Minor stumbling issue

[73F100Shortbed]

Ok guys give me your suggestions because I've been living with this issue for about 4 years or so. When I'm driving at slower speeds mainly I get a slight stumbling around 2200rpms or so. If I slow down or speed up it usually goes away. It isn't a huge deal just slightly annoying and I figure it is time to start looking into it a little more.

Here is what I have done so far:

-The distributor was replaced due to oil leaking on the points

-Timing is good

-Tune-up literally done about two weeks ago

-I had an issue where the points gap opened and made the problem like 50times worse. I fixed that.

-Today I bought a dwell meter to actually check the dwell instead of just points gap. It is right at 24 degrees (good according to Autozone website).

-I have two fuel filters. Both replaced 2 weeks ago.

-I've adjusted the fuel mixture to see if there is a difference and it doesn't really make a difference in relation to the stumble.

-I changed the accelerator pump that Ben suggested. That didn't help, but the old one was dry rotted so it wasn't a waste either.

I'm thinking of rebuilding the carburetor, but I don't want to unless necessary because otherwise it is working just fine. I think it is fuel related and the carb. is the only thing untouched between two engines.

 

[blacksnapon]

I know it sounds strange, but make sure #7 and #8 plug wire aren't routed close to each other.

 

[73F100Shortbed]

Not strange at all. I thought that was just more of an issue on Chevys. I will move them because they are routed right next to each other in the wire looms. Thanks

 

[LEB Ben]

Damn...I really thought that AP was gonna be the ticket. Choke is good? With the throttle at WOT, do the butterflies on the bottom open to 90*? Beyond that, I'd say a carb rebuild.

 

[73F100Shortbed]

Choke is fine and at wide open throttle the only problem I have is my gas gauge moves faster than the tach

I'm gonna move the wires like Vince suggested. I never even thought about that. Yet alwasy watched for it on chevys. Go figure

But my original thought was carb. rebuild too.

 

[Truckin4life]

From reading the title of the thread sounds like you need to pick up your feet.

 

[73F100Shortbed]

From reading the title of the thread sounds like you need to pick up your feet.

I finally post my first technical question in a long time on here and 5 posts in I'm already being harassed

 

[LEB Ben]

Sean...it would be a reach, but you think you may have a float problem?

 

[Alvin in AZ]

Is the carburetor a 2100 or 2150?
If so...
The fuel level should be about 7/8" below the edge of the bowl.
Raise it way up and see if it fixes the stumble.
If the "too high" of fuel level smooths it out...
I got a fix for that.

Ream the low speed circuit jets out using jet-reamers or welding
tip cleaners. A guy needs to know what he's got first so he can
make sense of the size change/s he makes.

Worked for me and many others "back when" the problem was
common, because guys I knew were still running these things
stock.

If it's a Carter... good luck getting rid of the stumble! LOL

Most guys just increase the "accelerator pump" shot.
Well, problem with that is, that thing is for -acceleration- not to
adjust the mixture while running it around just off idle, see?

I may be way off target here, but hope this helps you understand
what's going on so you can at least say "it ain't that". At least
that'd be a step forward from where you are?

Alvin in AZ

 

[73F100Shortbed]

Ben and Alvin I will look into that. I don't believe it is a float problem because it never acts flooded like there was too much gas. Never saw any gas leaking as if the carb. was too full or anything like that and it doesn't act like there isn't enough gas. I can floor it from a dead stop and it won't stumble or anything like that. I can drive highway speeds without an issue. It only seems around town mainly. I tried Vince's suggestion of moving the plug wires and I will see how that works on Saturday when I take it to a concert I'm going to. If that doesn't fix it I think I will be taking the carb. apart and I'll check the bowl level and all of that stuff.

 

[Alvin in AZ]

Yeah but.
What kinda carburetor is it?

 

[73F100Shortbed]

That I would have to look. I know it's a motorcraft but not sure which model.

 

[73F100Shortbed]

UPDATE:

I moved spark plug wires around like Vince suggested. When I drove today it ran really well for awhile. I drove about an hour to go to a concert and about '25 minutes away from my destination the truck started running rough and wouldn't rev past 2500rpms. It also backfired about 3 times out of the exhaust. Since we were in Camden my sister thought someone was shooting at us . I figured the points gap opened again, but kept on going because I wanted to avoid stopping on the side of the highway with my sister in the truck. We made it to the concert. When I left it was running fine again until I got on the highway and it starting running rough again for about 25 minutes or so then it got better again. I'm assuming the points gap didn't open since it would get better. I will check the dwell tomorrow and see if it changed and if it did I'll look at the points again. I'll pick up a carb. rebuild kit this week and I guess it won't hurt to change the fuel pump as well even though it is only 2 or 3 years old. Is there anything else I should check before the carb.? I think I went through just about everything.

On a better note even with it running all messed up someone stopped me in a fairly new Dodge to tell me how cool my truck was LOL

 

[lostinfords]

Camden...sure it wasn't shooting.....you ain't supposed to go to them neck of the woods unless you have kin folk der.... kind of like kentucky/tenn/wv area..., is the timing advancing at 2200 rpms? I usually set my timing by ear, maybe check to see if it is pulling vacuum at that rpm...assuming that you have vacuum advance...thay had that w/ points too....? right???

 

[73F100Shortbed]

LOL went to a concert there. Yes it has vacuum advance. I will see if it pulls vacuum and I will pull vacuum on the distributor to make sure it advances. That is a good suggestion.

 

[lostinfords]

would've been safer and cheaper w/ sirius radio in the parking lot near home.....

 

[73F100Shortbed]

would've been safer and cheaper w/ sirius radio in the parking lot near home.....

True but it's not that adventurous near my house

I checked the dwell and it is still right at 24. I will have to get my vacuum gauge and vacuum pump tomorrow probably as it's not at the house. Sucks having tools in more than one spot.

 

[Alvin in AZ]

Intermittent trouble,
backfiring out the exhaust and
not wanting to run above 2200 rpm
and kinda clears up after it sits.

Hmmm...
Trash in the fuel bowl?
Bad ignition wire/s? (they can be checked with an ohm meter)
What else you guys?

Alvin in AZ

 

[73F100Shortbed]

I'm going to take carb. apart this week. I'm not sure about it being bad wires though. I replaced them a few weeks ago and they have maybe 300 miles on them. I can check them though I suppose. I'll have to remember to get my multimeter tomorrow as well.

 

[blacksnapon]

Something I had to do quite frequently with point type ignition was to replace the mounting plate for the points. The pivot point tended to elongate. It was a bad enough problem that you can purchase just that part of the distributor.