4.3 Stumbles
Senior Member
True Car Nut
Joined: Feb 2015
Posts: 6,851
Likes: 1,015
From: Earth
Senior Member
True Car Nut
Joined: Feb 2015
Posts: 6,851
Likes: 1,015
From: Earth
Thread Starter
Member
Posts like a V-Tak
Joined: Mar 2018
Posts: 33
Likes: 4
From: Florida
Follow Up
Get another beer, this is a long one.
1997 Chevy Express 4.3 After
No codes
Short and long term fuel are fine
Cat in 187 out 229
Fuel pressure 52 lbs. (new fuel pump and filter) Fuel pressure holds for 10min after shutting off
Running around town it does fine.
BUT If I drive down the interstate 65-70 Mph (I'm an old man) for an hour or more. If I try to go above about 1/2 throttle it bucks and shakes, less than 1/2 throttle it runs fine. If I stop for half an hour or more it runs fine again.
If I let it sit in the driveway for 2 hours at idle I can't get it to act up. If I'm on the road by the time I get the dog box off to check fuel pressure the problem goes away.
What do I check next?
1997 Chevy Express 4.3 After
No codes
Short and long term fuel are fine
Cat in 187 out 229
Fuel pressure 52 lbs. (new fuel pump and filter) Fuel pressure holds for 10min after shutting off
Running around town it does fine.
BUT If I drive down the interstate 65-70 Mph (I'm an old man) for an hour or more. If I try to go above about 1/2 throttle it bucks and shakes, less than 1/2 throttle it runs fine. If I stop for half an hour or more it runs fine again.
If I let it sit in the driveway for 2 hours at idle I can't get it to act up. If I'm on the road by the time I get the dog box off to check fuel pressure the problem goes away.
What do I check next?
Thread Starter
Member
Posts like a V-Tak
Joined: Mar 2018
Posts: 33
Likes: 4
From: Florida
UPDATE!! Ok I have now replaced the fuel spider. I have reduced my problem to a stumble when I first step on the execrator. Only in open loop. Cleaned the IAC and MAF.. My fuel trims are fine. and problem goes away once it goes into closed loop.