Cliff DP
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Cruising
Joined: Apr 2013
Posts: 13
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Cliff DP
Looking for a solution to solve my restart problem.
My 84 xfire starts and runs great but after a twenty minute or longer trip and it's off for longer than a few minutes [ more likely an hour or so ] the restart is very rough almost like flooding. If I pump and feather the accelerator for five or six minutes it smooths out and runs fine. I recently replaced the injectors but that wasn't the answer. If I raise the hood/fenders for about fifteen minutes it acts fine. I suspect some sort of vapor lock. HELP
My 84 xfire starts and runs great but after a twenty minute or longer trip and it's off for longer than a few minutes [ more likely an hour or so ] the restart is very rough almost like flooding. If I pump and feather the accelerator for five or six minutes it smooths out and runs fine. I recently replaced the injectors but that wasn't the answer. If I raise the hood/fenders for about fifteen minutes it acts fine. I suspect some sort of vapor lock. HELP
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
sounds like a dying IAC... Idle Air Controller.
Also confirm that the fuel lines are good and not too close to the exhaust.
One last trick is to put in the higher pressure fuel pump from a 1985. The added pressure will increase cyclic flow and cut down on vapour lock.
Also confirm that the fuel lines are good and not too close to the exhaust.
One last trick is to put in the higher pressure fuel pump from a 1985. The added pressure will increase cyclic flow and cut down on vapour lock.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
I would be CLOSELY LOOKING at your COOLANT TEMP SENSOR located in the front of the intake manifold pointing towards the radiator area. It has 2 wires going to it(yellow and black)...and if it is still the original...I would REPLACE it with the improved designed sensor. GM had problems with the original design and made a change for a reason.
IF you do...the two wires HAVE TO be connected CORRECTLY.
You MAP ( manifold air pressure) sensor located on the firewall can also be an issue if the hose going to it is bad.
FUEL PRESSURE is important...and is tricky if you do not have the correct set-up to check it.
Throttle Position Sensor being set correctly.
Wire to the Oxygen sensor has come in contact with a metal surface and grounding. A scanner would let you know that immediately...if not...inspect it and make sure that the wire is AWAY from heat sources.
Vacuum leaks can also be an issue and the intregrator value data that shows up on a scanner along with the MAP sensor voltage at idle would tell you that.
A scanner is a MUST...to read the data when it is running. Without it...some variables will be left up to 'guessing its OK' way of thinking.
The COOLANT TEMP SENSOR is so important that it is the input to allow the computer to adjust your Idle Air Control Valves. WHICH is more than likely WHY it is fine when it is COLD....but 20 minutes later...it goes crazy.
If you do not have either...Get a factory service manual and a scanner. I could not do what I do with computer controlled engines without my scanners and manuals...along with numerous test leads and testing equipment.
DUB
IF you do...the two wires HAVE TO be connected CORRECTLY.
You MAP ( manifold air pressure) sensor located on the firewall can also be an issue if the hose going to it is bad.
FUEL PRESSURE is important...and is tricky if you do not have the correct set-up to check it.
Throttle Position Sensor being set correctly.
Wire to the Oxygen sensor has come in contact with a metal surface and grounding. A scanner would let you know that immediately...if not...inspect it and make sure that the wire is AWAY from heat sources.
Vacuum leaks can also be an issue and the intregrator value data that shows up on a scanner along with the MAP sensor voltage at idle would tell you that.
A scanner is a MUST...to read the data when it is running. Without it...some variables will be left up to 'guessing its OK' way of thinking.
The COOLANT TEMP SENSOR is so important that it is the input to allow the computer to adjust your Idle Air Control Valves. WHICH is more than likely WHY it is fine when it is COLD....but 20 minutes later...it goes crazy.
If you do not have either...Get a factory service manual and a scanner. I could not do what I do with computer controlled engines without my scanners and manuals...along with numerous test leads and testing equipment.
DUB
