injectors shutting down...help!

[drkjr]

Hi all... I've been perusing this forum for a while, but this is my first time actually writing....i need help! Actually my mechanic does...bastard's had my 1991 coupe for almost 2 weeks, and can't seem to find the problem...trial and error method, and it's costing me more and more dough! Here's the problem...

My car normally starts fine, but once in a while, usually on cold mornings, it'll just turn over, but sound like it's getting no fuel, won't kick over. If i wait between 10 and 30 minutes, it'll start... no big deal...that's just the beginning... the BIGGER problem is, when i am driving along, could be doing 50 mph, could be doing 20 (could be doing 100 !)...the car will just die... stall...i am now coasting... Service Engine Soon light comes on, once in a while the SYS will flash, but those 2 warnings are just temporary, they go away when i restart the car, which 95% of the time i can do while coasting off to the side of the road. Once in a while i have to pull over, wait 5 or 15 minutes, and then head on my way.

I'd also had a problem with my interior lights popping on sporatically, while i am driving, but my mechanic changed the switch in driver's door, and that fixed that problem. We both thought that that was what was causing the other problem, that it was security related, but no such luck.

He's changed the ignition module, that didn't work. He checked the fuel pump and IAC valve, he said both were good, that the car was getting good pressure. He's at a loss, and I am ****ed, it's my only car! He says that something is causing the injectors to shut down. Does anybody have any suggestions i can give him? Any help would be greatly appreciated! Thanks!

 

[Daryllawman]

On my 88, I had a problem like that.......It turned out to be in my sending unit for the fuel pump. It was burned at the connection end . Sometimes it would make contact and the car would run and when it wasnot making a conection the car would just die, no warning....I would have to coast to the shoulder of the road. The part I am talking about is when you raise the lid for the gas cap, there are four bolts that hold the sending unit and fuel pump together. As soon as I took these four bolts out and lifted it out, there it was....Burned at the connection......Don't know if this is your problem, but its worth a look. Good luck........:TALK

 

[silver 80]

If your service engine light came on did he down load the trouble code? might be a good place to start.
tom

 

[drkjr]

yeah, he tried that, but no codes were stored, the light only comes on as the car is stalling out, and doesn't stay on past the stall out, It doesn't seem like it is registering the problem. He said he is going to re-check it again, i just called him, but he was sure there were no codes stored.

thanks for the replies / suggestions!

 

[silver 80]

can he get it started?

 

[vigman]

Ahhh Intermittant problems

The FUN ones... ok I agree with Daryllawman there is a white connector ( on some models ) which is an RF ( radio frequency) supressor.. inside the fuel tank
. that is the positive feed for the actual fuel pump.. it opens up after time.

BUT I would inspect/ check the fuel pump relay FIRST!

2nd behind the distrib there is a 4 pin connector which is the connection point to the Knock sensor/timing retard package. Make sure the connection is clean & tight. It resides twds the firewall below the distrib.

3rd.. I would check all the grounds around the engine compartment & the engine frame ground.. see my post .. Getting Grounded.


Vig~

 

[drkjr]

Yeah, the car starts right up, 98 % of the time, and will run fine for a while, usually starts acting up after 30 - 45 min. or so...thanks again guys, i will pass on all of the suggestions to him.

 

[sanman]

ask him to check the egr valve,that will send the check engine
light to come on.your description of the problem sounds just like
the problem we had with our caddy sts,after 500 bucks to take the gas tank down and replace the fuel pump and filters it was
still dieing out at all speeds,after about 10-15mins it would start
back up and it was fine. finally a real mechanic found a bad egr
and havent had a problem since. i dont know if thats the problem but its worth checkin into......hey i got a new fuel pump:crazy

 

[drkjr]

will have him check it tomorrow, i'll keep ya posted... thanks!

 

[ArtZR1991]

I agree it sounds like the pump. This is a common problem, and a specific failure mode (no codes) on ZR1's which use two pumps, one for enrichment (full throttle and warm up). My main supply pump failed and when the enrichment pump shut of after warm up, the engine would simply turn off. After a short time, it would start, and then after warm up, would stop again. I got the replacement from NAPA.

If the pump has an intermittent voltage supply problem it would do that. It is also simple and cheap. The pump can be replaced by removing the filler assembly and pulling it out; the pump is attached. In fact, that is the actual procedure for the ZR1. The pump is cheap ($50?) and the labor is an hour or less.

Without knowing more, I'd go there first.

Best of luck!

 

[drkjr]

my mechanic checked the fuel pump, and everything relted to it, he said it was fine, i get good pressure, no problems there. I'm gonna tell him about the egr valve this morning... hopefully that's it, because if not, he seems to think it's gonna get mighty expensive!

 

[ArtZR1991]

I had read that you had already checked the pump. I was suggesting that you "keep it on the plate" because of the close symptom match, the lack of a code, and the intermittent nature of the problem.

