Any Other Suggestions...

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70Dart499

70Dart499

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Finally Got the Dart to the track today for the first time since the change over to ladder bars, and all in all, the chassis works great, ran a new personal best despite the issue. But now it seems that I am having a fuel delivery issue, I launch, and the car leaves good, picks up the front end a bit, and then about 40-60' out it acts like it is starving for fuel, it will bog two of three times, and then it will pick up and run fine. We checked all of the electronics, and everything appears fine. The fuel prerssure was set at 6 psi, and we raised it to 9 to see what would happen, and the issue got a little better, and the car picked up considerably during the second half of the run, so that is what leads me to belive there is a fuel issue. I don't have any jet extensions in my Demon, so I'm going to put those in and see if that helps. I am running a Holley Blue pump with a return line, and I'm also going to take the return line off, and put it back the way that it should be with just the regulator and no return. Anything else that you guys can think of that I should check?? Thanks.
 
Fuel sloshing in the tank or float bowls? Does the fuel pressure remain constant during the run? Especially when it bogs?
 
Lonewolf3165 said:
Fuel sloshing in the tank or float bowls? Does the fuel pressure remain constant during the run? Especially when it bogs?
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See, thats what I don't know, the only pressure guage I have is under the hood. I'm going to put another fuel pressure guage up on the cowl of the car so that I can see it as I go down the track, something I have been needing to do anyway.
 
I'd leave the return line as is especially if the fuel pressure didn't drop. Less strain on your pump.

You could cheat a little and raise the rear float level slightly. The extensions should help.

How did it 60'?
 
crackedback said:
I'd leave the return line as is especially if the fuel pressure didn't drop. Less strain on your pump.

You could cheat a little and raise the rear float level slightly. The extensions should help.

How did it 60'?
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It 60' around 1.48-1.50, without any spin, track was super greasy and it was 100* in the shade today, so all in all I'm thrilled.
 
That's a bunch better. Nice improvement. Keep working at it.

Was the chassis guy there? If not, get the bog sorted out and then have him come out.

Now the fun part. Finding what the car really wants in front end, tire pressure, launch rpm, timing, rear set up. Get a log book! :)
 
crackedback said:
That's a bunch better. Nice improvement. Keep working at it.

Was the chassis guy there? If not, get the bog sorted out and then have him come out.

Now the fun part. Finding what the car really wants in front end, tire pressure, launch rpm, timing, rear set up. Get a log book! :)
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Thanks, Yes, he was there, he helped me with some suggestions with the carb. We didn't tune the Chassis because it was pointless until we get the carb sorted out. He lives close to the track so he is going to come back once I get the carb sorted out. I've got a log book, and now I just have to start keeping better records. Pretty happy with a 7.01 with the bog, should be well in the 6's soon. :)
 
What size fuel line do you use? Might sound crazy and be pointless but i remember reading awhile back that some people who ran the 1/2" line for a drag car could have this issue because when launching the fuel wants to stay where it is in the line or even go backwards, cant remember who wrote the artice but they reccomended going to 3/8" line if possible to help relieve the issue because with more volume of line needing to be filled on hard launches the pump cant keep up. As an example if you go from 1/4" line to 1/2" line your actually tripling or quadrupling the fuel volume instead of doubling
 
How is your system laid out?Nice 60's times.Try extensions back in.X2 ,on log book.
 
Well my coffee has'nt kicked in yet. I see you you already said you dont have the jet extensions . Sorry. I bet they help.
 
Well guys I think I found the issue, when I pulled the line to the carb off of the regulator and I found a good sized piece of rubber stuck in the regulator. So after I found that, I drained the fuel cell, and I found several small bits of rubber in it. I then disconnected the fuel filter and it was nearly totally clogged with bits of rubber. It looks like the jack*ss (not the guy that put the ladder bars in) that I had working on this car when I first got it neglected to blow out the hoses before he put them together and put them in the car. Still going to put the jet extensions in, but I think the clogged lines were the cause.
 
Are the line old or brand new?

Braided steel lines and new blend pump gas will have the liner coming apart. Happens a bunch now.
 
i was having a problem like that it would fall flat then start pulling again went up a size on squirters but thats without knowing wat ur plugs looked like mine looked fine so we tryed it and didn't change the look just the fall out
 
crackedback said:
Are the line old or brand new?

Braided steel lines and new blend pump gas will have the liner coming apart. Happens a bunch now.
Click to expand...

Brand new, and I run race gas, so I don't think Thats the case, but I wondered if it might be. The pieces are pretty big though, looks like they were left over from when the lines were cut and made.
 
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