Stalling issue at autocross

[DNut]

Participated in my first autocross yesterday.

While nothing is permanently broken, I do have a new stalling issue to diagnose:



For those that don't know details on the car:

1987 Monte Carlo SS
SBC 350
Holley Stealth Ram controlled by a tuned '730 ECM
Used GN gas tank with a replacement GN fuel pump, newish (About 15,000 miles) fuel filter, and newish(Same mileage as the filter) fuel lines.
Small cap HEI ignition with an MSD 6A box

The car has NEVER had a stalling issue in the past when driving around town, but it didn't seem to like taking corners hard after the first run of each session.

For each autocross session, the first run always goes well, with the second and third runs resulting in the car bogging down and stalling out (Idle drops and you can "feather" the throttle to keep it from stalling, although that didn't always work) when accelerating out of a turn/ through a slalom.

Initially thought it was a fuel starvation issue, only I know that the tank was 100% full as I just topped it off. Given that the tank is a used GN unit and the fuel filter is a few years old, perhaps either one or both was getting clogged by sediment that was kicked up?


The car fired right up (Rolling restart as I lost power assist for the brakes and steering...NOT fun), within a few seconds each time this happened.

Also, the car didn't miss a beat when driving home, and I was getting on it hard once in a while to see if I could get the issue to happen when accelerating in a straight line. No issues there.

Any suggestions?

[squirrel]

Ditch the factory ecm, and use one that you can datalog with?

MegaSquirtIII is good for that, I hear. Has an SD card slot. kind of pricy, but it'll take you to a whole new level of learning.

Some setup required.

[DNut]

Ditch the factory ecm, and use one that you can datalog with?

MegaSquirtIII is good for that, I hear. Has an SD card slot. kind of pricy, but it'll take you to a whole new level of learning.

Some setup required.

I can datalog with the factory computer, although you need a laptop hooked up in order to do so.

Do you know if there's a plug and play Megasquirt for a Speed Density (90-92) F-body harness?

[Barry Donovan]

that is fuel filter.
pump can get caught up on some angles too, but that is odd problem.

if you had a large ignition it would give a kick and die instead of sputter and die..
it did keep working as you described, you have mellow ignition playing in your favor.

check for a return seep too..if its a never ending silt, the return may help. keep the tank cleaning, problem in out good filter. paper elements are hell on certain silt. sometimes they even respond and multiply. local calls it an algae.

[squirrel]

I can datalog with the factory computer, although you need a laptop hooked up in order to do so.

Can you find a parking lot to drive around in enough to recreate the problem, while you have a laptop hooked up?

Do you know if there's a plug and play Megasquirt for a Speed Density (90-92) F-body harness?

I don't know but you can wander around the web page I linked to and see.

[DNut]

Can you find a parking lot to drive around in enough to recreate the problem, while you have a laptop hooked up?



I don't know but you can wander around the web page I linked to and see.

Ah, I didn't notice the link, sorry about that!

Lohnes does need to get his butt in gear and do another slalom test with Buford. I'll try to piggyback that insanity with my car and see if I can get it to happen again.

[TC]

How much fuel was in your gas tank??

[DNut]

How much fuel was in your gas tank??

Completely full, as I had just topped it off about 2 miles away.

[Matt Cramer]

Do you know if there's a plug and play Megasquirt for a Speed Density (90-92) F-body harness?

Not at this point, but it's something we could do if demand is there. We'd probably get one for the '86-'89 setup first as we have those connectors on hand, but if somebody got together a group buy for the '90-'92, we could get that too.

[CDMBill]

I wonder about localized heating of the fuel supply in the rails or as it comes up to the rails. Even EFI will temporarily 'vapor lock' if the fuel is heated enough. Pump cavitation caused by the slosh is another possibility but seems unlikely given the 100% full tank.

Is there a sock or pre-filter that could cause pump inlet supply issues if clogged?

[DNut]

There is a sock that is attached to the pump, so that's definitely a possibility.

While I normally frown on just throwing parts at a problem, I just ordered a new replacement tank from Spectre along with a new fuel filter as both the tank and filter really should be changed out regardless. I'll buy a new sock for the pump when all of that comes in.

[SuperBuickGuy]

does the problem exist when the tank isn't completely full? I wonder if you're getting back-pressure in your return line. Also, maybe put a (oh good lord, all I can think of is "pipe bomb" as it's what Randal has on his Buick) a surge tank in your supply fuel line? I wouldn't change the computer

[TC]

I just ordered a new replacement tank from Spectre along with a new fuel filter

My friend is working on a Pathfinder that is doing the same thing, he's drive it a few miles and it would stall and not run, he'd wait a minute or two and start it and it'd start and drive for a few more miles, then stall again..... He says it's the filter clogging up with sediment........