Help with '72 1.7 FI issues, again! Options

[BK911]

Ok, I think I am giving up with the stock FI. It ran awesome up until about a week ago. When the car is cold, it bucks at a constant speed but runs awesome at full throttle. As it warms up, it bucks slightly at constant speed, but doesn’t want to accelerate. Almost seems like a fuel filter issue, but the filter is new and it runs at WOT when cold. The MPS holds vacuum. The CHT Ohm’d out fine, but I replaced it anyway with the same results. Leakdown ~10% across the board. I didn’t verify the ignition or fuel pressure yet, but they were right on last time I checked. All new vacuum and fuel lines.

According to the FI bible, it sounds like it could be the trigger points. So I am going to pull them and clean them up. Do I need to remove the dizzy to get the points out? I’ve cleaned them before and seem to recall it was much easier with the dizzy removed.

The trigger points are about $150. That’s about 1/3 way to a new set of carbs. I have a core 2.0 I was going to build up with carbs, so should I just get the carbs now? So I save $150 and will use the carbs when I build up the 2.0. Or maybe go with some sort of EFI?

The reason I bought this car was because it had the original FI. I would like to keep it, but I am getting tired of working on it. As soon as I get it running well, something else goes wrong. I would appreciate any input. What would you do?

Thanks,
BK

[Rod]

Sounds like your throttle position sensor is a bit worn.

A member on here makes them for the 2.0 mdel and he has promised me one for my 1.7l so hopefully he'll make some soon enough.

The tell tale signs are bucking/rough running at part throttle, your symptoms basically.... this will be considerably less than a twin carb setup and I too would stick with fi.

[TravisNeff]

For a test, unplug your TPS and take it for a drive. If the bucking is gone, that is your problem.

Finding a replacement might be tough. You can clean it up with spray contact cleaner (I heard an pencil eraser works too). You may need to move the fingers a little to a new contact patch if there is a bad groove worn.

Once you put it back in you need to calibrate it (there is an article on pelicanparts for the 1.7 calibration)

[BK911]

Thanks guys, I just read about 10 pages of stuff on the TPS. Looks like I will be having some fun tonight!

Hard to believe there isn't some 'paint' that you can repaint the contact patch. PBAs document lists a couple of things. I'll try to fix it first, then go from there.

[BK911]

You may need to move the fingers a little to a new contact patch if there is a bad groove worn.

Thanks! I moved the fingers a bit and it made a noticable difference. It's not perfect, but much better. I think I am on the right track though.

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