C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Cold Start Valve

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Old May 12, 2007 | 12:36 AM
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Default Cold Start Valve

So I went start my car today and it started idling really bad and I thought it was possibly the timing. Started to drive it home and then I started smelling gas. Turns out the Cold Start valve is leaking from the fitting in the fuel rail. I had the car towed home and called some parts places but no one has them. I was told I could only get it from a dealer or a junkyard. As far as I can tell its only the end with the fitting thats messed up. Can this be fixed? If not wheres the best place to find one?
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Old May 12, 2007 | 01:43 AM
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You might want to take a digital pic and post it showing exactly where the cold start valve/fitting is messed up. The Cold Start Valve (CSV) is a special fuel injector used only on 85-88 C4s. Neither GM nor the aftermarket manufacturers make them anymore. You won't find a new one anywhere on-line or at a dealer. If the problem is the injector, you could send it to Chris at CruzinPerformance to evaluate. He can usually rebuild one for a reasonable price. You could also look for a used one from the junkyard, but if it has been sitting for a long time, it probably will need rebuilding as well.

If the problem is the fitting for the fuel line into the injector, you may be able to find one in the GM dealer parts network under the CSV fittings group number, but more than likely, a used one from one of the CF recycling junkyard vendors will suffice for much less cost.
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Old May 12, 2007 | 02:02 AM
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Yeah its the fitting or the flare at the end of the pipe.
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Old May 12, 2007 | 02:14 AM
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Have you checked the o-ring in it?
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Old May 12, 2007 | 02:21 AM
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Originally Posted by evmlarry
Have you checked the o-ring in it?
!$%* no I didnt replace the one in the fitting. Which would probably explain why its leaking. Thanks.

Oh on a side note, is it possible to delete the Cold Start Valve? I ask because 89-91 L98's dont use them, just wondering.

Last edited by Demonic85; May 12, 2007 at 02:24 AM.
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Old May 12, 2007 | 11:15 AM
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On my '88 I hammered a butten in the CSV to seal it off and run the '89 code. Simple and works very well. You need to either order or make the butten to seal the hole for the CSV and then a screw in fitting with o-ring for the back of the fuel rail. Both can be ordered from http://www.hotrodlane.cc/ The PROM would need a Moates.net adapter and then have someone write the '89 code in.

You could not run the '89 code OK to, it just might crank longer to start.

Or fix up the leak to.

Last edited by Aardwolf; May 12, 2007 at 11:27 AM.
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Old May 12, 2007 | 11:39 AM
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I just took the CSV off and the O ring is still on the fuel rail end and it looks to be in good shape. So now i'm wondering why it would be leaking so badly??? Is there another way I could seel it up?

Aardwolf, that sounds like an awful lot of trouble to go through just to eliminate that.
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Old May 12, 2007 | 12:09 PM
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It took hardly any time or cost. Isn't there a part that holds the CSV in? A clip? I can't remember, maybe it broke.
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Old May 12, 2007 | 12:17 PM
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On the fuel rail end, the pipe slides into the rail and there is a large metal ring that stops it from going in farther. The o ring sits in front of that. Behind it is the screw fitting. When I start the car, fuel leaks through the screw fitting which you can see in the pic.
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Old May 12, 2007 | 08:21 PM
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Are you talking about the rear of the fuel rail, where the pipe end goes into the rail, and the 104 oring seal? if the oring is pinched and the pipe is not totally seated it will leak., also, check to see if the pipe has a crack or fracture...
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Old May 12, 2007 | 09:29 PM
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I pulled it out this afternoon and there were no cracks or damage to the lines or rail itself which was my initial concerns as well. I bought some new O-rings and if that doesnt work then i'm just going to cap it and say the hell with it.
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Old May 13, 2007 | 02:28 PM
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Originally Posted by Aardwolf
On my '88 I hammered a butten in the CSV to seal it off and run the '89 code. Simple and works very well. You need to either order or make the butten to seal the hole for the CSV and then a screw in fitting with o-ring for the back of the fuel rail. Both can be ordered from http://www.hotrodlane.cc/ The PROM would need a Moates.net adapter and then have someone write the '89 code in.

You could not run the '89 code OK to, it just might crank longer to start.

Or fix up the leak to.
Swapping in an 89 mem-cal is a good idea that works for 88 auto trannies, but it is not a sure thing for an 85 like 4ever21 has. The 85' uses 24lb/hr injectors and the 88 & 89 use 22lb/hr injectors. If the cold start enrichment table constants are the same or very close then it might work, but he must have an auto. If he has a manual tranny, it definately will not work. The 85 manual tranny is a 4+3 and the 89 manual is a ZF 6-speed, so a LOT of run time parameters would be way off. For that same reason you can't use an 89 manual mem-cal with an 88 manual.

He could just eliminate the CSV and plug off the opening. It will take a bit more time to fire up when cold, but nothing significant.

At this point though, it sounds like the fuel rail side o-ring or the screw cap over it are not seating properly. Should be easier to fix than plugging off the whole CSV system. It may be that the screw cap threads are munged up. Might have to remove the cap and clean them up with a tap.
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