454 dually vapor locking ideas?

[chris mc bride]

My lil brother called me tonight about his dually vapor locking and asked for any cures. He has already changed pump,new edelbrock carb,2 inche spacer and reroutes fuel line. Hes getting ready to install headers and true dual exhast,trying to get better milage and maybe help getting heat out of motor.
I've had tons expreiance tuning race car engines,but street stuff not my specaility.Only had few vehicles with this problem and nver realy found a good cure. Figure maybe some og you guys might have idea.

[chris mc bride]

Have problem with 86 dually vapor locking. Already have new carb,fuel pump,2 inch spacer and getting ready to install headers and exhaust. Wondering if maybe someone here knows of possible cure for vapor locking fuel system,also have rerouted fuel line. Not sure what to try next.

[texasfunk]

i had a HORRIBLE vapor locking problem with my 87 in the summer, i had an ingenious idea of using an old trans cooler i had, and running the fuel through that, it was always vapor locking in the fuel pressure regulator so i ran the fuel thru the cooler before the regulator, never had the problem again, and im more then certain there are actual "fuel" coolers out there, i just used what i had lying around out of frustration

[LONGHAIR]

Block-mounted factory style mechanical pump?

If so, an electric pump mounted in the rear as close to the tank as possible, will help you quite a bit. Installed this way actually puts the fuel in the line under pressure rather than vacuum. This helps with vapor lock by not allowing the pockets to form.

[cableguy0]

Try a wood or plastic spacer under the carb if hes got a metal one now. Also make sure the fuel cap isnt causing a vacuum in the tank stopping fuel flow. I have had to drill a small hole in fuel caps in the past to allow them to vent.

[chris mc bride]

thanks. I think he tried a holley blue pump with no help. He probaly had it at the motoro though.

[chris mc bride]

Thanks guys. Never thought about the cooler idea. Ironic since we use to cool our fuel for the funny car with a aluminum worm in a cooler full of ice. Funny now that nhra has a minimum temp for fuel in the nitro fueled cars and they think its new idea.
Also like the thought about the fuel cap,I had this on a injected car once. I guess streetcars do have something in common with race cars besides being expensive.

[cableguy0]

Its all the same junk. Street stuff usually just lasts a little longer.

[chris mc bride]

maybe with me driving it,its a tossup. Then again most street stuff don't make hp in the 3000 plus range. Man its shame too everyone should know the thrill of smacking a throttle watching the tack jump to 9000 before you can blink. Drop the clutch and hit a 100 mph in just over a second(unless its nitro then its 100 in about .8 seconds and 60 feet). Theres only one thing that comes close and I bet your old lady will not do that 24/7 anyway so might as well race also.
Sorry think I have a problem and need professional help,its called a sponsor.

[Robert1970C20rstbukt]

I haven't been having any trouble with my flatbed in this good 'ol Texas heat(mid to upper 90's) and it gets driven every day. It's running a 180 degree thermostat and it has a new HD aluminum radiator with an electric booster fan up front. When the old water pump went out I got a HD one to replace it also. I was thinking about getting a Mr. Gasket aluminum spacer kit for the carb awhile back but never did, might go pick one up anyway.

[LONGHAIR]

I knew that I had just replied to a post like this....

Merged, please don't do this. It is against the rules for a reason.

XIV. Multiple Posting - It is simply not acceptable to post your question more than once, or to post it in more than one forum. Choose the forum that your question or post best fits in, and place it there and only there. If, after posting, you feel it should be in another forum, private message the forum Moderator and ask if they would move it for you.

[Rich-Red86SB]

He's my story, my truck is a 76 GMC long bed 2500 454 with a 400 auto tranny 2 wheel drive. The truck has stock exhaust manifolds, dual fuel tanks with A/C and I've been fighting a vapor lock problem for years. First time it happened the A/C was on (100 degree day) and when I shut off the A/C it would stop. My first thought was a bad compressor just pulling the engine down making it work harder so I changed the compressor.
This seemed to help but the problem came back, so I thought weak fuel pump so I changed the stock type fuel pump (and took it back and got another one on exchange). I'm pullin my race car on the trailer (hot day) up a steep grade trailer and car about 4500 pounds (Cajon Pass for the Cali guys) and the vapor lock comes about half way up the pass acting like it's running out of gas, I limped it to the top and made it home. I thought cheap fuel pump so I went to NAPA and bought a good one, few weeks later same thing again. I read the truck manual and did a flow test on the fuel pump and it passed with flying colors.
I dropped the fuel tanks and pulled the tank socks off (they were dirty but not plugged) and kept the stock filter at the carb . Drove it again pulling the trailer and car and the problem comes back again acting like it's running out of gas going up the pass on a hot day. Now the problem came back again but this time I wasn't pulling a trailer just driving the truck on a hot day going up and pass. I have a thremo gun so I checked the temp on the exhaust manifold and it was about 420 degrees and with the stock pump a few inches from the exhaust manifold I thought it must be heat sink on the fuel pump so I made a sheild out of sheetmetal to sheild the fuel pump. What was interresting was when I put the thermo gun on the frame by the exhaust manifold the frame was 225 degrees and the stock steel line is bolted to the frame (soaking up that heat) to the pump. So I went to my local Heating and A/C parts house and bought a stick of 3/8 insulating wrap (not the 1/2 inch stuff from Home Depot it's way to big) and wrapped the fuel line from the frame to the fuel pump and up to the carb. Another thing is there is so much heat under the hood I made some 1 inch spacers (3/8 sockets work great) so the hood would not sit on the rubber seal that seals it to the body to let some of that hot air out of the engine compartment.
One last thing is gas, it's just not that good anymore with the blends companies mix up to meet air standards (summer blends) , I've read that some gas boils at 225 degrees so it could be a mix of problems that cause vapor lock. Tomorrow I'm going racing and I'll be pullin' the car and trailer back up the grade again so we'll see if my working and the fuel lines and sheild help . Rich

[westofb]

The old timers would put one or two wooden clothes pins on the fuel line from the pump to the carb...my granddad swears it works, I don't have a clue how it helps, but have seen them on more than one vehicle.

[irishman999]

I had a 74 dodge colt gt i drove around all through high school, every summer it would vapor lock bad, rebuilt motor and new everything including fuel pump. I just carried jugs of water around with me so when it vapor locked i would pour water on it and be on my way. Not a fix but kept me from being stranded.

[LONGHAIR]

Rich-Red86SB, your post is actually a "hi-jack" and should have been the start of it's own thread. Had you given all of that detail and then offered a solution, it would be ok.
Since it is already done (and not to confuse things) I will leave it for now.

To address your problem; once again, an electric fuel pump will often cure this problem. You mount the pump in the back, as close to the tank as possible, this puts it away from the heat. But the biggest benefit is that it puts the fuel that is in the line ahead of it under pressure. The pressure works to keep the vapor (bubbles) from forming, so the line is full of fuel.
Now, this is not to say that the other heat reducing things don't help. I would still do my best to re-route the line away from anything that creates heat. The insultation can't hurt either.

[Rich-Red86SB]

UPDATE= Drove the truck today pulling the racecar and trailer up the Cajon Pass, outside temp was about 90 degrees. I Had no vapor lock and truck ran great. Looks like what I did worked . Rich