Fuel Pump Pressure

[redfishtony]

OK, I know it can't be this hard. Last week I posted a question about my carb. I followed all of the addvice and bought another rebuild kit and rebuilt the thing again. I'm beginning to think I have the wrong fuel pump on the thing. The only way to keep gas from coming up into the carb is to hold down on the needle with my finger. As soon as I release the valve it will shoot out of the seat and hit the hood. The truck has a G vin number and the pump I bought shows it has 4.5-6.5 lbs of pressure. It really seems to have alot more than this. Has anyone ran into this problem or am I just doing something wrong. I looked at all of the available pumps from 68-74 and they all seem to be the same. Any suggestions.... Thanks, TW

 

[BroncoJoe19]

Does your float... float?

I had a porous float in the carb to my lawnmower. I sank to the bottom and flooded out.

 

[redfishtony]

The float is new and it seems to be working just fine. I'm not sure that enough pressure is being forced down on the needle in order to shut off the fuel. Seems to be to much fuel pressure. Thanks, TW

 

[Bully Bob]

Don't forget that's 4-6 psi (pounds per sq. in.)

That's enough to squirt 20 ft. ..!

Your pump is likely correct.

With airhorn off., & COIL un-pluged.., you should be able to crank the eng. & the float/fuel level should remain the same.

Double check your float adj. level via the instructions.

 

[redfishtony]

Something is just not right. I went today and picked up a fuel pressure regulater. It allow you to set the pressure anywhere between 1/2-6 lbs. When I set it to 1 it seems to solve the problem. I know this is not correct but it seemed to work. Truck ran without flooding the bowl and the fuel stopped coming through when the needle fell. I'm still not satified with the fix and think I might just need to change carbs. Any suggestion abiut changing carbs. The one I have is a Autolite 2100. Thanks, TW

 

[BamBam95670]

Have you put a pressure gauge in the fuel line to see exactly where the fuel pressure is?? I know you said you put a regulator on it, put I know there are some regulators out there without a gauge you just simply dial in the pressure by the number. Its always best the install a fuel pressure gauge as close to the carb as possible.

Just my 2 cents.

Charlie

 

[Bully Bob]

You're leaving something out here...,

Assume you have the airhorn (top of carb) off in order to finger things.

How does the needle come out unless the float is not in place.?

Are all the parts there.? Torsion spring., retainer., & of course the needle., clip., & anti-splash washer.

Is the float shaft in place & seated.?

I doubt there's anything wrong with this carb....something's just amiss with this float & needle/seat set-up.

Changing carbs (other than stock) can have it's own set of headaches.

BTW., factory spec is 4-6 PSI

 

[redfishtony]

I'm really starting to feel dumb. Bully Bob, you mentioned the float shaft and is it seated. The float shaft is in place, but it is lose in the notches where it sits. Is the float shaft suposed to snap down into the notches? If so I think this might be my problem. With the top off of the carb the float shaft comes up when the float is up. I noticed it appeared to be lose but thought thats how it was suposed to be. I thought that the top held it in place. I even looked at the underside of the top to see if there were tabs that went down into the notches to seat the shaft. Hopefully ya'll can follow my jabbering. I am going out to the shop right now and pull the top off and see if the shaft will somehow lock down in the notches. As always, Thanks for the great advice and information. TW

Also the small retaining clip is there just to keep the float from sliding side to side on the shaft.... correct. There is also a small spring that slides on the shaft that does not appear to be doing anything. All of the diagrams I can find do not even show this spring. Thanks again.

 

[Bully Bob]

That spring is the "torsion spring" & may be part of your problem.

the long end goes down.., & the 90'd end slips under the float hinge.

"Also the small retaining clip is there just to keep the float from sliding side to side on the shaft...correct.?"

NO..! & this may be your problem this clamps on the shaft., & locks down behind the seat., between it & the wall.

It's called "float shaft retainer"

Been a while since I worked a 2-V carb. but I think you're now on the road to recovery here...!!

HTH

B

 

[redfishtony]

Man the lights came on. I have not been installing the float shaft retainer in the correct postion. I think were gonna get this thing right afterall. I guess I can chalk this one up to learning. All in a days fun...... Thanks alot, i'll update everyone tomorrow.

 

[redfishtony]

Man it's amazing how well things work when they are installed correctly. I snapped the retaining clip in the grove on the seat and the thing is working like brand new. Now I am going to try and get the timing set. Someone told me to advance the timing a few degrees and the truck will perform better. Any thought on that? Again, thanks for all the help, Sincerely, Redfishtony >

 

[Bully Bob]

You're welcome., and...,

I think you said, a while back, it has an aft. mkt. electronic ignition....?

--- if so ., you can go a bit more in adv.

Have fun with you rig..!

B

 

[BamBam95670]

Good job Bully Bob...

I was just chatting with a friend about this issue and we came up with the same idea.. You beat me to the post...LOL

cheers

Charlie

 

[Seabronc]

I'll just add one more thing to do with that float. Check the float adjustment by removing the sight plug in the float chamber. The float chamber input valve should be adjusted so that fuel is just at the bottom of that hole. If it is too low then you will run into fuel starvation problems under certain conditions. If it is too high, you will have problems with flooding under certain conditions.

Good luck,

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