Sbc 350 fuel problems

[Ryanbrown36]

I recently put my sbc back together after diagnosing a “lifter tick” that turned out to be a exhaust manifold, but long story short I pulled the intake off, changed the fuel pump and new gaskets all around and it didn’t want to start at first but eventually got fuel coming to the carb and ran great again but after 10 mins of driving it cut fuel and wouldn’t start and supply line went dry, after messing around a filling the bowls through the carb I drove it back home and messed around with it again and did the same thing to me again. Any ideas what it could be? Don’t see any leaks or areas where it could be drawing air but will check more in depth when I’m off work tonight

 

[fast 99]

Check fuel pressure and volume. I had 2 new pumps fail in a couple weeks. Both times the fuel pump arms were stuck 1/2 way down. If it ends up being a pump buy one with the return spring on top of the pump arm [see picture] AC, GM or Delphi.

 

[Edelbrock]

It is having fuel supply issues after installing a new fuel pump? That's where I would start. Why did you replace the pump in the first place? Did these problems start after putting the new pump on? If so, put the old pump back on. Was the problem there before the pump was replaced? If so, then the old pump was not the problem.

 

[Ryanbrown36]

Check fuel pressure and volume. I had 2 new pumps fail in a couple weeks. Both times the fuel pump arms were stuck 1/2 way down. If it ends up being a pump buy one with the return spring on top of the pump arm [see picture] AC, GM or Delphi.

I will check fuel pressure and the new one I got is a Delphi

 

[Ryanbrown36]

It is having fuel supply issues after installing a new fuel pump? That's where I would start. Why did you replace the pump in the first place? Did these problems start after putting the new pump on? If so, put the old pump back on. Was the problem there before the pump was replaced? If so, then the old pump was not the problem.

I believe it was having some supply issues before as it had a bog around 1500rpm but kinda of came out of no where and continued to get worse so replaced it when I pulled the intake, haven’t tried the old pump yet but can also put that back on to try

 

[Edelbrock]

You would want to to fill the carb with fuel, and then disconnect the fuel line from the carb and put it in a bucket. Then start the engine and check to see how much fuel pressure and volume you have coming out of the fuel line. You don't need a lot of either, but you do need both. Then check the carb fuel inlet area and look for a tiny screen that might be plugged.

 

[Ryanbrown36]

You would want to to fill the carb with fuel, and then disconnect the fuel line from the carb and put it in a bucket. Then start the engine and check to see how much fuel pressure and volume you have coming out of the fuel line. You don't need a lot of either, but you do need both. Then check the carb fuel inlet area and look for a tiny screen that might be plugged.

Okay I will do that, when I remove the fuel line and crank I’m often get nothing then after cranking for a while and messing around with it I get solid flow again and will do its 10 mins of running

 

[Edelbrock]

Intermittent fuel flow? Where at? What do you mean? A clear fuel filter shows fuel sometime and other times not? The accelerator pumps spray sometimes and not other times? How do you determine that its lacking fuel intermittently? If its just based on if it will run or not, then the fuel issue would need to be verified by using starting fluid in the times that it wont run.

 

[Ryanbrown36]

Intermittent fuel flow? Where at? What do you mean? A clear fuel filter shows fuel sometime and other times not? The accelerator pumps spray sometimes and not other times? How do you determine that its lacking fuel intermittently? If its just based on if it will run or not, then the fuel issue would need to be verified by using starting fluid in the times that it wont run.

When it dies there’s no spray from the accelerator pump, looked to be fuel in the filter and was clean, immediately after it dies there’s is still fuel at the carb and will start back up but won’t last long.

 

[PrairieDrifter]

When it dies there’s no spray from the accelerator pump, looked to be fuel in the filter and was clean, immediately after it dies there’s is still fuel at the carb and will start back up but won’t last long.

When it dies you need to pop the fuel line off the carb and double check there is actually fuel flow.

Otherwise it sounds like a float sticking or improperly adjusted.

 

[Ryanbrown36]

When it dies you need to pop the fuel line off the carb and double check there is actually fuel flow.

Otherwise it sounds like a float sticking or improperly adjusted.

I have tried pulling the fuel line and most of the time there isn’t fuel, I also found a small blockage in the line a few mins ago and running a lot better now but still dying after 5-10 mins or running, think more carb stuff potentially so will mess with the floats now

 

[Edelbrock]

I would not touch the floats until you are certain that the fuel supply issue is resolved.

You need to have good fuel supply before doing anything else. If you have to, put a 5 gallon gas can on the roof of the truck, and run a fuel hose to the carb, with a syphon in effect. Now if that solves the problem, then you are playing with fire by messing with the floats. If the 5 gallon doesn't solve the problem, then its either a plugged inlet filter on the carb or the flats are sticking, improperly adjusted, or the fuel inlet is obstructed. right at the float.

 

[PrairieDrifter]

I have tried pulling the fuel line and most of the time there isn’t fuel, I also found a small blockage in the line a few mins ago and running a lot better now but still dying after 5-10 mins or running, think more carb stuff potentially so will mess with the floats now

Use compressed air then blow in the fuel line from the carb inlet back to the tank.

Don't mess with the carb until fuel flow is verified.

 

[Ryanbrown36]

Use compressed air then blow in the fuel line from the carb inlet back to the tank.

Don't mess with the carb until fuel flow is verified.

Okay haven’t touched the carb yet, will try that first. The fuel flow has been confusing as it will be dry most of the time when I remove the inlet
To the carb and then will immediately have fuel pressure when I crank with it off, then sometimes I will run the electric inline fuel pump and get nothing for a while and then after about a minute it gets good flow again. Very inconsistent on the fuel flow question so it’s got me working in circles a little

 

[PrairieDrifter]

Okay haven’t touched the carb yet, will try that first. The fuel flow has been confusing as it will be dry most of the time when I remove the inlet
To the carb and then will immediately have fuel pressure when I crank with it off, then sometimes I will run the electric inline fuel pump and get nothing for a while and then after about a minute it gets good flow again. Very inconsistent on the fuel flow question so it’s got me working in circles a little

Check for cracked hoses. Could possibly be the sock in the tank getting plugged up while running, then when the truck is off all the debris falls off the sock and it'll get fuel until it can't again.