89 350 tpi engine problem
Thread Starter
Heel & Toe
Joined: Jun 2014
Posts: 15
Likes: 0
89 350 tpi engine problem
Hi, hope you guys can help me. I have an 89 350 tpi engine in my 1963 chevy truck. I have recently developed a problem with the running of the engine which I cannot fix.
The problem is when accelerating from around 60mph to over take another car and around 1600 rpm the engine struggles to accelerate and holds back and will not pick up speed. It feels like the engine is miss fire butting does not back fire, it feels like it's lacking in something. If you push the throttle to the floor and the transmission kicks down a gear the truck picks up and takes of fine. I have changed. 8 injectors, 8 plugs and leads, dizzy arm, dizzy cap and coil, tps sensor, map sensor and oxygen sensor and I still have the fault
It only seems to do it between 1600 and 1900 rpm under load . If the engine is revving above 2000 rpm it's fine and runs really smooth.
, if any one has any ideas please let me know
Thanks for your help
The problem is when accelerating from around 60mph to over take another car and around 1600 rpm the engine struggles to accelerate and holds back and will not pick up speed. It feels like the engine is miss fire butting does not back fire, it feels like it's lacking in something. If you push the throttle to the floor and the transmission kicks down a gear the truck picks up and takes of fine. I have changed. 8 injectors, 8 plugs and leads, dizzy arm, dizzy cap and coil, tps sensor, map sensor and oxygen sensor and I still have the fault
It only seems to do it between 1600 and 1900 rpm under load . If the engine is revving above 2000 rpm it's fine and runs really smooth.
, if any one has any ideas please let me know
Thanks for your help
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
Did you disconnect the EST connector, (Tan wire with black stripe near the driver side firewall on an 89 Vette) before setting the timing?
Also, what is the Fuel Pressure? should be 37-42psi with the vacuum hose disconnected from the fuel pressure regulator diaphragm and engine on. You can also, connect the fuel pressure gauge to the schrader valve on the fuel rail and tape the gauge to the windshield. Take a drive and see what the fuel pressure is when you accelerate. If the fuel pressure drops significantly, there's your problem. The fuel pump is weak.
.
Also, what is the Fuel Pressure? should be 37-42psi with the vacuum hose disconnected from the fuel pressure regulator diaphragm and engine on. You can also, connect the fuel pressure gauge to the schrader valve on the fuel rail and tape the gauge to the windshield. Take a drive and see what the fuel pressure is when you accelerate. If the fuel pressure drops significantly, there's your problem. The fuel pump is weak.
.
Last edited by GKK; Jun 1, 2014 at 04:36 PM.
Thread Starter
Heel & Toe
Joined: Jun 2014
Posts: 15
Likes: 0
Thanks for the reply
I keep reading about this tan and black wire, but it cannot see it, the truck has an American auto wire harness in so not 100% sure if the wire will be the same color as in the original car, also no I have checked fuel pressure, this my next line of investigation, I haven't go a fuel pressure gauge to check
I keep reading about this tan and black wire, but it cannot see it, the truck has an American auto wire harness in so not 100% sure if the wire will be the same color as in the original car, also no I have checked fuel pressure, this my next line of investigation, I haven't go a fuel pressure gauge to check
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
The EST Timing wire is the connector located in the middle of this picture, coming out of the thick plastic wire bundle.
Disconnect this wire, adjust the timing and then Reconnect.
Disconnect this wire, adjust the timing and then Reconnect.
Last edited by GKK; Jun 1, 2014 at 04:57 PM.
Thread Starter
Heel & Toe
Joined: Jun 2014
Posts: 15
Likes: 0
Doh, I do not have the original but I have a wiring diagram for the engine, so may be able to work it out, do you think it could be timing issue as it runs fine above that certain rev range, I do think it's kinda a fuel issue, have you ever come across this issue before
Thanks
Thanks
Pro
Joined: Oct 2008
Posts: 708
Likes: 28
Robbs - Why not contact American Auto Wire and ask them where the EST disconnect is? You don't need the original wiring, however it is much harder to troubleshoot issues like this when you don't. If you didn't disconnect it then your timing isn't correct. Low rpm + high load is where timing issues are most apparent.
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Safety Car
Joined: Jan 2004
Posts: 3,783
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From: Northern California
Drifting
Joined: May 2013
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From: Reno Nevada
At least you learned how to set base timing? Have you been able to pull codes? Is it speed density, or mass air? What transmission, and if 700r4 is the tv cable adjusted correctly. You know it's not any of the parts you changed already. What did you do prior to it starting?
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
Thread Starter
Heel & Toe
Joined: Jun 2014
Posts: 15
Likes: 0
Thanks for all the advice, I have checked the TV cable and made a small adjustment. Also I checked the timing and found out that it was on 12 degrees instead of 6, so hope to go out on road test tomorrow and see how it goes
