Hunting down flooding problem

[SmokinBBC]

Trying to hunt down my flooding problem.

Can a mechanical fuel pump fail causing it to have too much pressure? I know it sounds crazy since my previous pump failures delivered no fuel.

 

[mrvette]

IF you have a mechanical pump that needs a return line, and it's been blocked off, you need to have one for that pump.....

the shit I learned the hard way some 40? years ago....

best bet is to go electric and fuggetaboutit....

:shocking:

 

[SmokinBBC]

IF you have a mechanical pump that needs a return line, and it's been blocked off, you need to have one for that pump.....

the shit I learned the hard way some 40? years ago....

best bet is to go electric and fuggetaboutit....

:shocking:

Return line is hooked up. I wonder if it is blocked. Would that cause a flooding problem?

 

[JeffP1167]

loosen gas cap and see if it still does it.

 

[mrvette]

IF you have a mechanical pump that needs a return line, and it's been blocked off, you need to have one for that pump.....

the shit I learned the hard way some 40? years ago....

best bet is to go electric and fuggetaboutit....

:shocking:

Return line is hooked up. I wonder if it is blocked. Would that cause a flooding problem?

I never got into it with gauges and shit, so I unsure, just what I been told, any return line blockage makes for more pressures at the peak of the stroke/diaphram movement....that CAN knock the float seat off.....

now why they ever bothered about all that shit during the mid/late 60's I have NO idea....all I know is a old Carter AFB style carb never had the issue, but a Qjet did...why?? dunno...but Qj obviously needs far less pressure and pulse variation was a killer for it....

IMO, it was variation in design to accommodate the QJ carb....prrtt:

 

[SmokinBBC]

loosen gas cap and see if it still does it.

I didn't have a chance to do this before I worked on the carb. What should I look for if I loosen the cap? I have a non-vented cap...is there a vent valve somewhere on the tank?



I picked up an Echlin kit from NAPA and compared it to the other one that I had in there. No difference except for the clip that goes on the needle. The old clip looked bent. I am wondering if this caused it to get hung up somehow.

Took it out this morning and ran it gently and a little vigorous with no flooding. AF was where I expected it to be under all conditions. Didn't do a WOT run as it was 91 degrees at 10:00am here and I didn't want to risk breakdown and having to wait for a tow(Suppose to be somewhere around 97 ; the heat index around 107.)

 

[big2bird]

now why they ever bothered about all that shit during the mid/late 60's I have NO idea....all I know is a old Carter AFB style carb never had the issue, but a Qjet did...why?? dunno...but Qj obviously needs far less pressure and pulse variation was a killer for it....

It was to eliminate vapor lock Gene.

 

[big2bird]

loosen gas cap and see if it still does it.

I didn't have a chance to do this before I worked on the carb. What should I look for if I loosen the cap? I have a non-vented cap...is there a vent valve somewhere on the tank?



I picked up an Echlin kit from NAPA and compared it to the other one that I had in there. No difference except for the clip that goes on the needle. The old clip looked bent. I am wondering if this caused it to get hung up somehow.

Took it out this morning and ran it gently and a little vigorous with no flooding. AF was where I expected it to be under all conditions. Didn't do a WOT run as it was 91 degrees at 10:00am here and I didn't want to risk breakdown and having to wait for a tow(Suppose to be somewhere around 97 ; the heat index around 107.)

Get a new nitrophyl float from NAPA, a new kit from Cliff at CF, then rebuild it. It may have crap in there. Fuel pressure should be about 4lbs , no more.

 

[SmokinBBC]

loosen gas cap and see if it still does it.

I didn't have a chance to do this before I worked on the carb. What should I look for if I loosen the cap? I have a non-vented cap...is there a vent valve somewhere on the tank?



I picked up an Echlin kit from NAPA and compared it to the other one that I had in there. No difference except for the clip that goes on the needle. The old clip looked bent. I am wondering if this caused it to get hung up somehow.

Took it out this morning and ran it gently and a little vigorous with no flooding. AF was where I expected it to be under all conditions. Didn't do a WOT run as it was 91 degrees at 10:00am here and I didn't want to risk breakdown and having to wait for a tow(Suppose to be somewhere around 97 ; the heat index around 107.)

