Big Blue, the 67 Crown Coupe - Managing Director Edition

[imon_2nd]

Progress Update
Headlight switch cleaned and reconstructed with a fuse replacing the bimetallic thingy that prevents current overload in the switch. Right front brake caliper replaced. New brake fluid. Transmission pan gasket replaced and trans fluid replaced. Rebuilt alternator and voltage regulator. New battery. At this point, I'm confident that the car is solid and can be driven anywhere, anytime. Except for the "where's the gas in the float bowl?" morning start issue, all that's left is nit-picky stuff that I'll get to over the winter. No, I'm not going to list the nits. I mean, who cares which cigar lighter doesn't have power?

 

[MarPar]

I mean, who cares which cigar lighter doesn't have power?

this guy does...

well, thankfully not anymore. carry on! lol

 

[commando1]

I mean, who cares which cigar lighter doesn't have power?

Sorry, Dave. I do. I'd HAVE to replace it.
Damn, I have issues, huh?

 

[imon_2nd]

Sorry, Dave. I do. I'd HAVE to replace it.
Damn, I have issues, huh?

Funny!

 

[imon_2nd]

So, to test the hypothesis that boiling gas in the fuel line where it passes along and over the valve cover was causing enough vapor pressure to push gas out of the float bowl and into the manifold, I insulated the fuel line in that area. The problem remains. My suspicion is that the relatively new fuel pump is not an OEM type or NOS and is allowing back-flow. I know, long shot. I'll install a check valve in the line to test that idea.

 

[pgadler]

So, to test the hypothesis that boiling gas in the fuel line where it passes along and over the valve cover was causing enough vapor pressure to push gas out of the float bowl and into the manifold, I insulated the fuel line in that area. The problem remains. My suspicion is that the relatively new fuel pump is not an OEM type or NOS and is allowing back-flow. I know, long shot. I'll install a check valve in the line to test that idea.

Depending on what Your analysis gives You, don't repeat my error. I went for a NOS fuel pump, which let me down after less than 100 miles. NOS = age does not effect the diaphragm favorably = deteriorates. A new of reputable origin/make is recommended.

 

[imon_2nd]

Depending on what Your analysis gives You, don't repeat my error. I went for a NOS fuel pump, which let me down after less than 100 miles. NOS = age does not effect the diaphragm favorably = deteriorates. A new of reputable origin/make is recommended.

The pump itself seems to be working fine; plenty of throughput. I can't tell looking at it what make it is, only that it's less than a few years old (bright and clean).

 

[imon_2nd]

Installing a check valve in the fuel line after the filter made no difference in the "first start" problem. A neighborhood mechanic I know said he solved a similar problem in a 1966 Chevelle by replacing the OEM fuel pump with an electric pump. Not sure I want that. There is a carb expert, Marty Vannich in Sacramento who said he can figure out what's going on. I hope so. Meanwhile, I accidentally broke the dip stick tube off at the block. Ordered a replacement.

 

[Zymurgy]

I will be curious what you find out. I was having the same problem, before I had a secondary problem, which forced me to add an electric fuel pump and by pass the mechanical.

I will say it is nice if it sits for a month, with the electric fuel pump, it allows it to fire right up. I believe if it sits for a couple of weeks, even with everything running correctly the carb drains and is hard to start.

If you come to the point of adding a fuel electric pump I can give you advice from my trial and error installation. I am very happy with the end result, but would still prefer to have the mechanical.

 

[detmatt]

I added an electric pump to work in conjunction with the stock mechanical pump late in the summer and it's working good.

 

[Zymurgy]

I added an electric pump to work in conjunction with the stock mechanical pump late in the summer and it's working good.

The electric fuel pump runs all the time correct? I was originally thinking I would use the electric pump to prime and then shut it off, but figured it would not flow through the disabled pump. I never got to try this since I have a push rod for the mechanical fuel pump stuck in the block. (another long story)

 

[commando1]

I added an electric pump to work in conjunction with the stock mechanical pump late in the summer and it's working good.

In parallel or in series, Matt?

 

[detmatt]

Electric pump mounted on the rear shock crossmember about 14 feet behind the mechanical. It currently runs when the key is in either run or start which means I can't listen to tunes without it running. I need to add a switch. I added it out of paranoia just before the last long road trip of the season along with putting a spare fuel pump pushrod and gasket in the tool kit.

