1968 Chev K10 Carb.

[JASkin]

I have a 1968 Chev K10 3 door Suburban that came with a 307 but has a 350 in it now. I have owned this Suburban since 1970. It has a Rochester Quadrajet 4 Brl. carb. on it - 7042208 OC 1172 which was on the engine when it was installed years ago by a mechanic I bought it from when mine had problems. It has a 4 speed manual transmission, manual steering and manual brakes. I need a different carb as I have to pump and pump to get it started. Had a new manual fuel pump installed and a carb kit put in but after it sits a few hours it will not start without pumping,I installed a one way valve in the gas line at the carb so the gas would not drain back but did not help. What would be a good alternative?

Jas

[LockDoc]

Originally Posted by JASkin

I have a 1968 Chev K10 3 door Suburban that came with a 307 but has a 350 in it now. I have owned this Suburban since 1970. It has a Rochester Quadrajet 4 Brl. carb. on it - 7042208 OC 1172 which was on the engine when it was installed years ago by a mechanic I bought it from when mine had problems. It has a 4 speed manual transmission, manual steering and manual brakes. I need a different carb as I have to pump and pump to get it started. Had a new manual fuel pump installed and a carb kit put in but after it sits a few hours it will not start without pumping,I installed a one way valve in the gas line at the carb so the gas would not drain back but did not help. What would be a good alternative?

Jas

Are you sure the choke is working correctly and are you setting the choke each time before you try to start it?

LockDoc

[JASkin]

Originally Posted by LockDoc

Are you sure the choke is working correctly and are you setting the choke each time before you try to start it?

LockDoc

When I had the original engine with a 2 Brl it had a manual choke but this has an automatic choke --I wish it was a manual. It used to start good--I just use it mostly in the Winter to get thru the snow we have.

Jas

[HO455]

From way over here it sounds as if your accelerator pump in the carburetor has failed. A common problem with the fuels we get to use these days. Do you have a stumble when accelerating?
A quick check would be to look down the primary bores of the carburetor (a flashlight will help) and wing the throttle open. You should see two solid streams of fuel shoot into the carburetor bores. You will need to hold the choke open to do this and you do not need to have the engine running to do this.

[JASkin]

Originally Posted by HO455

From way over here it sounds as if your accelerator pump in the carburetor has failed. A common problem with the fuels we get to use these days. Do you have a stumble when accelerating?
A quick check would be to look down the primary bores of the carburetor (a flashlight will help) and wing the throttle open. You should see two solid streams of fuel shoot into the carburetor bores. You will need to hold the choke open to do this and you do not need to have the engine running to do this.

I had new accelerator pump and complete overhaul kit installed about 2 years and have hardly driven it. I checked the primary bores as suggested and no fuel--I know that the fuel is not draining back down the line but could it be draining into the motor? Would a electric fuel pump help more if I can find what is going on now?

Thanks,
JAS

[oldchevynut]

I suspect that you are on the right track. I believe there are wells in the bottom of the fuel bowl that are sealed with solder. Over time the solder dries/loosens/cracks allowing the fuel to drain down into the intake manifold, creating the conditions you describe. It can be repaired.

[HO455]

The fact that the truck runs but no accelerator pump shot to me means that the either the accelerator pump seal has failed or the check valve for the accelerator pump is stuck.
My money would be on the pump seal failing. It is quite possible that the seal's lip stuck to the pump bore when the fuel evaporated and then when the pump was operated it tore the lip and now it won't seal. Or the seal is stuck to the bore and the whole cup has pulled off of the accelerator pump shaft.

This link may help explain what I believe your problem is.

http://www.v8buick.com/index.php?thr...-issue.263146/

[LockDoc]

Originally Posted by JASkin

When I had the original engine with a 2 Brl it had a manual choke but this has an automatic choke --I wish it was a manual. It used to start good--I just use it mostly in the Winter to get thru the snow we have.

Jas

Even though it is an automatic choke you still have to set it before you start the engine. Here is how the owners manual says to do it. If it is an electric choke you have to have the key on for a couple of seconds before setting the choke.

Owners manual says:

"Fully depress accelerator pedal and slowly release. With foot off of the accelerator pedal crank the engine by turning the key to the start position and release when the engine starts. If the engine starts but fails to run, repeat the above procedure.

When the engine is running smoothly the idle speed may be reduced by slightly depressing the accelerator pedal and then slowly releasing."

On another note, It would be a good idea to have the air cleaner off the first time you do this to see if the choke plate is actually closing. If the engine is cold the choke plate should be fully closed after setting it according to the manual.

LockDoc

[HO455]

Originally Posted by oldchevynut

I suspect that you are on the right track. I believe there are wells in the bottom of the fuel bowl that are sealed with solder. Over time the solder dries/loosens/cracks allowing the fuel to drain down into the intake manifold, creating the conditions you describe. It can be repaired.

It is possible that your well plugs are leaking, but usually this is an overnight issue and resolves itself once the fuel pump has refilled the float bowl. Once again is possible that it could be leaking enough to drain the bowl in several hours and you could have a weak fuel pump that is taking forever to fill the float bowl. However I feel that you would have other symptoms if these were the case.

I have had to try as many different 3 accelator pumps to get one to work and stay working on my daily driver.

[JASkin]

Originally Posted by LockDoc

Even though it is an automatic choke you still have to set it before you start the engine. Here is how the owners manual says to do it. If it is an electric choke you have to have the key on for a couple of seconds before setting the choke.

Owners manual says:

"Fully depress accelerator pedal and slowly release. With foot off of the accelerator pedal crank the engine by turning the key to the start position and release when the engine starts. If the engine starts but fails to run, repeat the above procedure.

When the engine is running smoothly the idle speed may be reduced by slightly depressing the accelerator pedal and then slowly releasing."

On another note, It would be a good idea to have the air cleaner off the first time you do this to see if the choke plate is actually closing. If the engine is cold the choke plate should be fully closed after setting it according to the manual.

LockDoc

The choke does close as it was set when they rebuilt the carb and it was fully closed when I checked it to see if it was sprayinfg any gas.

[JASkin]

Originally Posted by oldchevynut

I suspect that you are on the right track. I believe there are wells in the bottom of the fuel bowl that are sealed with solder. Over time the solder dries/loosens/cracks allowing the fuel to drain down into the intake manifold, creating the conditions you describe. It can be repaired.

Thanks for the reply, I might look for another rebuilder to tear it down as I don't feel comfortable doing it.

JAS