A sign of a bad accel pump is a dead spot/hesitation or stalling like when pulling away from a dead stop.
If you give it a lot of gas sometimes it will back fire up thru the carb called a lean back fire but I have never seen it out the exh.


I would go back thru the firing order to make sure you did not get a plug wire mixed up when you did a plug and compression check.


Another test you can do but has some risk is to have the motor running and pull 1 plug wire at a time and see if it makes any difference on how it runs. If that hole is firing right the motor should slow down and shake a little till you get the wire back on the plug or in the cap.


I just thought of something. I had a car that had new plugs installed, bad carb. Motor was only run a few times to move the car around but sat most of the time.
Well 1 day needed to move it and it idled ok but would back fire out the exh. any time you gave it gas.


Because it sat I was thinking stuck exh valve but it idled good and a compression check was good also. So I did the plug wire test and found the dead hole. Moved plugs around and found the dead hole moved with the plug.
Installed a new set of plugs & wires as I was there and it runs great.
I don't know what went on with that 1 plug but the whole set got filed in the round bin!


So if your plugs were fouled, mine were not and looked brand new as the carb ran lean, they could be bad and look good like mine was and cause the back fire.
Dave ----

 

OK, truck much better now. I really thought this was carb related, as it starting not running well after the rebuild. Goes to show you not every idiot can rebuild one of these. Found this where he indicates venturi check ball/weight could cause my problems.
Motorcraft 2150 Technical

Pulled it off truck again (I am getting fast) and took apart that screw, weight and ball, and carefully put it back together. The only change. Put it back on truck, and drove it around block 3 times. There is some cold idle issues, but when I got back to house, it was idling on it's own which it has not done for some time. Put tach on it and it is at 950, higher than the 650 the label states.

I never adjusted the idle speed, and this is first time I have had a tach on it. I suppose it was always idling there, I will see if I can lower it and have it idle at 650. Then make adjustments with float level and idle adjustment.

 

Good to here you found the issue.
Yea 950 is a little high.
Lower it and adjust the 2 idle mixture screws again and see if that gets it better.
If you have a timing light I would check it also before calling it done.
Dave ----

 

Cool ! I'll call you when I need a quick 2150 "pit change" ! The cold idle issue might have to do with it needing a slight choke adjustment. Like Fuzz mentioned, 950 is a tad high at idle. I'd be comfy with it at 750-800 warm, 900-1k cold.

 

I just turned it down to 650, it is purring. The brake fluid to clean things off is needed before I break out the timing light .

When I put a vacuum gauge on it to adjust idle screw, is manifold vacuum what I want to look at, or a port off the carb? That plugged hose off the manifold is showing just shy of 20 lbs.

 

Good to hear it is purring!
Watch the brake fluid if you get it on paint it will act like paint remover.
Carb cleaner or brake cleaner, maybe that's what you meant, would be better to use.
Manifold vacuum and 20 HG is good.
Dave ----

 

Sorry, meant brake cleaner.

anyone know where to pull vacuum for gauge when adjusting idle adjustment screws on carb? I assume manifold, but maybe carb?

no biggie if not, I will just move gauge until I find somewhere it makes a difference.

 

agreed. I finally have some decent weather and the time to get back on this. It's still backfiring. Cleaned off the timing triangle marker, then put some nail polish on 10 BDC, per my radiator sticker.

And about the only place I can put a timing light is underneath it, but that works. Maybe I can prop it up somehow so when I'm above I can see it while adjusting distributor. But that is the current question. How?

This is what I think is the screw to loosen so I can twist distributor. Is this the correct screw, it is right above the vacuum connection.

 

No, not that screw; you want the bolt that requires a half-inch wrench down where the distributor base meets up with the block, below the vacuum advance can but above the water pump/timing case cover.

 

Ok, thanks, found this one (circled). Even found a 1/2" wrench that would fit it behind the AC compressor bracket. Loosened it, but the distributor cap will not move. Is that the wrong bolt, or just needs encouragement or what?

 

Wrong bolt. You want the bolt right under the dist. It pushes down on a fork looking plate that holds the dist in place.

You also need to find the pointer on the timing cover. That is where you need to shine the light. You can't shine the timing light anywhere you please, you have to be looking at the pointer. I know, it's hard to see down in there but it is possible to do it.

 

This is what you are looking for to loosen the distributor. This picture shows a nut and a stud, but most are just bolts.

 

Here's the timing pointer you are looking for. It may be on the driver's side or the pass side.

 

Thanks guys. I'm not sure I can see this bolt without taking off the AC compressor bracket, but I will see if my neck can crane some more.

I found the pointer, and it is almost impossible to point the timing light at it from above, if you do, your full attention needs to be on holding it, because it will be right next to radiator fan. I can point at it from below pretty easily, and I think see it from above.

 

You can not look from the bottom as the numbers are at top.

You also don't need to do both at the same time.
loosen the distributor so you can turn it by hand but will not move when running.
Then use the light to see where it is at.
If it needs to be changed stop using the light, turn the distributor a little then check again.
once set tighten distributor and check timing 1 last time.
Dave - - - -