Anna, so you essentially did a "downgrade" from the feedback setup to the older dsII system? I use that term loosely as the feedback carb stuff of the mid 80's was a terrible idea. All the carb'd vehicles I have ever owned have had drivability problems I was never able to figure out. So I'd need to swap out the dizzy, and the spark module?

 

The rig only has 108k on it. Would the timing chain be worn already? Either way, perhaps I'll do the test tomorrow. Got to grab my tools from work. I should note, it doesn't do this when cold, only when it's warmed up. It has a fluctuating idle when it's cold though.

 

One diagnosis of a vac gauge needle that increases like that iirc, is an exhaust restriction.

Not saying that this is your problem for sure, but check the directions that came with the vacuum gauge. One possibility is that the catalytic converter is partially plugged? Worth eliminating as a factor.

 

no offense, rusty, I thought perhaps you meant to post on another topic. I recently did a fluid/filter change on the tranny

 

108k is plenty of time for the timing chain to go stretchy.

 

Yes it could be called a downgrade... But is the long run I believe it is a much more stable system with much less maintenance problems. Parts for the TFI feedback system are much harder to find these days. As for the DSII ignition, I searched around and found that you can still buy Motorcraft ignition modules instead of getting a after market ones, I bought a Motorcraft module for mine.

Yes you would have to change to a Duraspark dizzy and module. You also have to change to a DSII wiring harness. The good news is that the 85 e150 is already wired for either TFI or DSII ignitions. In 1985 the e150 with a 302 engine had the tfi ignition with feedsback carb while the 85, 86, and maybe 87, 351 and larger engines used the DSII ignition... Essentially once you have a DSII harness, it is plug and play. Finding a DSII harness is the problem. I wound up with 3 different harnesses from junk yards before I found the plug and play harness.
Knowing what I know now, I would have just made my own harness. Which brings up the subject of connectors, you do not have to use the stock connectors used in 1985, they can be changed out to newer style connectors pretty easy.

Here is the thread where I did my DSII ignition swap.
https://www.ford-trucks.com/forums/1...eeclv-tfi.html

Now most of it is pretty simple now that I understand the wireing.. Mine is still not finished though. I swapped the dizzy, coil, harness, added the module, set the timing, and went for a ride around town. It was doing great and so I stopped and filled up the tank with gas. Later that day the engine quit running due to a fuel problem. It had quit once before with half a tank of gas in it. I believe that the fuel sending unit pick up tube is rusted into or has a hole in it.. I spent the next month getting parts. I ordered a new fuel tank, sending unit, tank vent valve, fuel filler hose, and non feedback carburetor. By that time It got too hot down south here for me to work on it outside. now that it has cooled down I plan to get back to it..
I took the engine cover off and ran a fuel line from the pump up into the cab and dropped the end into a gas can.. It starts and I can move it around that way so it is not just sitting...

I am leaving the EGR on mine so it has to be changed too as the one on the TFI ignition is controlled by the EEC. I picked one up at the junk yard off of an 84.. You will also have to rerout some vacuum lines to make the EVAP system work.. I am lucky as I have my mothers 78 E100 to look at!

If you do decide to swap ignitions, one thing to think about is emissions testing in your state. Over 25 and you dont have to worry about it here in GA. I have read that as long as you leave the cat and smog pump hooked up, that it will pass emission testing as long as they don’t do a visual inspection looking for the TFI ignition on a 1985.

once the conversion is done the engine compartment will be much cleaner with all the extra wiring and vacuum lines gone!

 

I'm going through with the DSII conversion. So far, I've got a carb that I need to rebuild, a distributor, a couple wiring harnesses, and a DSII module. Need to sort the wiring out I suppose.