G50 fuel tank and pump questions

[Infinitiguy19]

I hear many say "ALWAYS keep the fuel above 1/4 full" it used to be 1/2 full but it changed. And as one member pointed out the pump sits higher than a tank that is half full. So how can it be cooled if that is so?

I also hear people say to keep the fuel tank above 1/4-1/2 full to avoid sucking up the bad stuff at the bottom of the tank. I ask yet again how can that be IF the fuel pump pickup also is as close to the bottom as possible?

I am not arguing these points I just hope someone can better explain them to a idiot like me.

[qship96]

Simple.....they are both internet myths. You are correct, the sock sits down low in the tank,so any crap that is in the tank will either get stopped by the sock or make it through and get pumped into the fuel filter where it will be trapped unless too small for the filtering element to stop.....then it just gets injected into the cylinder and burned out the exhaust.....99% of "normal" people never give this crap a second thought or even worry about ever changing their fuel filter and happily motor on down the highway .....same with the 1/2 or 1/4 tank full nonsense.....I ran my tanks of fuel down til the low fuel light came on for years and years in my Q {trying to see how many miles I could get on a full tank before light triggered{usually 400 highway miles} and original pump was replaced at 110,000 miles because i could "hear" it if I listened hard for it.....pump probably would have gone 150,000+ miles if I ignored it like 99% of owners who dont get wrapped up in these internet boards.Bottom line, read and learn, but use your own best judgement when it comes to acting or spending $$$$ on your car

[Q45tech]

The pump circulates at least 4 times the engine demand thru engine compartment where it picks up heat, therefore in summer traffic it is not unusual for a near empty tank to rise to 160F vs 120F or 100F with a higher fill condition.

[yodawill2000]

Simple logic at its best...

[Infinitiguy19]

The pump circulates at least 4 times the engine demand thru engine compartment where it picks up heat, therefore in summer traffic it is not unusual for a near empty tank to rise to 160F vs 120F or 100F with a higher fill condition.

I am surprised no company has found a way to scam people out of there money "claiming" to cool the fuel pump which would truly provide a longer life.

Thanks for clearing it all up everyone.

[Q45tech]

Returnless fuel systems must measure the gasoline temp in tank to more accurately control the injector trim, even with the new wideband O2 sensors.

As I've always said the 90-95 Q45 were crude at best, but things like air flow control of rail intake pulse damper as a double check or trimode fuel pump speed from ecu showed they tried with limited ecu power of late 80's and early 90's.

The density of gasoline (C8H18) is 0.694 g / cm^3 at 300 K and 0.622 g / cm^3 at 400 K. Density shouldn't change that much relative to the ground temperature (300 K =80 F). ....................that's ~ 10% so things could get leaner when not at cruise [o2 control].

[Infinitiguy19]

For a quick second I thought about using the air temperature sensor from a J30 and a fuel temperature from another model Infiniti. And see what Wes can do with the ECU so they are recognized. But I am no engineer and thats far too much work for little gain right?

When the VH45DE is like new it runs perfect so even though the ECU is "stupid" its far better than having a stricter OBD2 ECU that can't be modified, or isn't worth the labor to try it in the case of the 1996 Q45.

[Q45tech]

Gain in what? stock ecu is very rich at WOT so summer heat [of gasline leans it = good]. Even modified ecu has some safety reserve as do the cats in how many seconds WOT can be maintained.

[Haitian_King]

The pump circulates at least 4 times the engine demand thru engine compartment where it picks up heat, therefore in summer traffic it is not unusual for a near empty tank to rise to 160F vs 120F or 100F with a higher fill condition.

I am surprised no company has found a way to scam people out of there money "claiming" to cool the fuel pump which would truly provide a longer life.

Thanks for clearing it all up everyone.

Shhh! You'll give the scammers ideas!