'85 FJ60 "popping" @ carb and runnin poorly

[WNCskydiver]

Hey a newbie here, that is new to the forum and LC ownership. Bought a '85 FJ60 about a month back and it has been running PERFECT put about a 1,000 miles on it and then...

It's an '85 FJ60 with a 2F motor, seems to be "desmogged" though I am not certain. Has a Holley Carb model 7448 (350 cfm) Headers and no cat converter. Drove it all over last Sunday even towed my boat a very short distance to launch it and ran great. Stopped for some dinner about and hour stop or so and when i started it back up it ran like total Pi$$. Seemed like it was missing and had a major loss of power. When you punch the gas form an idle it makes a "pop" noise at the carb even has a blow back of fuel. I first check for quick obvious vac leaks, tried some carb cleaner etc. you know gas station 10 pm kinda stuff nothing.

I have replaced the plugs, plug wires, Dist. cap and rotor button, had no change what so ever.

I'll admit I am probably in over my head working on this thing too much, BUT I thought maybe the noise/fuel blow back at the carb might be a good clue for some of you FAR more gifted and knowledgable wrench's than I.

Any help would be great otherwise I gotta find a good mechanic here in Western NC.

Thanks

 

[D'Animal]

It sounds to me like you may have knocked some carbon loose and it is bouncing around in the valve seat area or you distributor is cracked.


Did you adjust the valves?

 

[lehiguy]

It's a Holly carb. Start there. There are four screws in the front that will reveal pretty much everything. Check for debris stuck in the jets, check the power valve (the round thing with a diaphram in it) to make sure it isn't torn. Make sure the choke is staying off. Downey is the place to go for Holly stuff, they claim to be able to make them work very well. They are not very complex, in fact, they are the simplest carbs I have ever seen, but they are not my favorites.

 

[90FJ62]

WNCskydiver
There area few of us cruserheads around the Asheville area. Send me a PM if you still need a mechanic.

Dave

 

[D'Animal]

Even though it is a Holley Carb, They generally do not go bad during dinner.

It's a Holly carb. Start there.

He pulled a load and then ran into the problem. You may be right about some debris since his secondaries probably have not been opened up in awhile.

 

[lehiguy]

Even though it is a Holley Carb, They generally do not go bad during dinner.





He pulled a load and then ran into the problem. You may be right about some debris since his secondaries probably have not been opened up in awhile.

There are no secondaries on this carb.

 

[D'Animal]

There are no secondaries on this carb.

LMAO

Rules that out then.

 

[lehiguy]

LMAO

Rules that out then.

There were times when I was in the unfortunate situation of having a Holly on a Cruiser, when there seemed to be absolutely nothing amiss, yet it ran like poo. Then it would "self heal" and run well again. I hated them! Rochesters and Webers never throw tantrums like Hollys do.

 

[D'Animal]

My Holley 350 with the "Off-Road" kit runs great unless you are beyond a 38degree slope. Then it stummbles a but. I could eliminate the stumble if I extended the pipe.

There were times when I was in the unfortunate situation of having a Holly on a Cruiser, when there seemed to be absolutely nothing amiss, yet it ran like poo. Then it would "self heal" and run well again. I hated them! Rochesters and Webers never throw tantrums like Hollys do.

 

[Heartworm]

Did you set your ignition timing when you changed out the parts? The popping you are hearing is not a backfire is it?

 

[D'Animal]

Bad sparkplug.

I had a new Autolite that would slip the insulator cone when hot. It was a bear to find the problem.

 

[lehiguy]

My Holley 350 with the "Off-Road" kit runs great unless you are beyond a 38degree slope. Then it stummbles a but. I could eliminate the stumble if I extended the pipe.

I still feel the sting of defeat from the Holly. When it was in a good mood, it ran super strong, but it was inconsistent. I would like to try again just to verify my manhood is intact, but now I have a 350 with TBI and no 2F to practice on. I pride myself on my carb tuning abilities, but that one just never got to the point where I was satisfied. Oh well!

 

[D'Animal]

I still feel the sting of defeat from the Holly. When it was in a good mood, it ran super strong, but it was inconsistent. I would like to try again just to verify my manhood is intact, but now I have a 350 with TBI and no 2F to practice on. I pride myself on my carb tuning abilities, but that one just never got to the point where I was satisfied. Oh well!

Owning and running a Holley and chasing vacuum leaks is like having two wifes. When one is happy, the other is not. When they are both happy, well, it won't last for long.

 

[WNCskydiver]

Sorry been gone for a bit...

Heartworm: The problem occurred before changing parts (d-cap, rotor, plugs, wires) but NO I did not adjust timing. The "pop" is not a backfire so to speak as there is not an ignition. With the breather off a mist of fuel will actually spit back up through the carb.

D'animal: Since i replaced plugs after the problem, with no change, I have ruled out a bad plug. I have NOT adjusted valves.

Lehiguy: I think the next step indeed is to begin to disect the carb. Check for debris, though i see no need for major adjustment as it was great one minute and crappy the next?

As for vaccum leaks I have done a visual, touchy feelt check and found nothing. Fortunately this thing is desmogged and far fewer vaclines to chase. Though I do have one "vacant" vac line hiorn on D-cap any guesses what went/goes there???

 

[Heartworm]

Any chance that an intake valve is sticking open? Sporadically prehaps?

 

[lehiguy]

If you are backfiring through the carb, it is likely too lean, meaning something is resricting fuel flow through the carb. It really is a simple thing to take apart and the gaskets usually survive several removals without disintegrating, but they are easy to find at any auto parts store that has performance stuff. You might want to contact Downey and get the spring-loaded needle and the high elevation power valve anlong with the vent baffle and the vent chimney. If you don't have those things, off-road will be hell.

 

[WNCskydiver]

lehiguy

I too have suspected a problem at the carb from the very start. I am aware though that carb problems are often the first blame, but not always the culprit.
Last night I did remove front cover for carb and look for any trash/obstructions and none were visible. I also checked float movement and level, both seemed correct. I will remove carb completly to get a better look inside as soon as time allows. Although is it better to try and check operation with carb installed????? The gaskets will need to be replaced as the one i removed so far fell into about 5 pieces.

 

[WNCskydiver]

Speaking of my "first suspect".....
What about bad fuel??? On the day the problem started I ran the tank pretty low and then filled completely, with 89 octane fuel. This would have been my first suspect for sure except the fact that I drove another 25-35 miles after fueling before problem started.
Could/would it take this long for new fuel from tank to reach engine and begin to be consumed????
Would bad fuel cause the "backfire" through the carb??

 

[WNCskydiver]

Update: Tanked up on new fuel and used STP additive then put miles and time on engine with no change. So ruling out "bad gas" I'm still stumped.

 

[90FJ62]

There are a bunch of us meeting Thursday Night at the Chili's on Tunnel. Bring it by and i bet we can get you pointed int eh right direction.

Dave