fuel level and performance

[thistle3585]

My engine is acting as if its not getting enough fuel. The fuel level is about .5" from the top of the bowl. With the air horn off, if I push on the float and increase the fuel level then it idles more evenly and when I rev it up it doesn't pause or sputter. The problem is that I can't bend the fuel filter tab for the float to ride high enough to allow the fuel level to rise higher. The float hits the air horn. I just recently bought a rebuilt carb and have gone through the carb several times to make sure it was clean. The fuel/air mixture needle valves are set properly. I'm thinking that either the jets are the wrong size or possibly my timing is way off. Right now the timing is at 12. Shouldn't I be at 6-8? Do I set the timing then tweek the carb or vice versa? I believe the jets are either 44 or 46, but need to check on that.

 

[Lumpy Grits]

When's the last time you changed the fuel filter?
Or had your fuel pump tested for psi?
LG

 

[thistle3585]

I just put a new fuel filter on and I have an inline gauge that shows the pump to be operating about 6-7 psi. I do have a fuel filter before and after the pump. I also recently replaced the sending unit.

 

[Lumpy Grits]

Have you ck'd for vacuum leaks?
Are all the intake manifold bolts tight?
LG

 

[Fastatv]

My engine is acting as if its not getting enough fuel. The fuel level is about .5" from the top of the bowl. With the air horn off, if I push on the float and increase the fuel level then it idles more evenly and when I rev it up it doesn't pause or sputter. The problem is that I can't bend the fuel filter tab for the float to ride high enough to allow the fuel level to rise higher. The float hits the air horn. I just recently bought a rebuilt carb and have gone through the carb several times to make sure it was clean. The fuel/air mixture needle valves are set properly. I'm thinking that either the jets are the wrong size or possibly my timing is way off. Right now the timing is at 12. Shouldn't I be at 6-8? Do I set the timing then tweek the carb or vice versa? I believe the jets are either 44 or 46, but need to check on that.

I had a similar problem on a my AMC 360 and a MC2150 carb. It would not idle correctly unless I had the float set higher than spec. Dang-dist thing to me as I am def a carb guy. Anyway, I got tired of screwing with it, purchased a new kit, cleaned it, rebuilt it, now perfect. There a few parts missing from the carb, one was the accelerator pump weights, there was no baffle for the needle and seat, and something else but I cant remember. Anyway, when you cleaned...rebuilt the carb, are u sure all parts were there?

 

[thistle3585]

Yes, everything was there. I bought this carb about six months ago from a guy that many people on this forum recommended. Could it be the jets? What size would be recommended. This is strictly a daily driver and doesn't see any off road action at all.

I actually had a vacuum leak last fall and went through the manifold bolts and it went away.

 

[Fastatv]

Yes, everything was there. I bought this carb about six months ago from a guy that many people on this forum recommended. Could it be the jets? What size would be recommended. This is strictly a daily driver and doesn't see any off road action at all.

I actually had a vacuum leak last fall and went through the manifold bolts and it went away.

I doubt its the main jets, if the mains were too small, you would have issues with making power, not an idle issue. Sounds like there is something amiss with the idle circuit, or something installed incorrectly, or another vacuum leak? Did you use the correct power valve gasket?

 

[Lumpy Grits]

Ck the bolts again on that manifold-
IF it was run'n good and now doesn't. Don't think it's the jetting.
Get a vacuum gauge and see what it tells you.
https://www.youtube.com/watch?v=SdlNwm8OHco
LG

 

[thistle3585]

I drove it a little bit getting it from my house to my shop where I can work on it. I had to nurse the manual choke in and out as I drove depending on whether I was accelerating or cruising. I have a metal float which I'm going to put in and see if that does anything. I'll track down a vacuum gauge and see if that tells me anything.

 

[Lumpy Grits]

Ck the adjustment/position of the accelerator pump too.
LG

 

[thistle3585]

The accelerator pump rod is in second hole down and on inside of the pump arm.

 

[Lumpy Grits]

Can you adjust it to give more 'squirt'?
I really don't know your carb very well. I know others here do.
LG

 

[thistle3585]

Yes, I can but doesn't that only add fuel when accelerating? If I'm holding a steady speed then it isn't doing anything. I currently either need to pump the accelerator to get more fuel or fiddle with the choke because it starts to bog down at a cruising speed.

 

[Fastatv]

Yes, I can but doesn't that only add fuel when accelerating? If I'm holding a steady speed then it isn't doing anything. I currently either need to pump the accelerator to get more fuel or fiddle with the choke because it starts to bog down at a cruising speed.

OK, sounds like you have two problems. So is the idling issue resolved?

 

[Torxhead]

One of the major issues I have seen with carbs is a correct float level. Have you at least done that, Sorry, but I have to ask. Along with that is checking spark plugs for the correct fuel burn, which relates to the correct float level.

 

[Lumpy Grits]

What spark plugs are you run'n?
R-U sure the ign timing is set to the OEM specs. Using a timing light--
X2 on get'n the float set 'rite', is the first thing needed.
LG

 

[duffer]

I had to nurse the manual choke in and out as I drove depending on whether I was accelerating or cruising.

That is usually an indication of a vacuum leak someplace.

 

[jammer1]

I'm having a hard time understanding what the problem is. If the jeeps warm and you have to put the manual choke part on to keep idle or to help keep it going during cruise you can have either a vacuum leak or the idle jets or passage partly blocked. When warm if you remove the air cleaner and put your hands over the throat of the carb (block air flow) you should be able to stall the engine (or come very close). If it doesn't stall or come close it could be getting air from the vacuum leaks and you will be running lean. If you don't get it to stall, you could have a dirty carb and not getting enough fuel (putting choke on limits air which would richen mixture.. An example is my power washer. When the carb gets fouled up I can't keep it running unless I have it half choked, then it will run at about half throttle. Carbs dirty so I need to reduce the air to richen the fuel to air ratio. May be one of the two.

 

[thistle3585]

The problem, as I mentioned in the first post, is that my engine acts as if it isn't getting enough fuel. It idles poorly at 800 rpm and it bogs down when I'm cruising so I need to either fiddle with the choke or pump the gas. This doesn't happen when the fuel level is higher in the bowl but my problem is that I can't adjust the float to get the fuel high enough without it hitting the air horn. I'd prefer not to drive around without an air horn.

I have a completely rebuilt carb, good fuel pressure and new fuel filters. I've set the timing to 12 degrees with a light. I just got a vacuum gauge and will check that today. Is there a better place to attach the vacuum gauge to get the best reading?

 

[Lumpy Grits]

Is 12* the factory set'n?
Did you unplug and block the vacuum line from the dizzy when you set the timing?
LG