plsony

Any one with any thoughts?

CFI-EFI

You seem pretty well prepared to deal with this on your own. When the injectors quit, how is the fuel pressure? The two main things that stop the fuel from coming out of the injectors, are supply to the injectors and the injectors not firing.

RACE ON!!!

mikey whipreck

It seems they stop? Are the injectors proper resistance (I believe 9 - 13 ohms, but I'm not sure)? Could it be an ECM issue? sounds like an electrical problem iwth the injectors to me... andyou don't mention looking for anything like that...

but this is just a stab...

MaxLean

Do you have a scan tool? If so, monitor the relevant items when the problem occurs. My gut feeling is ignition module (I've seen them fail where they will still fire the coil, but not send an rpm signal to the ecm) or ecm. This is of course barring a wiring or ground problem which I'm sure you've already inspected. Good luck!
Scott

plsony

So far I have replaced the fuel pump and the fuel filter. I always get good pressure even when the injectors wont fire. I have also replaced the ecm but I had to use the chip from the previous ecm. I do have an electrical issue with the cooling fan. I had to resort to wiring it up straight from the battery after changing the relay and both sensors. In the winter and spring everything runs well. the last couple of years after changing a few components I thought I had licked it but just when I think I got it the problem reoccurs. I dont know if it is just my imagination but the last two years it died on July 3rd. The first year I was coming home from the fireworks and last year it died in the late afternoon just before leaving to see the fireworks. It sounds crazy but it is true. I have read some info on the oil pressure switch somehow controlling the injectors. I looked through a wiring diagram but something just does not seem right. After all the repair manuals only seem to cover 85 and up and my oil pressue stays constant between 60 and 85 on my read out. Any other suggestions? Even crazy ones will be considered at this point!

plsony

Anyone have any thoughts on possibly the throlle position sensor causing an issue?

MaxLean

The only control that the oil pressure switch has on the fuel system is that it is a suplemental control for the fuel pump. Normally the ecm controls the relay for the fuel pump, but the oil pressure switch is wired in parallel such that the pump will also run when oil pressure is present. As for the TPS, that's easy enough to find out by measuring the voltage on the output line when the problem occurs. Normal TPS voltage with the throtle closed should be around .5v. You didn't answer my question of if you have access to a scan tool.....


When the engine dies (and presumably doesn't restart), do you have fuel pressure????

siggy_freud

Does it start at all during those months without pouring fuel down the intake?

Could it possibly be vapor lock? I would guess that or either too much electrical resistance caused by heat.

Dont think of dates as they mean nothing. Think about what changes between the months it does run and what doesn't. Seeing as its now January it should be running fine. That gives you a few months to figure things out .

FD2BLK

If it's heat related you could use a hair drier and try to warm up some of the sensors and see if you can duplicate the problem

VetNutJim

Go to where the fuel pump receives the +12 volts and ground at the top of the tank. Remove,clean and reinstall the connections for the pump power.

The fuel pump RELAY is on the left front inner fender well.
REPLACE that relay. Oh put some of that diaelectric grease on the relay connections to keep it from coroding.

There seems to be an intermittent connection somewhere in the fuel pump supply.

Oh, get yourself a FP gauge so you can check the FP when the engine quits running.

THis WILL tell you if the problem is on the pump electrical portion or in the ignition portion of your engine control system.
Step ONE should be to check fuel pressure as so many above have reccomended.

plsony

During the installation of the fuel pump all new connectors were used. Since I replaced the pump before July it ran well but then reoccured. The only way it will start is to prime the engine. I do have a fuel pressure regulator that I ran at hte pump and after the fuel filter but I need to make an adapter to attach it to the throttle body as it is a TBI engine. I have already replaced the pump switch in the engine compartment. In all my attempts I never kept track of where or not I pushed the gas pedal after pour in gas. It is now Janurary and it is running fine. I thought maybe somehow humidity has something to do with it but it did get warm and humid here before July 4th. I would take it to a mechanic but my fear is that it will not reproduce the issue or I will spend a fortune and find out too late that the problem still exists. Thanks for your ideas. I am still listening to all ideas if anyone has other ideas or if someone knows someone that had a similiar expirence. The other issues as I mentioned before about the cooling fan and also the air conditioner does not work or spin. I dont know if it somehow ties into the ignition or fuel injection. I do have a scan tool but it is a cheap one and does not return any codes. Even using the paper clip method on the ADL does not show any codes.

Jloshotz

I have seen this and it is a real world problem. It did not happen on my vette, but on another GM product (95 S-10 Blazer) It stumped alot of mechanics before it fell into my hands, and was a very intermittent problem. Re-check the connections from the pump harness to the sending plate (inside tank) and note if one or more are discolored. (Caused by high resistance) I hate to make your post seem redundant, but this is easily overlooked. Clean them well and get a new connector harness if necessary. I did this on the blazer about 18,000 miles ago and problem has not re-occurred. My appologies if you have been through this already.....

plsony

Thanks guys. I now have a few more angles to try. I will keep you posted but results wont be know atleast well into July. Thanks

smacko

You obviously should've bought the optioned Vette with RPO code '084AD'; the one that WILL run from August to December! hehehe
Just kidding, sorry to be a pain.

If all else fails use the opportunity to upgrade to a later model by selling the 84 (During the earlier months of the year!)