Now that I am just about to drive it cross-country for a new job and new life, my totally stock '95 Formula develops its first big problem. It has been spending a lot of down time the past few years since I was working out of state and driving my other car, but it has still been running great, smooth, and clean when I take it out. But today the LT-1 seemed a little rough idling, and running surprising rich -- unburned gas smell -- and although it seems to run strong and seemingly on all cylinders when I floor it, it now cranks but does not start unless I put it to the floor --- that's right, like a gas-flooded carburetored car. Also a strong gas odor persisted after I shut it down at home, and it seems to occasionally be alternately running cool and then a bit hot since I flushed the cooling system last month (maybe air in system?). I don't have a clue what this new gremlin could be --- injector, EGR, O2 sensor, optispark, etc. but I need to fix ASAP. Any help you can provide would be greatly appreciated. Thanks up front for suggestions.

 

I'd start with a new fuel filter and some fresh gas ,Ethanol free if you have it in your area.

 

You also may have fouled injectors from old fuel spooge in them.. I'd try the above with a healthy shot of seafoam in the fuel and a Italian tune up...
Also if your that rich you may have washed the cylinder walls down and a shot of oil in each cylinder then spin it over with the plugs out... Then fresh plugs.

If it got parked with ETH fuel,, its hard on rubber bits..

 

Cranking but only starting when floored, my guess is you have a leak somewhere. If your not seeing any fuel on the ground check the, Injectors, regulator, pump itself.

Have you checked fuel pressure, and how long it maintains it?

Mike

 

the whole running rich and idling rough thing has me questioning one of your sensors. even if you have a leaky injector the O2's should compensate for the extra fuel and lean out the mixture. I would check your MAF first. pull the PCM fuse for 20 minutes to reset the PCM then unplug the MAF and see if anything has changed when you drive. a junky MAF will cause hard start scenarios too. I don't think anything is wrong with your ignition system or fuel pump. Also it makes sense that the car would run fine at WOT because the PCM is commanding fuel to be dumped in anyway. if unplugging the MAF fixes it, then use MAF cleaner on it. does the car run rich in both open and closed loop? if it runs fine in open loop but not closed loop that narrows the issue down to the O2's. any trouble codes? are you able to check the spark plugs to see if any are fouled?

 

Quite possible the cap/rotor on the opti may be bad. Also the engine in our cars is a Gen II LT1 whereas the LT-1 is a Gen I.

 

Check for Vacuum leaks

 

My TPI had the same symptoms... found a leak at the fuel rail. The gas I was smelling was coming from under the hood. Car ran very hot due to lean condition, but I could smell gas.