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New brake pads causing fule starvation ?? by rollertiprocker
Started on: 04-27-2008 04:38 PM
Replies: 15
Last post by: rollertiprocker on 04-29-2008 10:06 PM
rollertiprocker
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Report this Post04-27-2008 04:38 PM Click Here to See the Profile for rollertiprockerClick Here to Email rollertiprockerSend a Private Message to rollertiprockerDirect Link to This Post
I just installed Porterfield R4S street porformance brake pads on my stock 85 brake system and wow what a difference. Very dramatic decrease in stopping distance with no fade. Much less pedel effort and incresed control. I wanted to try this option before going for a brake upgrade with all the cost and effort. My Carbomat pads were an improvement maby 20% over the old stock pads when hot and none at normal temp. These pads are a 40% increse cold or hot - so much so the the engine stalled from 70 mph to 0. I assume the gas went to the front of the tank and starved the pump. I also had a half tank on the guage. I have never done that even with quater tank on other pads. That must be a big G force increase to shift the fule that much. Like I said the car stops much better. Did it again with much less brake with guarter tank. I dont recall much in the way of baffles in the tank to prevent this from happening. Am I missing something else. I have been able to stall the car with eighth tank going around corners and quick take off. There is some danger in an emergency haveing the car stall. The guage will go down to E and and take almost 9 gal to fill up so fule pick up appears normal. Do I really need to drop the tank and install some type of baffle and of what design? Anyone else have same issue?

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Rodrv6
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Report this Post04-27-2008 06:12 PM Click Here to See the Profile for Rodrv6Click Here to Email Rodrv6Send a Private Message to Rodrv6Direct Link to This Post
While I've never heard of that problem, I can see how it could happen with our long, narrow tanks. The plastic baffles in the tank tend to crack and come apart with age which could allow the fuel to slosh away from the pump pickup. It may be possible to install a baffle through the fuel pump access hole that has a flap valve that would keep fuel around the base of the pump, but I don't know anyone who's done this.

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rollertiprocker
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Report this Post04-27-2008 08:21 PM Click Here to See the Profile for rollertiprockerClick Here to Email rollertiprockerSend a Private Message to rollertiprockerDirect Link to This Post
I filled the car with gas and it was abe to stop and not quit running so it is the gas sloshing to the front. It's a long stop from 70 so the gas has plenty of time to move forward. All in all sooner or later it will cause an issue. Who wants brakes you can't use full out. It not real difficult to drop the tank, I have done twice. I guess something with a flaper door that goes up maybe six to eight inches so the tank will fill ok and keep the gas at the pick up. After all I only need enough fule remaining to keep the engine running 8 to 10 second That is not much gas. Enough to keep the pickup submerged in fule.

If the pump gets air, why does it not keep pumping all by it self and just refill the injectors after all the key is still on. When I came to a stop the pump is not running. I wonder if the computer turns the pump off when the engine has no rpms to report to the computer? I have to turn the key to on and off several times to reprime the injectors and then it kicks off. Any way the engine stops and has to be restarted. I guess it would be the same if the car was running out of gas just driving down the road sooner or later the pick up will run out of gas to pump and the car will coast to a stop.
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darkhorizon
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Report this Post04-27-2008 11:31 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonDirect Link to This Post
I have the opposite problem, I lose fuel when I get on the gas.

I think its just the way the tank is designed.
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AutoTech
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Report this Post04-27-2008 11:59 PM Click Here to See the Profile for AutoTechClick Here to Email AutoTechSend a Private Message to AutoTechDirect Link to This Post
 
quote
Originally posted by darkhorizon:

I lose fuel when I get on the gas.

I think its just the way the tank is designed.


Wow, how can you live with that? lol

There are baffles in the tank, and most likely are broken. You guys need to replace the tank.
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gt88norm
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Report this Post04-28-2008 12:38 AM Click Here to See the Profile for gt88normSend a Private Message to gt88normDirect Link to This Post
Crumbling baffles being a geriatric condition of the tank; I think it's time for one of
our benevolent after-market purveyers to give some serious consideration to this
looming condition. Paired with a vapor purge system similar to the '87/'88s, all
could benefit from an up-grade kit. Just a thought, I don't relish the Idea of a future
hunt for a tank, should the occasion arise for replacement.
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gt88norm
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Report this Post04-28-2008 12:43 AM Click Here to See the Profile for gt88normSend a Private Message to gt88normDirect Link to This Post

gt88norm

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Another thought . . . does the ECM shut down the fuel pump in a low/no oil pressure situation?

Norm
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AutoTech
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Report this Post04-28-2008 01:22 AM Click Here to See the Profile for AutoTechClick Here to Email AutoTechSend a Private Message to AutoTechDirect Link to This Post
No, the ECM grounds the relay when it sees an RPM signal. The sending unit is back-up only.

