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kna4977
03-04-2007, 07:38 PM
After researching on the main page and reading the posts here in the Fuel Systems forum, I have some questions.

1. I understand stock fuel pump pressure at baseline is 33PSI, and that for every pound of boost it increases 1 PSI assuming the pump and regualtor are healthy. I have also seen that the stock GN pump is capable of pumping 28 Gal/Hr and has a PSI shutoff of 50. However I saw in another place on this forum that someone was getting 55 PSI out of a stock pump. How is this possible if the cutoff is 50 PSI?

2. Will a TurboTweak Chip in combination with a stock pump and hotwire increase the output of the stock pump? I really only need 45 to 50 PSI for what I am looking to do. I would really like to avoid dropping the tank if at all possible.

3. I've read the homemade fuel pressure gauge recipe, and I've had recommendations for the VDO gauge, but, ultimately how do you measure it? Where and how do you attach the gauge to the car? Do I place it on the end of the fuel rail? What kind of fittings do I need to do this? Do I need a mechanical or electronic gauge or will either one work?

4. When I look to do fuel system modifications everything states "depressurize the system 1st". What's the best way to do this. The most attractive suggestion to me is to disconnect the power to the pump and run the car till it quits. Is this safe?

5. What's the best way to route a hotwire kit underneath the car versus inside the car as the technical article on the main page suggests?

Keller
03-04-2007, 08:08 PM
- The only way to overcome the max pressure of a pump if it has an overpressure mechanism is to shim the relief spring in the pump. One vendor (Red) does this.

- I think using a 20+ year old stock pump on ANY TR short of one in a museum that will never be started is completely and unquestionably foolish. The technology has improved and the weaknesses have been solved. Why not use the better solutions? (I take it you still you still use a well, outhouse, and candles as well? Got tired of milking the cows, myself.)

- Chips do not help, change, or improve pumps.

- 'Hot wire' kits can improve the voltage to the pump, thus possibly raising its volume - NOT pressure. A pressure change might be evident, but the volume is the expected improvement.

- Electrical gauges are inaccurate and expensive. End of rail is where a mechanical gauge will be connected. The proper fittings and such are available through TR vendors.

- Even if your run the car to depressurize the system, you won't get rid of it all. The valve in the rail must be removed to truly remove all pressure.

- What 'in car' hot wire article are you referring to? All solutions I am aware of require wiring underneath the vehicle. Although I routed most of a commercial kit through my frame rail for maximum protection.

Overboost
03-04-2007, 08:41 PM
depressurize by wrapping a rag around the cap at the end of your fuel rail and then slowly open the cap. if you wait an hour or so after its been shut off, there is not much pressure as it has bled off back to the tank.
and when you depressurize the system, then read the article on how to change your pump. it takes a few hours but in the end it is well worth it because sooner or later, like a stock mass air, you will be replacing the stock pump.
do it before you replace an engine along with it. you will be glad you did.

kna4977
03-04-2007, 08:47 PM
- The only way to overcome the max pressure of a pump if it has an overpressure mechanism is to shim the relief spring in the pump. One vendor (Red) does this.

- I think using a 20+ year old stock pump on ANY TR short of one in a museum that will never be started is completely and unquestionably foolish. The technology has improved and the weaknesses have been solved. Why not use the better solutions? (I take it you still you still use a well, outhouse, and candles as well? Got tired of milking the cows, myself.)

- Chips do not help, change, or improve pumps.

- 'Hot wire' kits can improve the voltage to the pump, thus possibly raising its volume - NOT pressure. A pressure change might be evident, but the volume is the expected improvement.

- Electrical gauges are inaccurate and expensive. End of rail is where a mechanical gauge will be connected. The proper fittings and such are available through TR vendors.

- Even if your run the car to depressurize the system, you won't get rid of it all. The valve in the rail must be removed to truly remove all pressure.

- What 'in car' hot wire article are you referring to? All solutions I am aware of require wiring underneath the vehicle. Although I routed most of a commercial kit through my frame rail for maximum protection.


More questions:



How do you shim the relief spring?