 

[commando1]

along with putting a spare fuel pump pushrod

 

[saylor]

ok wow I'm surprised no one has tied you to a tree yet for saying you are thinking about an elec FP.

there are write ups on this forum about adding an elec pump - one is written by me, and there are others. I'm using elcheapo Mr G pump from ohreallys?
I got 2.5 yrs out of the first mr G pump. my homeboy has a holley blue pump and loves it, on a Pontiac groundpounder.

I was fighting heat issues when I added elec FP, but I do have fuel drainback with the elec FP - i.e. the float bowl goes dry to use your term.

here are some random things to think about:

1.) did you R&R all rubber lines in the fuel system? back at tank, frame rail ,etc.
2.) elec pump requires you add a relay at minimum, you also need to add an oil pressure switch, and a roll over switch if you are really cool.
3.) elec pump pushes fuel from tank forwards. mech pump sucks fuel forward from the tank. vanilla shake and drinking straw is best example.
4.) I added a manual prime switch and mounted under dash so I can turn on pump & prime carb after the car has sat a while or first start.
5.) something about tank vents clogged and also if the cap is vented or not - someone else chime in here please I forget this one.
6.) do you leave the mech FP, and add elec FP? I put a FP blockoff plate and some pooky. other ppl run both pumps. drawback is flooding crankcase with gas.
7.) are we having boiling/heat issue up top at carb? heat crossovers blocked yet?

ill think of some more.

try not to die -

- saylor

 

[65sporty]

7.) are we having boiling/heat issue up top at carb? heat crossovers blocked yet?


try not to die -

- saylor

I had the same thought, also is the carb leaking from the bottom into the manifold and draining the float bowl. I have seen this with some GM's they drain from the core plugs on the bottom of the carb.

 

[imon_2nd]

ok wow I'm surprised no one has tied you to a tree yet for saying you are thinking about an elec FP.

there are write ups on this forum about adding an elec pump - one is written by me, and there are others. I'm using elcheapo Mr G pump from ohreallys?
I got 2.5 yrs out of the first mr G pump. my homeboy has a holley blue pump and loves it, on a Pontiac groundpounder.

I was fighting heat issues when I added elec FP, but I do have fuel drainback with the elec FP - i.e. the float bowl goes dry to use your term.

here are some random things to think about:

1.) did you R&R all rubber lines in the fuel system? back at tank, frame rail ,etc.
2.) elec pump requires you add a relay at minimum, you also need to add an oil pressure switch, and a roll over switch if you are really cool.
3.) elec pump pushes fuel from tank forwards. mech pump sucks fuel forward from the tank. vanilla shake and drinking straw is best example.
4.) I added a manual prime switch and mounted under dash so I can turn on pump & prime carb after the car has sat a while or first start.
5.) something about tank vents clogged and also if the cap is vented or not - someone else chime in here please I forget this one.
6.) do you leave the mech FP, and add elec FP? I put a FP blockoff plate and some pooky. other ppl run both pumps. drawback is flooding crankcase with gas.
7.) are we having boiling/heat issue up top at carb? heat crossovers blocked yet?

ill think of some more.

try not to die -

- saylor

Thanks for the write-up, saylor.

The fuel lines, pump, filter, check valve and rebuilt carb are all new or less than a year old. I insulated the fuel line along the stretch between the alternator and the carb. At this point, I'm sure the problem is not boil-off or backflow. There are no signs of leakage around the carb itself. Could be some internal assembly error in the carb that is allowing fuel to get past the float valve and into the intake manifold, though that would mean gas is flowing "uphill," which seems unlikely. I'll post about this again after our local old-school carb expert checks it out.

 

[imon_2nd]

The local carb expert took a look at Big Blue and concluded that there's probably a bad seal inside the carb at the accelerator pump that allows gas to seep into the intake manifold. I think I'll live with this problem since it's only a once-in-the-morning thing and other times starts instantly.

 

[73 T&C]

Have the same problem so any ideas out there would be appreciated. It started about three or so months ago.

First thought is that I need to tighten the screws down on the carb to make sure they are snug.

Thinking that it could also be a cracked bowl. Ouch.

 

[commando1]

The local carb expert took a look at Big Blue and concluded that there's probably a bad seal inside the carb at the accelerator pump that allows gas to seep into the intake manifold. I think I'll live with this problem since it's only a once-in-the-morning thing and other times starts instantly.

It does make sense to me on why you dont want to rebuild the carb.