I have a 75 1.8L and am having a problem with a intermittent loss of power and bucking.

Car typically runs fine at first when cold, plenty of power but very soon has some bucking / loss of power under acceleration. The problem will either go away for awhile or turn to a constant loss of power(about 1/3 loss). Once the power goes it usually does not come back until after the car has sat overnight.

its all stock 1.8 with fuel injection except Ignitor electronic ignition. I'm thinking perhaps something fuel or vacuum related but am all that experienced running these sorts of things down.

Any suggestions of recommended paths of troubleshooting?

Mike,

I had a siomething like that when one of the wires on the dual relay got loose. The feul pump was not getting constant 12v. Ended up mounting the dual relay on the fire wall so I can keep an eye on the wires.

Sounds 99% fuel related

Check pump , replace filter and clean screen on the tank pickup. Check bottom of tank for carrot juice sludge

I had intermittent power loss....would run fine then all of a sudden it felt like it was running on three cylinders (75 1.8l here). Turns out I had loose connections on the fuel injectors. I finally caught it at idle running bad, pulled plug wires until I found what cylinder wasn't running...then happened to jiggle the fuel injector wire at the connector and it popped back on. Old wires, old connectors...sometimes leads to issues.

I had a spark plug wire do something like that. It checked out fine and ran great for about 10 minutes and then bucking and rough running and all.......

Left overnight.... it healed itself. Seemed the conductor in the wire turned into a non-conductor when hot....

When your car is bucking, pull over and pull the plug wires off one at a time while the engine is running. When you pull one off and nothing happens, that's the problem cylinder.

Try swapping out the plug wire for that cylinder. I always save the longest old plug wire when I put on a new set and keep it in the car for troubleshooting.

Ken

Thanks!

I have a new fuel pump, filter and plug wires.... It does look like one cylinder is not working properly. THe one hardest to get to under the air intake box. I do happen to have one new injector which I will try this week.

I was having similar issues. I'd pull each plug wire and injector plug to see what wasn't working. it ended up being an injector. I traced the wires back and found that one of the ground plugs for the injectors was on the brink of breaking (probably the cause for the idle roughness). replaced all the injector ground connectors with new ones and no more issue!
Silly place for a ground crown...

It could be a warped flapper in the Air Fuel Meter (usually caused by a backfire).

Engine warms up, the metal case for the AFM expands and the flapper starts starts to drag or get hung-up.

This is easy enough to check. With the engine hot, try manually operating the flapper with your fingers and see if the movement is smooth.

Another thing to try is testing the spray pattern from the injector. I did this recently and found one squirting instead of spraying. Helps to have a friend there to crank while you are watching the injectors. Use 2 small glasses and do 2 injectors at the same time. Don't forget to remove the HT wire from the coil. Don't remove the points wire. This will prevent any injectors from working.

It looks like it was a Fuel injector. I had bought one a year or so ago to have a spare and it came in handy. What the opinion out there about replacing only one injector? SHould I also do the other 3?

Thanks!