Here's what's going on....

I have a 400 in my Bronco with an Edelbrock performer 400 and a Holley 4160.

I've been having issues with inconsistent fuel delivery..sometimes the truck would run great..sometimes like crap, like it was starving for fuel, the engine would buck/sputter.

I initially thought it was an ignition related problem, pretty much replaced all of the ignition system so I can rule that out. I did find a bad starter relay which I think was causing some of the problems.

One big thing that I've been noticing is the amount of fuel in the fuel filter, it varies.
I have a clear Wix filter so I can see the fuel level.
I've noticed at times where I'm hardly getting any fuel to the filter while the engine is running, other times it's full up.

I started to work my way through this problem last night. I replaced the fuel pump, finished up
around 10pm..didn't start the truck to test as it was late. The filter was dry.

Went back to check my work around noon today...somehow the filter was full of fuel...wtf?
How's that happen without running the engine?

Started the engine up, watched the fuel filter as it ran..it slowly ran out of fuel, just enough would barely squirt up the line to keep it running. I tried to speed up the idle, no change..barely any fuel getting to the filter.

The next thing I did was replace all the soft lines. Started the truck to check for leaks.
the engine was running..again, barely any fuel to the filter. Is it running off of the fuel in the bowls of the carb?

Tried again, took the cap off of the fuel tank, let the engine run for 5 minutes...no change.



Today I'm going to verify that the pump was installed correctly...under the cam lobe...I could've botched that.
I didn't turn the engine to get #1 cylinder @ TDC...just took the old one out, installed new.
The pump did go in easily and I was able to get both the top bolt and bottom nut tightened up
without any issues.

Is it possible that I lost the prime in the line by replacing all of the soft rubber 3/8th's
and there's an air blockage? I'd think that a new pump would pull that out.

My tank has the evap line on it. It's been disconnected/plugged and the evap canister removed by the previous owner.

Could it be an issue with a clogged pickup in the tank..that's the only thing I haven't torn into yet.


Thanks in advance.

 

When was the last time the tank was dropped and cleaned or internally inspected? You have fuel sending unit in the tank that has a filter "sock" on the end of the pick up tube that could be clogged and caked over with gunk?

Did you use low pressure compressed air blow out your steel lines when you replaced the rubber ones?

I have seen new fuel pumps go bad on the 1st run, but have not ever see a filter fill itself up.

With the evap line capped you might be vapor locking, un-cap the line, or take the fuel cap off and see how she runs?

I am pretty sure the filter will not always be full....

This little dry rotted/cracked line caused me all kinds of hard start problems.

 

Also be aware that you can get what looks like the correct sending unit, but it will have the WRONG size fuel line neck. I believe you should get one with a 3/8's neck, NOT a 5/16th's??

 

You checked for holes in your float?

 

You asking about his sending unit float? All that will do is give him a false fuel gauge reading, it has no affect on the fuel delivery.

 

I haven't dropped the tank since I've owned this truck.

I don't have access to a compressor right now.

Hrmm...I'm getting a trickle of fuel into the filter..I've seen it before where it's been repeated strong squirts.


I had the cap off while the engine was running yesterday, didn't see a
difference in the amount of fuel getting into the filter.

You could be 100% on that..just seems that I can recall that filter being at least 1/2 way full any other time that I looked at it in the past.

That would do it...sneaky lil' bugger.

 

Yep, I confirmed that it's the 3/8" inlet size before installing it.

 

Which float are you talking about...the ones in the carb or the one in the tank?

 

A hole in the float in your carb may explain why gas has pushed back into your filter as the carb was heated by noon. The bowl may have filled, float sank, opened the needle and gas expanded?

I dont know, just brainstorming.

 

Yeah, I get what you're saying. I thought of that too.
When I finished the install the filter was empty, but somehow
managed to fill itself without the engine running.

I just went out and fired Ol' Girl up, let the engine run for 5 min.
I witnessed better/stronger squirts today compared to last night.
The pump was filling the filter about 1/4 of the way full.

 

I meant that if you get a new sending unit (that goes in the tank) make sure its metal neck that the soft line connects is the same size as the old one.

But sound like it fixed itself?

 

Ok, gotcha.

I'm not sure if it's "fixed".

Maybe I'm freaking out over nothing...I'm just used to seeing more
fuel in the filter...after replacing the fuel pump and soft lines, it seems as
if I've went two steps back.

I'm going to go out in a bit and give her a good road test, see if it's cured
the fuel starvation issues that I was having over 40 mph.

 

I bet clogged caked over fuel tank sending unit filter "sock". Have you ever put a overhaul kit in the carb?

 

The carb that I'm running now is a fairly new Holley. It saw low hour
use on a '67 Mustang GT with a 390..mainly dyno pulls.

I swapped out my Eddie 1406 with this 4160 to see if there was any diff in
performance.

I like the Holley, crisp/quick carb..but I prefer the Edelbrocks mech secondaries.

 

Quick update...

I took the Ol' girl out for a test drive to see what was going on.

The truck started up fine, idled fine...away I went. Drove about 5 min and
pulled over into a parking lot to check the fuel filter...full of fuel!

I drove around for another 30 min, total distance per GPS 11.67 mi.
surface streets averaging 26 mph...a few blasts up to 50 here and there.

No failures to report, the truck ran smooth, a tad on the rich side but good overall.

Came home and parked the truck. No fuel in the filter...hmm...looked for evidence of any fuel leaks on the fuel pump or any of the soft line connections..none.

I did two things before I went out on my test drive...

1. I cut a section of 3/8" vacuum tubing and slid it over the steel fuel line that leads up to the carb to insulate it a bit.

2. I removed the bolt from the evap canister line on the tank. The P.O. stuck a bolt in the line to cap it off.

I'm still puzzled by the lack of fuel in the filter. I don't know how big of a deal it is, just seems odd.