help mpg drop after new nozzles

[burn_your_money]

Because the feed side is under suction, you will almost never see it leak, but it will draw in air

[fatmobile]

Air bubbles in the fuel are usually caused by a restriction in the fuel system.
 The vacuum caused by the pump pulling against the restriction will expand any air in the fuel. Doesn't mean there is a leak.
 It means your filter is clogged or somethiing.

[derekp]

Well, it drives better, the cold start smoke is tremendously diminished too.
Too early to tell what my advance-by-ear did to fuel mileage.
What are the signs of "too much advanced" IP?
Also I now see that I've got air bubbles in feed and return lines at idle (the bubbles diminish if I rev the engine up) , so I'm trying to plod my way thru air leaks or line restrictions.
Consensus seems to be if the water separator is a problem, remove it.
I guess that would be ok to do as I just discovered theres a drain on the fuel filter - though it may be a bit messy to drain that given its location.

Outside of air leaks or restricted lines, is there anything else that could cause air in both feed and return lines? I'd only recently noticed the air, yet I'd replaced some of the soft returns on the injectors. visuals of existing lines dont show any cracking either. I've got clear line ordered to replace the stuff I cant see thru, not quite sure what to do beyond visuals and the vacuum gauge test.

Thanks for the tip on IP being retarded with replacement of nozzles!

[derekp]

The check valve after the water separator was causing 5 inches of vaccuum at the IP. A 6 month old fuel filter was good for another 1/2 inch of vaccum.

Are there fuel filters of the mesh type (instead of the bosch paper type) that would be less restrictive?

Whats the purpose of that check valve - is it for a federal safety standard or is it to prevent line drainback when car shuts off

Also, why the heck do I see air bubbles in filter to ip line when I shut car off?


thanks again all for the info on IP timing and air leaks

[Smokey Eddy]

Just a side note, i hope this isn't off topic, but how much can a clogged cat drop your milage?
That sparked my interest

I made a post where people listed signs of too far advance IP timing. Use the search and tick the box "include all words" i wish that was set as the default