U/SA help request - Page 2

Mike Graham · 03-02-2015, 05:12 PM

I don't discount that it could be ignition. It has a Digital seven with the MSD coil.
I am very meticulous when it comes to ignition wiring. The MSD has 8 ga wire directly to battery for power and the same to the block for primary ground. The MSD has no low voltage alarms recorded. will re check all of that. We are going out Friday and will swap boxes and coil.
I thought Mark was right and I would find a bunch in the filter or in the trans pan. But more subtle than that.

Mike Pearson · 03-02-2015, 06:11 PM

If its been sitting a while I would check the valve springs too. Might even have a broken one or two. something like that could happen between two runs. Most likely not the MSD or coil. Anything else change electrically? The digital boxes don't like any "electrical noise". Did you run a leak down or compression test?

Bob Gullett · 03-02-2015, 06:14 PM

Years ago we had a fuel pump go bad. Had pressure but no volume. Or a plugged fuel filter. It caused us a major performance loss and didn't affect the running of the car. No engine miss or nothing. Changed pump problem cured.

Paul Wong · 03-02-2015, 06:53 PM

[QUOTE=Bob Gullett;463588]Years ago we had a fuel pump go bad. Had pressure but no volume. Or a plugged fuel filter. It caused us a major performance loss and didn't affect the running of the car. No engine miss or nothing.

I lost a class race a few years ago to Bob because of a fuel pump failure in a "U" car. fuel pump just failed to keep up because of lack of volume.

Jeff Stout · 03-02-2015, 07:01 PM

Quote:

Originally Posted by Bob Gullett

Years ago we had a fuel pump go bad. Had pressure but no volume. Or a plugged fuel filter. It caused us a major performance loss and didn't affect the running of the car. No engine miss or nothing. Changed pump problem cured. Also I've seen where someone is using a cheap brand of synthetic oil causing poor ring seal.

Spent about 1200.00 to find it was the pump. Had gauge mounted in front of windshield and always stayed above 6 lbs. So I chased everything else until I changed pump as someone suggested to do and shazam.

Bob Gullett · 03-02-2015, 08:46 PM

Quote:

Originally Posted by Paul Wong

I lost a class race a few years ago to Bob because of a fuel pump failure in a "U" car. fuel pump just failed to keep up because of lack of volume.

That's the only way I can beat that U car! LOL

Kingpen · 03-02-2015, 09:35 PM

You said you ran 8 gauge wire from ign box to power source but ground to the block,I had 2 different boxes in 2 separate cars that gave problems until I grounded box directly to the battery.might be worth a shot......Victor

Bill Bogues · 03-02-2015, 10:53 PM

a few season's ago our car slowed down 4 tenths from one race to the next. After going through all the usual stuff in the engine.trans and so on it turned out to be the rubber hose in the brake line at the rear end had collapsed and wouldn't release the brake pressure all the way. Changed the hose and car picked right back up. Might be something to look at.

RJ Sledge · 03-03-2015, 01:26 AM

Mike

That sounds weird that you could lose 4 tenths and only slow down 4 mph. How did the short times compare to the first run??

Like Bill B said check your rubber brake hoses, I've had some that would collapse and hold pressure.

Keep us posted on what you find.

Good Luck

RJ

Mike Graham · 03-07-2015, 09:58 PM

The rest of the story. I steal the datalogger out of the SS car and we head to Wildhorse
Pass. When the car leaves the fuel pressure drops to zero and never recovers the rest
of the run. Enough fuel that the car doesn't miss.
The idea of let's not over spend on the fuel system didn't work out. I would have never thought that a 110 gph pump would not be enough for a 225 hp stocker.
So on goes the 400 gph spare for my car. Problem solved. Right back to where the et should be and the car is now consistent.
As a side note. The pro bracket cutoff here is 13.99 and here car won't run that in the heat. So I prep a 1.21 carb thinking that it will pick the car up enough to run 13.99 during the day. That carb picked the car up 6 tenths and almost 6 mph. 13.42 at 98 mph on the first pass.

