Intermittent “Lean Spikes” on Air/Fuel Ratio Gauge...

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RockyUSA
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Joined: Sun Jul 03, 2016 10:10 am
Location: Tucson, Arizona, USA

Re: Intermittent “Lean Spikes” on Air/Fuel Ratio Gauge...

Post by RockyUSA »

Fuel delivery problem solved:

* New Carter M6903 Fuel Pump (Mancini Racing)
* New fuel pump pushrod (probably my primary problem)
* Metal 3/8" Stainless Steel Supply line all the way to the tank
- Insulated as it passes behind the exhaust, all the way to the carb
* Metal 5/16" SS return line all the way to the tank

Lots more clean-up and "fettling".

I am certain I am getting at least 15 more horsepower from my engine! 8) (Or at least I hope so, because this project was a LOT more work than I was planning on!)

Rocky
‘71 TVR Vixen 2500 - (M Series Tribute)
'72 Interceptor III - 133/5597
'73 DeTomaso Pantera
'74 Toyota Land Cruiser FJ-40
'95 Jaguar XJS Convertible
Moparguy
Posts: 18
Joined: Wed Jan 16, 2019 3:06 pm
Location: USA

Re: Intermittent “Lean Spikes” on Air/Fuel Ratio Gauge...

Post by Moparguy »

a carb is NOT fuel injection , dont expect to see one behave as such
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RockyUSA
Posts: 1653
Joined: Sun Jul 03, 2016 10:10 am
Location: Tucson, Arizona, USA

Re: Intermittent “Lean Spikes” on Air/Fuel Ratio Gauge...

Post by RockyUSA »

The little smiley faces are indications of a things called "jokes"....

:)

Rocky
‘71 TVR Vixen 2500 - (M Series Tribute)
'72 Interceptor III - 133/5597
'73 DeTomaso Pantera
'74 Toyota Land Cruiser FJ-40
'95 Jaguar XJS Convertible
Joe Schiavone
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Joined: Wed Apr 30, 2014 7:28 pm
Location: United States

Re: Intermittent “Lean Spikes” on Air/Fuel Ratio Gauge...

Post by Joe Schiavone »

If you go with an Elec pump going through the mechanical pump you may want to replace the mechanical pump at a designated time in years. The downside of both is the diaphragm in the mechanical pump rupturing and allowing the gas from the elec pump diluting the oil. Do not know the appearance on the dip stick probably not likely. Just something to think about. RacerJoe
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RockyUSA
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Joined: Sun Jul 03, 2016 10:10 am
Location: Tucson, Arizona, USA

Re: Intermittent “Lean Spikes” on Air/Fuel Ratio Gauge...

Post by RockyUSA »

Mystery Solved:

I learned that the way an Air / Fuel (A/F) Meter works - the system is ONLY looking at the oxygen levels for the determination of a Lean / Rich condition. So if you have intermittent ignition (which actually puts out pulses of exhaust that are too rich, as the fuel is not burned) - the sensor reports it as too lean (because there's a lot more uncombined O2 in the gas stream. This is because the sensor can't assess how much hydrocarbons are passing the sensor.

So my "intermittent lean spikes" were being caused by an intermittent ignition issue - since corrected.

Rocky
‘71 TVR Vixen 2500 - (M Series Tribute)
'72 Interceptor III - 133/5597
'73 DeTomaso Pantera
'74 Toyota Land Cruiser FJ-40
'95 Jaguar XJS Convertible
User avatar
RockyUSA
Posts: 1653
Joined: Sun Jul 03, 2016 10:10 am
Location: Tucson, Arizona, USA

Re: Intermittent “Lean Spikes” on Air/Fuel Ratio Gauge...

Post by RockyUSA »

Unbelievable what you can find...

In a recently posted document on the JOC Board...

"001-JML-Interceptor-Mechanics-Course-Notes-J-Series.pdf"

Interesting info on the Fuel Pump Pushrod, and exhaust manifolds! I am sure there is a lot more!

Rocky
Fuel_Pump_Pushrod_Issue_Jensen.JPG
Fuel_Pump_Pushrod_Issue_Jensen.JPG (128.74 KiB) Viewed 1739 times
IMG_0491_Fuel_Pump_Pushrod - Cropped.JPG
IMG_0491_Fuel_Pump_Pushrod - Cropped.JPG (43.63 KiB) Viewed 1739 times
‘71 TVR Vixen 2500 - (M Series Tribute)
'72 Interceptor III - 133/5597
'73 DeTomaso Pantera
'74 Toyota Land Cruiser FJ-40
'95 Jaguar XJS Convertible
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