low rpm's

[kelscrusader]

I recently purchased an '87 Fabuglas Crusader with a 4.3L OMC Cobra. When I got the boat the tach didn't work, have since replaced tach. while out boating at wot the rpm's are only 1850, the speedometer reads 30 mph.
On a recent outing the boat backfired twice at wot, after that it had a hard time getting up on plane. What could cause this. Any help would be appreciated.

 

[Bondo]

Re: low rpm's

Ayuh,... Your Tach is still Wrong.... No way you're doing 30mph at 1850rpms...

The Backfiring is no doubt caused by a Lean condition...Changing the fuel filters might fix it....

 

[Maclin]

Re: low rpm's

Make sure you have the switch on the tach set for a 6 cylinder, should be settings for 4-6-8.

 

[kelscrusader]

Re: low rpm's

Bond-o and Maclin thank you both for the help. When I installed the new tach I looked at the switch twice and thought it was set correctly both times but it wasn't, it is now. I got a new filter and will try it out this weekend. Thanks again for the help.