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My 85 won't start

gmhowe

Well-known member
Joined
Nov 14, 2002
Messages
437
Location
glendale, az
Corvette
1985 4+3 black cpe & 96 LT1 CE
Backed it into the driveway yesterday it died but it was where it was supposed to be so didn't think anything about it. Went to start it today and it tried, sputtered then just cranks with nothin. Any ideas ? :confused
 

KANE

Moderator
Joined
Mar 2, 2002
Messages
3,244
Location
KY
Corvette
Dark Blue 1982 Trans Am(s): Polo Green 1995 MN6
Backed it into the driveway yesterday it died but it was where it was supposed to be so didn't think anything about it. Went to start it today and it tried, sputtered then just cranks with nothin. Any ideas ? :confused

Wow. Where to start...

Does the fuel pump energize?

Read this so you'll have an idea how the car starts-
http://www.corvetteactioncenter.com/tech/howto/idx.php/0/016/article/

Jump the ALDL- see what codes you get.
NO CODES: Your problem isn't from a monitored function
CODES: Your problem is in vicinity of a monitored function


Let me know if any of this helps- then we'll work from there.
 

gmhowe

Well-known member
Joined
Nov 14, 2002
Messages
437
Location
glendale, az
Corvette
1985 4+3 black cpe & 96 LT1 CE
not sure about the energize, but put on the fuel pressure guage and turned the key and got 10 lb of pressure, the car will sputter and run for about 3-4 sec then dies again. No codes, even replaced the fuel pump ( had a spare ) same thing.
 
T

tdr1919

Guest
not sure about the energize, but put on the fuel pressure guage and turned the key and got 10 lb of pressure, the car will sputter and run for about 3-4 sec then dies again. No codes, even replaced the fuel pump ( had a spare ) same thing.

But you should be seeing around 40psi of fuel pressure, sure you dont have a restriction, or bad fuel filter, maybe pressure regulator?

Tom
 

Black 86

Member
Joined
Sep 9, 2006
Messages
17
Location
texas
Corvette
1986 Black coupe
check fuel level mine will do this if the fuel gauge reads reserve and i back it in the drive. I gues the pitch of the driveway send the gas to front of the tank.
 

KANE

Moderator
Joined
Mar 2, 2002
Messages
3,244
Location
KY
Corvette
Dark Blue 1982 Trans Am(s): Polo Green 1995 MN6
Tank is 3/4 full

I'm going to assume that your spare pump worked correctly and pressurized the line to the correct PSI.

Fuel filter- have you changed it?

Next- fuel presure regulator. You may want to change that. If for no other reason, you can tune it with more precision than the stock FPR.

I'm thinking your 9th injector is providing just enough fuel to kick it over in the start sequence, then when the ECM attempts to regulate the mixture and it stumbles and dies. That would explain why it would attempt to start.

I think you have a problem with getting enough fuel to the injectors. Did the hose get disconnected that links the FPR to the back of the plenum? Check that- sometimes that will prevent the car from running.
 

gmhowe

Well-known member
Joined
Nov 14, 2002
Messages
437
Location
glendale, az
Corvette
1985 4+3 black cpe & 96 LT1 CE
No clue about the pulsator, just frustrates the hell outta me, one day fine the next no run
 
S

speedmaster4

Guest
pulsator is gizmo that the pump discharges into,inside the tank...when you changed pumps you should have pushed the male end of the pump into the female end of the pulsator.... been known to leak, fuel sprays right back into the tank...possible cause for only 10 psi.
 
T

tdr1919

Guest
Before you go crazy replacing everything 10 PSI is NOT going to run your engine. first thing did you do what Dark shark suggested? you need to check for codes.
You only replied you changed the fuel pump. you must systematically test and elliminate. Checking for a code is about the easiest thing you can do. Maybe you have a relay that is not working properly. there is a proceedure in the FSM for testing the fuel pump.
Tom
 

gmhowe

Well-known member
Joined
Nov 14, 2002
Messages
437
Location
glendale, az
Corvette
1985 4+3 black cpe & 96 LT1 CE
Thanx for all the info, now all I need is some time to check things out, have to install a trailer hitch on my wife's Yukon for her wheelchair. Will keep all posted as to what I find out.
 

gmhowe

Well-known member
Joined
Nov 14, 2002
Messages
437
Location
glendale, az
Corvette
1985 4+3 black cpe & 96 LT1 CE
Changed the Fuel filter, no change. New Fuel Pressure Regulator, no change. Went to put in new fuel pump and noticed that the Pulsator had a rip in it. Thanx
Speedmaster4
 

gmhowe

Well-known member
Joined
Nov 14, 2002
Messages
437
Location
glendale, az
Corvette
1985 4+3 black cpe & 96 LT1 CE
But car now idles between 3600-4000 rpm, any ideas about that now. Used to idle between 7500 and 8000
 

3dale1

Well-known member
Joined
Mar 12, 2005
Messages
158
Location
PA
Corvette
65 convertible L-76
Just some unsubstantiated advice here, but give it some time. run the car a little. When I unpllugged the MAF and other sensors in the TB area when the plenum was off, and then reassembled, idle was all over the place, without throwing a code. Then things "literally" smoothed out. Maybe computer resetting itself?

Also, when you changed the FPR, maybe one of the vacuum lines was disturbed or broken.

Maybe time to clean the IAC?

Just some thoughts. IMO, probably something small now that your fuel pressure problem can be eliminated as a source of problem.

Joe
 

gmhowe

Well-known member
Joined
Nov 14, 2002
Messages
437
Location
glendale, az
Corvette
1985 4+3 black cpe & 96 LT1 CE
Ill check it out tomorrow, by the way what is the IAC ?
 

gmhowe

Well-known member
Joined
Nov 14, 2002
Messages
437
Location
glendale, az
Corvette
1985 4+3 black cpe & 96 LT1 CE
Did notice that the plenium was rather dirty, what is the best way to clean it out, maybe just some engine degreaser ???
 

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