Better solutions cost $. I'm trying to avoid $ while maximizing performance. The other thing to consider here is that while all of the faults may be solved by now with newer technology is that this car has low miles, so the pump is probably in as good a shape as the weatherstriping........Like New.....

What will raising volume do? How will raising volume not increase pressure? Will it make it run rich??

I plan on running it till it quits to minimize pressure then release the valve...

The article on the main page the guy routed it through the inside of the car, I don't know about you but I have seen the Coyote and the Roadrunner and recognize a big potential for fire on the inside of the car if you do this...................Here's the link: http://www.gnttype.org/techarea/fuelsystem/hotwire.html

kna4977
03-04-2007, 08:50 PM
depressurize by wrapping a rag around the cap at the end of your fuel rail and then slowly open the cap. if you wait an hour or so after its been shut off, there is not much pressure as it has bled off back to the tank.
and when you depressurize the system, then read the article on how to change your pump. it takes a few hours but in the end it is well worth it because sooner or later, like a stock mass air, you will be replacing the stock pump.
do it before you replace an engine along with it. you will be glad you did.

Why would I have to replace the engine or stock MAF?

Overboost
03-04-2007, 09:05 PM
no no, what I meant was, the stock mass air is unreliable. you WILL have to replace it sooner or later.

the stock fuel pump WILL need to be replaced. I would prefer sooner. the engine will need to be replaced if the stock fuel pump performence deminishes to the point that it still works, yet causes enough detonation due to lack of fuel to keep up with turbo output to the point of degregation of the engine.

in other words, if the stock pump fails (it will, eventually) that it COULD cause your motor to burn a hole or two in a piston, due to spark knock.

that is all just an elaborate way of saying, change the stock pump, dont bother trying to make it "keep up"....

kna4977
03-04-2007, 09:48 PM
no no, what I meant was, the stock mass air is unreliable. you WILL have to replace it sooner or later.

the stock fuel pump WILL need to be replaced. I would prefer sooner. the engine will need to be replaced if the stock fuel pump performence deminishes to the point that it still works, yet causes enough detonation due to lack of fuel to keep up with turbo output to the point of degregation of the engine.

in other words, if the stock pump fails (it will, eventually) that it COULD cause your motor to burn a hole or two in a piston, due to spark knock.

that is all just an elaborate way of saying, change the stock pump, dont bother trying to make it "keep up"....

After reading this I am leaning away from modding all together. It seems like that with each mod, a weaker link is gonna show its face, which will result in more work. I don't wanna push the stock pump to the point of ruin, nor any other part. I just don't wanna go there.....I have all the necessary parts to upgrade the car, but am too scared at this point to push it......With that in mind, I'm getting ready to return back to purity, stock airbox and all.......anyone wanna buy a Walbro pump, Hotwire, Turbo Tweak Chip etc.?

Overboost
03-04-2007, 10:24 PM
some mods are good, some need more mods to go with them.
a replacement pump is always good. even if bone stock. 20+ year old pumps = failure in the future. even old cam driven mechanical pumps will need replacing. as far as chips, pumps and hot wires, they are all good, you wont need anything else to go with them, they just help out what you already have.
now when you replace turbo's, injectors, mass air flows....so on, then you need to do other things as well...
dont cut short and not repalce something so critical as a fuel pump. its simple and can do no harm...but the benifits are endless..

kna4977
03-04-2007, 10:38 PM
some mods are good, some need more mods to go with them.
a replacement pump is always good. even if bone stock. 20+ year old pumps = failure in the future. even old cam driven mechanical pumps will need replacing. as far as chips, pumps and hot wires, they are all good, you wont need anything else to go with them, they just help out what you already have.
now when you replace turbo's, injectors, mass air flows....so on, then you need to do other things as well...
dont cut short and not repalce something so critical as a fuel pump. its simple and can do no harm...but the benifits are endless..

I'm Discourraged and Done, Stock or Bust............

