tuning help/gasconsumption

[jdmckay]

Hi Guys,

MM 2L is not running well. Issues are:

- under twenty MPG
- dieseling after shut off

motor rebuilt motor with approx 30k miles.

Did tune up: distr. cap, rotor, plugs, ignition wires.

Weber carb w/ electric fuel pump.On 2/14/17 a diagnostic specialist worked on it and mileage has decreased significantly.

[pennyman1]

Ok - what was the "diagnostic specialist" trying to fix on your truck? My bet is either the choke is not working, the mixture is adjusted rich, idle speed too high, or a combination of all three. Timing may be advanced as well. You need to undo what he did to get your mileage back.

[geezer101]

+1 on pennymans' recommendations. Some shops have absolutely no idea about old school and can undo a good tune with a couple of turns of a screwdriver. They do dumb sh*t like adjust the idle speed with the distributor and open the throttle stop too far or mess with the air/fuel screws etc. You are lucky that you've done the Weber swap and there aren't many adjustment points. The factory Mikuni can become a nightmare when someone starts randomly turning screws... Be aware that the jetting for the 32/36 Weber out of the box isn't ideal for the G63B and using the right jets + a trial and error tune can make a night and day difference in performance and power. OOC what pump are you using (you've probably posted it up previously but I'm too lazy to search lol)