Poor MPG!

Ligotino1 · Post by **Ligotino1** » Wed Feb 18, 2009 1:47 pm

The spring itch is upon me and my mission is to get my 81 Spider back to normal. This is a wonderful car that used to get 30mpg despite having problems starting when cold. I resolved the cold start problem a couple of years ago but the mpg is in the toilet. Too many years have passed since the car ran 100% and I have done many things to fix it. I currently have the "ex fuel sensor" light on and I want it off

I called IAP and asked a sales rep for some advice and he thought it might be the cold start injector stuck open all the time. I replaced this injector several years ago from IAP but I have had no luck with electronics from IAP, has anyone else experienced a similar problem and poor mpg because of this injector?

htchevyii · Post by **htchevyii** » Wed Feb 18, 2009 2:52 pm

The light comes on at a preset mileage, there is a blk box under the drivers dash with a reset button. Oxygen sensors are cheap and wear out. I would think it would run very rich if the cold start inj was stuck. I wonder if the coolent temp sensor could cause this?

mdrburchette · Post by **mdrburchette** » Wed Feb 18, 2009 3:14 pm

I would think the O2 sensor would cause a rich condition too if it were faulty. Can you tell if it's running rich?

So Cal Mark · Post by **So Cal Mark** » Wed Feb 18, 2009 3:40 pm

without at least a volt/ohmmeter you will be reduced to swapping parts in trial and error. Possible causes could be AFM, temp sensor, pressure regulator, vacuum advance, catalytic converter, thermo time switch, injectors, fuel hoses or brake drag, etc. Sorry for the vague answer, but you've given nothing to do any diagnosis with

Ligotino1 · Post by **Ligotino1** » Thu Feb 19, 2009 7:10 pm

With the exception of the two sensors located on the top of the head I have changed them all. The thermo time switch has been replaced twice. I have just recently replaced the O2 sensor and it had no effect on the MPG. I replaced all the injectors and tested the pressure regulator valve. I smell rich exhaust on downhill descents but when it idols it spews carbon and fuel odor/water from the exhaust.

Ligotino1 · Post by **Ligotino1** » Thu Feb 19, 2009 7:22 pm

I also have a voltmeter and ohmmeter. The ohm reading across the two post of the cold start injector is 1. does anyone know what it should be?

adrians · Post by **adrians** » Thu Feb 19, 2009 8:08 pm

Ligotino1

Every bit of information you'll ever need about the Spider Fuel Injection system - including trouble shooting.

http://www.artigue.com/fiat/pubs/Artigu ... 124_MM.pdf

Regards

Ligotino1 · Post by **Ligotino1** » Thu Feb 19, 2009 8:59 pm

Thank you very much, I cannot wait to read this. The shop manual is completely useless unless you need to know how to replace something!

Ligotino1 · Post by **Ligotino1** » Wed Feb 25, 2009 2:14 pm

I just reinstalled the battery today from a long winter nap and tested the cold start injector (it worked fine). According to adrians troubleshooting manual (thank you very much it has been a great help!) I have to check the the ohms of the temp sensor and the fuel pressure. I also reset the ex fuel sensor light, what a relief thank you for that post on the reset button location. I thought the two might have been related. Does anyone know what the reading for the O2 sensor should be at different temperatures?

Poor MPG!

Poor MPG!

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