C4 Starting and Running Problem

Tue 01 May 12 09:53

C4 Starting and Running Problem

Our 1992 automatic has done less than 29,000 miles and was running as sweet as a nut. As recently as January it was driven for long distances with no problems. A week later it was difficult to crank but started and ran fine. A couple of hours later when we attempted to restart the car it was cranking but not firing. It eventually fired but ran 'lumpy' and uneven.

Two weeks later the car cranked but wouldn't start. A little bit 'sticky' on cranking, we presumed it was down to battery discharge. We hooked it up to our tractor to jump-start but no joy. After about 20 minutes of cranking the car fired up with a bang and took a lot of throttle to keep going but then evened out. 45 minutes later, steam was coming out of the front right wing. The coolant was bubbling and steaming from the coolant tank so we switched off.

We restarted the car and got the 'Coolant Low' message, which was no surprise. Now it's starting but taking a lot of throttle to start. When it does start, any throttle movement in Drive causes it to stall.

Any assistance will be appreciated, thanks.

Last edited by Red House Classics on Tue 01 May 12 10:54; edited 2 times in total. [10 %]
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Brian Smith
Regional Rep - East Anglia

1969 Convertible matching numbers L46, 4-speed manual, Monza Red
2010 Subaru Legacy 2.5i SEn, 4-speed auto/step-shift, Obsidian Black

Tue 01 May 12 12:03

Re: C4 Starting and Running Problem

Hello,

This problem sounds like it may be the throttle position sensor which is mounted on the side of the throttle body, I had a similar problem on my 1996 Trans Am and Collector Edition Corvette. It won't be related to your overheating problem though.

Hope this helps

Colin

Last edited by ukzo6vette on Tue 01 May 12 12:05; edited 1 time in total. [12 %]
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2004 Z16 Commemorative Edition, Build 1906 of 2025, Born 06/09/2004 - CCW T10 19" Polished Alloys, Corsa Xtreme Cat-Back, JBA Ceramic Headers, Halltech Venom II AIS, MGW Shifter, Baer Brakes, Predator Tuned and Corbeau A4 Leather Recliners

Tue 01 May 12 12:09

Re: C4 Starting and Running Problem

A lot of people point to the Optispark. Sometimes this is not justified but here it may be the problem with the rough running as you a;lso have a coolant issue.

Was there coolant under the car?It is possible it may have leaked from the water pump onto the optispark.

I would check this first and if it's not leaking I'd very carefully add coolant and check the car is full of coolant with no airlocks. Otherwise you could do some serious damage - running it on low coolant...

Does seem like the starting and low coolant issues may be connected....

Malc

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No corvette at present.
2005 Mustang GT 5-speed

Previous Corvettes:

1984 red Crossfire auto
1993 red LT-1 auto
1990 black Callaway Twin Turbo 6-speed
1996 CE LT-4 6-speed

Tue 01 May 12 12:48

Re: C4 Starting and Running Problem

Thanks Colin and Malc, enquiries elsewhere also suggest the Opti-Spark might be the cause. I'll report what we find.

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Brian Smith
Regional Rep - East Anglia

1969 Convertible matching numbers L46, 4-speed manual, Monza Red
2010 Subaru Legacy 2.5i SEn, 4-speed auto/step-shift, Obsidian Black

Wed 02 May 12 23:36

Re: C4 Starting and Running Problem

This sounds exactly like the problems I had with my 94 C4 two years ago. It was the optispark again (2 in 8 years).

If the car stands in a garage damp can get in through the breather hole, or as Malc says and as happened first time with me the water pump failed and p!ssed all over the thing killing it instantly.

Jason