My 85 vette has been having this flooding problem going on two years now. When I start the car it will hardly run it pours out black smoke until it stalls. If you leave it for a while and come back it mite start and run just fine the next time(maybe), it can do this hot or cold, I've had it flood after driving it for hours then after shutting it down and restarting again, it never screwes up after its running. Last summer I took the car to MO. and back to NH about
3500 miles and it never acted up once, two days later it did it again, it's getting worse because it can't get through one day anymore without it acting up. The car has had a new MAF sensor twice also a new fuel pump, coolant temp sensor and cold start switch. I've been told maybe its a bad cold start valve but when I went to the Chevy parts counter they said they don't list any part like that. I've really had enough with this any help someone can offer would be great I figure someone out there has had to have the same problem!!! Thanks
:banghead:
85 vette flooding: Update
Sence I furst posted this problum I've done some things 1-put in new o2 sensor, Also new fuel filter than I checked fuel pressure and all checks came out good it takes a long time for the fuel pressure to drop so theres not any fuel leaking at the injectors. When car is running, its running about 37 psi the one thing I wasn't sure about was if I was supposed to unplug the vacuum hose to the fuel pressure regulator for the test? It runs 37 psi when its running good and when its flooding. rons85 said "It might be just that the system is going really rich right away when it starts up, not that it's getting fuel into it when it sits" I think thats right, I think the problem is an electrical one but what?? I also put in a new coil. Any thoughts anyone thanks Cruiser



[Modified by cruiser1600, 9:38 PM 5/2/2004]

 

Maybe you have a leaking injector(s). Send them to Rich at Cruzin' Performance for cleaning and flow testing.
www.cruzinperformance.com

 

You don't mention replacing the O2 sensor. It could also be due in part to a bad O2 sensor, but it's probably leaky injectors. Once the car reaches operating temp it goes into closed loop and the ECM uses the readings from the O2 sensor to recalibrate fuel mixture on the fly. If the O2 sensor is going bad it will slowly throw off the ECM's ability to adjust fuel mixture. Since you made a long trip with good results, the O2 sensor is probably OK. If it is more than 5 years old, you might consider having it replaced just in case. Should be about $25 and you can do it yourself or have any decent oil change facility do it for you.

If it is your injectors then it could be any one of the 9 fuel injectors installed on 85-88 C4s. As you found out, the 9th injector or the Cold Start Valve (CSV) is not available new anywhere. You will need to have a rebuilt one. I agree with the previous post. Pull all 9 and send them to Rich to be rebuilt. he does a very good job and it will make a HUGE difference. Problem solved.

You could also get a CSV from the junkyard, send it to Rich for rebuilding, and order new Ford Motorsport 24# units for the other 8 injetors. That way you have all new injectors of a quality brand and a properly working CSV while not having to have the car out of service for more than the day it takes to do the swap. I believe that the 85s came with 24# injectors as opposed to 22# units for later C4 Vettes. Since the FMS 24# units work real well in the cars that came with 22# units, they should be perfect in your 85. Rich may be able to get you a good price on the FMS injectors. If not, Summit racing http://www.summitracing.com always has a competitive price on them.

 

Thanks to Bluevette85 & Mike_88Z51 for your responses. I found the information that you both gave useful and I am going to try and change the 02 Sensor first because it's cheap, but, it sounds like you are probably right about the injectors and that will be the next thing that I do, Thanks again for your help. -DUDE-

:iagree:

 

Actually - it isn't that hard to diagnose leaking injectors. Put a pressure gage on it, turn the key on (watch the pressure come up). When the pump shuts off (should run for about 2 sec.) turn the key off and watch the gage - the pressure should stay up and constant. It Will slowly leak down, but should take several minutes. If it goes down more quickly than that clamp off the fuel return (first) and supply lines back at the tank and see if that changes things. There is a proceedure in the shop manual for doing all of this, but that's the gist of it. Next time it wants to start up flooded pull a couple of plugs out of it and see how/if they are actually wet with fuel, that should tell if you have raw gas leaking into the manifold. It might be just that the system is going really rich right away when it starts up, not that it's getting fuel into it when it sits. BTW several things can make it go rich like that after sitting - high fuel pressure (regulator bad or sticking), poor spark (coil problem?), bad MAF, etc. Sounds to me like you have something that doesn't always "turn on" right after it's sat not running. I'd start by verifying the fuel pressure, then put a scan tool on it and see what the sensor readings are when it acts up...


[Modified by rons85, 5:13 PM 4/27/2004]

 

Thanks rons85 for more useful info I've got some good things to start with now, thanks again DUDE :thumbs:

 

One thing I didn't mention before about when its flooding is that if I unplug the MAF sensor it will idle fine and after it warms up about 20 mins. you can drive it down the road just fine with the MAF unpluged: Cruiser1600