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Posted by: thon3720 Mar 7 2008, 10:40 PM

I have a 73 2.0l with stock FI. I got the car after it has been sitting for about 10 yrs. After gettting it to run I changed the oil, cap, plug wires, plugs, and fuel filter. The car starts and runs every day but after 50-100 miles it starts to run rough and looses power. It still will start every day without trouble and idles fine. The only item the previous owner replaced that he thought was the problem was the pressure sensor. Any help would be appreciated.

Posted by: dw914er Mar 8 2008, 05:02 AM

mine will idle a bit rough (low) after it gets pretty warmed up, but that is because i have the fuel pump in the stock location, so it tends to suffer from vapor lock

Posted by: ejm Mar 8 2008, 05:43 AM

Could be fuel starvation. There is a screen in the bottom of the tank on the fuel outlet. Look throught the filler hole with a strong flashlight and see if there's a lot of sediment in the tank.




Vapor lock causes hard starting because heat creates bubbles in the fuel. Your low idle is most likely something else.

Posted by: dflesburg Mar 8 2008, 06:12 AM

Have you tested your fuel pressure. Should be 28 psi but in hotter climates up to 31psi would be acceptable. Could be anything from weak pump, bad MPS or clogged filter.

good luck

Posted by: hi4head Mar 8 2008, 07:50 AM

In the title to your note you mention "fouling plugs".

Have you taken them out and looked at them? How do they look and does each look similar? (i.e. wet, black and sooty, dry and brown, etc.)

Chris

Posted by: 73Phoenix20 Mar 8 2008, 08:39 AM

Sounds like something is causing the "Brain" to go rich after warmup...

Cylinder Head Temp Sensor???

Manifold Air Pressure Sensor???

Check those out first....

Posted by: Rand Mar 8 2008, 10:40 AM

How would running rough and fouling plugs be caused by fuel starvation or low fuel pressure or bad pump or clogged fuel filter? Wouldn't those be more likely to cause a lean mixture? I would think the symptoms mentioned would be more likely to be caused by the opposite.

Rich mixture things to check would be:
Does the MPS hold a vacuum?
Is MPS vacuum hose in good shape and connected properly?
Temp sensors good?
CSV leaky?
Fuel pressure too high? (over 30psi?)

And Ben, I agree with Ed on the vapor lock issue.

Posted by: Jeffs9146 Mar 8 2008, 11:40 AM

Step #1 check the plugs
Step #2 check the points
Step #3 check the filters/screens
Step #4 check vacume lines
Step #5 check CHTS
Step #6 keep checking stuff!!

Posted by: dw914er Mar 8 2008, 02:59 PM

ahh, yea, the hard start


i am thinking of recently, with my fi leak on the intake runners, those are causing that


(dont worry, i am going to fix them next week when i am back in town)

Posted by: Rand Mar 8 2008, 03:05 PM

To the original poster, thon3720: Your car sat ten years, and your symptoms aren't too bad - replace the rubber hoses that have deteriorated, starting with the MPS hose. And vacuum test that MPS. (Simple to do with a "mityvac" or such.... Just pull a vacuum on it and see if it holds.)