The Stovebolt Site Forums The Shop Area Engine Shop Need Carb / Fuel Help

Hello everyone, I did a search and did not find much help so that is why I am posting.

My old original carburetor was leaking and running poorly so I heard of someone on this forum putting a later model carb on their 235. I have a 52 AD with a 58 235. I am not sure what year the old carb was, 52 or 58. The replacement is one I purchased off of e-Bay and it is for a early 70's model Chevy truck. The carb fit ok, the linkage hooked right up but it appears the fuel pump which I replaced about 200 miles ago can't supply the fuel. Is that even possible? If I disconnect the fuel line at the carb and crank the engine fuel sort of squirts out but not with very much pressure. Should I try a later model fuel pump and which years will fit? Or should I buy an electric fuel pump and which is the most refliable? Any help will be greatly appreciated.

One bonus to the later carb is an electric choke and an AC solenoid that will kick on when I turn on the AC. I sure hope I can get this to work.

Thanks

i would put a pump on demand electric pump in line with the mechanical pump .FRB

FRB
FRB Model Unique Features:
For applications where battery life, low noise and best
durability are important and fuel quality is questionable

· Flow: to 225 lph (60 gph)
· Ampere hours: up to 70% less than FRA & FRC
· Continuous duty life (diesel fuel): &gt18000 hrs
· &nbspWeight: 0.83 kg (1.83 lbs)
· &nbspPump cycles only when fuel is demanded
· &nbspReplaceable filt

Rcimp,

My bet is the fuel pump is fine but that the carburetor float is stuck, inlet if plugged or some other problem with blockage. The pump, if it outputs at all is usually fine..it's hard to judge pressure and volume by merely disconnecting the fuel line.

The carburetor has a fuel bowl that will sustain it for awhile and the new carburetor shouldn't tax the stock pump at all.

My first guess is that the carburetor had problems from the git go and maybe that's why it was peddled on e-Bay...either that or is has sat for a long time and has filled with critters.

If the pump worked on the previous carburetors then I would think it is fine...take a look at the new carburetor.

Stuart

Havr you been able to run the engine at all with the new carb? If not, the needle valve is probably stuck, refusing to let the float bowl fill with gas. Take some sort of squeeze-bulb device like a turkey baster, etc., and fill the float bowl through the vent tube, which is usually just above the choke plate. That should let the engine run for half a minute or so on the fuel in the float bowl, even if none is coming into the carb from the fuel line. Goose the throttle a couple of times to see if the incoming fuel pressure will unstick the needle valve. If not, you'll have to pull the top off the carb and find the source of the blockage. At idle, a good fuel pump should supply at least a pint of fuel in 30 seconds, if it's being collected in a catch bottle of some sort. Stay away from electric pumps. Unless they have some type of safety circuit such as an oil pressure switch wired in series, they can really flood an engine in a hurry.
Jerry

Thanks for the input, I will see if the needle is stuck shut. I was leaning that way, I just never thought a needle could actually be stuck hard enough to keep the fuel pump from unsticking it.

I just hooked up a hose and blew air throught the inlet of the carb with my own lungs. There didn't appear to be any blockage, should I still take the top of the carb off?

If you can blow through the fuel inlet, the pump should be able to provide plenty of gas to the carb. Have you determined that the pump is actually pumping gas yet? You can loosen the two bolts that attach the pump to the engine a couple of turns each, and work the pump housing up and down by hand to see if you can get it to move a little more gas. Once the pump and the fuel lines are full, it should supply enough gas to the carb to keep the engine running.
Jerry

I took the fuel line off of the carb and cranked the engine over and fuel came out of the line, it kinda spurted out, not much pressure just spirts.

At cranking speed, that should be plenty to get you started. As the engine speed increases, the spurts will change to a pulsating stream.
Jerry

Then why doesn't the carb fill up with fuel? I can blow through the fuel inlet on the carb, the carb is getting some fuel that is spurting through the lines, but the carb is not filling up. I am baffled!!!

Try rigging up a gravity feed gas can to see if you can get the engine running that way. The original suggestion I made about filling the float bowl through the vent tube was to get enough gas into the carb to make the engine run a little- - - - -maybe long enough to get the pump working.

Do whatever it takes to make the engine run for a minute or so- - - - -filling the float bowl with a syringe, gravity feed tank- - - -something. Then you can make an educated guess about whether or not the pump will work. As long as you're guessing about it at cranking speed, you're never going to make any progress.
Jerry

Rcimp,

You keep mentioning the carburetor isn't filling with fuel...how are you determining this? Short of pulling the top off, the only way to determine that would be a no-go on the accelerator pump squirt, and that test isn't iron clad.

If you can blow through the carburetor fuel inlet, and the fuel pump is squirting fuel, my guess would be the carburetor has to be filling with fuel.

The other thing to keep in mind is the suction side of the fuel pump. If it's plugged, even a good pump won't function. The fuel pump won't put out any more than a restricted inlet would allow.

Stuart

I figured it out, and I am embarrassed to say what I found. I took the top off of the carb and it did have fuel in it. I got my son the crank the engine while I manually operated the accelerator and used my hand as the choke butterfly. It started right up and ran until I took my hand off. I started looking around, here comes the embarrassing part, two vacuum lines unplugged and sucking all kinds of air. I plugged them up and reinstalled the top and now it starts and runs pretty good. I have a leaky choke pull off to replace, and a little fine-tuning and I think (with God's help) I should be ok. I should have caught this, I am sorry I wasted your guy’s time. Thanks for your inputs.

Randy

No pun intended. But,

For some aplications. I will give an example on a project my shop did this summer. It was a Nash Metropoitan that Has a 1800cc MGB Motor with a aftermarket Header and intake with a new carb set up.

The stock car used a fuel pressure of 2.0

The New carb Requires 3.5 Pressure.


There is a very good chance that if the fuel pump is rebuilt and the fuel lines are clear and have been checked at the fuel tank. and with a New fuel filter. There is no reason for a blockage.

If the Carb is still NOT filling up the res. with fuel. Than there is a fuel pump problem.

Here is the issue.

Is the pump the Orig. style and number for this motor. Check the parts number. While a pump may look correct. There is Dif. part numbers as the chaft must ride on the crank in that special place. so, some pump have dif. lingth etc..

If that does check out. Than I would say that the pump is to small for your NEW carb.

The Fix.

Find out what Your NEW carb requires for Pressure. Find a service manual for that carb.

You can get a electric pump and a fuel regulator and adjust it as needed.

Using a larger carb will require spark plugs that run hotter to burn the extra fuel. Keep this in mind.


I would not have done what you have as it will snow ball with other needed mods.

I would just replace it with another orig. carb. unless you do want to modify the whole engine.


I don't know what carb you had but, my 49 235 Used a Carter W1

There is one that was just put up on ebay that is a rebuilt unit.

Good luck and feel free to contact us for help. We will try to help where we can.