85 vette flooding

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  #1  
Old 05-10-03, 01:11 PM
64n85vette
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Angry 85 vette flooding

1985 corvette, 5.7 350 l98, tuned port injection, 4+3 Manual trans, 95,000 miles

I'm at the end of my rope. I bought the car in pieces and put it to gether, at this time there are no trouble codes and most of the sensors are new. The car smoked a little and I originally thought it might have been valve seals so I changed them and it still smoked then I thougt maybe rings but the car started flooding and I realized that the smoke smelled like gas. It will not run unless I disconnect the fuel pump then it runs for five minutes and dies if I reconnect the pump. I've since replaced the fuel pressure regulator, blew out the return line, listened to the injectors (they all sound like they are opening and closing), Checked the cold start valve (did not appear to leak)and fuel presure is optimal. I don't know what else to do.

Help me please.........
 
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  #2  
Old 05-10-03, 01:47 PM
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That's a tough one. If you bought the car in pieces, how do you know you have the right pieces? If, for example, the injectors are too big you're going to have these issues. If you're sure everything is correct from a fuel perspective, check air and electrical. I would think that if it were running rich enough to smoke that the ECM would throw a code. I dunno if that car is MAP or MAF, but if it is MAF check your MAF sensor. If MAP, check the MAP sensor.

I had a Mustang GT that was loading up really bad - smoking and cats glowing red hot. I checked EVERYTHING air and fuel related. Turned out to be a shorted plug wire. One of the cylinders was firing intermittently. When it didn't fire, raw fuel was dumped into the exhaust. Believe it or not, it really didn't have an obvious miss. I pulled wires one at a time until I pulled one that made no difference - that was the dead one.

As an aside, if you're sure it's running that rich you should stop driving it. Washing the cylinders down with fuel will wipe the motor out in a hurry (gasoline is a crappy lubricant).

Jim
 
  #3  
Old 05-10-03, 03:03 PM
64n85vette
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Thank you for responding.
It is a maf system and the sensor is good(I had modified it as well). It has a new engine temp sesor, oxygen sensor, catylitic convertor, filters, plugs and wires.
The injection system was one of the only things intact when I bought it and it appears to be stock.
I had the car running decent aside from a little smoke, but something happened. Now I can't drive it, it won't run with the fuel pump active. I can't think of anything else.
 
  #4  
Old 05-10-03, 03:45 PM
benbyit
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hey, i have a 85 did the same thing and i tried everything including crying. turned out to be an o-ring on the bottom of one of the injectors. was letting those cylinders fill with fuel. such a small thing, but almost impossible to find because it looked exactly like the new one.(showed no damage or wear) i could get it to run if i disconnected the fuel suppy, not as long as you but roughly about a min., but the min i reconnected, stalled. probably be a miracle if thats your problem, but ya never know. good luck, benbyit
 
  #5  
Old 05-10-03, 04:13 PM
64n85vette
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Thank you for your insight benbyit.

I had thought that an injector o-ring malfunction would be noticeable by a gas leak. Is this not correct,because that would definitely be a possibility considering it's milage. I think I may just replace them anyway. I will get on the computer tonight and let you know how it went.

Thanks 64n85vette
 
  #6  
Old 05-11-03, 11:56 AM
Joe_F
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Not to sound like a hardass, but whatever you've budgeted for fixing this Vette, double it---it's easily going to cost alot.

Assume everything done before you is suspect, chances are it is. Corvettes are usually menageries of parts because on a Chevy small block, just about everything "Fits".

Go back to a correct, stock MAF. If that is off the mark, the car WILL flood and run terrible. This year Vette makes low HP, a modded MAF won't net you much but more problems.

Check all the fuel injectors electrically for the correct ohm value to make sure one isn't shorted--those early Bosch injectors were prone to problems.

Install a new set of plugs. What do they look like when you have this problem?

How did you check the fuel pressure?
 
  #7  
Old 05-11-03, 06:49 PM
64n85vette
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Well the injector upper and lower o-rings are now new and the problem lingers on.

The only modification to the maf sensor is the lack of screens and I don't think it's causing the problem but it may be contibuting.
The injectors are between 16.5 and 16.8 ohms and do not appear to be stuck open. I measured the fuel pressure with a pressure gauge on the fuel rail. It reads 25 lbs with the key and standing after turning it off, and 40 lbs while cranking and drops
to around 25 lbs after turning off.

The project was going pretty good till I came upon this setback.
 
  #8  
Old 05-12-03, 06:17 AM
Joe_F
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Go back to a stock MAF WITH the screen. Let's see what we have there.
 
  #9  
Old 05-13-03, 09:00 AM
64n85vette
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Well I have a stock maf sensor in place and don't have any change in the situation where do we go from here?
What about emissions control, or a sensor that could malfunction without triggering a trouble code. Bad gas?
Would leaking rings cause this? I checked the cylinder compression and they jump quick, hold and seem consistant. The plugs are new and I cleaned them without any change. When the plugs foul they get soaked with gas thats slightly dirty (seems normal).
 