And frankly, because it is easy.

Now we're all curious. Let us know what you find.

Regards,

 

[drkjr]

ok, he says it is not the EGR valve. He says it is definitely something electrical, that is just causing the injectors to shut down randomly. He changed the BCM (?) about 6 months ago, i guess that's one of the computers behind the dash. Now he thinks it might be the ECM (computer under the hood?) going bad. Does anyone know how much that would cost to fix/replace? I've already paid him over $400, without getting fixed, (but i do have a new ignition control module out of it, and switch in my door!) I hate to have him keep "guessing" at my expense! Is an ECM expensive? Thanks for all the help and suggestions.
Doug

 

[vigman]

Ok ...look

IF the ecm tanked.. you would get an error code....


Again check the following

1) Inspect fuel pump relay & socket

2) Replace pump ( for good measure ) pumps aren't much good past 80,000.

3) Inspect/ tighten & clean grounds where indicated by visual inspection.

4) Your injectors are BATCH fire.. so it's NOT just 1 injector failing the 8 are split into two banks of 4.. this makes me LEERY of the mechanic's competancy ( Replace fuel filter and or mechanic )

5) I assume the car NEVER fails in his shop?
Which would indicate mechanical/electrical failure.. from a bump or jar to the vehicle.
Inspect the fusible links.

6) Remove, clean & reseat the ECM connections.

Vig~

 

[drkjr]

Actually, believe it or not, he is usually very competent, and is pretty much a corvette expert, he came highly recommended by a lot of people in my area. He is just so damn busy that he can't find the time to devote to troubleshooting this problem, it happens sporatically, and only once so far for him, so it's hard for him to really grasp what happens to me when i am driving it for a while, it usually takes a half hour or more for the problem to start. He said to call him back around noon, so then i will pass along your suggestions to him....thanks!

 

[LOU96LT4]

Very unlikely, but I had a similiar problem, however not on a corvette. I would be driving along, and suddenly the car would shut down. Very sporadic. Pull over, restart and go on my way.

It turned out to be an electrical problem with the wires coming through the firewall. There was not sufficient insulaion, and a charge would build up and short out the system. Once it discharged it was like nothing was wrong, and the car wwould run fine.

Good luck.

 

[ArtZR1991]

I agree with above, and I can certainly sympathize with how you feel. As to costs, the computer is not that bad, given what it does. I replaced the one in my ZR1 to correct an idle issue, and it was $180. But as I think about it, the mechanic had to hook up a laptop and use some GM software to catch it while driving (everyone says that was done just so he could drive the ZR1 all day!), because no codes were being set.

My fuel pump issue was different, and I did it myself, after a tip from people on the forum. Cost was $30-50 complete, and I did the work. I still have a hunch that that is where your issue is.

Obviously we don't know spit, because you are with the car, and we are not. My only suggestion is that if you are going to do "trial and error", a terribly frustrating way to do it, but often the only way, then I suggest the pump as a start because it is easy and cheap, and its symptoms match dead-on, especially the intermittent part. If you go this way, be sure to follow the above advice about grounds and connections as well. Grounds are a big issue on the Corvette, because the car is fiberglass, and in particular, fuel and water will corrode the ground over time.

Again, best of luck, and keep us posted.

Regards,

 

[Tight Pie]

just a shot in the dark

is there a fuel cutoff based on oil pressure? if for some reason you have an electrical short or open coming from the oil pressure sending unit causing your lights to flicker, and telling your fuel system you dont have any oil pressure, your engine would die. and the problem clears up as the connection regains contact. just a thought.

 

[SR94]

I had a similar problem on my daily driver (a chrysler). It would sputter and/or just die at random times. Turned out to be a flaky crankshaft position sensor. Chrysler ties this signal into the fuel pump relay - makes sense when you think about it. I don't know if the corvette uses a similar setup, but it might be worth looking into.

good luck

PS I see your in NY. If your near NYC, I can recommend a really good vette mechanic just over the GW Bridge in NJ.

Steve

 

[drkjr]

Hi Vigman...

Regarding your last post on this subject, my mechanic says that if the ECM is bad, it wouldn't give a code, because it can't diagnose itself. Does that sound right to you (or anybody?) I only ask because the other day, you'd said it would give a code, and he really seems to think that's what the problem is, even though it isn't spitting out any codes at all. He ordered a new one, supposed to come in tuesday, but i am hesitant on letting him put it in as another guess. i'm really thinking about having him just change the damn fuel pump and fuel filter first, since everyone seems to say that that is fairly cheap. i guess it couldn't hurt, the car's pushing 75k miles (although it only reads 16k on the odometer...changing out that BCM ccomputer reset me to zero last year!) so it'll probably need a new fuel pump soon anyway.

thanks again everyone