car died on starting line

[coilwire]

Have been having a bad year at the strip. The last three races the car has been dieing at the starting line. The lights come down and I go from idle to wot and loose all power. I thought it might be carb problems so I rejetted the carb to 74's in front and 76's in the rear, 40's for the power valves and 50cc accelerator's. That did not do it. First run Sunday was good then everything went down hill. On the second run went from 13.71 to 16.49. Car died coming out of the burnout box and my fuel tank made a heck of a noise. Got back to the pits poped the fuel tank door and thought it would tear my hand off eith all the pressure. The third run it died coming off the starting line and at about the 300ft mark started loosing power. Hung my head in shame,only 30mph in the 1/4 compared to 101 ont he first run. Got back to the shop pulled the tank vent line off and ran air through it. everything was clear.

If anyone has had a similar problem what did you find.

I am running a torker 351 intake with a holly 750 dp built by bill mitchell putting out about 830cfm This problem has just started about 3 weeks ago

Thanks everyone

Jim

 

[Wolverine]

It seems like I am suggesting vacuum gauges for everyone these days. But, you could really use one to see what is happening to your vacuum when you go to wide open throttle. I also posted a VACUUM GAGE diagnostic on the forum a few days ago so you can try that as well.

You have to do this when the engine is under load, so you need to run a vacuum line into your driver's compartment.

Someone here will correct me, but if your car is NOT backfiring, maybe you are flooding it off the line.

In regards to your gas pressure at the tank, your car was OEM'd with a charcoal canister under the hood, passenger side, near fire wall. This canister vented out the pressurized gas from your tank. If you don't have this canister, you have to find the line and then either add a canister/filter/vent of some type or you have to replace your non vented mustang cap with a vented cap....good luck with that.

Personally, it sounds like you have 2 separate issues. But, someone here will correct me.

 

[Jeff73Mach1]

I think it is ignition.

 

[jorgem2]

I had the vent fitting on top of my tank corroded and clogged. If you blew air into your tank do you think maybe you cleared it now?

Be careful blowing air into tank with gas cap open, If the level is high it will spray fuel out the back. My lawn reminds me every day.

Do you still have the filter sock inside the tank on the withdrawal tube? Is it restricting the fuel flow?

Float level too high in the carb, flooding over at takeoff.

Try to check or change one thing at time to try to isolate the problem without adding to it.

Best of luck

 

[c9zx]

Given what you said, it sounds like heat is inducing the problem. What are you running for fuel delivery and ignition? Was the tank less than 1-4 full?

Chuck

 

[BigPinoyHunk]

is the car real hot when it happens? make sure you are not getting any vapor lock in the fuel system.

also make sure your fuel pump is taking a DUMP! I had 2 bad holley black pumps before i got a good one when i switched to a aermotive pump.

mechanical pump? when i brought my car back from the storage and it sat for 3 years, after a month of driving around again. i had a stock fuel pump replacement and i would get some fuel surges from the engine when just cruising and when i wanted to hit it hard off the line. the pump was taking a dump and i replaced it with a summit high volume pump and the problem went away. at least a stock'ish fuel pump isn't expensive but you could also get a summit high volume pump for about 50 dollars or less.

 

[coilwire]

Jorgem, pulled the fuel tank and pulled the vent fitting, it was gruddy and clogged. I will be pulling the filter sock tomorrow.

Wolverine will be putting a vacume guage on the car once I get the tank back on and running.

Chuck the tank was 3/4 full. Temp in the staging lanes and the starting line was about 104 d.. For fuel delivery I am running a Holly blue fuel pump with 3/8th line all the way. For ignition I am running a MSD 6al box,SS Blaster coil and a Pro billit distributor.

Olie, after I get the car running I am going to temproialy hook up a fuel pressure guage to my cowl to see what is happining when I go from idle to wot. At idle I am running 7lbs. pressure.

Thanks to everyone who has responded,I am at wits end. This has been going on for a month now.and is getting very frustrating.

I will keep everyone posted on what I find and how it all turns out. Next race is the 29th.

Jim

 

[Wolverine]

It will be something obvious and easily repaired....then you will be screaming down the track....

 

[TommyK]

Have been having a bad year at the strip. The last three races the car has been dieing at the starting line. The lights come down and I go from idle to wot and loose all power. I thought it might be carb problems so I rejetted the carb to 74's in front and 76's in the rear, 40's for the power valves and 50cc accelerator's. That did not do it. First run Sunday was good then everything went down hill. On the second run went from 13.71 to 16.49. Car died coming out of the burnout box and my fuel tank made a heck of a noise. Got back to the pits poped the fuel tank door and thought it would tear my hand off eith all the pressure. The third run it died coming off the starting line and at about the 300ft mark started loosing power. Hung my head in shame,only 30mph in the 1/4 compared to 101 ont he first run. Got back to the shop pulled the tank vent line off and ran air through it. everything was clear.

If anyone has had a similar problem what did you find.

I am running a torker 351 intake with a holly 750 dp built by bill mitchell putting out about 830cfm This problem has just started about 3 weeks ago

Thanks everyone

Jim

The fuel tank had pressure or vacuum? If vacuum the problem is venting. Pressure would be an unusual problem.

 

[coilwire]

Pulled the fuel tank.the vent tube at the top of the tank is restricted. I am going to open it up a little and and then pull the sending unit to make sure the sock is not plugged.

Jim

 

[jorgem2]

Pulled the fuel tank.the vent tube at the top of the tank is restricted. I am going to open it up a little and and then pull the sending unit to make sure the sock is not plugged.

Jim

The vent on the tank has a very small hole and I believe a check valve ball. Mine was so corroded I drilled it out thru the nipple to increase vent size. Unfortunately I dont have the rollover protection of the vent valve check ball.

Best of luck

 

[sm3570]

The vent on the tank has a very small hole and I believe a check valve ball. Mine was so corroded I drilled it out thru the nipple to increase vent size. Unfortunately I dont have the rollover protection of the vent valve check ball.

Best of luck

Jorge, if you roll your car the check ball will be the least of your worries.