fuel consumption way up!!

pooldoo73 · 08-23-2004, 06:10 AM

I have a older Stamas hull with twin mercruisers. Bought the boat at the beginning of June 2004 for a bargain, but realizing I had some work to do. I used the boat for about a month and a half before having to pull an engine to replace the oil pan gasket, timing chain cover, etc. No big deal. Did some other maintenance work while it was out in order to be finished with that engine in relation to updating. The carb was never removed nor was the distributor ever pulled out either. Since reinstalling the engine, my fuel economy has left

. I was making approximately 2 mpg and now down to just better than 1 mpg. Any ideas on what could have caused this? The engines are GM inline-6 292. No performance enhancing features added nor was there a noticed performance swing, although there really isn't much performance. Cruise at about 30mph and 3100rpm. Ideas would be greatly appreciated.

auguste · 08-23-2004, 07:26 AM

Welcome to the board . . . lots of great info here

Did I catch you right that you removed one engine or did you do both engines?

Your fuel consumption reduced by almost 50%

that truly sucks

I see that you removed the timing chain cover . . . I am not sure about your engine but when my brother and I worked on his engine the timing chain had slipped a notch . . . his engine still turned over etc. but it became a real gas guzzler

Has the overall performance and top speed of your boat changed in any other way?

Good luck solving your problem

pooldoo73 · 08-23-2004, 08:07 AM

I only pulled one engine. These engines don't have a timing chain, its 2 gears that turn on each oother, one on the crank and one on the cam. I didn't notice any reduction in performance or anything like that. I never run wot, but running at 3100rpm the throttles are about even, the synchronizer shows both engines turning the same, etc. No excessive smoking, that you can see at least. Anyway, thanks for the welcome.

wetspot · 08-23-2004, 12:38 PM

Check your ignition timing. May have a bad spark plug. Otherwise the carb may have got something (dirt) caught in the float while the engine was being worked. Those are the easy things to check, otherwise, you may have other issues.

I am truly surprised to hear that you could get 2mpg out of a boat with 2 carbed engines! Most boats I've seen with similar setup get about 1 to1.25 mpg.

Good luck.

BONZO · 08-23-2004, 12:43 PM

Quote:

wetspot - 8/23/2004 11:38 AM
I am truly surprised to hear that you could get 2mpg out of a boat with 2 carbed engines! Most boats I've seen with similar setup get about 1 to1.25 mpg.

Good luck.

I agree. How did you figure your fuel burn ?

pooldoo73 · 08-23-2004, 11:15 PM

My boat is a 1969 Stamas 26' x 9'. hard top cuddy. It weighs about 7500 lbs. full of gas. My fishing destination for all of my trips so far has been a rig about 40 miles from the boat landing, by GPS distance. I have 2-40 gallon saddle tanks and an 80 gallon center tank. I run the boat at about 3100 rpm's which puts me about 30 mph. I can go out to the coast, stop a few places to catch bait, go fish at the rig, stop at a few places on the way back towards home and have to swap from a 40 gallon tank within 10 miles of the boat landing. The guy I bought the boat from could run 129 miles offshore with the boat loaded with 6 people and dive equipment for all and have no concerns over fuel supply. I will be slicking out the hull this winter and painting it due to its scratched and pitted condition and really expect to increase my mpg a noticeable amount. The bottom has the smoothness of a meatloaf.

pooldoo73 · 08-23-2004, 11:20 PM

These are the first mercruisers I have ever owned. I have been in and on and driving boats my entire life, literally. These engines are a big change to the outboards I have always been around. What types of other issues may need to be considered? Hopefully it will only be for learning purposes right now, but I am interested in every little thing that folks can teach me about my 2 new power plants.