed that and went back out. The "steam" disappeared so think the motor was leaning out. Only ran the boat for 10 minutes before fixing the cracked fitting so hopefully didn't burn it up. Fuel ball was "normal" when I reached the dock, nothing like when before the fuel pump rebuild. Not hard as a rock but not empty either.

Relaunched and same thing. Ran great for 5 minutes at 3,500 rpm or so but when opened it up to 5,000 rpm, lost 500 rpm or so then jumped up, the dropped, then jumped, then went back to the dock.

My 2 thoughts are: junk in carb bowls that get sucked in when turning hi rpm or electrical issue.

Any thoughts. Sorry for the long post but wanted to give full picture of the situation."
 
"ck for fuel restriction...any

"ck for fuel restriction...any horns going off?
have u tuned it up lately,not just new plugs?
have u inst a new water pump kit?
filters---ck/change all.."
 
"oh,..just for your info---mos

"oh,..just for your info---most shops are not rebuilding the pumps due to warped hsg's...sucking air...and not functioning,correctly."
 
"Thanks for the replies. To a

"Thanks for the replies. To answer a couple of questions and ask a few more..
1. I can't visibly see a fuel restriction and the opaque filter that is in the front of the engine seems to stay full (before the fuel pump rebuild, it would empty out)
2. I had the carbs rebuilt in September and a few other things done. I changed the sparkplugs in July 2007 and cleaned them with a dremel wire brush a couple of weeks ago. What else is there to tune up other than carbs and plugs?
3. Have not installed a new waterpump kit. Can a waterpump kit create a high speed drop in RPMs?
4. Would an airleak in the fuelpump manifest itself only at high rpms?
5. Thinking about the fuel restriction..does this motor have a safety that would cut back the rpm in the event of a restriction. IE - during a turn when the motor turns and the hoses all flex and bend with it, perhaps the fuel line gets a slight kink. Would a sensor "sense" the slight restriction and cut back the rpm?
So, sounds like powerpack, ignition system, etc. are being excluded at this point. All replies appreciated."
 
"Put new water seperator fuel

"Put new water seperator fuel filter (looks like an oil filter) on last week.
When carbs rebuilt in September, he replaced the filter that goes to the vapor seperator on the front of the engine. No horns going off either but I didn't run it long once the rpms started jumping around."
 
"make sure u have 3/8 fuel lin

"make sure u have 3/8 fuel line thru out..ck fuel for WATER by pulling a sample thru bulb.ck anti syphon valve--on outlet,on tank.if there?"
 
"make sure filter is tight...s

"make sure filter is tight...sucking air?conns tight?try pumping bulb,when prob,occurs.."
 
"Thanks jwb for responding. He

"Thanks jwb for responding. Here's more information in response to your suggestions:

1. Will try pumping bulb when I have another person onboard; as far as I can tell all hoses are 3/8". All connections appear tight as hose clamps have replaced zip ties except where the pulse hose attaches to nipple in block (using spring clamp). will check tightness of fuel water seperator; will pull sample of fuel;
2. What is a VST? Vapor separator?
3. Here is a tidbit that I can't resolve: When I rebuilt the fuel pump and put it back together, I found a black o-ring on my workbench. I've tried to figure where this could go on the fuel pump or related item (I took the who fuel pump bracket off the motor with accessories). The only place I can see that it goes is under the VRO cover. Going to check tonight but the o-ring is perfectly round, not pear shaped like the diagram of the vro o-ring. The o-ring is big enough to fit on my pinky upto my middle joint. It's black, not purple. I'm thinking maybe it goes there and at hi-rpm air is getting in. Would air in the fuel make the rpms bounce around at high speed but okay at idle and low rpm?
4. At what rpm does the high speed jet kick in? If there is junk in a high speed passage, when would it affect performance?

Will work on tonight and post tomorrow."
 
"Scott, I just sent you a pict

"Scott, I just sent you a picture of a VRO and where the O-ring goes via e-mail... check your
e-mail, I was not able to upload the picture here..."
 
"Thanks nicknack2 for the pict

"Thanks nicknack2 for the picture. Unfortunately, the o-ring I have is about the size of a quarter. I think it must be from a different project and was just laying around.

I am going to install a new fuel line between the primer bulb and the engine cowling. The existing hose is very plyable and cracked so I have little faith in it.

I did notice a bit of ooze (oiley goop) below a spark plug. Perhaps a plug was not tight enough? Would that cause a drop in rpms at high speed as if it were drawing air in? After getting hot?
Is Fuel supposed to get to the front of the vro pump. I'm not using oil injection, it has been disconnected and I'm premixing. This evening, I took the front off to make sure the pear shaped gasket was there and fuel came out. I guess that's normal?

Did not check the fuel for water. Will do on Wed morning.

I'll keep plugging away but after Wed morning, to the shop if not fixed."
 
"Personally with the symptoms

"Personally with the symptoms you have I would be looking for an ignition problem. Loosing a consitent 500 rpm's sounds like you are dropping and regaining a cylinder. Check the plugs, look for one that looks slightly more oil fouled than the others. If you find one, start looking at that cylinders ignition components."
 
"Rollie,
I was looking around

"Rollie,
I was looking around last night and noticed oiley stains around one sparkplug. I'm thinking it was to loose and when the engine heated up I lost compression? Getting it off required a wrench but not a great deal of torque. Would that be something that would manifest itself at higher rpm? or coincedentaly(sp?) at higher temps?"
 
"Rollie,
I was looking around

"Rollie,
I was looking around last night and noticed oiley stains around one sparkplug. I'm thinking it was to loose and when the engine heated up I lost compression? Getting it off required a wrench but not a great deal of torque. Would that be something that would manifest itself at higher rpm? or coincedentaly(sp?) at higher temps?"
 
"Scott, don't think the pl

"Scott, don't think the plug being not as tight as it should will be the problem. I found a bad coil on my 200 Yami by borrowing 3 used ones from the local shop. Replaced 3 on the motor with the used ones. My rpm drop went away....from there changed them one at a time to locate the faulty one. Took 2 coils back to the shop and paid for 1. If you can borrow some coils it is a great way to pinpoint this problem, otherwise it it hard to duplicate a high rpm miss in the shop or on the bench."
 
"Thanks Rollie,
I tinkered wi

"Thanks Rollie,
I tinkered with the thing all day yesterday and finally gave up and took to the shop. Will let you know the outcome. It will probably be something stupid like the wrong fuel/water seperator filter or fouled plugs.....I'll let you all know the outcome. At some point, I'd rather be fishing then seeing another Saturday pass by while stuck on the trailer.

Again, thanks everyone for your suggestions. By the way, for future reference, can I drain the carburator (sp?) bowls by unscrewing the big brass screw on the front of each carb? I should have done that to see if any junk came out. It's confounding that the thing would idle all day but not run well at high rpm."
 
"here's an update. The me

"here's an update. The mechanic put a new ignition system and optical sensor on the motor but that did not solve the problem. He then hooked a separate tank directly to the engine filter (bypassing everything on the boat) and that did not solve the problem. The problem only happens when the engine is hot and running at high rpm. Either there is a leak in the fuel pump like jwb said (housing may be warped) or there is a leak developing when the motor heats up. When the mechanic's assistant pumped the bulb, the motor ran fine. will post later this week when resolution achieved. I have a used ignition kit if anyone needs one."
 
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