Strange no start this morning

[greg92jeepxj]

I'm still a bit confused as you are . I was thinking the pressure to the needle and seat was too strong causing overflow bypassing the idle circuit and squirting raw fuel above the throttle blades due to excessive pressure . That is what usually happens when too much fuel enters the idle circuit , it overloads and in effect , overflows to the port above the idle mixture screws . That causes the raw fuel to flood the engine. Would have thought , as you'd expect to that the fuel pressure regulator should have cured that . One question ; have you just tee'd in the FPR alone or was the metering rods and jets re-installed ? If not , wondering how the FPR will work,out with the rods and jets back in .

 

[JPNinPA]

No disrespect. But, Could a fuel and vac line be swapped allowing fuel to be drawn directly into the intake? I pulled a diagram of the carb and if I have the correct one there is a vac line at the base that is the app size for a fuel line.

 

[Turbogus]

I dig Greg, but I never changed the jets, rods or springs from when it was running nominally.

No problem JPN, at this point even rude help would be welcome. At first I thought the same but I am certain of which line goes where.

 

[greg92jeepxj]

Ok , so the metering rods and jets are in place with the fuel,pressure regulator . The fact that there is still flooding is above strange at this point. I respect your trying to change float settings to a leaner set but hasn't achieved results . You've turned in the idle mixture screws full closed and that didn't help. Would you agree the fuel is just bypassing ? I believe you know this and are trying to find why . Wondering is there supposed to be a restriction on the inlet to reduce a rush of fuel into the float bowl ? That seems left field what I've just stated but it seems to me there is little to no control of the quantity of fuel flowing to the float bowl therefore going full rich . The only other thing I can think of is the metering rods themselves . Ok , just like when the power piston on a Quadrajet carb gets stuck full lean or full rich , the metering rods will do the same . Even if the rods in your AFB are free to move , could it be possible that vacuum is pulling them full rich when the engine is cranking and vacuum is strong ? I know where the vacuum port is on a Quadrajet for the metering rods but not certain for the AFB . This is something I meant to post earlier but was sidetracked and lost train of thought. Sorry about that. It seems that further exploring into the float bowl and maybe the throttle body portion of the carb need to be looked at ? Trying to remember how far you have gotten into this carb already besides the floats. I just keep thinking metering rods now and the vacuum port that controls the signal , idle and acceleration .

 

[greg92jeepxj]

Sorry , that was wrong . The metering rods are supposed to be pulled down ( lean ) at idle by the vacuum port. When vacuum decreases on acceleration ,'the rods open in response to vacuum signal. This has me thinking. Vacuum signal , throttle body , vacuum ports , thinking ......

 

[Turbogus]

You've turned in the idle mixture screws full closed and that didn't help. Would you agree the fuel is just bypassing ? I believe you know this and are trying to find why.

These Carter AFB's are unique that the "Mixture screws" control the air circuit, rather than fuel so even with them screwed all the way in the carb will still flow fuel as part of it's design.
The Metering rods reside in the Air Horn, the upper part of the AFB's with their three stage tips passing through to the Jets that are screwed in to the Throttle Body. They fit into channels in the Air Horn and are suspended by springs that are swappable for fine adjustments. In my case neither the rods, springs nor the jets were changed from when it was running fine. However in an earlier post I did mention the the secondary jets that thread into the float bowls were missing. At first I added a pair of jets that matched the primaries by numbers but they had no affect to the no start issue so I removed them and went back to normal float level to start over but this issue persists.
I noted that the fuel filter, all the years I've had this Jeep was reversed by the P.O. with steel fuel line covered by braided rubber fuel line. I took care of that last night.
Since I'm running out of ideas I can only guess that when I soaked the air horn and throttle body in a can of Carb Dip that I've had in my SAE rollaway may have gunked up a passage somewhere. After this I did blast both with spray can carb of fresh carb cleaner but again I'm dubious that this is the issue.

 

[greg92jeepxj]

That what I get for not reading back to previous posts for clarity . Sorry , so it was the secondary jets missing . Guessing the previous owner pulled out the secondary jets to get a richer mixture WOT ? Be that as it may , you've still got wet plugs and BB isn't running. Not to keep asking same questions repeatedly , but with the air horn off and carb mounted , engine off , do you feel the float needles are seated ? Questioning my understanding of this design . The mixture screws provide air to raise idle , not fuel . Thanks for clarification. If primary metering rods are either seats or at first step to allow fuel to idle circuit and accelerator plunger , would that mean the secondary jets are flowing raw fuel with no restriction from their metering rods due to jets not installed ? I don't think you would just do that know that would happen. I know you have a much better understanding of this carb and edelbrocks redesign from the original AFB . I don't think they've changed much other than the interchangeable jets and metering rods . I'm missing something , and possibly falsely accusing the secondaries of flooding the primary circuit . That's not supposed to happen . They're two separate circuits . Like two separate carbs . But I'm trying as you are to find the bleeder , or where the carb is internally hemmorraging . How far off am I ? I don't know whether to point at the floats , the rods , the mets or the passages . Stymied .

 

[greg92jeepxj]

Is it possible the secondary float chamber is responsible for flooding the engine ? That would mean the secondary float chamber would be low or dry with air honrn off , engine off . Maybe I'm thinking too much but trying to think where the raw fuel is coming from that is saturating the engine causing the no start . Am I wrong ?

