Went on my 2nd test drive and broke down!

[62 Barnfind]

I picked up my cut drive shaft Friday afternoon and installed it Saturday and I thought it would be ready to go. So I decided to go on a test drive around the block. Everything went good with the T5 but my engine is having problems. So i re checked the timing and did some carb adjusting and went for the 2nd drive. This time I want further and the engine didn't have power like it should all the time. It would come and go. It stalled out and I managed to get it to the paint shop that my friend owns. I messed with it for a few hours and go it to have power but then it went away and stalled. Ever since I moved the fuel tank to the rear and now it seems like the engine is starving for fuel. Is it to much for the mechanical pump? Do I need to install a electric in line to help the pump? Getting a little frustrated with this!

[leonphelps]

what size fuel line? Also, are you positive you have the lines not leaking? If they suck air, you would have no power.

[62 Barnfind]

Originally Posted by leonphelps

what size fuel line? Also, are you positive you have the lines not leaking? If they suck air, you would have no power.

I'm running 5/16 line from the tank to the hard line on the frame. Then 5/16 to the pump, from pump to 5/16 steel lines to the carb. When I squirt gas into the carbs it runs and has power. I pulled the top off the first carb and only has 1/4 full in the float bowel. The engine ran good before I switched the tank from the cab to the rear under bed. So I feel is a fuel delivery problem. I wonder if the inline low volume fuel pump will help the mechanical pump?

[LostMy65]

Many vehicles of that era had their tanks in the rear with nothing more than a mechanical fuel pump. So I'm not sure adding an electrical fuel pump is the solution.

[71swb4x4]

Have you checked your fuel filters? Both online and in the carb? Messing with the lines during the tank move could have broken small particles loose.

After checking that I would put a small 1 gallon gas can somewhere and suck fuel from that. Maybe put it under the hood and go for a short drive. If that works well then move the can to the rear, hook a short line to the hard line, and try again. If it doesn't work then, maybe you have a weak fuel pump or something clogging the hard line.
If that works you may have an issue in the tank. Remember, new parts doesn't mean good parts. Maybe the pickup line is clogged with solder or something else from the manufacturing process.

[LostMy65]

You could temporarily run a hose from a gas can to your mechanical fuel pump and see if it makes a difference. - just as a process of elimination.

[oem4me]

I agree with the above suggestions to provide a temporary fuel reservoir close to the pump. For this purpose I think you could use nearly any container that fit in your engine compartment. I used a two liter soda bottle with two holes drilled in the cap. One hole fit the rubber fuel line tight, the other a tiny vent hole. Zip tied it in place through some existing holes in the side panel and it worked perfect.

[Blue666(2)]

While using the small gas can to isolate problems, be sure to look for points where you may have twisted or pinched closed the steel or rubber fuel line. Some rubber lines can pinch closed under the vacuum pressure of a mechanical fuel pump.

[TJ's Chevy]

5/16 fuel line is a wee bit small imop. I have converted all my lines to 3/8 for more volume. But I am running a work horse of an electric pump which is mounted about 2 feet from the rear frame tank.

Start with the simple, Tank vent working properly?

Loose lines? Pinched lines? How much metal line? How much rubber?

How old is the mechanical pump?

Also you Are running two carbs. That does have an affect as more gas is required.

The thing I found out about the in cab gas tank was that gravity help a ton with feeding the pump. If you were to cut the line at the bottom of the cab you could drain the tank by siphoning! And that makes less Pulling for the pump. But now with the frame mount tank you don't have that advantage so the pump has to Pull and Push and feed two hungry carbs.

Check over all lines and then crank the engine with a line disconnected and see if the pump is working. If it's Not it could be bad, new ones are cheap so you might try another.

If that all fails then I recommend this pump. With this pump fuel pressure or volume will Not be an issue.
https://www.summitracing.com/parts/c...00hp/overview/

[urmyboyblue]

I agree with the basics- check the tank vent, etc. But, also consider changing the fuel pump. I had one get weak on me one time and cause all kinds of issues. If you replace it, get one from NAPA. I bought one from Autozone and it lasted one year. Replaced it for free due to their warrantee, the new one lasted a year and stranded me 30 miles from home. Bought a NAPA version and drove it till I got rid of the truck. I did warrantee the AZ version and thru it behind the seat for a back up.

If you decide on an electric pump, I suggest a Mallory if they are still made or a gear rotor version of the Holley. Not the vane type! The vane type is noisier and doesn't last as long as the gear rotor type. Also plumb the fuel system as a bypass version with a return to the tank. That will keep the fuel pump cooler and it will last longer.

At least you have it narrowed down to the fuel system.

[vince1]

If the tank has no venting make sure the cap vents inwards.

[PGSigns]

I would put a new pump on it. A factory tank location will feed the engine with a pump on its last legs. Your line size is fine unless you are feeding a ton of HP. Sounds like yours will not pull fuel from the back.
Jimmy

[The Rocknrod]

Sounds like a vent or I read somewhere that there was a piece of foreign material in the tank that kept drifting into the suction tube and stopping it up. When they stopped. . .

[TJ's Chevy]

Originally Posted by urmyboyblue

If you decide on an electric pump, I suggest a Mallory if they are still made or a gear rotor version of the Holley. Not the vane type! The vane type is noisier and doesn't last as long as the gear rotor type. Also plumb the fuel system as a bypass version with a return to the tank. That will keep the fuel pump cooler and it will last longer.

Highly debatable.

The rotary pump I had on my 66 lasted 2 years. The vane type is not that noisy. I have that carter on my gmc and on my 66 chevy and have had zero problems. Stone cold, stinkin hot, pump works great. Couldn't say that about my rotary. Plus this carter is a well known work horse.

Edit. Not to mention my dad has had this same carter on his 77 chevy c20 with a 572 big block for almost 10 years!

[62 Barnfind]

Thanks for the suggestions. I was going to do the gas can idea I just ran out of time yesterday. It's over at the paint shop and they left at 2:00pm and I didn't want to keep them longer. It pas to have a friend with a shop. Next Saturday I'll work on it again if he did' get to it first. the fuel pump has been on it for over a year so It could have went bad when the engine was dissembled. I just wanted to throw the problem out there and see what everyone else opinion was and see if I was missing something. thats why this forum is great! Everyone helps.

[andyh1956]

AGAIN- you must KNOW the operating PRESSURE / VACUUM!!! Plumb a vacuum gauge at the inlet of your fuel pump & a pressure gauge at the outlet of the pump. These two gauges will TELL you where the problem is!

[shp4man]

Drive it around again till it does it. Then take the gas cap off. Big sucking sound? Leave it off. Fixed? Modern non vented cap?