It makes no sense to have the fuel pump running if the engine cuts out. First off, it is a safety factor. Secondly, if it were to continue to run, the pump would be constant - key on, engine off. How convenient would that be?
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rollertiprocker
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Report this Post04-28-2008 02:10 AM Click Here to See the Profile for rollertiprockerClick Here to Email rollertiprockerSend a Private Message to rollertiprockerDirect Link to This Post
I was on the web searching for answers to the fuel pick issue and found a very clever idea. The idea is have two pick ups in the tank - one in back with the pump and a second one connected with a hose in the front of the tank. If a pickups has no fuel it shuts off and lets the one with fuel continue to feed fuel. The trick is very fine screens in the bottom of each pickup. Ever spray a screen with water - it stickes in the little holes. Same thing happens when the pickup has no fuel the screen is filled with fuel and is sucked up and flat disk closes off the pickup. The pickup that is submerged allows the fuel to flow will not close. If the tank is full both flow, when the fuel level gets lower the fuel starts sloshing around - one or the other will pick up fuel. Cool. About $25 each. from http://autoperformanceengineering.com/ I emailed them to see if it can be connected to a standard GM fule pump. They are made by Walbro, they manufacture fuel pumps. Check it out
Chuck
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tjm4fun
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Report this Post04-28-2008 05:42 AM Click Here to See the Profile for tjm4funClick Here to Email tjm4funSend a Private Message to tjm4funDirect Link to This Post
just a thought, but have you ever had your pump out? is the sock still attached? and in good shape?
Now I've seen that condition, but the only time in either of mine it killed the motor, Iwas running on fumes anyway.
While I may not have rocket accleration, my brakes do work well enough that I shifted my top c/a pin in a hard stop, and even with
less than a 1/4 tank, the motor never missed a beat....
As for the restart issue, haveing more than once run out of gas, it always picks up the prime pretty fast, you should verify your system is working properly electrically.... the easiest test for the relay is the 2 sec primn with key to run, but not started.
the rest was already explained about the ecm the pulses form the ignition module and the oil pump safety switch.,.,
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FieroBrad87
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Report this Post04-28-2008 06:26 AM Click Here to See the Profile for FieroBrad87Click Here to Email FieroBrad87Send a Private Message to FieroBrad87Direct Link to This Post
I guess my baffles must be broken because my fuel gauge is all over the place.
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gunslinger
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Report this Post04-28-2008 09:14 AM Click Here to See the Profile for gunslingerSend a Private Message to gunslingerDirect Link to This Post
I have seen that problem before and there are several alternatives:

Use a one way valve in the fuel luine close to the tank that allows the fuel to flow in one direction,
Modify the tank to use an external pump like the older style pump BMW or Mercedes,

These are much easier than opening up the tank to add baffles.
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Francis T
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Report this Post04-28-2008 02:54 PM Click Here to See the Profile for Francis TClick Here to visit Francis T's HomePageClick Here to Email Francis TSend a Private Message to Francis TDirect Link to This Post
I put those pads, SS lines, high temp fluid and slotted rotors on my 86 and no more fade at all. Like the setup so much I'm doing the same thing to my 87. Some ehre use that setup for autox, don't think it will cut it for the hard and frequent higher speeds of road racing. For the street, it's a big improvement over stock and easy to do.

 
quote
Originally posted by rollertiprocker:

Very dramatic decrease in stopping distance with no fade. Much less pedel effort and incresed control. I wanted to try this option before going for a brake upgrade with all the cost and effort.


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Report this Post04-29-2008 05:55 AM Click Here to See the Profile for IntelClick Here to visit Intel's HomePageSend a Private Message to IntelDirect Link to This Post
Some new cars have some kind of non sealed foam stuffed into the tank preventing fuel from moving around.
You problably wouldn't get the same amount of fuel in the tank though.
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SCCAFiero
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Report this Post04-29-2008 09:01 AM Click Here to See the Profile for SCCAFieroClick Here to Email SCCAFieroSend a Private Message to SCCAFieroDirect Link to This Post
I don't have any problems with fuel starvation until my tank gets between 1/4 and 3/8 tank. This is a full track car with full race pads and race tires. Once it gets to around 1/4 tank it will start to starve about the same amount whether I am turning, braking, or even accelerating. It's probably time to drop your tank and see what's going on in there.
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rollertiprocker
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Report this Post04-29-2008 10:06 PM Click Here to See the Profile for rollertiprockerClick Here to Email rollertiprockerSend a Private Message to rollertiprockerDirect Link to This Post
Thanks to all af you and for the advice. Yes have had the tank out last year when I installed a V6 pump to replace my 4 cyl pump - as I recall it had about quarter tank of gas (maybe less) while I was holding the tank to install the gas moved front to back just and did not feel restrected in any way. I will fix the problem one way or another and let all of you know how it turned out

By the way the brakes are fantastic - I would recomend this change to anyone who wants to improve there car.
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