  #10  
Old 05-13-03, 09:38 AM
Joe_F
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What do the plugs look like when you remove them? Is any one cylinder worse than the next?
 
  #11  
Old 05-13-03, 10:00 AM
64n85vette
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The plugs all look the same, In good condition but wet.
 
  #12  
Old 05-13-03, 10:39 AM
Joe_F
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Have you checked all of the ECM grounds and had the ECM checked out itself? I assume you have the GM service manual and know where all the grounds are and what to check.

(If you don't have the GM manual, STOP here and go buy one! It's necessary for this type of work/restoration).

With that being said, any parts store can send the ECM out for testing throught their electronics supplier.
 
  #13  
Old 05-13-03, 11:40 AM
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Originally posted by 64n85vette
The plugs all look the same, In good condition but wet.
How old is the gas? If it's more than 6 months old, top it off with fresh gas. Or better yet drain the tank and put fresh gas in it.

Since it's not throwing a code, it obviously doesn't think anything is wrong. I'd think it would at least throw a code saying that the O2 sensor is always reporting a rich condition.

It really sounds like a case of mis-matched parts. You're sure you have the right ECM, CALPAK, chip, etc.? Correct coil pack and firing order? Right sized injectors? Someone didn't put bigger injectors in it somewhere along the line did they? If so, the injector pulsewidth the ECM is using corresponds to smaller injectors.

If you had a HUUUUUGGGGE vacuum leak (or were getting air anywhere downstream of the MAF) then the O2 sensor would always show lean (again, should throw a code) and would call for more fuel thus creating a rich condition.

Even if the check engine light isn't on, try pulling the codes anyway - maybe the check engine light isn't working?

Keep us updated....

Jim
 
  #14  
Old 05-13-03, 11:45 AM
Joe_F
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To know if you have the right ECM, you'll have to jot down all of the codes on the service parts ID label (should be on the spare tire carrier on this year Vette).

Take the whole cover with you to the dealer. Ask them to look up both the PROM and the ECM. They will likely need to refer to the codes on that label. That tells the rear end ratio, emissions package, tranny type, etc. That is usually required in the parts book to see if you have the right thing or not.

This of course assumes that the cover you take out of the back is the correct one from the vehicle and it really is a 1985 Vette and has the electronics and powertrain for one .
 
  #15  
Old 05-13-03, 11:49 AM
64n85vette
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Thank you guys for your help, I'm going to take all the advice.
Going over everything with a fine toothed comb is my m.o. simply because I won't feel right untill I Know everything is in good working condition, if there isn't a problem with something than I one step closer to completion.
I get back to when I know something, Thanks again
 
  #16  
Old 05-17-03, 06:09 PM
64n85vette
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New development!

I have fuel in my oil, this does not look good.

What are the possibilities?
 
  #17  
Old 05-17-03, 07:48 PM
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Originally posted by 64n85vette
New development!

I have fuel in my oil, this does not look good.

What are the possibilities?
That's just a byproduct of the car running really rich. Piston rings are good at keeping crankcase oil out of the combustion chambers but not at keeping the thinner gasoline from the combustion chambers out of the oil. That's why I said before that you should avoid running it - you're watering down your oil and lubricating your pistons with fuel. Fuel is not a good lubricant.

I wouldn't worry about it - fix the rich condition and the oil will be okay (once you change it, of course).

Jim
 
  #18  
Old 05-18-03, 05:31 AM
Joe_F
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I agree. Change your oil and filter frequently as you navigate the problem through so as not to damage anything.
 
  #19  
Old 05-18-03, 08:36 PM
64n85vette
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I think the mystery is solved.

The computer is definitely damaged.
What could I have done to cause this?
 
  #20  
Old 05-19-03, 01:39 AM
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Originally posted by 64n85vette
I think the mystery is solved.

The computer is definitely damaged.
What could I have done to cause this?
Wow. I've never seen an ECM do that. I don't know a lot about what actual loads are imposed upon the ECM itself, but clearly there is either a dead short somewhere, a part that's drawing a lot more juice than intended, or you're sending voltage to a part of the ECM not designed for it (crossed wires somewhere). You may eventually wind up tracing each wire out of the ECM to its ultimate destination.

Again, make sure that everything under the hood that has an electrical connector (sensors, injectors, etc.) has the correct part number.

Cross-reference the P/N on the ECM and find out what other cars shared it. Then go to your local salvage yard and grab a couple. My local salvage yard sells them for $5. You may go through a few by the time you sort this out.

You're gainin' on it, though......

Jim
 
  #21  
Old 05-19-03, 03:42 AM
Joe_F
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As I said in a prior post, the ECM can be sent out for checking BEFORE damning it as bad! It's an expensive mistake if you are wrong.

If the unit is bad, THAT same one can be repaired easily by an auto parts store's electronics supplier. However, as mentioned all grounds and inputs must be sound. Assume they are not and that everything is screwed up in this "hack" job.

Go to the dealer with the codes and verify which ECM you should have. Don't have the wrong one rebuilt!!!
 
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