Intermittent Cut Out at Idle and Cruising

[jskarateka]

Cut out on me once last fall while cruising about 35 mph for about a second then recovered. At that time I connected to the Powerlogger when I got it home and could not find anything wrong. Wiggled all connectors I could get to under the hood and it never did it again.

It was fine this year up until today. Cut out on me several times at idle and while cruising, did not think I was going to make it home. When it cuts out it is complete, like you turned the key off. No SES light, no flickering dash lights or gauges. Does not seem electrical.

While sweating bullets on the way home, one of the times while cruising about 25 mph, the RPMs started to drop instead of cutting completely out, and I had to give it a little more peddle. When this occurred I remembered to look down at the wideband and it had dropped down to between 8-9 and stayed there for about 20 seconds with the throttle in the same position. It then went back up to 14-15 where it usually is at that speed and ran normally.

When I got it in the driveway I connected to the powerlogger and let it idle for about a half an hour while I watched the fuel pressure gauge under the hood, but of course it didn’t happen again. Fuel pressure is 43lbs line off and about 38 line on and steady. I had someone look while I torqued it to about 5 lbs and rose as it should.

Does this sound like the fuel pump going bad? It is about a 9 year old Walbro 255 from Full throttle speed. About 10K miles and maybe 80 quarter mile passes.

I have attached 2 screen shots from the Powerlogger, one at idle and one at about 2000 RPM. Unfortunately, I am not logging fuel pressure.

Thanks in advance for any help.

 

[turbo nasty]

Check the orange wire which is the ecm feed off of the pos battery post. Wiggle and shake the wire with car running. Its fairly common that the lil black block on the wire (which is the connection for the fusible link) can break there or around there. Also not sure why 3rd gear is showing selected when parked. Might have a bad 3rd gear switch in trans or the circuit grounded somewhere. Also try and get a log when its happening

 

[mikestertwo]

Really can't tell much by those screen shots other than your 3rd gear status is on which it shouldn't be. Probably have a bad status switch or a wiring problem.

 

[jskarateka]

Check the orange wire which is the ecm feed off of the pos battery post. Wiggle and shake the wire with car running. Its fairly common that the lil black block on the wire (which is the connection for the fusible link) can break there or around there. Also not sure why 3rd gear is showing selected when parked. Might have a bad 3rd gear switch in trans or the circuit grounded somewhere. Also try and get a log when its happening

Forgot about the ECM wire/link, I will check that. I wouldn't think it would cause it to lean out like that though (referring to the time I had to peddle it more and the wideband dropped to 8-9 for about 15-20 seconds while cruising).

Didn't notice the 3rd gear indicator. I'll check my old log files, and check to see what it shows with the trans connector unplugged. I was going to drive around for awhile with the powerlogger recording but I'm afraid of getting stranded.

 

[jskarateka]

Forgot about the ECM wire/link, I will check that. I wouldn't think it would cause it to lean out like that though (referring to the time I had to peddle it more and the wideband dropped to 8-9 for about 15-20 seconds while cruising)..

Just realized I have that backwards, 8-9 on the wideband means it rich'nd up? I also did witness once at idle, that the RPMs started to drop down gradually for a few seconds, then die. I'm going to do more testing tonight after work, but from what I've read it could be about a dozen things. Hardly anyone posted back what their fix was.

 

[John Larkin]

Mine did it until I tightened the harmonic balancer. It would walk out and lose the connection at the crank sensor.

 

[scgnx2]

When my lt1 MAF started to fail, my car did similar things. It would cut out at cruise momentarily and then seem fine. It progressively got worse to were the motor would literally shut off during normal driving.
Replaced both the old translator plus with a new translator and new LS1 MAF.

 

[jskarateka]

Check the orange wire which is the ecm feed off of the pos battery post. Wiggle and shake the wire with car running. Its fairly common that the lil black block on the wire (which is the connection for the fusible link) can break there or around there. Also not sure why 3rd gear is showing selected when parked. Might have a bad 3rd gear switch in trans or the circuit grounded somewhere. Also try and get a log when its happening

FIXED!

Started it up and let it idle for a couple of minutes. Popped the hood and tapped the fusible link for the ECM by the black block and it instantly puked. Was a break where it came out of the black part just like you wrote. Hopefully all good now.

THANK YOU TURBO NASTY, and thanks to all others who responded!