Back Firing

[tartan18]

Today I was replacing the windshield washer tubing in the engine compartment. When I started the car it ran very rough and then it back fired. The engine will idle about 850 rpm but the moment I try to add throttle it hesitates and sometimes quits. I tried to find out what I might have done to cause this problem -- no obvious disconnected wires or vacuum hoses.

Your suggestions on where I should check or what I should do. Thanks a lot !

[Exit98]

Check the easy stuff first. You probably already did, but spark plug and coil wires from the distributor and so forth. Vacumn lines.

[azruss]

this is a long shot. did you reverse the wiring on the washer pump. Also look around the area that you were messing with...like check hoses going to the vapor cannister. Think simple!
Corvallis, eh. Very nice town except you have to be a beaver fan. Go ducks! There are a couple of large steel buildings just south of hiway 34 as you approach the freeway. I designed and built that facility. Google says it is now Turf Merchants. Spent lots of time driving the back roads SE of Corvallis in my Spider and a semi pulling doubles.

[courtenay]

Are you fuel injected or carbed? If Fi, you might have disloged the big hose to the AFM. I had that happen with similar results to the problem you're having.

[mdrburchette]

I wonder if the distributor is locked down. It might have gotten bumped. More than likely though, a plug wire may be loose.

[tartan18]

Thanks for all of the suggestions but still no luck. I checked the distributor, vacuum lines -- all the obvious things but the strange thing is that I don't have any spark -- nothing from the distributor so obviously no combustion. I don't have a wiring diagram for the car (finding one for a 1975 is proving to be a challenge) so I would appreciate any additional ideas of what to check next. Much obliged for all the help thus far.

[So Cal Mark]

with no spark, did you check the primary wiring to the coil? The harness from the dist to the coil runs right in front of the cowl, so you may have pulled it loose or pinched it when replacing the cowl

[digitech]

Don't see how it runs rough/backfires with no spark.

[tartan18]

I should have clarified ... the car went from rough idle to backfiring and NOW it won't even start (no spark). I will re-check the wiring around the coil and distributor this morning. Yesterday ended with a very high level of frustration.

[RoyBatty]

You have probably had a failure of your points or condenser coincidental to your washer tube work.
Did you have the key on without running the engine to check your washer pump?
You may have arced the points.
Take a look at them and replace the combo if you find the points are burned.
My dual points distributor would run like you initially described until the car fully warmed up.
I installed a new condenser to the cold running set of points and all ran smooth after that.
Good luck.

[tartan18]

Roy, that is exactly what happened -- I tested the new windshield washer pump without starting the engine. I've cleaned the points and tried to start the car but still no spark. Because I am going to get Allison's new electronic ignition system I don't want to invest a lot of money in getting this dual point dizzy working but I would like the car to at least run until I can afford the electronic system. So I will keep looking for a solution. Thanks everyone for the ideas.

[tartan18]

To close out this tread -- the car is running great. It turned out exactly as suspected that the problem was the ignition coil was bad. Once it was replaced I had spark. Problem solved. Thanks everyone for your help.