 

[Turbogus]

There is a vertical baffle in the float bowls that may inhibit fuel surge but now I'm going to recheck the bowl vent for any blockage as this is the only step that's left inkeeping with the 'original state. Also going to reattach the choke housing fresh air tube line. I had forgotten about the latter until yesterday that my friend that I bought this AFB back from gave me the original installation guide from when I bought it new back in '88

Goes to show this IS a real AFB, a fun little time trip for me too.

 

[greg92jeepxj]

I don't know what had me thinking this carb was an Edelbrock . Well sir , you've got yourself a real vintage piece of carburetor there ! The wheels are always turning inside your head I can see. Knowing you can use that carb for more than one application ( bolt pattern aside ) , your just ready to make power with whatever your runnin' . 1988 . That was a good year for me too . But unfortunately it was the end of my party days . The next 26 1/2 years ( 2 1/2 to go to pension ) have been spent being in compliance in my safety sensitive position . 1988 was a good year. Well , back to the carburetor . So the plan is to go back in to make certain every part is doing its job and spruce it up so it properly ventilates if any condition like that exists. Well , that certainly can happen just like excessive crankcase pressure forces oil out of seals , raw gas can be forced through jets and gaskets as the fuel,pump is constantly pumping in gas under pressure great enough to keep the needle off the seat of there is no way to release this pressure out a vent tube or exit to a charcoal canister . I know you'll take a long , hard look at all when you crack the air horn . I'm actually waiting with baited breathe . Haven't seen an AFB in place since my early wrenching days in the junk yard. Everything after that was Holley double pumpers and quadra jets. Maybe a thermoquad or a stromberg once . Didn't cut my teeth on a stromberg so I opted out when someone asked if I can open one up . Was present when a thermoquad was being surgically opened up and that was like passing the bar in carb repair ! The more I think about it , the more I like your AFB carb. I just know that this problem can be rectified without much drama and theatrics since it's not too technical and mostly passages do the work. It a tuner's carb and I'm sure all will work right in your capable hands . Just don't like how Murphy's law is getting in the game here . Glad you schooled me on the principle of the inner workings of this model . My dad might remember this style of carb and how it's fed but he's spoiled by fuel injection now and hasn't laid a screwdriver to a mixture screw in a long time. So excessive pressure is our enemy now . That'll cause gas pains . Well mr. Turbogus , looking forward to you sipping this carb back into shape . Appreciate the detailed update . Thanks

 

[Turbogus]

Thanks for your encouraging words Greg, I've got an old crusty Holley in the wings so if cleaning up those spark plugs (again) and moving to smaller jets doesn't do it I will really be at a loss.

 

[greg92jeepxj]

Your welcome sir ! I do have full faith in you and my reason for following this thread is not only to try to give assistance with what carb experience I have but carburetors still interest me and i like following how this problem is working out . Frustrating as it is , I guess I still like the challenge ? Nice to know you got a back up carb though.

 

[Turbogus]

Well it turns out the carburator issue was only part of the equasion. Hi gang, been a while since I posted. 'Easy Bake' was in a collision and I've been wrapped up in insurance blues. Around the same time I had a stuck intake valve on my 360 and now that it's all repaired I'm installing the head using a Fel-Pro gasket. This sounds elemental but it's been over 20 years since I installed a cylinder head. I've cleaned all of the surfaces and the bolts, chased the threads in the block and now on to installing the cylinder head gasket.The instrustions in the Jeep TSM reads something like coat both sides of gasket with a non hardening sealer.
While the Fel-Pro instructions mention using sealer on the metal side. what gives?

 

[superj]

i never have and i have only used felpro gaskets. i guess reading the instruction sometime would have told me to do that but i never even looked at it.

the head gasket we did before thanksgiving is still fine though, no sealer used in it. its on a 4.0

 

[Turbogus]

Thanks SuperJ!
Keep this thread alive, need more opinions about that 360

 

[superj]

i use fel-pro on my old bmws and never used sealer either. and some of those are up around 5-800k miles now.


thats weird, to put sealer on a head gasket.

 

[Dragon5126]

to rule out ignition grab ye olde xenon timing light hook it up and put it on the coil to distributor cap wire. make sure it is ON so the strobe fires and either point it under the hood at the drivers seat or have someone else crank the engine, if the ignition is good you will get a continuous stream of flashes as the ignition fires as it would for every spark plug ( this is easier to see than just one post off the cap would be) it should be rhythmic and steady no gaps or jitters. Remember, trouble shooting isn't to find the problem, its to eliminate what the problem isn't, until you finally locate what it is. When its obvious ( car is sitting at an angle to the driver side rear, problem flat tire) it isn't really trouble shooting. Trouble shooting is for situations like this, where you don't have an obvious answer.

 

[Turbogus]

Last year, I think it was I posted a thread about and occasional 'spit' through the carburator. Thus began running through the primary electrical system, three rebuilds of the carburator only to find that the intake valve on No. 2 was stuck open by carbon.
Had that taken care of at a machine shop and upon reinstalling the head I noticed that 3 of 4 rocker bridges were bent to the degree that the rocker wasn't making direct contact with the center of the return spring. Reading the FSM about torqing these things incrementally left and right side I thought they may be brittle. With nothing to lose I put the bent ones in a vise and straightened them out with a wrench.
With that done I'm now having a hecofa time trying to get that damm power steering pump bracket bolted on again!

 

[Dragon5126]

The only good thing about electric power steering...

 

[Turbogus]

Well it's all back together and I've just got to change the oil and filter and I'm off to the races.