Actually the larger wire would be a band aid. If the pump is losing voltage at higher RPM under load its commonly the alternator or the pump, most cases the alternator. Verify the fuel pump is okay, the best way to check is to log fuel pressure at the dyno, or just hook up a fuel pressure guage and tape it to the windshield and have a friend watch it while you drive WOT in 3rd gear to the upper rpms. Racetronix makes a relay harness that steps up the voltage to the pump under WOT, which would hopefully prevent it from dropping the rest of your system voltage.

By checking voltage I mean verify the sensors are getting 5V for reference with the key on engine off. it's likely they will show fine until the engine is under load as well (thinking the fuel pump is slamming a load at that point)

Hope this helps,
-Christian

 

just FYI i'm running my stock fuel pump with a 138k on it right now.

 

Christian if my fuel pump was going out or losing pressure wouldn't it show up as my car starting to run lean on my datalogs? Once again i'm just learning but it seems the car would begin to run lean, then probably pick up some Knock or something. Am i thinking right? Thanks for all your suggestions and help. I appreciate it.

 

It's possible you're running lower fuel pressure the entire run (should see 46 psi at WOT.)
Something is causing a big voltage drop at WOT, and the most common culprit is the fuel pump. Do the fuel pressure guage test, it'll help to eliminate one other possibility.

 

Just an update i pulled off some valve springs and checked them and they tested out fine. I'm still going to install some Comp R lifters, probably this weekend. I'm also probably going to look into the fuel pump problem. If the pump is bad or eating up to much juice i'll replace it. Is there a good Hi-performance replacement. I've looked up fuel pumps for our fbodies and all of them are "universal fit" I want one made for our cars if at all possible.

 

Racetronix makes a great plug and play upgrade:

http://www.racetronix.com/Racetronix..._Pump_Kit.html

HTH,
-Christian

 

Ok guys i replaced the lifters with some Comp R's and they still didn't seem to help it pull any better on the top end. I'm still gonna look into the fuel pump but i don't see how the fuel pump could of affected the MAP reading. The only thing i could think of is if i have several problems like the lifters and the fuel pump. I never degree'd the cam could that be a cause of the MAP reading. I'm really getting frustrated here guys any more input. I need to start looking at Ls1's for sale.

 

Don't abandon hope. Replied to your PM:

I remember the thread. Since all of the sensors were dropping voltage (MAP and TPS share the same 5V reference voltage) I thought you had a voltage drop issue. I really don't think the 48mm TB is the problem. I'd splice into the wiring going to the MAF and hook it to a Multimeter. With the key on engine off you should be reading close to 5Volts between the ground and the 5V reference input voltage (output voltage will just be a little lower) run the length of wire long enough to run under the edge of the hood, around the passenger door opening. With a passenger watching (don't try this driving alone.) have the assistant watch the voltage as you run up to 6000 rpm in 3rd gear (1st and 2nd won't give you enough time.) If the voltage drops on the input voltage (not output voltage, we already know that drops) then you know something is dropping the system voltage enough to affect the sensor readings. If not, then you know the readings are correct. I will bet money the voltage drops. I would then do the fuel pressure gauge test the same way to verify the fuel pump is dropping off at higher RPMs.

Also it's very easy to degree a cam, you should be able to get a degree wheel for under $25 anywhere. For the first time it shouldn't even take you an hour to get the measurements. That will be one less thing to think about.

Hope this helps,
-Christian

 

Check the FP and Alt...after that make sure the valves and pistons didnt meet....

 

A little bit of an update. I added a 58mm Tb. to help make sure that there will be no intake restriction and would make sure there couldn't be a 88 on the MAP. I've installed comp R's and had a few of the valve springs checked. No real improvement. No one i knew had a Fuel pressure gauge and autozone doesn't have one to rent. So rather than paying $45 for a new one i just ordered a whole new racetronix setup as i have a 140k miles so i'm sure i'll need a pump soon. I've only installed the Harness no pump yet and it brought my 12.4-12.6 voltage on my scanmaster up to 13.5ish at all times. I'm probably one of the few people who wouldn't take their car out and run it hard but i didn't get a chance. I'm hoping this is my problem. Its at least the source of my low voltage.

 

Don't give up! You have a nice looking car that is going to fly once you get this sorted out.

Since you're down about 80rwhp it's almost got to be a combination of things.
I can tell you the racetronix fuel pump kit helped my car with a tune for 30rwhp and I only have the hot cam with stock heads in the car right now.

Since the car isn't pulling and your springs are fine I would think something is wrong with the installation of the cam. I would also do that compression test just to verify everything is ok with that.

My hot cam pulls to 6500 with stock heads yours should be doing that easy.

Good luck

 

I think my fuel pump is starting to go now. After installed the harness the next morning i drove my car to work then stopped off at the parts house on the way home. After i came out i tried starting it and all it would do is crank and crank and crank. It wasn't hitting at all. I finally decided i should listen to see if my pump was coming on so i turned the key and i couldn't really hear anything. So then i stuck my head out the window and turned the key and i heard it kick in. I turned the key back and forth letting the pump prime and then i cranked it and she started right up. Then just last night after it sat for a while i went out and cranked it and it didn't start immediately it cranked for a few seconds then hit. So i would say its either fuel or fire. The ignition system has maybe 30k on it and the fuel system has 140k. So i'm leaning towards fuel. I'm probably gonna install the Racetronix pump this week unless the car dies sooner. I really don't think it could be the cam 1 tooth off. My friend built it and he races all the time and has a 8-9 sec car. I used the Oversized sprocket gear on the extreme duty chain so there was no play in the chain. I verified the dots lining up as well as a 3rd guy before we put the motor together. We also had the motor out of the car so we had a good clean look at it. I'm not saying it still couldn't of happened but that is my last idea. I think my plan of action is to check out the fuel system then probably, the degree the cam and check the compression.

 

well i'm in big trouble now, my rear tires aren't going to last very long as traction is nonexistant. I finally got it fixed it was the fuel pump. It has never run this strong before. I wish i would of found it out a long time ago rather than putting 20k on the motor before finding this out. Either way i'm glad its fixed. This car is awesome now.

 

thats great!
get that thing back to the dyno. I'm curious to see what a heads/cam car can pick up if mine picked up 30rwhp from the pump & a better tune.

 

Whats it dyno at now? I want to know how much hp you were loosing from the bad fuel pump. I have the same setup on a 93Z with total engine airflow stage 2 heads. The car feels like it has about 250RWHP, Alvin said the chip is bad and is causing me all sorts of problems. I hope when he sends the new chip, there's about 140rwhp hiding in there somewhere. I'm glad you found out what was wrong with it. Let us know new dyno numbers.