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.

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.

Dave Noll · 03-08-2015, 11:06 AM

Quote:

Originally Posted by Mike Graham

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.

Uh-oh, do you mind if I ask if that was a new 110gph pump ? My combo uses a 1.21 carb on a 351c but my Carter pump is rated lower.

03-02-2015, 05:12 PM	#1
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	#2
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,473 Likes: 632 Liked 1,987 Times in 599 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	#3
Bob Gullett VIP Member Join Date: Mar 2002 Posts: 1,108 Likes: 58 Liked 510 Times in 117 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	#4
Paul Wong Member Join Date: Jan 2003 Location: Las Vegas Posts: 385 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.

03-07-2015, 09:58 PM	#6
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.