 Backfire in the throttle body |
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| gjames |
 Apr 13 2020, 08:29 AM
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#1
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Newbie  Group: Members Posts: 10 Joined: 3-March 13 From: Virginia Member No.: 15,606 Region Association: None  |
My 914 had not run for 3 years. I soaked the cylinders in WD40 for a couple days before starting. I discovered heavy rust in the fuel tank so I replaced:
Tank, hoses and pump. Injectors and engine bay fuel lines And Flushed the long fuel lines until they ran clean The engine started but there was no power, poor idle I Replaced: Points/plugs/condenser/coil. Reset timing and idle (The dwell is no high side- 58) Power is back and idle is good. The Problem: When I give it gas, it will back fire into the throttle body. It seems to happen a 2k - 3k rpm range. It's doesn't happen every time. Ideas? |
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Replies(1 - 9)
| 914bub |
Apr 13 2020, 08:42 AM
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#2
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Member Group: Members Posts: 433 Joined: 16-August 13 From: Modesto CA. Member No.: 16,260 Region Association: None |
QUOTE(gjames @ Apr 13 2020, 07:29 AM)  My 914 had not run for 3 years. I soaked the cylinders in WD40 for a couple days before starting. I discovered heavy rust in the fuel tank so I replaced: Tank, hoses and pump. Injectors and engine bay fuel lines And Flushed the long fuel lines until they ran clean The engine started but there was no power, poor idle I Replaced: Points/plugs/condenser/coil. Reset timing and idle (The dwell is no high side- 58) Power is back and idle is good. The Problem: When I give it gas, it will back fire into the throttle body. It seems to happen a 2k - 3k rpm range. It's doesn't happen every time. Ideas? Have you checked valve adjustment? |
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| BeatNavy |
Apr 13 2020, 09:00 AM
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#3
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region 
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A couple of questions / points:
1. Which engine (e.g., 2.0) / injection system is this (or is it not FI)? 2. Were you seeing symptoms of something when you stopped driving it? 3. Agree, valves worth checking 4. Set dwell to 45 - 50 and THEN set timing. Changing timing will alter dwell. |
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| gjames |
Apr 13 2020, 10:54 AM
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#4
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Newbie Group: Members Posts: 10 Joined: 3-March 13 From: Virginia Member No.: 15,606 Region Association: None |
QUOTE(BeatNavy @ Apr 13 2020, 11:00 AM) A couple of questions / points: 1. Which engine (e.g., 2.0) / injection system is this (or is it not FI)? 2. Were you seeing symptoms of something when you stopped driving it? 3. Agree, valves worth checking 4. Set dwell to 45 - 50 and THEN set timing. Changing timing will alter dwell. Oops.....it's 2l with FI. I will reset the dwell and timing...and then the adjust the vales. thanks for the suggestions. |
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| gjames |
Apr 13 2020, 10:56 AM
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#5
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Newbie Group: Members Posts: 10 Joined: 3-March 13 From: Virginia Member No.: 15,606 Region Association: None |
QUOTE(gjames @ Apr 13 2020, 12:54 PM) QUOTE(BeatNavy @ Apr 13 2020, 11:00 AM) A couple of questions / points: 1. Which engine (e.g., 2.0) / injection system is this (or is it not FI)? 2. Were you seeing symptoms of something when you stopped driving it? 3. Agree, valves worth checking 4. Set dwell to 45 - 50 and THEN set timing. Changing timing will alter dwell. Oops.....it's 2l with FI. I will reset the dwell and timing...and then the adjust the vales. thanks for the suggestions. The motor ran ok before its nap. |
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| ClayPerrine |
Apr 13 2020, 12:00 PM
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#6
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Life's been good to me so far..... Group: Admin Posts: 15,518 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille
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Double check your firing order on the distributor cap. Two swapped plug wires can cause a backfire and sluggish running like you describe.
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| BeatNavy |
Apr 13 2020, 12:18 PM
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#7
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region
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Yeah, Clay's got a good point. Esp. since you had the cap off and were doing some ignition related work.
Here's a visual reference:  |
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| gjames |
Apr 14 2020, 08:39 AM
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#8
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Newbie Group: Members Posts: 10 Joined: 3-March 13 From: Virginia Member No.: 15,606 Region Association: None |
Thanks for the responses!!!
Last night I reset the points gap and got the dwell within specs, and then I reset the timing. The problem is now fixed. |
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| BeatNavy |
Apr 14 2020, 10:28 AM
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#9
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region
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Excellent!
What part of VA are you from? |
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| drem914 |
Apr 14 2020, 11:27 AM
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#10
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Senior Member Group: Members Posts: 1,033 Joined: 16-May 08 From: Trabuco Canyon, CA Member No.: 9,062 Region Association: Southern California
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QUOTE(gjames @ Apr 14 2020, 07:39 AM) Thanks for the responses!!! Last night I reset the points gap and got the dwell within specs, and then I reset the timing. The problem is now fixed. Glad to hear. You don't need your throttle body damaged do to a serious backfire. |
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