Ready to scream

pinestump2

New Member
May 31, 2010
14
michigan
Boat Info
1986 Seville 17'
Engines
mcm 140
I,m having an ongoing problem with my 140hp 86' Seville. We took it out this past weekend and it ran great. We cruised for about 10 min. at slow speed, maybe 5mph, then opened it up for about another 5 min. It planed out great and ran smooth. Then we slowed back down to a slow cruise for 20-25 min and it still ran smooth. Then I tried to open it up again and it just sputtered and backfired and bogged down like there was no power.The engine temp was at about 165. It never did stall but you couldn,t open it up. This has happened over and over even after taking it to our mechanic. So far, we,ve had a carb kit;replaced the fuel pump filter and a tune-up kit put in. We also had an electronic ignition conversion kit put in. That really screwed things up,so we had the origional ignition re-installed. If we run it at slow speed, it runs fine. Any ideas on what's causing this, or how to fix it?
 
What do the fuel filters look like?
 
We just replaced the fuel pump filter. (It didn't look bad)

We have had this boat in to the mechanics SIX times for this same issue. The ignition system has been replaced. The coil. It's been tuned up, timing re-set, carb rebuilt. Treated the gas with Seafoam ... etc. We lost almost the entire boating season last year because of this.

The boat has spent more time on the trailer going back and forth to the mechanics, than she's been in the water. It's really frustrating.

Any other ideas?
 
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I would say take your carbs to a gear head. Race shop and have them rebuilt. installing a kit in one will do nothing at all for it f it's not cleaned right. I cant tell you how many carbs come to me with a new kit in them and dirty as hell. None of the knock outs were taken out and just nasty as hell. Now back firing could be there was no WD40 sprayed in the caps and it's cross firing. 2 separate problems but you think you your self. they must be related. But only show them selfs when the 2 problems merge as one.


EDIT. I just scanned over your post. Did any one test the fuel pressure or replace the fuel pump?
 
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I want to add that the boat only does this after it has been run 45 minutes to an hour - never acts up when you first take her out.
 
Hydro lock?
 
After reading Heather's post I would say that she is onto something requarding the carburator, I would have someone else look at it.
 
Vapor lock is invariably a temperature issue. Basically, I'd look for a point on which the gas line gets too near a heat source. Beyond that, I'd agree w/heather: the carb's secondaries may not be working/aren't kicking in totally. However, this should still allow her to idle indefinitely...only is an issue when she is throttled up.
 
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I second the gas tank vent... if the screen is gone or found gone and replace! I hate them bugs that sneek in this will indeed cause the issue described
 
The fact that it does run fine at higher rpms, even if for only a while, would seem to rule out any mechanical issues with the engine (timing, etc). What's left would be the fuel or fuel system as suggested.

Vapor lock wouldn't occur unless the engine was shut down for a short time- allowing time for the fuel to vaporize. In adddition to what has already been suggested, I would try running the engine on a small portable tank ( under load- on plane) to isolate the fuel system. It could be as simple as bad fuel- particularly if you have ethanol fuel that's been sitting for a while.

Another note.. this should show up as gunky carb as well, but IF you do use ethanol fuel do a visual inspection of your fuel lines. Older fuel hose is not ethanol resistant and gets gummy and deteriorates into the fuel delivery system. Since there was no sign of this in your carbs it's probably not your problem, but you should inspect them anyway.
 
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The fact that it does run fine at higher rpms, even if for only a while, would seem to rule out any mechanical issues with the engine (timing, etc). What's left would be the fuel or fuel system as suggested.

Vapor lock wouldn't occur unless the engine was shut down for a short time- allowing time for the fuel to vaporize. In adddition to what has already been suggested, I would try running the engine on a small portable tank ( under load- on plane) to isolate the fuel system. It could be as simple as bad fuel- particularly if you have ethanol fuel that's been sitting for a while.

Another note.. this should show up as gunky carb as well, but IF you do use ethanol fuel do a visual inspection of your fuel lines. Older fuel hose is not ethanol resistant and gets gummy and deteriorates into the fuel delivery system. Since there was no sign of this in your carbs it's probably not your problem, but you should inspect them anyway.

Our mechanic has been kept busy rebuilding carbs since ethanol found its way down here.

Did this start right out of the blue or after a certain "event" engine work, different fuel dock, etc)?

I share your frustration. Our 260DA did something similar except the problem got progressively worse and eventually wouldn't throttle up from the beginning but will idle all day long.

I pulled the pickup tube (clean), changed filters (clean), dosed with Solitron but no help. Took our mechanic out for a spin and he didn't think it was the carb, guessed a weak fuel pump. We go down tomorrow to get her back from the mechanic. Will let you know what happens...
 
I want to thank all who has replied! We are checking out the fuel system. We are also changing out the inline fuel filter to the carb again tomorrow. We thought this was changed when our carb work was done - but I don't trust the mechanic that has been working on our boat now.

We've thrown over $1000. at this problem so far, with parts and labor. I think we are now in the market for a different mechanic. We have a Skipper Buds an hour or so away that is a Sea Ray dealer, we may have to take her in to them.

KRB64 let us know what you find out!

When we finally get our boat back up to speed (pun intended) we will also report back.
 
The carb filters on your boat have a very fine mesh screen and should be changed every year along with the other filters, water separators and oil. As someone earlier suggested, the fuel lines could be suspect as well depending on their resistance to ethanol. If your carb filters contain debris, it could be from bad gas, or the fuel line failing. If it's old rubber, the filters will clog again.

Your $1,000 may have been well spent. At least you have some new parts that should last. But, when it comes to gasoline engines, they only need spark, air and fuel. The cheap and easy things to check are the flame arresters, water separators, fuel filters. If those are good to go look at more expensive possiblities such as ignition parts and fuel pumps. It's usually the cheap and easy things that fail first and this is from a lack of ongoing maintenance.


I've got some older tractors, leaf blowers and string timmers that have worked fine for years. One of my blowers failed and gasoline started running out of the carb and it quit. Got the other one out and filled it up. Minutes later the same thing. Ethanol.....both needed carb kits and new fuel lines. One tractor needed a new gas line and filters and has been running like a champ after the ethanol cleaned the fuel tank and it had new parts installed down stream. The string trimmer was so old I threw it away and bought new.

I love all of these new energy initiatives. They are so good for all of us.
 
KRB64 let us know what you find out!

Well our mechanic's wife ended up getting sick and required surgery so he wasn't able to get the boat done. He did give me free run of the shop though so we went on down. I was able to rewax and work on a few other little things on the boat in the shade and on the hard.

Supposed to be done Tuesday. Not sure when I'll have time to run back down and splash but I'll let you know the results when I do.

BTW, did you clean out the anit-siphon valve? Probably not the culprit but easy enough to do when checking the fuel pickup screen.
 
boating.jpg


We took the boat to a different marina, found a new mechanic.

Left him a list of what's been done to our Seville so far, and we left instructions to go inspect and go through the entire fuel system - from the vent, to hoses, filters, carb. :thumbsup:

A set of fresh eyes on the problem and a mechanic that agrees that we are having some sort of fuel related issue.
There is a 2 1/2 week turn around time right now on repairs. So we will update once the boat is back in the water.
 
run the boat with the fuel cap off, or crack it open a little bit
 

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