[Chris Finch]

I have a '93 18' Mariah El Diablo and have loved it, until recently. I'm the original owner and everything about it is still good except for this one problem and it's a real pain because it doesn't happen enough you can plan on it and when it does, it never fails, we have a whole boatload of people we've gotten together for a day on the lake and then we end up getting towed back in.

We will head out to our favorite lake and the boat starts like a charm at the ramp and runs well for about the 10-15 minutes it takes us to get to a cove we like to ski in. I'll cut the engine off for about 5 minutes while the first person gets in the water and ready to ski and the engine just won't start again. It will still crank but just won't fire. I can let it sit for 5 minutes or 30 and it doesn't seem to matter. This past weekend I cranked for about an hour and almost had it going again as it got real close but I cranked so long that I burned out my starter. I have a new starter now ($360 more in the hole) but don't think that's been the problem. Fortunately the battery stays up long enough for me to do all this cranking but there's no rhyme or reason for it. I've had a mechanic look at it and he can never replicate the problem. It happens about 1 out of every 4 or 5 times we take it out and will run fine in between times.

I used to run the radio while we were waiting for the first skier to get ready but thought that for some reason that had something to do with it so this past weekend I didn't even do that and it made no difference. It's to the point you really don't want to go out with anyone and take the risk I'll have the same problem again.

I've had the fuel line cleaned before and also repleaced plugs and all but nothing seems to help.

Any help anyone can give will be greatly appreciated as one of the boat shops around here now has a policy that they won't work on anything over 15 years old and I'm running out of options.

Regards,
Chris Finch
Cary, NC

[darkcalling]

Not for sure but that sounds very much like a vapour lock issue some vehicles, have is you venting back in place properly since the line cleaning or any other fuel changes you have made? I assume your running a 4.3 or 5.0?

[Chris Finch]

Thanks for your help. I'm not exactly sure what size engine. It's a 4 cylinder if that helps at all.
(Sorry but not very mechanically inclined).

If it were a vapor lock, what would be the way to alleviate the problem?

[darkcalling]

Vapour lock is an air pocket in the fuel lines usually caused by an improper venting system or some kind of crimp in either the fuel lines or vent lines for the fuel system. The other issue maybe similar to another members problem, though my experience is only with the v 8s mainly but the mechanicla fuel pumps get weak over time and as the engine heats they seem to show their weakness more often. I would check the lines first though.

[usmckao]

I had the same problem with a Chapparal with an OMC motor. Rebuilt carb, tuned it, replaced electrical components. I still had the same problem. Would run great until it was really warmed up then it seemed to not get fuel and would die. Could never restart it. 5 mechanics did not know what was going on with it. I found the culprit... The mechanical fuel pump. When I took it off, there was so much gummed up nastiness sludge that when it got hot, the sludge wouldn't allow fuel to carb. Replaced it and ran wonderfully. Food for thought!

[DFZ272]

Sounds like a fuel system problem, but the 3.0 liter 4 cyl has a couple of other items that need to be checked. It has a points type ignition system which can give fits if not properly maintained. This system has is a little more maintenance intensive than more modern systems. My advice total tune up, ie. check fuel pressure, check carb adjustments and/or clean/rebuild the carb, check points condition/adjustment, check timing, check igniton coil, etc. One simple thing that I have seen before is a plugged fuel tank vent, this can easily cause the problems you describe. I would check the fuel tank vent first then move on to the tune up phase. Hope this helps
Happy Boating
Dan