New fuel pump, still no gas to carb

[fatastronaut]

Hello!

I've got a 1986 Chevy C10, 350 with a 700R4. Long story short: life happens, and unfortunately it's been sitting about a year and a half. Last time I started it, it fired up but was having trouble idling & kept stalling out.

Here's what's happened since I got back to work on it:

 1) Replaced the dead starter, put in a brand new battery, and it's turning over great but still not firing.
 2) Pulled the line/hose that connects the fuel pump to the carb and it's bone dry.
 3) Installed a brand new fuel pump, still nothing getting up to the carb.
 4) Disconnected the new fuel pump to make sure I installed it correctly. Some gas leaked out of the line from the tank, but there was hardly anything coming out the other side of the pump. Wet with gas, but barely.

Forgive me - I'm a novice, and I know this will probably make some of you cringe, but in a moment of frustration I put a little gas on the carb, turned the key and...it fired up for a brief second before cutting out again.

Not sure what's preventing fuel from making the journey up to the carb. Would a dirty/out of tune carb make this happen? Another bad fuel pump? Blockage somewhere in the fuel line? Also, the push rod that activates the fuel pump - how hard should that be to move? Mine is pretty easy to move back & forth in there.

Any ideas as to what the problem could be, or what to test next? Any help is greatly appreciated! I love this truck and can't wait to get it back on the road. It continues to be a great learning experience.

[bd]

Single or dual tanks?  Carefully inspect all of the rubber hoses between the fuel tank(s) and the pump.  Make sure all are correctly connected and that none are kinked, cracked or spongy.  Replace as needed.  Verify there are at least five gallons of fresh fuel in each tank.  Once that is completed, check the fuel filter for restrictions or replace it then check the fuel pump draw (>20" vacuum), pressure (5-7 PSI) and delivery (minimum of 1 quart in 30 seconds of cranking).

The fuel pump pushrod should move easily in its bore.

[fatastronaut]

Thanks bd, really appreciate the help. It's got a single tank, plenty of fresh fuel. I'll trace the line back to the tank and check for trouble. Pulled the filter out of the carb and it looks totally fine, though I'm gonna replace it anyway. Might give the carb a deep clean as well.

Good to know about the push rod. I was worried something was wrong with it.

if people learn by making mistakes, by now I should know just about everything!!!

you said it!

[JohnnyPopper]

Not a cringe worthy idea, priming the carb is a smart thing if done carefully and not Too much.

It tells you that the ignition system is working, and that you put the starter in correctly!

You can take about 3 oz of gas, and funnel it into the main vent to fill the carb bowl. 3/8 vertical tube just forward of the choke plate.

This will allow you to start the truck and run until the gas runs out.

In that state you can check the pump rate per bd.

Rinse and repeat till you find the prob, and please let us know how it goes. Otherwise we'll never know how goofed up our suggestions are!

[Jake]

Sounds very much like clogged fuel line, tank filter.
Remove fuel filler cap, pull the fuel line off the fuel pump and gently apply controlled and very mild air pressure (3-4psi max) into the fuel line going towards the fuel tank.
Listen for the air bubbling in the fuel tank.
If all sound clear and open, reconnect pump and try starting again.
If this does the job, you may want to remove fuel tank, rinse an inspect.

Alternately, remove fuel line from fuel pump, locate fuel tank venting line and apply mild controlled air pressure. Fuel should come out of disconencted fuel line at pump.   

Jake

[fatastronaut]

Latest update in the saga:

Traced the fuel line from the pump all the way back to the tank looking for cracks or bad hose, so far so good. Disconnected the hose on the "send" line right at the top of the tank, lo and behold, it's dry as a bone. I've got at least a couple gallons in the tank, so something should have been making it that far.

Think it might be time to drop the tank. I'd like to get a good look at it, clean it out, clear any clogs, etc. Worst case, I can pick up a new tank, or at least a new send unit.

I'll keep y'all posted! Thanks again for the help.

[roundhouse]

You can run the inlet line from the pump into a gas can to check and see if the pump is working

Might help isolate the problem
If it works using a small gas can or jug then you know the problem is somewhere in the lines or tank

The filter sock in the tank could be clogged

[bedwards]

Depending on how your truck is sitting, a couple gallons in the tank may not reach the inlet sock.

[JohnnyPopper]

Sounds like another owner that had his truck parked on an incline...

[fatastronaut]

what's that about old trucks keeping you humble? y'all were right - even with fresh gas, seems like there wasn't enough fuel to reach the send unit. d'oh! (in my defense the fuel gauge is broken, so i thought i had a lot more in there than i did). i added more to the tank & it fired right up. even drove it a couple blocks to a gas station for a full tank and some air in the tires. no leaks, drove just as good as i remember.

now for the bad news.

i came back the next day to start working on everything else i need to fix, and it won't fire up again. it's turning over, sounds like it wants to run, but nothing. i keep the battery on a battery tender, and now i KNOW it's got plenty of fuel. what's next? check the spark? points & distributor cap?

i'm still going to clean out all the fuel lines, give the carb a complete rebuild & deep clean, and inspect the tank. not sure what to test next.

i thought i was back in business, but you know how it goes with these old machines.

thanks again all - this forum has been a blessing in helping me learn.

[VileZambonie]

Twice you've said it has plenty of fuel. How much fuel is in the tank? Is it leaking out?

[bd]

I agree.  Does the carburetor dry out overnight or after a couple of days?  How many squirts of fuel will the accelerator pump deliver in the morning before going dry?


In addition, your 1986 truck should have HEI electronic ignition, not points and condenser.  When was the last tune-up performed?  Pick up an HEI spark tester...



             ...and check for a healthy blue spark while cranking.  Inspect the spark plug for fuel fouling (a coat of black soot encasing the business end)...




Post a pic that clearly shows the condition of the electrodes.

[JohnnyPopper]

Okay, this is very old school;

Loosen the distributor clamp enough to move the distributor with some resistance.

Have someone turn the engine over while you slowly move the distributor to advance or retard.

If you have any ignition system even partially operational, you should get her to start.

That said, you can then find the rest of the 'problems'.

[fatastronaut]

There's no gas leaking out - that was user error on my part. So it doesn't happen again, I topped it off - gas tank is full. As far as the carb drying out, I'll get back to you on that. Carb intake stayed wet enough to start several hours apart on Saturday, Sunday it didn't start but I didn't have time to pull any hoses. I'll post a pic of the spark plugs as well, soon as I can get over to my garage. Just grabbed an HEI spark tester - thanks for the tip!

I'm new to the 4-wheel world and this is my first truck ever, gonna be a lot of boneheaded questions coming from me. Before I ask another, gonna go read through the forums and look for a service manual with a tuneup routine.

I appreciate the help everybody

[bd]

Factory GM light duty truck 1986 Service Manual