Hello everyone!
I am having an issue that recently arose while driving my car. A while back it was a super hot day here in Canada...I was driving and everything was good, I decided to pull over and check my postal box. I left the car running and by the time I got back to my car the engine had stalled out. I thought that was odd but when I tried to restart my car it wouldn't run. I tried multiple times an nothing. It would only turn over.
It seemed like it was flooded. I put the pedal to the floor to clear flood mode. It bogged and hesitated and almost wanted to run. I was close to home and didn't want to leave my car there so I thought maybe I could disconnect the fuel pump relay to help clear the flood. After a bit from turning over, the engine started up and it was running somewhat decent, almost normal. So I drove it like that for a few blocks back to my house.

Here is some background on my car/engine combo...
1983 Z28 with an 88 TPI 355cu. and T56 tranny / 10bolt 3.73 gears
Motor is moddified with Vortec heads, SLP Runners/Headers
32lb injectors, 52mm Throttle Body, Corvette high volume oil pump
1227165 ECM, APYPWB.bin
Comp Cam XR276HR-12

I only have a basic tune on the chip because I'm still learning but the car is very drivable. I had prom setting issues initially but the only major issue was with the MAF sensor detecting more airflow because of the cam. I have changed that setting in the chip because I kept getting a SES light for high maf and it drove like crap when the code was set. I do know that the cam overlap is causing the O2 to see oxygen in the exhaust stream which will add more fuel. Maybe that's part of my issue?

I'm not sure if I should have this in the prom section but I believe It's related to how the TPI starts and runs with the fuel pump relay or oil pressure switch.

My questions are... how would it run with fuel pump relay disconnected? Was there enough oil pressure during cranking and the switch allowed it to run? What needs to be replaced or changed?

This situation also happened at the gas station today as well but I shut the car off to fill up. Tried to restart and it bogged and stalled right away. I did the same thing with disconnecting the relay to get it to start then plugged the fuel pump relay back in and drove home.
I'm also wondering if the super hot day out when it originally happened had something to do with it? I have no hood installed to make it easier to work on but the sun is blasting the relays by the brake booster along with engine heat of unwrapped headers.

Thanks guys, I'm scratching my head here!

 

When it doesn't start, did you check for good strong spark? It seems you have fuel if you can force it to run, but did you check fuel pressure under the no start or forced run condition? I had something like this pop up in my 90 tpi car and after hrs of FP/OPS circuit troubleshooting I had no spark.... Could your icm be going? Just my

 

I had a similar problem on my Camaro years ago. It was the ICM. A bad ICM will cause the car to be hard to start. The ICM basically controls timing when starting and in limp home mode. After the motor is running the ecm takes over control of the distributor.

Good luck

 

I too suspect the ICM. The reference pulses to keep the fuel pump running come from the ICM. If it is intermittent, or only causing a problem when hot (typical). This could be a symptom of fuel ad no spark until it cools enough. Then why you are moving with no hood, things get cooler until you stop and idle. I remember 20 years or so ago you could get ICMs tested, but I don't know if part stores do that any longer.

FWIW, your car probably runs like crap with the code on because nothing in the nAlpha tables have been adjusted for your setup.

 

So, if the FP relay was on, no issue, as pressure builds up then excess fuel would be returned to the tank (assuming you put the TPI set up in correctly). The OP switch will close and give power to the FP. So if FP relay is disconnected, and the OP switch give FP power, it would still be the same as the FP relay being on, in effect the OP switch just bypasses the relay.

So assuming all wiring/etc was retrofitted as-factory, I don't think the issue is with the relay...that said, might be some odd coil short in it that is drawing power to the ignition, not real likely, but for 20 bucks US you can swap in a new one.