03-02-2015, 05:12 PM	#11
Mike Graham Member Join Date: Jul 2002 Posts: 410 Likes: 1 Liked 341 Times in 67 Posts	Re: U/SA help request I don't discount that it could be ignition. It has a Digital seven with the MSD coil. I am very meticulous when it comes to ignition wiring. The MSD has 8 ga wire directly to battery for power and the same to the block for primary ground. The MSD has no low voltage alarms recorded. will re check all of that. We are going out Friday and will swap boxes and coil. I thought Mark was right and I would find a bunch in the filter or in the trans pan. But more subtle than that.

03-02-2015, 06:11 PM	#12
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,449 Likes: 615 Liked 1,926 Times in 579 Posts	Re: U/SA help request If its been sitting a while I would check the valve springs too. Might even have a broken one or two. something like that could happen between two runs. Most likely not the MSD or coil. Anything else change electrically? The digital boxes don't like any "electrical noise". Did you run a leak down or compression test? __________________ Mike Pearson 2485 SS

03-02-2015, 06:14 PM	#13
Bob Gullett VIP Member Join Date: Mar 2002 Posts: 1,106 Likes: 57 Liked 506 Times in 116 Posts	Re: U/SA help request Years ago we had a fuel pump go bad. Had pressure but no volume. Or a plugged fuel filter. It caused us a major performance loss and didn't affect the running of the car. No engine miss or nothing. Changed pump problem cured. __________________ 68 Chevy11 327 F/S Last edited by Bob Gullett; 03-07-2015 at 10:46 PM.

03-02-2015, 06:53 PM	#14
Paul Wong Member Join Date: Jan 2003 Location: Las Vegas Posts: 384 Likes: 101 Liked 419 Times in 85 Posts	Re: U/SA help request [QUOTE=Bob Gullett;463588]Years ago we had a fuel pump go bad. Had pressure but no volume. Or a plugged fuel filter. It caused us a major performance loss and didn't affect the running of the car. No engine miss or nothing. I lost a class race a few years ago to Bob because of a fuel pump failure in a "U" car. fuel pump just failed to keep up because of lack of volume.

03-02-2015, 09:35 PM	#17
Kingpen Member Join Date: Feb 2006 Location: sooner state Posts: 105 Likes: 3 Liked 64 Times in 22 Posts	Re: U/SA help request You said you ran 8 gauge wire from ign box to power source but ground to the block,I had 2 different boxes in 2 separate cars that gave problems until I grounded box directly to the battery.might be worth a shot......Victor

03-02-2015, 10:53 PM	#18
Bill Bogues Member Join Date: Apr 2005 Location: Bethany La. Posts: 323 Likes: 96 Liked 169 Times in 53 Posts	Re: U/SA help request a few season's ago our car slowed down 4 tenths from one race to the next. After going through all the usual stuff in the engine.trans and so on it turned out to be the rubber hose in the brake line at the rear end had collapsed and wouldn't release the brake pressure all the way. Changed the hose and car picked right back up. Might be something to look at. __________________ Bill Bogues 4696 STK

03-03-2015, 01:26 AM	#19
RJ Sledge Senior Member Join Date: Jun 2007 Posts: 783 Likes: 502 Liked 288 Times in 90 Posts	Re: U/SA help request Mike That sounds weird that you could lose 4 tenths and only slow down 4 mph. How did the short times compare to the first run?? Like Bill B said check your rubber brake hoses, I've had some that would collapse and hold pressure. Keep us posted on what you find. Good Luck RJ

03-07-2015, 09:58 PM	#20
Mike Graham Member Join Date: Jul 2002 Posts: 410 Likes: 1 Liked 341 Times in 67 Posts	Re: U/SA help request The rest of the story. I steal the datalogger out of the SS car and we head to Wildhorse Pass. When the car leaves the fuel pressure drops to zero and never recovers the rest of the run. Enough fuel that the car doesn't miss. The idea of let's not over spend on the fuel system didn't work out. I would have never thought that a 110 gph pump would not be enough for a 225 hp stocker. So on goes the 400 gph spare for my car. Problem solved. Right back to where the et should be and the car is now consistent. As a side note. The pro bracket cutoff here is 13.99 and here car won't run that in the heat. So I prep a 1.21 carb thinking that it will pick the car up enough to run 13.99 during the day. That carb picked the car up 6 tenths and almost 6 mph. 13.42 at 98 mph on the first pass.