Vapour Lock or just Fuel Starvation?

[uk409deuce]

Help!

I Just completed a 400 ish mile round trip in my coupe. During which it started playing up with what seemed like Fuel Starvation but it has been suggested that it might be vapour lock. Engine is a 409 with 690 heads and factory dual quads rebuilt to stock specs with stock style chrome fuel line from the pump up to the filter in front of the front carb. What happens is if I "get on it" and get on the second carb it 's OK in first / second then when I get in to third it bogs down like it's running out of fuel then I have to shift in to 4th and pedal it until it picks up. This I thought would be fuel stavation, but If I pull in for gas when I pull off after filling up it does it even before I get on it and I have to pedal it for half a mile or so, This sound like vapour lock? Fuel line is 3/8th and both the inline filter by the tank and the one before the carbs are not clogged and there are no kinks in the fuel line. Engine runs @ 160 - 170 degrees on the open road and will rise to 195 when switched off while I fill up. Any help and advice welcomed................... :?
Gary

 

[tripowerguy]

How close to a header or other exhaust part is any of the fuel line. You could be boiling the fuel along the way to the carbs. If you have an electric fuel pump it would push the fuel rather than draw the fuel. I don't know all the factors but it could be weak fuel pump also. Put a pressure gauge on fuel line and crank engine but do not start engine, the pressure should hold for at least 15 minutes. If it leaks off then you have a bad fuel pump. And think that because it is brand new that it is good. I have a brand new chrome fuel pump in my tool box that isn't worth a flip. The only reason I don't throw it away is because it is chrome. Roy

 

[mercsrus51]

vapor lock??

Happenened on my 348,,,,,after I tested the fuel pump, it showed 6 lbs,,,and I drilled tiney holes in my gas cap...just in case.... it went away after the car sat for a day, and nevr returned (yet) still cannot place the problem,,,but it felt the same way , like fuel starvation... world of the wierd for Hot Rodders...your not alone brother....

 

[Tony Shaffer]

Fuel problem

Hello from the USA,
This is Tony from Day Automotive in Independence, Mo. We built your engine with Phil. You know (fast Phil from Parkville) that's his nickname! Your problem could be vapor lock, but I would check to make sure that your gas tank is vented properly. Any problem with venting could cause exactly what you are describing. It basically amounts to lack of fuel for what ever reason, whether it be carb. over heating or gas line overheating or venting of some sort. It could even be the pump, but I would check the simple things first just to make sure that some little bitty silly problem doesn't make you go whacko. There are some other things to check on air inlet and such but check this first and let me know. Hope you are having super fun with your "09". The best from the USA "409's forever"
Tony
Day Automotive

 

[Tom Kochtanek]

Little known fact about Wirral

We all owe a big favor to Wirral's most famous 'unknown' son, a chap called Crapper, who came up with the greatest modern invention as listed in the top 100- the toilet system. It is the number one invention followed by the computer, the printing press, fire, the wheel, radio, etc.

Having completed my first of what I hope to many visits to England, I would guess your 409 car sticks out like a sore thumb in that country. With gas prices around $8 per gallon (check that out, Bob!) it would be an expensive trek to venture 400 miles. Maybe it wasn't vapour lock, but a choking off of the carbs with knowledge of that most precious petrol atomizing in the intake runners

That said, my impression is that most cars in the U.K. seem to be small, nimble and bestowed with fewer cylinders than normal. That's why your 409 must standout. What is it installed in? Would it be one of our beloved "X frame cars?

Cheers!
TomK

 

[JimKwiatkowski]

Tom,go to uk's thread (just finshed my car) to look at his photos to see what the 09 is installed in.It's a cool looking ride

 

[bobs409]

If I had to pay $8 per gallon, my 409 would get run about 10 miles per year.

BTW, I woudn't say a 409 would stick out like a sore thumb.... more like a thumb with a huge diamond on it. (just messin' with ya)

 

[droptop62]

Tom.
Just read His Name, it tells you all you need to know, "UK409DEUCE"
if that aint a big enough clue, read his signature.
and like Jim K. said, check out the pictures in the thread Jim mentioned

 

[uk409deuce]

Thanks for all the input, I will work my way through the simple stuff this weekend, the tank is vented with a rollover valve so maybe it is stuck, plus there is one part of the fuel line that runs close to the pipes were the exhaust cut out drops under the chassis rail, not dangerously close but close enough to get warm so I will move it. Also is a 3/8" Line adequate for these dual quads ? or would 1/2" be better?

Tony, you do really, really nice work! Thank You.

I have got to get it sorted as my brother has twice beat me with his small block car, and he doesn't believe me about the fuel starvation : he just thinks his car is faster

I did not know that the Crapper was invented here and I lived here all my life, you would think we would have a huge monument or ???..

 

[Tony Shaffer]

Crapper and fuel problem

I didn't know about the crapper being invented in the UK. That's cool! The monument thing, you could have something there. After you look at everything this weekend as you described, if that doesn't fix it, then we go to the carbs and related items. You may even have to install a fuel pressure guage on the car to observe just what is happening. We can't have a small block beating your "09" You could always fly me over there as your tuner and we could take care of that small block. I'm glad that you are happy with the engine. When I do work for someone that lives that far away I have to take a 3rd look at everything that I do. I normally only check things twice. Thanks again for the compliment. I'll be waiting to see what happens. Good luck.
Tony
Day Automotive

 

[Phil Reed]

yeah right???

Only check things twice????? For us local guys...since we're so close...he just doesn't check anything at all!!!!!

Oh well...I get to take 2 more motors to Tony next week. I wanted to take them over this week but he had already used up ALL his horsepower allotment for this month so I get to start him out on next month!!!!!

 

[Tom Kochtanek]

Maybe November?

After Phil uses up the October horsepower allotment, I hope to bring the battered "068" QB to Tony for a refurbushment. Perhaps November?

Sorry I didn't get out there last Thursday, Tony. My meeting ran late and I figured I'd be back again soon. Going to see Wayne Euper Saturday, not sure if you're open then. Let me know and we'll see if things work out. No big hurry. Still have a lot of work to do on the vehicle

Best,
TomK