Get a new nitrophyl float from NAPA, a new kit from Cliff at CF, then rebuild it. It may have crap in there. Fuel pressure should be about 4lbs , no more.

It has the Nitrofill echlin float. If it does it again, I'll get the kit from Cliff. All passages cleaned and verified no dirt or blockages.

BTW, the return line is hooked up and I never had a vapor lock issue even under the most extreme heat.

 

[SmokinBBC]

Well....it happened again. This time I waited a half hour before calling AAA.

Got it restarted, and after 5 minutes I could get it to idle. Had to lean it out a bit but it idled. Looks like the power piston is not being pulled down. Engine pulls 11" vacuum at idle.

At home now and pulled the carb....the piston won't seat...that little plastic doughnut won't seat....my guess is that when the carb gets to operating temp, the piston pops up and dislodges the doughnut and then the primary rods are always up. No seal, no vacuum to seat the piston. Maybe?

The spring is the original. I compared it to a set that I have and it is pretty soft, so the piston should seat....always has before.


After so many flooding problems....I think it is time for a different carb.

 

[010752]

Do you mean that the retainer won't stay seated?
You can stake it a bit, but when the gasket and top is on it can't come out of it's seated position. You should be able to see if it gets pulled down thru the vent tube.

Maybe you're getting inconsistant fuel pressure or too high a pressure, have you run with a pressure gauge to check.

 

[SmokinBBC]

Do you mean that the retainer won't stay seated?
You can stake it a bit, but when the gasket and top is on it can't come out of it's seated position. You should be able to see if it gets pulled down thru the vent tube.

Maybe you're getting inconsistant fuel pressure or too high a pressure, have you run with a pressure gauge to check.

Yes, the retainer won't stay seated. I checked it while idling after I got it restarted and the piston was all the way down. I also checked before I put the carb back on and it was fully retracted and the spring was operating properly. So, If it was seated when the top was installed, then it was fine.

I haven't checked the pump with a guage yet. That's next. The engine ran fine at idle and when I goose it and run it in neutral.....did this quite a bit (1/2 hour or so) before driving it when I reinstalled the carb. I tried to get it to flood in the driveway.

 

[SmokinBBC]

Finally got around to testing the pump with a buddies help. The pump ran inconsistent at idle...needle flickered. But ran a pretty consistent 4 at 1000rpm. Fuel pumps are cheap, so I replaced it and tested the new one. Just about the same readings just slightly lower. Not the 3psi that Jeff mentioned but consistent.

Checked my fuel return lines and it is fine. No noticeable pressure build up in the tank when cap is removed. The vent is on top of the tank, so no way to verify it is clear other than visual inspection. Maybe someone has an idea here?

The flooding was happening in 95+ degree weather and from what I've read, the fuel pump can get hot enough to somewhat boil the fuel and increase the pump pressure. The pump is in the stock location with the stock manifolds. Engine does not run hot. Normally about 190 at the top rad hose.

I pulled the carb apart. 2 things that I noticed.

First, the idle channel restriction was missing on one side. I bought a set, resized them and popped them in. The one that was still in there was .072. (to large for my car..the news was are sized to .060) No wonder I could never get a consistent idle. Now the idle screws actually have an effect. I have 13afr at idle with 3.5 turns and 12.5 at 3.75 turns. I have no idea how the one restriction went missing. It may have fallen out when I was cleaning the carb a while back...but those things shouldn't just fall out. Maybe it popped out when I was shooting air through the channels???)

Second, I vacuum tested the needle on the seat. There was no vacuum hold at all. So I took a spare check ball and put it the seat and gave it a few raps with a punch. Vacuum tested again and now it holds vacuum at all pressure.

I am thinking that the combination of the missing restrictor and the poorly seating needle was the problem all along and reared it's ugly head during the hot summer temps.


Anyhow, I have run it around the neighborhood a couple of times, let it sit a few minutes so it could get good and hot....ran it again, let it sit about 10 minutes (this only got it to 202 degrees at the hose). Got in and raced it to the gas station...shut it down and filled it up...raced it back home....running it through the gears...jerking the gas peddle....down shifting....no flooding.

It felt good to pull it in the driveway under it's own power rather than on a flatbed. I am keeping my fingers crossed that I fixed whatever problem it was since I really don't know what the problem was. :crap:

Damn, what a pain in the arse.