1986GN
03-04-2007, 11:58 PM
wow youre giving up to easy all this members are giving you good advise.the stock pump and wirring were not sufficient even when new! imagine 20 yrs later!this is thge best site to get advise from people with great experience! my 2 cents

PaCemkr86
03-05-2007, 12:09 AM
are you scared to drop the tank or what ?

kna4977
03-05-2007, 09:31 AM
I'm not scared of the job........I'm scared of my luck...........Usually when I do a job, it doesn't turn out like you would hope and usually opens up a whole other can of worms........

Keller
03-05-2007, 02:59 PM
the stock mass air is unreliable. you WILL have to replace it sooner or later.
I disagree. I cracked my original MAF years ago do to my own mishandling. However, was able to repair it and sold it cheap. *sigh* I'm still using a stock MAF and see no problems. But that's not the issue at hand.

I guess he'll have to sell the inoperable car when the pump does quit or he pops a gasket when it leans out.

kna4977
03-05-2007, 07:20 PM
I disagree. I cracked my original MAF years ago do to my own mishandling. However, was able to repair it and sold it cheap. *sigh* I'm still using a stock MAF and see no problems. But that's not the issue at hand.

I guess he'll have to sell the inoperable car when the pump does quit or he pops a gasket when it leans out.

Definately not interested in popping a gasket........I was under the impression that if the pump was pumping no fuel, the car would just quit running...How will it blow a gasket/harm the engine under those circumstances??......I would think that if all the other systems are operating properly (cooling, electrical, oil), there would be no problem as far as harm to the engine as everything would still be doing it's job except for the fuel system, and if there is no fuel, it would simply not run............I've had several vehicles in the past where the fuel filter became clogged and the car just quit running........which would mimick a dead fuel pump.......no harm done, just replace the filter and keep on going.....Any thoughts...............??

Keller
03-05-2007, 08:01 PM
So, He Who Has No Name (kna4977 for short) is getting on the highway one day and decides to hit it just for fun. He slaps the loud pedal to the floor, and the boost goes to 15 since he's kept it 100% stone stock - just like he swore he would back in '07. As all 245 of those ponies are summoned, the aging fuel pump (not to mention the fact that it long been pulling a substandard current and voltage through the stock wiring because of the seven connections it must go through between the alternator and pump) starts to wheeze like an octogenarian with emphysema trying to run a sprint. In reality, that's essentially what it is. Because this has been a long time for a pump past its prime. Not to mention wiring far too inadequate right from the factory. After all, this car was never really designed for this powerplant originally. Sure, others had some up with better, proven solutions. But He Who Has No Name really didn't trust these things. Nor his own handiwork.

So the pump had been singing at a full 10.5...maybe 11 volts...pumping its little heart out...trying to feed sufficient fuel to keep those injectors singing along and stoking the fire. But, it just can't continue. The best has passed. It starts to falter. The flow becomes intermittent. Sure, the turbo was at full song. But the fuel is now not quite so steady. First one hiccup. Then another. Mr. kna4977 felt the hesitation at first, but thought it was just a bump in the North Carolina tarmac. As the pump gives up, pressurized air overpowers, and the LC2 sings a song far too lean and off key. He hears a loud *pop*. The power drops rapidly. He wonders, "What the...this car is like new?!?!?" The "Service Engine Soon" provides a warm, auburn glow over his face as the GN quietly rolls to the side of the road, trailing a cloud of oil and water behind.

The rest of the story, He Who Has No Name, is up to you.

http://www.gnttype.org/nats/97nats/images/troub_2a.jpg

kna4977
03-05-2007, 08:29 PM
So, He Who Has No Name (kna4977 for short) is getting on the highway one day and decides to hit it just for fun. He slaps the loud pedal too the floor, and the boost goes to 15 since he's kept it 100% stone stock - just like he swore he would back in '07. As all 245 of those ponies are summoned, the aging fuel pump (not to mention the fact that it long been pulling a substandard current and voltage through the stock wiring because of the seven connections it must go through between the alternator and pump) starts to wheeze like an octogenarian with emphysema trying to run a sprint. In reality, that's essentially what it is. Because this has been a long time for a pump past its prime. Not to mention wiring far too inadequate right from the factory. After all, this car was never really designed for this powerplant originally. Sure, others had some up with better, proven solutions. But He Who Has No Name really didn't trust these things. Nor his own handiwork.

