Logo
FULL SITE MENU

carb?

D

denis_k

Member
I have been trying to chase down fuel consumption on one of my 454 changed wires plugs still port is burning 3-4GPH more. Not much knowledge about carburetors, but i did notice the numbers stamped on them are different, maybe old owner of the boat just installed much higher cfm carb on 1 side because both engine run great. any advice is welcome is it time to change the carb? looks like fuel pump has been replaced not to long ago. Quadrajets by the way if it makes difference
 
If it is a marine grade q-jet, they will both be rated 750 CFM. The flow rating won't have any direct impact on the fuel consumption. wires changed - good.

Have you verified the timing is advancing on both engines and is within spec?

What are you using to measure GPH?

Recent compression or leakdown test results?

Hooked up a vacuum gauge lately - same on both engines (vacuum vs rpm, from idle to cruise)?

You'll find fuel consumption directly related to intake manifold vacuum on a sound, well-tuned engine.
 
1. Time the motor at 3,000 rpms to see if the advance is working correctly. This requires putting timing tape on the pulley (available at Jegs or Summit Racing on line), or buy/ borrow an advancing timing light.

2. How clean is your flame arrestor? Mine was a "bit" dirty and that motor burned at least 10 % more fuel.

Jeff
 
Flame arrestor was dirty cleaned that. thank toy for advice guys I just want to check with you what is the correct gap for the plugs i set them at 035 and a someone told me it needs to be at 033 engines are 1984 will the wrong gap have affect on fuel consumption.
Thank you.
 
I think i found the problem the true test is going to be this Sunday after a 40 Mile fishing trip. I didn't check wires, because i changed them before boat went back in the water I guess one wire was defective the one which goes to the center of the cap it was arching so bad i smelled it pulled the wire and it was so bad i needed new distributor cap so changed that and another set of wires. I am actually shocked the engine was running with the wire being so bad. Should I change plugs again?
 
No. Just make sure all of your wires and tight in the cap and going to the right plugs after changing the cap.

Jeff
 
Difference in fuel consumption got better after changing wires and the cap but is still higher and i noticed some unburned fuel coming from port side a little slick forms by the exhaust when boat idles in the morning it gets better as engine warms up but i can still see a little film forming on the water at idle.
What am I looking for next any suggestions are appreciated Thank you.
 
How long has it been since the carbs were apart? any idea who did the last rebuild and what parts were installed?

You mini version of the gulf of mexico in the exhaust is a positive sign of being too rich. A common cause is a "wet" float; almost as common is a marginal needle and set. Another likely suspect is the choke not opening fully - could be binding in the linkage or the coil could have failed mechanically.
 
I had this boat for 2 years no info on how long this carb been on it i know its a reman not original should i just get a reman and replace it i never rebuild one before i am more familiar with diesels so it is all new for me. Main question is running rich like that is the problem with the carb right?
 
most likely the carb but check the choke for full open (engine warm) before parting with the $$ for another carb.
 
With the possible exception of those old, aluminum bodied Carter AFBs, most carbs can be renewed indefinitely. The "Evil-Nol" stuff eats them up.

Jeff
 
Back
Top