Re: Anti-Siphon Valve Location? '96 Chaparral 1935SS
Don,<br />Thanks for the hints. Here's a break-down of the problem and my trouble-shooting so far. I have 2 primary symptoms which I'm not sure are the same problem, but could be related. Engine is a 4.3L Merc LHX+ (4bbl weber)<br /><br />1. RPM fluctuation under load<br />- this started about 3 months ago<br />- most common at 2000 - 3500 RPM<br />- engine would gain 200-400 RPM in "real" power randomly without a change in throttle position, sometimes would stay, sometimes would drift back down<br />- seemed worst in rough water, but given its randomness I wouldn't stake too much on this<br />- inspected ignition system and replaced worn wires, cap, and rotor (plugs are new as of last summer)<br />- idle RPM jumped 300RPM since replacing all the ignition components, last test run was flawless in terms of RPM fluctuation, but I'll wait to declare victory<br /><br />2. Sudden engine stoppage w/o warning<br />- 1st happened 4 months ago returning from a normal run, engine just died at cruise on plan, restarted immediately, couldn't reproduce problem<br />- 2nd and 3rd occurance last month, same situation running normally and engine dies, restarts immediately, happened twice in quick succession then no problem. That day I also had significant problems with RPM fluctuation and very rough water (which made for a stressful day since the engine quit 4 miles out from land in any direction)<br />- 4th occurance after last test run with no RPM problems, was flushing at idle and engine quit, would restart for .5-1s then quit again, left overnight and started and ran normally prior to cleaning the A-S valve today.<br /><br />#2 seems to clearly be a fuel system problem. I've purchased a spare oil pressure switch as I've heard these can partially fail and cause intermitent headaches. It could conceivably be causing #1 by underfilling the carb under load. Of course, it could also be a failing fuel pump, air in the lines, blocked vent, etc... I'm glad I can do the work myself, I'd hate to think what my labor bill would be otherwise. It'll be nice to have it back running well.<br /><br />- Virgil