Too Much Fuel

[FORSFED]

Can anyone think of what would cause too much fuel on a stock car? I've narrowed the problem (high rpm misfire) with my car down to this, but can't figure out why.

I know this is the case for 2 reasons::
1. leaned out afc and problem went away but was too lean so I adjusted back
2. disconnected vac line to fpr and plugged it. went for ride and no problem except was lean again.

Fuel related, I've replaced the filter and fpr and ran a bottle of redline cleaner through the tank. Now what should I be checking?

[john]

You said that the car has minor mods right? Maybe he put on injectors and forgot to tell you. I would try checking them.

[FORSFED]

The only mod it has is a 2.5" catback exhaust. The couple other little mods with the intake I have since returned to stock in an effort to fix the problem. Injectors are stock, not upgraded.

[Iceman]

running rich can be a lot of things check for vacum leaks though.. I need more information to really tell you what the problem is..

[At-Least-It's-An-Evo]

Have you changed plugs?

[1ViciousGSX]

Originally posted by FORSFED@Nov 6 2003, 10:23 PM
Can anyone think of what would cause too much fuel on a stock car?* I've narrowed the problem (high rpm misfire) with my car down to this, but can't figure out why.*

I know this is the case for 2 reasons::
1.* leaned out afc and problem went away but was too lean so I adjusted back
2.* disconnected vac line to fpr and plugged it.* went for ride and no problem except was lean again.

Fuel related, I've replaced the filter and fpr and ran a bottle of redline cleaner through the tank.* Now what should I be checking?

oversized injectors without any fuel management
bad MAF
leaking/sticking injector/s
dirty air filter
restricted fuel return line to the tank
BOOST LEAKS/metered air not making in into the cylinders

You say you leaned it down and the problem went away, but it was too lean, so you put it back? If that fixed the problem which had to put it at the correct mixture, why would you say it was too lean, it was probably correct?

Is the vacuum line for the FPR coming off of the correct port? It should be connected to a direct manifold vacuum source.

[JET]

I am with Vicious, sounds like a boost leak.

[FORSFED]

oversized injectors without any fuel management
- stock injectors on car
bad MAF
- Replaced that with no better luck
leaking/sticking injector/s
- Need to check this
dirty air filter
- Filter is ok
restricted fuel return line to the tank
- No visual defects
BOOST LEAKS/metered air not making in into the cylinders
- Have checked for and fixed all intake leaks

I did lean it out about 20% on the top end where the misfire was occurring. This eliminated it, so I took a log and towards 5-7K there was a knock count of 2, 19, and 39 through 1st 2nd and 3rd gears along with declining o2 voltages all the way down to 0.76V. I did this only one time as to not damage the car. I slowly started to richen things back up and it only took a few percent before it was once again misfiring so I zeroed it out and left it.

As for the vacuum source for the fpr, it is correctly hooked to the solenoid that's connected to the one nipple on the manifold.

I'll be tearing into it this weekend quite a bit I think so hopefully something will pop up. Thanks

[1ViciousGSX]

Try running the FPR line straight to the manifold, bypass the solenoid.