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Guys

I have an urgent need. I have just spent hours reading the posts on here regarding vapor lock and I may have it, but i may have something else going on as well. I need to fix this tomorrow as I'm taking some buddies out and want the boat running nice.

I have a 94 Echelon with the 350 magnum carb version. I am running last years fuel that I winterized the boat with, I added stabil.

4 days ago I went out on th eboat and after an hour or two of boarding we were approaching the dock and th eboat stalled out and would not start. This is a pain to all us ski boat drivers as it's just a heavy lump that seems to deliberatly float in th ewrong direction when no power is being applied. Anyway after two more days of boarding the boat was running very well, no more instances. Last night I went out and the boat started first time but seemed a little rough at idle. This progressed to the boat stalling at every attempt to idle. The only way the boat would start was to put it in neutral and with full throttle start the engine. This worked until it took about 20 minutes of trying to get it going. we left the lake. Here's my thoughts:

1) 10% Ethenol fule from last year even with stabil in it is bad. But why would it run well the previous two days?

2) Vapor lock? But why would it run rough straight away, the engine was not hot at that time.

3) My temperature gauge has not worked yet this season. I believe that the sender is the one next to the thermostat housing. I'll check that out tonight. If that seems OK then I'll pull the thermostat and check that is operational. i pulled it out last season during the winterization process. Would a bad thermostat or a sticking thermostat cause this problem. it runs fine for two days and then like crap for a day.

I would like to think that it's vapor lock but that does not seem realistic as because of teh rough idle at the start of the day. I also know that dirty filters etc... could cause this and I will be replacing those soon. I only bought the boat last year so I know it needs some TLC on the maintenance side of things.

Any quick comments will be appreciated as I want to get to this tonight.

Thanks.

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There can be many causes for your problem.

1. check all filters, including one at the carb fuel inlet, also check the check valve on the tank.

2. my guess is a carb rebuild is needed, many potentials for the symptons: i. dirty float bowls and debris in one of many small nozzles in the carb, ii. accelerator pump circuit dirty or not functioning correctly, iii. choke improperly set, iv. debris in idle circuit, improperly set idle screws, v. loose venturi's or other allowing air to enter one of several fuel circuits.

3. bad fuel or water in fuel could easily cause the problems, which could also lead to a carb rebuild need.

4. does not sound like vapor lock

The carb is actually pretty straightforward and fairly easy to rebuild. It is a Weber 750 cfm 4 bbl which is similar to a Carter AFB or Edelbrock 750 cfm unit. There ar differenced in the respective tune up parts in terms of how they match the needles and jets as a set.

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Trash goop and sludge from the old gas can/will foul your carb jets. Try cleaning it our or you may need to do an overhaul of the carb. You should also replace your fuel filter while you are trying to clean your carb. Good luck getting it cleaned out.

Vapor lock usually happens in injected motors that are run then let to heat soak in their own heat for a while, fuel boils in the fuel rail and pump.

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Thanks guys, I knew it would lead me to the carb. I have not tested the temp sensor yet, I have just bought some seafoam as I don't fancy a carb tune up/clean now the season has just started. I'll let you know how it goes.

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