So the pump had been singing at a full 10.5...maybe 11 volts...pumping its little heart out...trying to feed sufficient fuel to keep those injectors singing along and stoking the fire. But, it just can't continue. The best has passed. It starts to falter. The flow becomes intermittent. Sure, the turbo was at full song. But the fuel is now not quite so steady. First one hiccup. Then another. Mr. kna4977 felt the hesitation at first, but thought it was just a bump in the North Carolina tarmac. As the pump gives up, pressurized air overpowers, and the LC2 sings a song far too lean and off key. He hears a loud *pop*. The power drops rapidly. He wonders, "What the...this car is like new?!?!?" The "Service Engine Soon" provides a warm, auburn glow over his face as the GN quietly rolls to the side of the road, trailing a cloud of oil and water behind.

The rest of the story, He Who Has No Name, is up to you.

http://www.gnttype.org/nats/97nats/images/troub_2a.jpg

Keller, I understand how strongly you feel about this........I didn't request or need an elaborate story for you to make a point.....I wish you would just tell it like it is and give me a simple answer........... but from my previous communication with you, that's not gonna happen. One thing you forgot to consider was a hotwire...........Also, I don't understand why you try to make me seem like I am asking stupid questions on every post I make............What gives????...........When I think back to college, I remember the teacher saying the only stupid question was the question unasked as there will most likely be others with the same question...........................If this is not what this forum is based on...........................then?????????........ .....

PaCemkr86
03-05-2007, 08:59 PM
ok.. long story short.. the stock pump and wire harness is barely enough to supply the engine in factory trim, much less after 20+ years of aging

Get a walbro 255 pump and hot wire kit.. and be done..

even if you dont upgrade the engine for Xtra HP its a great safe gaurd even for a stocker

kna4977
03-05-2007, 09:28 PM
ok.. long story short.. the stock pump and wire harness is barely enough to supply the engine in factory trim, much less after 20+ years of aging

Get a walbro 255 pump and hot wire kit.. and be done..

even if you dont upgrade the engine for Xtra HP its a great safe gaurd even for a stocker

Thanks for being straight-forward....Will a Walbro 340 + Hotwire be just as good??

PaCemkr86
03-05-2007, 09:33 PM
Thanks for being straight-forward....Will a Walbro 340 + Hotwire be just as good??

yes a walbro 340 aka 255 lph

kna4977
03-05-2007, 10:30 PM
Although I understand that I will need a Walbro pump, ..........i'm still not understanding how running short of fuel is gonna cause problems....Can anyone besides Keller shed some light on this??

Keller
03-05-2007, 10:33 PM
Hadn't we conveyed precisely that weeks...perhaps months...ago?

kna4977
03-05-2007, 10:35 PM
Hadn't we conveyed precisely that weeks...perhaps months...ago?


I don't know......did you???......I uninvited you from this post.....obviously you didn't understand my wording........!!!!!!!!!!!!........let me spell it out.......stay away if you are an A-HOLE!@!!!!......Keller>>>>>>>>>>>>>WHY IS KELLER SUCH AN A_HOLE???.....where can I post this????????

PaCemkr86
03-05-2007, 10:55 PM
Although I understand that I will need a Walbro pump, ..........i'm still not understanding how running short of fuel is gonna cause problems....Can anyone besides Keller shed some light on this??

your turbo buick will still accellerate " build boost, burn tires etc.." even when your pump is starting to get weak "less fuel" and will start causing engine damage without you knowing it.

IL KIM
03-05-2007, 11:51 PM
I have a Word version of the Walbro 340 pump and hotwire installation. Send me your e-mail if you want to review it. I found dropping the tank and changing the pump and running the hotwire was rather straight forward and easier than I thought it would be.

kna4977
03-06-2007, 09:43 AM
Great! thanks for your help you have a PM........Although something like that might be beneficial to everyone looking to do the same, and might belong on the main page with the rest of the technical articles

kenmosher
03-06-2007, 10:38 AM
Alrighty, although Scott had some fun with that literary masterpiece (nice!) ... it illustrates the point that has been made several times in several of your threads.

