Jerking/bucking
Thread Starter
Burning Brakes
Joined: Jun 2001
Posts: 924
Likes: 0
From: Columbia South Carolina
Jerking/bucking
Good afternoon,
When driving at less than 45 MPH and until the 'Vette (1987) warms up,the car bucks and jerks.After warm up and at faster speeds it runs smooth and fast.I have changed plugs,wires,coil,cap,rotor,O2 sensor,& air filter.There are no codes,and SES light is not on.
I have an FSM,but don't know what to look for.Have any of you with 87's experienced this issue? If so please give me your thoughts.Thanks in advance.
tankman
When driving at less than 45 MPH and until the 'Vette (1987) warms up,the car bucks and jerks.After warm up and at faster speeds it runs smooth and fast.I have changed plugs,wires,coil,cap,rotor,O2 sensor,& air filter.There are no codes,and SES light is not on.
I have an FSM,but don't know what to look for.Have any of you with 87's experienced this issue? If so please give me your thoughts.Thanks in advance.
tankman
Pro
Joined: Jan 2008
Posts: 584
Likes: 1
From: Near Lockport NY Black 1986 Coupe
When you say "warms up", what temp do you mean? 110, 120, 130, 150? Usually, atleast on a cold day, you should wait until it warms up to a good 120-130 before a cruise.
If it's stumbling when over 130 then it may be a problem with the injectors, even though it doesn't happen when hot. It may also be the fuel pump and/or filter.
I hope you find out what's wrong.
If it's stumbling when over 130 then it may be a problem with the injectors, even though it doesn't happen when hot. It may also be the fuel pump and/or filter.
I hope you find out what's wrong.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Time for a fuel pressure test, ohm the injectors, hot/cold, possibly CSI. IAC, carboned up. After checking fuel pressure and ohming injectors I'd run a can of SeaFoam throught it. I typically put a half can in the tank ans suck the other half through the brake booster vac. line. Just make sure if you do to follow the rest of the instructions.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Time for a fuel pressure test, ohm the injectors, hot/cold, possibly CSI. IAC, carboned up. After checking fuel pressure and ohming injectors I'd run a can of SeaFoam throught it. I typically put a half can in the tank ans suck the other half through the brake booster vac. line. Just make sure if you do to follow the rest of the instructions.
Check that fuel pressure regulator (FPR) too....with a bleed down test or pull the small vacuum hose off the FPR and see if gas shoots out...if it does its bad.
Thread Starter
Burning Brakes
Joined: Jun 2001
Posts: 924
Likes: 0
From: Columbia South Carolina
Okay.Thanks to all three of you guys.I didn't know I should have waited until the eng.warmed to 120-130 
,I'll start doing that.Then I'll proceed with the other advice you all have offered.
Thank you very much.
,I'll start doing that.Then I'll proceed with the other advice you all have offered.Thank you very much
.
