 Way too much gas, 73 1.7 with FI |
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| EJP914 |
 Jun 24 2026, 09:10 AM
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#1
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Member  Group: Members Posts: 295 Joined: 14-June 03 From: Monroeville, PA Member No.: 821  |
hello!
Looking for some ideas on why the spark plug electrodes are wet with gas after running the car for only about 20-30 seconds. Something is causing way too much fuel into the engine. Car starts at the turn of the key, but stumbles and runs rough. Exhaust smells like gasoline. I have checked, replaced, or installed known good parts. New plugs, points, condenser. Cleaned trigger contacts. Distributer other wise works as it should. Swapped in known good relay board and relays Swapped in known good ECU. Installed new fuel injectors, Standard Mfg type. Fuel line pressure at 25 lbs. Swapped in “adjusted” MPS. (Maybe still too rich?) Timing is good but not spot on. I have not yet checked CHT sensor or cold start valve (may be stuck open?). Not sure what else to check? I have never seen this much gas get pumped into an engine. I would very much appreciate any advice and/or guidance. Thanks. EJP914 |
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| FlacaProductions |
Jun 24 2026, 09:13 AM
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#2
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Advanced Member Group: Members Posts: 2,237 Joined: 24-November 17 From: LA Member No.: 21,628 Region Association: Southern California 
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I'd check the cold start valve.
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| brant |
Jun 24 2026, 09:43 AM
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#3
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914 Wizard Group: Members Posts: 12,218 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
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CHT and mps failure both cause excessive rich conditions
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| JamesM |
Jun 24 2026, 09:43 AM
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#4
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Advanced Member Group: Members Posts: 2,257 Joined: 6-April 06 From: Kearns, UT Member No.: 5,834 Region Association: Intermountain Region |
QUOTE(EJP914 @ Jun 24 2026, 07:10 AM)  Swapped in “adjusted” MPS. (Maybe still too rich?) I have not yet checked CHT sensor or cold start valve (may be stuck open?). Those are the three, but im leaning towards the MPS. For the cold start valve to be stuck open it would first have to open which takes either very cold temps, or a grounded out wire to TS1. Quick test, you could try unplugging the injector but I doubt that is your issue. CHT failures usually result in a no run condition. Rich to the point of having to floor it to keep it idling. |
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| emerygt350 |
Jun 24 2026, 10:08 AM
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#5
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Advanced Member Group: Members Posts: 3,646 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
Check you cht just in case. Easy peasy. Then check your mps. I am betting it doesn't hold vacuum.
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| burton73 |
Jun 24 2026, 10:30 AM
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#6
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Senior member, and old dude Group: Members Posts: 4,034 Joined: 2-January 07 From: Los Angeles Member No.: 7,414 Region Association: Southern California
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I don't know why your car is pumping too much fuel but, I want to point out that you definitely need to change your oil or you can spin a bearing. I did that in a MFI 911 way back when I was 27
Best Bob B |
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| emerygt350 |
Jun 24 2026, 02:01 PM
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#7
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Advanced Member Group: Members Posts: 3,646 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
QUOTE(burton73 @ Jun 24 2026, 10:30 AM) I don't know why your car is pumping too much fuel but, I want to point out that you definitely need to change your oil or you can spin a bearing. I did that in a MFI 911 way back when I was 27 Best Bob B Yeah. Check your oil... It may be mostly gas. |
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| wonkipop |
Jun 24 2026, 03:38 PM
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#8
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914 Guru Group: Members Posts: 5,573 Joined: 6-May 20 From: north antarctica Member No.: 24,231 Region Association: NineFourteenerVille
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another possibility. fuel pressure regulator diaphram failure.
can leak fuel back down the vac line into the air distributor plenum. |
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