car trouble before bullettproof HELP

[theracedude]

53 chevy with 350 and 2 holley 94's, manual fuel pump, standard fuel pressure regulator with a glass filter.

the other night the engine started to stumble and would backfire when i let of the gas. so i started changing parts like plugs, cap, rotor, filters, etc. i decided that because it was backfiring from both the left and right exhaust pipes that it could be running lean. i looked at the glass filter and the fuel was very low. i changed the fuel pump and blew through all the lines. still very low fuel in the filter.

i ran a line from the filter to a 1 gallon can and the filter was full all the time, WTF

what i'm concerned with is that the fuel filter is empty most of the time. it fills about 1/8 full then runs dry, it does this every 8 seconds. its not vapor lock or a crushed line. air blows through the system well and the car runs fine. but i will be running at high speeds for 6 hr to billettproof and sure don't want to run lean. what do you think?

 

[earthman]

Venting? Have you recently replaced the gas cap with a non-vented one?

 

[donsrods]

I didn't realize you were on this forum too, sorry. I posted a PM for you on the HAMB that outlines some things to check.

I am betting the metal screen sock on the end of your tank pickup has gotten plugged up. Put some compressed air to the pickup at the tank and blast the sock off. It won't cause any problem inside the tank. Take your cap off first or your 15 gallon tank will become a 20 gallon tank.

The key is that your car runs ok on a separate tank.

We want to see you make it to BP guy!!!!!!

Don

 

[theracedude]

Venting? Have you recently replaced the gas cap with a non-vented one?

no, same cap

 

[Gastrick]

I know you said that it's not vapor lock or a crushed line, but it still seems like some sort of obstruction somewhere. Maybe crap in the bottom of the tank that sucks into the pick-up after a little bit.

I've seen weak fuel pumps display the same symptoms too. It may siphon fuel easier from a bucket than it does from your tank. To me, it seems like one of those two things. I've got a new mechanical pump for a sbc you can have if you want to try it.

And for what it's worth, the glass fuel bowl on my filter is usually not full and my system is up and running with full pressure and no problems.

 

[440shorty]

quick question

When you ran it from the gas can, was the gas can above the fuel pump, so that it gravity - fed the fuel pump?

I bought a car that had a lawn mower tank strapped under the hood because the fuel line back to the tank had rusted and the owner just wanted to be able to move it around the yard. That little tank was connected to the inlet side of the fuel pump. I drove it home like that. After fixing the fuel line to the real gas tank, the car would not run - fuel pump was so weak that it could not lift the gas to the carb! A new fuel pump solved that problem.

I'd say either the fuel pump is weak or the sock in the tank is clogged, as has been mentioned before.

Good luck!

440shorty

 

[harleyboy]

This probably isn't it but I had a glass filter on my Model A and had the same problem. I thought it was a vapor lock but couldn't get it straightened out. I finally found out that the filter was on backwards. The fuel would come into the inside of the screen and I couldn't see the fine rust that was trapped inside the screen instead of on the outside. What gas that was coming thru the screen was clean as could be, but the inside was clogged up. Once I found this and truned it around I never had the problem again. HB

 

[zzford]

This probably isn't it but I had a glass filter on my Model A and had the same problem. I thought it was a vapor lock but couldn't get it straightened out. I finally found out that the filter was on backwards. The fuel would come into the inside of the screen and I couldn't see the fine rust that was trapped inside the screen instead of on the outside. What gas that was coming thru the screen was clean as could be, but the inside was clogged up. Once I found this and truned it around I never had the problem again. HB

Sometimes if you install the fuel filter backwards, it will cause the engine to run backwards as well. A car with a 3 speed in it will have 3 speeds in reverse and only one forward.

 

[Mudbone40]

Some good thoughts on here so far, do you have a pressure guage that you can temporarly plumb to line going to carbs? Most pumps put out around 6-8 lbs. pressure on carbureted engines, just a thought, good luck on billetproof.

 

[Gastrick]

Any update racedude?

 

[theracedude]

update, blew into the fuel line and hear the bubbles in the tank. sucked fuel with no trouble. all lines are metal and in good shape or new when rubber. need more time to work on it...

 

[shizzy]

is the filter before or after the pump? My Olds gave me troubles just as described when i had the filter before the pump. I moved it to the other side of the pump and no issues.

 

[theracedude]

is the filter before or after the pump? My Olds gave me troubles just as described when i had the filter before the pump. I moved it to the other side of the pump and no issues.

i will try it, thanks

 

[theracedude]

fixed!, the cup on the acellerator pump swelled up and locked up. had a black cup and i changed to a blue one. also i had a rocker too loose and a bad pressure regulator. should have been easyer to find but like my wife said i am a dumbass. thanks for eveyones help...btw the filter is still very low but there seems to be no problem with it.

 

[Gastrick]

Good news racedude. See you at Billetproof.