Ok, here's the deal...I have a 97 M6 with 42k on the clock. I've been trying to lay off the throtlle quite a bit lately, basically staying below 3000. I have been trying to stick with Shell gas because I have heard they have the best amounts of detergents and highest quality gas, blah blah blah. So now lately it has been really hesitant to start (cranks fine, just doesn't fire) and my gas mileage has just dropped to under 14 mpg (keep in mind, religously staying below 3000 RPM). I tried to do a search, and am still stumped. I have been playing around with the airbox trying to eye-up for a homemade intake, but too close w/ASR, but took out some of the crap by the filter, and haven't really paid attention to it (the filter) lately. I'm just kinda confused, like I said, and with premium jumping $.30 to $2.80 ish, I'd like to get it figured out...I have kinda been thinking fuel filter, but any input would be helpful. Thanks in advance to all.

-Jeremy

 

We assume that the air filter was fine since you looked at and once the car starts it idles and drives fine. Also it has not lit the SES. Stop me if I assume too much.

Does it get harder to start the longer it sits?

Since you have a starting issue AND bad milage, I recommend you pull the vac line off the fuel pressure regulator and see if it's wet. If it isn't, put a vacuum on the hose while it's connected to the FPR and be sure it holds for a minute or so.

See if holding the throttle to floor helps it start easier the next time you go to start it.

One last thing, check your oil right away for the smell of gas. If so you need to change it and find the problem a little quicker.

The next thing to check is if the injectors are leaking.

 

Nope, you are correct.

Um...well, if it sits for 2 hours versus overnight, yes. I did leave it sit for 2 or 3 days and it didn't seem to change from the conditions of overnight.

Nope, its good.

Huh?? Leave it connected, or disconnect and plug it?

Nope.

I'll be changing it in the next day or so here, but if there is gas, would it be excessive blowby, or fouled plugs, or what?

Thanks very much for the info, I just really want to get this figured out...

 

I had a similar problem turned out to be the fuel pump check valve. once i changed out the pump it starts great.... now to fix the outher 10 problems on my Z