Truck Won't Start, No gas to Carb

[AJH]

I took my truck (84 K10) to my in-laws house, about an hour and a half from where i live, to get firewood. We drove the truck back to their woods through a flat field with a small hill before the woods, loaded it, drove back to their house (like half a mile). We probably placed like 200-300 lbs of wood in the bed, nothing it should not have been able to handle. I also got 1 cubic yard of mulch twice in the truck this summer.

So we get ready to leave, and we usually take a country road about 8-10 miles from their house to a freeway. I start the truck up and we go down the 1/4 mile long drive way, then we get on to the country road. I start trying to give 55 and it get to about 40-45 miles per hour and it sounds like it is getting choked out and slows back down to 35 which it doesn't have a problem doing. I drive it like this for like 3 miles and stop it and check the oil and see if it is leaking anything and press the throttle cable on the carb and gas is coming out so I restart it and drive a little further. Then it stalls out.

I check again and it is getting gas but won't start. After like 10 minutes I try again and it starts and I drive it back to my in-laws house and it does 55 no problem. I park it in their driveway and it stalls out. It's not getting any gas. It will start with ether or gasoline in the carb but then stalls out later.

The truck has a 355 with a Holley 600cfm Carb. (stupid question, but is there a fuel filter in this particular carb?)

I have already replaced the fuel pump

I replaced the inline fuel filter (which is why I ask about the Holley carb having one I'll add the part number shortly)

When I disconnect the fuel line at the fuel filter and put the fuel line in a gas can the truck runs no problem, no stalling. So this leads me to believe there is a problem with something in the tanks. Both fuel tanks are full, but when the gas gauge is on the on the passenger side tank it appears to be getting "fuller."

Any ideas?

 

[scottybaccus]

The tank screens can get clogged with rust, and then they collapse under the suction of the pump. Go ahead and get new screens and drop the tanks...

UNLESS, your starvation issue is affecting both tanks regardless of which you select. That will indicate a concern with the selector valve.

 

[AJH]

I am unable to get the truck to get fuel with either tank selected. If it is the selector valve how hard are those to replace, as in does a tank need dropped or anything and where is the selector valve located? The selector valve does make noise, just like it did when I know it was working.

 

[chengny]

When I disconnect the fuel line at the fuel filter and put the fuel line in a gas can the truck runs no problem, no stalling. So this leads me to believe there is a problem with something in the tanks. Both fuel tanks are full, but when the gas gauge is on the on the passenger side tank it appears to be getting "fuller."

Boy, you certainly did most of the troubleshooting/diagnostics I can think of!

You have isolated the problem to a fuel flow problem on the suction side of the pump. The fact that the gas gauges are acting funky would indicate a tank select valve issue. But since you did not switch tanks in the immediate period before this issue developed, lets look at causes other than with the tank select valve first.

Next step is to check for flow in the tubing/hoses between the tanks and fuel filter inlet. Use the filter inlet as a forward test point because and you got flow through it (and the engine ran) with a hose submerged in a gas can.

Do you have access to a compressed air supply? If so, remove the hose at the fuel filter
See if you can blow air backwards through the gas line - from where it connects to the filter - and get flow into the tanks. Pull the gas caps, apply air pressure to the common line at the filter inlet and listen at the tops of the tank fill pipes.

If you can hear flow/bubbling at the fill pipes, that proves you have no restrictions between the tanks and the filter inlet.

Shift the selector valve left and right and listen at both fill pipes. If you hear air coming into both tanks, and it changes as the switch is operated - that verifies proper operation of the tank select valve.

While an assistant applies air pressure as described above, get under the truck and inspect the gas line(s) from the fuel filter to the tank tops. What you are looking for now is not an obstruction/restriction, but rather a leak to atmosphere in the suction piping.

A leak on the suction side of the fuel pump will allow air to be drawn into the fuel supply. This can cause:

1. The fuel pump to loose suction and fail to deliver gas to the carburetor

2. An excessive amount of air in the fuel supply to the carb which fills the bowl with air.


If you don't have any compressed air supply, you can try just blowing back with your mouth. That will probably work for the flow portion of the test, but most likely will not help for the second part of the test (checking for an air leak).

 

[chengny]

I am unable to get the truck to get fuel with either tank selected. If it is the selector valve how hard are those to replace, as in does a tank need dropped or anything and where is the selector valve located? The selector valve does make noise, just like it did when I know it was working.

How hard a tank select valve R & R job is? That's a matter of opinion. Also depends on how rusty your frame is, what tools you have on hand, etc. It does not involve dropping a tank.

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Procedure:

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WARNING: To reduce the risk of personal injury when disconnecting the fuel hoses and lines, cover the fuel hoses and lines with a shop cloth to collect the fuel, and then place the cloth into an approved container.

REMOVAL:

The auxiliary fuel tank control valve is located under the right hand side, center of vehicle, attached to the inner side of the frame.



1. Disconnect negative battery cable from vehicle battery.
2. Raise vehicle.
3. Remove hose shield, when required.
4. Remove electrical connector from valve and switch assembly.
5. Remove fuel feed and return hoses. Note position and color markings on hoses.
6. Remove selector valve and meter switch from frame.

INSTALLATION:


1.Install the selector valve and meter switch to the frame.
2.Connect the fuel feed and return hoses, taking care to install hoses in the correct positions.
3.Connect electrical connector to valve and switch assembly.
4.Install hose shield, when required.
5.Lower vehicle.
6.Reconnect negative battery cable to vehicle battery.
7.START vehicle and allow to run while checking for fuel leaks.


Test procedure:

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[AJH]

Thanks for the suggestions everyone. I won't get to go look at the truck again until next weekend but I'll definitely do those tests and work on the selector valve if I need to.

 

[AJH]

Thanks for the help everyone. There were multiple problems. The first was that the valve was bad. The second was that there was an air leak in the passenger side fuel line. So it's up and running now. On to the next task!