tim 90

90 vette starting and idleing problem. will start after sitting overnite but idle has become choppy with an internal rattle. can drive on local streets but can stall out at any time then have to wait 10-20 min to restart. usually garage all winter and start occasionally. tach has stopped working as well gas gauge. other gauges work fine. any suggestions? HELP

Cliff Harris

Put a fuel pressure gauge on it. Tape it to your windshield. Check these pressures:

1 - Key on, engine not started.
2 - Engine idling.
3 - Engine running at higher RPM, like over 2000.
4 - Engine turned off after running for a while.
5 - Same as #4, except 30 minutes after engine was shut off.

There are specific reasons for each of these tests and you need to do ALL of them to truly see what is going on.

Churchkey

90 injectors fail due to corn gas. Your running problem then needing to wait until the engine cools to restart is indicative of failing injectors. One would surmise that if 1 injector fails the engine would misfire on that cylinder. The TPI uses a batch fire (non sequential) system, if 1 injector shorts out the rest of them do not work very well or at all.

Ohm test each injector cold then hot they should ohm out 14-16 ohms.

If you need injectors suggest contacting Jon @ FIC for a set of Bosch 3's.

The rattle: Car is a 6sp? If so the dual mass flywheel is rattling due to engine misfire.

BTW, I put Bosch 3's in my 90 about 5 years ago it has not missed a beat.