terrible gas mileage and gas smell

[Kozworth]

Hey guys,
I have an 88 325is and lately I've been getting low teens mpg. Here are some symptoms.

Strong gas odor under the hood at times,
looks 'wet' but not literally, where injectors mate the lower intake mani
idle has been at 1k as opposed to 800.
Fpr vacuum line does not have gas in it
no gasoline leaks when parked
cluster is finnicky (mpg does not work, and speedo is bust)
fuel guage sender seemed in working order
gas odor inside cabin (probably fp and sending unit orings)

Those are just some things I thought might help diagnosis. Like I said, I am shifting moderately ( 3500 rpm ) and still getting garbage mpg.

[yert315]

do you notice excessive smoke from the exhaust?
Have you inspected all fuel lines in the engine bay?

[SlamedIAm]

Possibly leaky injectors. How old is your o2 sensor?

[paperplane94]

Could be injectors as said above.

There is no gas in the FPR vacuum line, but can you smell gas in it if you sniff away from the car (with the hose disconnected, somewhere not smelly)?


I would test fuel pressure to help rule out the regulator.

Then I would check all the fuel lines, metal or rubber, for any breaks, cracks or the like.


What else is there?

[Kozworth]

AAs for smoke, it seems a little excessive but it is cold out aswell. I have no clue on the age of the o2sensor eithor

[603Racing]

Could be injectors as said above.

There is no gas in the FPR vacuum line, but can you smell gas in it if you sniff away from the car (with the hose disconnected, somewhere not smelly)?


I would test fuel pressure to help rule out the regulator.

Then I would check all the fuel lines, metal or rubber, for any breaks, cracks or the like.


What else is there?

+1 on these suggestions, quick and free to do these.

[Kozworth]

Possibly leaky injectors. How old is your o2 sensor?

Could be injectors as said above.

There is no gas in the FPR vacuum line, but can you smell gas in it if you sniff away from the car (with the hose disconnected, somewhere not smelly)?


I would test fuel pressure to help rule out the regulator.

Then I would check all the fuel lines, metal or rubber, for any breaks, cracks or the like.


What else is there?

Heres just an update of what I am experiencing lately.

In the past 3 days, ive put in 50$ into my tank and right now im at 1/4 tank.

Before this, i had an awful valve specs, they are in region.

In the 3 days of going through 93 octane in my 325is chipped, I drove ~50 miles monday, ~80 miles tuesday, and ~50 miles today.

Since i have 1/4 left, Say its 40$ into my tank or 11.5 gallons, for 180 miles. Thats a solid 15mpg on highway speeds of 55-65mpg mostly.. Since im driving all highway to school.

FPR line did not smell strongly of gas, it smelt a little but nothing to throw any flags, it was mild.

As for o2 sensor, I have no clue on its age or condition (seems pretty rusted into the downpipe).

I am still getting a gasoline smell mostly at WOT, but i have the gaskets to replace under the FP and sending unit.

I do not really smell gas along the front of the car, but kinda in the back. I have a leak free gas tank in it.

As for the lines, I honestly dont get time to check them, I am basically not stuck put for living situations, let alone have a garage and most of my tools to check underneath.


On another forum, ive read a lot of guys getting 20-30 mpg solid on their 325is. This brings me to another question, my OBC isnt working it jsut flashes dashes, is there a way to check this out any further? I am curious to see what it claims im getting for mpg.

[jlevie]

If you are smelling gas, there is most likely a leak somewhere in the fuel system or associated with the tank. I would say that the car is unsafe to drive until the leak is found and fixed.

[paperplane94]

^+1 !!!

Only you can prevent e30 fires.

[Kvasi]

Pull the back seat and check the hoses on top of the tank.

[Kozworth]

Today, checked at my fuel pump.

Underneith, there was no visible gas leaks, I even looked during/after i drove the car with the fuel pump cover off.

Replaced the fuel pump gasket, and fuel level gasket, but the sending unit is still the original (didnt order enough). When smelling both units closely, the fuelpump/fuel level unit smelled moreso compared to the sending unit.

I do not get a gas smell from what i believe, yet again I have had a cold and now my interior smells slightly of gas.

Under the hood, it does not smell like gas, from the rear it does. BUT, i feel like its mostly from the exhaust, as if I am running rich. It does it during cold start, which makes sense since the car is in open loop, but when its warmed up (assuming its in closed loop), still smells like gas. I tried hard and cant smell it from where the tank is, and the tank is a considerable ammount farther then the exhaust tip.

I also do not notice any gas on the ground after parking, which gas is pretty hard to miss once it splashes on my driveway. So from that assumption, my lines should be good but will check at work on sunday.

I am still getting ~15mpg, my only real options are:
Double check tank and lines
o2 sensor
Injectors leaking or clogged possibly

I am also getting an idle around 550, which is low. It normally idles around 650-700, and the idle sounds like the car is cammed. I will try to get pics and videos up for you guys tomorrow since it is my day off.

Thanks again, sorry for this paragraph of diagnosis

[ruabel2]

Had a similair problem. It ended up being the intake manifold gasket. Hope this helps!

[immajackuup]

exhaust leak.

[gtdragon980]

Check the following...
C191 connector!! mine had this problem and i was running super rich with shitty idle
Coolant temp sensor, not the one for your gauge, but the one for the ecu
TPS

I know these can cause bad rich symptoms, so check those out. Your gas mileage sounds like what I was experiencing, but my problem consisted of numerous things including my odometer counting too slowly which fucked up my readings.

ninja: oh and vacuum leaks can make everything just that much worse!

[Kozworth]

C191 connector is just on the ecu I assume?

Ill look into cts I did not know that there were two. I know one is in the tstat housing which I assumed was for the gauge, where is the other cts? I don't have the bentley at hand, ill look up how to check these out