Fuel delivery issue

[xtremjeepn]

Suggestion, but with the mech pump (by itself) hooked up, does it pull fuel out?

NO.

what about the electrical pump by itself? 

NO.

Is the selector valve still on the truck? 

Yes. I bypassed it yesterday. Took off the mecanical pump and just tried to pull fuel with teh electric pump hooked to a stand alone power source. NOTHING!!

I can pressurize the tank and force fuel out the lines but can't get it to pull on it's own.

Sounds like you need a couple hours break from it.  Which is why I am on here now....

70 degrees here yesterday and a blizzard today. So I am taking a break. hate crawling under the truck in the dark of the garage without natural light.

[xtremjeepn]

LS6 454 not totally stock.

Stock non-efi tanks.

Extra pump helps in heat/altitude/off camber starts. Other than that it should run fine on just one of the two pumps. 

I drove the donor truck with this engine in it for a couple of months with just an electric pump.  Just happen to have a brand new mechanical pump laying here so thought I would use that.  In the frustration yesterday I installed a new electric pump to see if I could draw fuel with that. (easier to diagnose with a pump you can just hook a battery chargers to and run it without cranking the motor for hours)

[TexasRed]

There are some inline pumps that put out less than 8 psi. It would be cool to have one when you don't drive it everyday. My truck, if I didn't start it everyday would have near dry fuel bowls after a couple days. The electric could help with filling up the bowls before turning over the engine a bunch of times. The purpose of keeping the mechanical would be simplicity and reliability (more redundancy).

[Stewart G Griffin]

No...i insist that you continue working at it until you get it running.

What type of carb do you have?

So, you are saying that this very engine had the standard fuel pump mounting blocked off, and you were driving it with just the electric pump?  Did you have a regulator and if so, what pressure was it set at?

With the new, current 2pump setup, what is, if so equipped, the pressure regulator set at?

[xtremjeepn]

No pressure regulator. Fuel pump itself only put out 3-6psi.

Running a Holley Truck Avenger carb.

[Stewart G Griffin]

So this is one of those solid-state low pressure pumps?

i guess the next question is exactly what brand and model of pump?
Also, what type and brand of mechanical pump?

It would be cool (and helpful) to have pictures of the setup.

[BIGK30]

Any chance the float is stuck closed in the carb? if so it would not let fuel in. just a thought.

[xtremjeepn]

With the fuel line OFF the carb I can't get fuel to it. So not a carb issue.

[VileZambonie]

Use one pump or the other but you can't have both. 

(not really true, many people use electric pumps as "helper" pumps for the mechanical.)

Yes really true, there is no need for a helper pump. If you want an electric pump the mechanical pump should be eliminated and a pressure regulator will be needed.

[Stewart G Griffin]

i can see that an electric would be helpful for high altitude and/or high heat applications, (and even for extreme angle conditions, although i feel the carb choice isn't) but i feel we should concentrate on just one pump for now to get it running; (preferrably the mechanical)

A picture of the setup would be oh so helpful in diagnosing the problem.  (hintity, hint, hint)

[Captkaos]

I know you said it ran in a donor truck, but you changed fuel systems.  We know it isn't your engine that is a problem so the only difference is the fuel supply system.  Did the engine ever run when it was in this truck?  What do the tanks look like inside on the new truck?  I had one stopped up (the Jimmy I am working on) and it the tank was  so rusty on the inside that even though I could blow pressure through it, there was so much rust scale that it clogged up the supply everytime.

Pull the feed line off the mech. pump and drop it in a bucket of gas to see if it is pumping, then do the same with the electric one.  If they both can pull gas through, you know it can only be the tank, fuel lines or the sending unit....

[xtremjeepn]

Motor has not run in this truck yet.


I pulled the filler hoses off the tanks to inspect them before pouring in fuel. Both tanks were clean as a whistle inside. There was about a 1/2 inch of old fuel in each. I scrapped the bottom of the tanks with a metal rod to see if they had sediment in them and they were perfectly clean.


I will have to try to draw from a fuel can to make sure it runs that way. I have not had a chance to go back and work on it yet.

[76_Scottsdale]

I would drop the tank and make sure the pickup tube is down low enough. It's possible that you are able to force fuel through it but it's not long enough to pickup fuel.

[Captkaos]

Cole, I am going to merge the Fuel issue stuff into your other post to keep you "build" post cleaner...

[VileZambonie]

I still don't understand why you have an electric pump in the system. If you aren't able to deliver fuel and the pump is good/hooked up correctly this means you have a restricted or pinched line.

Just for haha's run a new rubber line (test hose) from the tank to your mechanical pump. then from your pump to a glass jar. Make sure there is fuel in the tank and you prime the pump by putting some fuel in the hose. Crank it and see what happens. Either your mechanical pump is bad or you have a restriction in one of your lines. Don't give up!