90 ZR1 Randomly Dies

[fastpace]

Did a bit of searching but wasn't seeing anything quite following my symptoms (many related to dieing at idle, cold or warm, or running rough).

Have a 1990, last drove it maybe 4 weeks ago and went to take it out today. Started right up like normal, pulled it out and left it idling while moving stuff around. Got back in the car and then it died at idle (hadn't fully warmed up yet), thought it was weird but it started right back up and ran smooth. Pulled out got a couple miles down the road and died again. Some cranking, then started again. Died about 6 times in a 2 miles loop getting it back home, each time happening after a shorter run time.

When running it runs very smooth, not noticeable issues. When it dies, the tach stays right around where it was, if you push gas it does/goes no where, and once you let off it dies and drops to 0. It doesn't fire right off, sometimes takes some cranking.

About 1500 miles ago I replaced to single fuel pump, new injectors, new spark plugs, and replaced some vacuum lines. Since then it's always run great. I will assume all other parts are original to the car.

Any common issues or quick things to check?
I'm thinking cam or crank sensor. Is there an ignition module? Any help is appreciated.

[Andy]

Maybe a new fuel filter?

[WARP TEN]

Or fuel pumps? --Bob

[tiegsd]

I suppose I'd start with pulling codes.

[fastpace]

Maybe a new fuel filter?

Installed a new wix filter at same time as fuel pump, so less than 2k miles. Also brand new pump sock and hanger assembly.

I'll still plan to add fuel pressure monitoring to my trouble shooting list.

Or fuel pumps? --Bob

Has a new single Walboro.

I suppose I'd start with pulling codes.

After restarting the car there was no CEL present.

[aafc]

I had this same problem last year on way to National Corvette museum. On I-75 north in Georgia. Cruising along at 75 mph fuel pressure drops, pull over called AAA for tow. After setting for awhile at auto shop I was able to restart car. At this point I decided to go back home ( The Villages ). Car stalled 3 more times by the time I got home.
After checking I was able to isolate the cause of the failure. Fuel pump
relay# 1 would lose power at times.
Using the 8A section page 8A-22-6. That relay controls fuel pump relay #2
Replace fuel pump relay #1( 20 plus years old ) and car started right up.
No guarantee that this might be your problem, but it gives you something
to look at.
Hope this may help you.
John
1990 white/black # 2546
one of a few 4l8OE eq ZR-1's

[secondchance]

About 1500 miles ago I replaced to single fuel pump, new injectors, new spark plugs, and replaced some vacuum lines

When you say single fuel pump, you mean modified pump running on one pump?

[fastpace]

I had this same problem last year on way to National Corvette museum. On I-75 north in Georgia. Cruising along at 75 mph fuel pressure drops, pull over called AAA for tow. After setting for awhile at auto shop I was able to restart car. At this point I decided to go back home ( The Villages ). Car stalled 3 more times by the time I got home.
After checking I was able to isolate the cause of the failure. Fuel pump
relay# 1 would lose power at times.
Using the 8A section page 8A-22-6. That relay controls fuel pump relay #2
Replace fuel pump relay #1( 20 plus years old ) and car started right up.
No guarantee that this might be your problem, but it gives you something
to look at.
Hope this may help you.
John
1990 white/black # 2546
one of a few 4l8OE eq ZR-1's

This is a very interesting thought and would be a pretty easy check, thanks!

About 1500 miles ago I replaced to single fuel pump, new injectors, new spark plugs, and replaced some vacuum lines

When you say single fuel pump, you mean modified pump running on one pump?

I used the Flyman pump assembly, you end up removing/isolating the 2nd pump wiring.

https://www.zr1.net/forum/showthread.php?t=33899

[secondchance]

I used the Flyman pump assembly, you end up removing/isolating the 2nd pump wiring.

Just wanted to make sure that you had a factory two pump set up and replaced one pump or had a new single pump set up. OEM dual pump set up will run fine until magic coolant temp and stall out if the primary pump has gone bad Sind secondary pump turns off. We can rule this one out.

[mlipmd]

Another suggestion - You didn't run out of gas did you?
Happened to me once when the gauge read about 1/8-1/4 full and the car died at a stop sign but started right up again and I drove home for about 5 miles with no problem. I was looking at the gauge but it turned out the tank was empty, and after filling it up with gas it never happened again. Added a bottle of Techron a couple of times with fill-ups to clean off the gauge and it seems more accurate now. Or you can remove the pump and clean off the gauge yourself. Being aware of your trip mileage in between fill-ups is another way to avoid this. May not be your problem, but just another thought.

[fastpace]

Another suggestion - You didn't run out of gas did you?
Happened to me once when the gauge read about 1/8-1/4 full and the car died at a stop sign but started right up again and I drove home for about 5 miles with no problem. I was looking at the gauge but it turned out the tank was empty, and after filling it up with gas it never happened again. Added a bottle of Techron a couple of times with fill-ups to clean off the gauge and it seems more accurate now. Or you can remove the pump and clean off the gauge yourself. Being aware of your trip mileage in between fill-ups is another way to avoid this. May not be your problem, but just another thought.

Another good and unique suggestion. I had just below half a tank because I remember thinking I was about to be 15 mins early for where I was going and thinking I might just stop to top off to waste time. My gauge is quite accurate and I installed a new sending unit with the pump replacement.

I'll be back home and have some time to play with it this weekend so will have the chance to test the relay and will also hook up a few pressure gauge while it idles.

[-=Jeff=-]

Randomly dying with not codes. I would check the crank sensor. They tend to crack then get oil and leak and cause issues.

[viper107]

did you check for codes OR COMMUNICATION with ecm, is the ecm communicating with all sensors?

[Young1]

I agree with Jeff. Also mine randomly died before the camshaft sensor code appeared. Some rough running and firing happened before the crankshaft sensor died also. I think these two sensors time out from age.

[Bristowb1]

Any Updates?

[fastpace]

Any Updates?

Once it finally cooled down in Houston, I got the chance to troubleshoot it some. I quickly saw I wasn't getting consistent fuel pressure. Tracing the electrical, I ended up finding that one of the pins for the fuel pump connecting to the bulkhead on the inside of the sending unit had backed out of the connector. I converted to a single pump not too long ago and I guess the pin wasn't fully seated in the connector or the tang inside the connector was damaged. It was making intermittent contact and then eventually no contact. I went ahead and replaced the connector body and it's been trouble free for a couple months and several hundred miles now.

[WARP TEN]

Once it finally cooled down in Houston, I got the chance to troubleshoot it some. I quickly saw I wasn't getting consistent fuel pressure. Tracing the electrical, I ended up finding that one of the pins for the fuel pump connecting to the bulkhead on the inside of the sending unit had backed out of the connector. I converted to a single pump not too long ago and I guess the pin wasn't fully seated in the connector or the tang inside the connector was damaged. It was making intermittent contact and then eventually no contact. I went ahead and replaced the connector body and it's been trouble free for a couple months and several hundred miles now.

Glad you figured it out! --Bob

[tiegsd]

Once it finally cooled down in Houston, I got the chance to troubleshoot it some. I quickly saw I wasn't getting consistent fuel pressure. Tracing the electrical, I ended up finding that one of the pins for the fuel pump connecting to the bulkhead on the inside of the sending unit had backed out of the connector. I converted to a single pump not too long ago and I guess the pin wasn't fully seated in the connector or the tang inside the connector was damaged. It was making intermittent contact and then eventually no contact. I went ahead and replaced the connector body and it's been trouble free for a couple months and several hundred miles now.


Good news. Will put that in the bag of tricks.