Low alternator output affects diesel fuel economy

[somerandomguy1]

Good morning,

On a 1990 Toyota corolla with diesel engine if the alternator is not charging especially with ac on, can a low alternator output affect fuel economy?

Cheers

Jorge

 

[Donald]

One would have to know the type of injectors and injector pump. Probably all mechanical. So probably not.

The low alternator output (assuming tight belt and wiring not corroded) is some of the 6 diodes are broken in the bridge. Coming out of the alternator is 3 phase AC. Six diodes convert it to DC.

 

[somerandomguy1]

Correct, mechanical fuel injection with rotary type fuel pump.

Correct probably some diodes in bridge are broken. I was told the alternator could be rebuilt.

Could a bad timing belt bearing or acessory belt bearing such as ac, power steering or alternator bearing cause bad fuel consumption?

Cheers

Jorge

 

[Donald]

I would think most things that would effect fuel economy would be fuel system related such as bad fuel or clogged injectors.

A/C does effect fuel economy but not much.

If a bearing was worn or almost seized enough to cause a loss of fuel economy it would not last more than a minute or two.

Lasty not properly calculating fuel economy by the driver or different driving conditions.

 

[mk378]

It's mechanical injection. The engine doesn't depend on electricity at all. The only thing electric is a little valve that stops the flow of fuel when you turn the key off.

Having the cam out of time will hurt your performance and mpg.

 

[kschachn]

Good morning,

On a 1990 Toyota corolla with diesel engine if the alternator is not charging especially with ac on, can a low alternator output affect fuel economy?

It would make the fuel economy better if the alternator output is low. Your battery would eventually drain out however.

 

[eljefino]

Do you have adjustable valves on that thing? That would be a great place to start. And like said above, cam timing.

 

[somerandomguy1]

I would think most things that would effect fuel economy would be fuel system related such as bad fuel or clogged injectors.

A/C does effect fuel economy but not much.

If a bearing was worn or almost seized enough to cause a loss of fuel economy it would not last more than a minute or two.

Lasty not properly calculating fuel economy by the driver or different driving conditions.

Here is a guy who claims his fuel economy went up 5 mpg after changing belt pulley bearings: https://www.nissanclub.com/threads/freaky-mpg-after-pulley-replacement.447489/

Cheers
Jorge

 

[kschachn]

Here is a guy who claims his fuel economy went up 5 mpg after changing belt pulley bearings: https://www.nissanclub.com/threads/freaky-mpg-after-pulley-replacement.447489/

Cheers
Jorge

Depends on how bad they were. But to obtain that dramatic of a change would have meant the bearings were sucking an enormous amount of frictional energy and probably causing the whole assembly to glow red. For that reason and for the reason that people ascribe all sorts of goofy reasons to real-world fuel economy changes, I'm going to say it's just a bit of exaggeration.

Calcuate out how many joules of energy that had to be to cause a 20% decrease in fuel economy. Then think about the fact that just as much energy had to be radiating away from the assembly during operation.