Vette Stalled...
Thread Starter
Race Director
Joined: Sep 2005
Posts: 10,878
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St. Jude Donor '07
Vette Stalled...
... and had a hard time staying running. ('85 43+, 68k.)
This is a surprise to me, considering how nicely it was running the last few days. I was on my way home from a 40 mile drive. As I was about to make a turn, the engine stalled. I tried to restart. It would run a few seconds and die. It would rev just fine, but not idle one bit. No codes!
(Note: It idled fine for me when I ran some tests this evening.)
Recent work over the winter:
IAC - Corrected hunting idle and is steady @ 700rpm warm now.
CAI
Underdrive pulleys
AFPR - 40psi primed, 36psi idling.
Diaphram - Old one was losing its rubber coating! 37 psi max.
Radiator
Radiator hoses
Alternator
160 Stat - May be causing open/closed loop issues... Move to a 180?
And:
Fuel pump - 1 year ago
Dist cap/coil - 1 year ago
Rotor - 1 year ago
Wires - 1 year ago
Plugs - 1 year ago
Module - 1 year ago
What could this be???
There is a chance that I have a questionable oil sending unit. I have a slight oil leak somewhere between the engine & trany. Looking for a rack to get a peek. The oil sender may have dropped the idle psi rating to under 4psi. That would cut the fuel pump. Keeping it @ 1000 rpm once it started got me home. It would start easily, but die after a few seconds.
Thoughts?
This is a surprise to me, considering how nicely it was running the last few days. I was on my way home from a 40 mile drive. As I was about to make a turn, the engine stalled. I tried to restart. It would run a few seconds and die. It would rev just fine, but not idle one bit. No codes!
(Note: It idled fine for me when I ran some tests this evening.)
Recent work over the winter:
IAC - Corrected hunting idle and is steady @ 700rpm warm now.
CAI
Underdrive pulleys
AFPR - 40psi primed, 36psi idling.
Diaphram - Old one was losing its rubber coating! 37 psi max.
Radiator
Radiator hoses
Alternator
160 Stat - May be causing open/closed loop issues... Move to a 180?
And:
Fuel pump - 1 year ago
Dist cap/coil - 1 year ago
Rotor - 1 year ago
Wires - 1 year ago
Plugs - 1 year ago
Module - 1 year ago
What could this be???
There is a chance that I have a questionable oil sending unit. I have a slight oil leak somewhere between the engine & trany. Looking for a rack to get a peek. The oil sender may have dropped the idle psi rating to under 4psi. That would cut the fuel pump. Keeping it @ 1000 rpm once it started got me home. It would start easily, but die after a few seconds.
Thoughts?
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by williammackean
The oil sender may have dropped the idle psi rating to under 4psi. That would cut the fuel pump. Keeping it @ 1000 rpm once it started got me home. It would start easily, but die after a few seconds.
Thoughts?
Thoughts?
RACE ON!!!
Thread Starter
Race Director
Joined: Sep 2005
Posts: 10,878
Likes: 1
St. Jude Donor '07
There are sites that claim if the oil sender drops below 4psi that a switch will cut the fuel pump. Is this true, or 'kinda' true, or not at all?
How would I troubleshoot the relay? I'm not entirely sure what relays are what. There are a couple large relays on the DS of the distributor on the firewall. Is that it?
How would I troubleshoot the relay? I'm not entirely sure what relays are what. There are a couple large relays on the DS of the distributor on the firewall. Is that it?
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Nope. It's 100% b.s.
When it has over 4 psi, the oil sender will power the fuel pump through the "off" contacts of the fuel pump relay, which can happen only if the ECM is not turning on the relay. The relay would have to be in pieces for neither to power the pump. And it would never prime the system or start to begin with.
Relay isn't your problem.
Also, a 160 stat will not cause open loop issues, that's another myth.
Last edited by CentralCoaster; Mar 22, 2007 at 10:22 AM.
Safety Car
Joined: Dec 2004
Posts: 4,088
Likes: 0
From: Poop land
I would hate to say it but I will anyways. A flaky connection to the MAF or a bad MAF itself will cause an immediate stall. In my case, sometimes there were MAF codes, other times there were none. If you restart it again, the car would idle but as soon as you tap the gas pedal, you'd stall it again. I'd check the MAF connector first. 
Thread Starter
Race Director
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St. Jude Donor '07
I'll check the MAF connection more closely. I have some contact cleaner I'll use, too.
It ran better today. It didn't stall. A couple times the idle dropped to a steady 620rpm from a typical 700rpm.
Could much of this be the computer learning the new IAC, CAI, Tstat, and underdrive?
I should buy the test harness kit from MAM so I can test and tweak these things.
I'm also hoping this is due to the old gas. I'm not going to panic unless it continues thru the next tank and fluid change next weekend.
Other thoughts? This is helping me a lot. Mythbusting is a good thing.
It ran better today. It didn't stall. A couple times the idle dropped to a steady 620rpm from a typical 700rpm.
Could much of this be the computer learning the new IAC, CAI, Tstat, and underdrive?
I should buy the test harness kit from MAM so I can test and tweak these things.
I'm also hoping this is due to the old gas. I'm not going to panic unless it continues thru the next tank and fluid change next weekend.
Other thoughts? This is helping me a lot. Mythbusting is a good thing.
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Thread Starter
Race Director
Joined: Sep 2005
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St. Jude Donor '07
I replaced that when I did the ignition system last year.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
How would I troubleshoot the relay?
I beleive the '85 will run with the MAF disconnected, indicating a bad MAF. I tried this test a few years ago and my '88 would NOT run with the MAF disconnected.
Safety Car
Joined: Dec 2004
Posts: 4,088
Likes: 0
From: Poop land
Originally Posted by 65Z01
I tried this test a few years ago and my '88 would NOT run with the MAF disconnected.
Thread Starter
Race Director
Joined: Sep 2005
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St. Jude Donor '07
So far it's just a one-time thing...
I have the MAM electronic harness test kit on the way. I'll take a bunch of readings and clean every connector I can find...
With some mods, I'm sure I need a chip-tune. Maybe in a couple weeks...
I have the MAM electronic harness test kit on the way. I'll take a bunch of readings and clean every connector I can find...
With some mods, I'm sure I need a chip-tune. Maybe in a couple weeks...