Basically, install a good in tank pump, use a hot wire kit to shore up the old OEM wiring, and make sure you have good fuel pressure.

This is a superatmospheric engine (i.e. boosted). Unlike a normally aspriated motor, it is easy for it to get much more air than fuel in a short amount of time, thus causing extreme lean conditions.

In a boosted motor, lean causes several things:


Extreme combustion temperature spikes
Detonation (due to the spikes)
High EGT
Damage to head gaskets (if you are lucky)
Damage to pistons, rings, valve faces (if you're not)


An N/A engine experiences the same problems when it leans out, just not as quickly or as violently (usually).

kna4977
03-06-2007, 10:45 AM
Alrighty, although Scott had some fun with that literary masterpiece (nice!) ... it illustrates the point that has been made several times in several of your threads.

Basically, install a good in tank pump, use a hot wire kit to shore up the old OEM wiring, and make sure you have good fuel pressure.

This is a superatmospheric engine (i.e. boosted). Unlike a normally aspriated motor, it is easy for it to get much more air than fuel in a short amount of time, thus causing extreme lean conditions.

In a boosted motor, lean causes several things:


Extreme combustion temperature spikes
Detonation (due to the spikes)
High EGT
Damage to head gaskets (if you are lucky)
Damage to pistons, rings, valve faces (if you're not)


An N/A engine experiences the same problems when it leans out, just not as quickly or as violently (usually).

Thanks for being straightforward.........Never owned or understood a boosted motor before now......So, I assume this type of damage will be something that happens all of the sudden, or would it be gradual, or just depend??..............Are there any indicators to look for?

IL KIM
03-06-2007, 08:28 PM
Sent you the Word file on installing the hot-wire kit. The pump removal/replacment is in this site. http://www.gnttype.org/techarea/fuelsystem/fpinstall.html

In my mind, the type of failure would depend; on how much boost the engine sees over the period of time when the pump fails or runs at less than optimally, amount of heat build-up, etc. Interestingly 've run out of gas 3 times to know computer helps me out - first I can't go over 60mph, then 50mph, then 40mph, etc. Made it to the gas station twice (coasted in once). Didn't have a chance on the 3rd time - sender failure gave false reading, but I knew what was happening.

Overboost
03-06-2007, 09:08 PM
:deadhorse sometimes the failure, and possible engine demise, can be sudden or it can be gradual. thats the problem, you dont know.
so it is better to stop the problem, before it happens. :chain: and causes all sorts of headaches.

kenmosher
03-07-2007, 10:41 AM
Thanks for being straightforward.........Never owned or understood a boosted motor before now......So, I assume this type of damage will be something that happens all of the sudden, or would it be gradual, or just depend??..............Are there any indicators to look for?

As mentioned, it can be either depending on the severity of the problem ... if the car is chronically lean under boost, but not severely, it can gradually cause inaudible detonation ... which pits the tops of the pistons, valve faces, combustion chamber, eats away at the fire ring in the head gasket, etc. until one day something fails more dramatically.

OR, you can jump on it, the car goes severely lean, the boost spikes, the EGTs spike, and the headgasket goes *POP*. It all depends ...

Indicators include:
- Compression test indicates low cylinder
- Fuel Pressure drops under boost (should rise 1 psi for every psi of boost)
- "Ping" during WOT
- Scan Tool indicates low O2 sensor readings, spark retard during boost, etc.
- Loss of power under boost

kna4977
03-07-2007, 11:02 AM
As mentioned, it can be either depending on the severity of the problem ... if the car is chronically lean under boost, but not severely, it can gradually cause inaudible detonation ... which pits the tops of the pistons, valve faces, combustion chamber, eats away at the fire ring in the head gasket, etc. until one day something fails more dramatically.

OR, you can jump on it, the car goes severely lean, the boost spikes, the EGTs spike, and the headgasket goes *POP*. It all depends ...

Indicators include:
- Compression test indicates low cylinder
- Fuel Pressure drops under boost (should rise 1 psi for every psi of boost)
- "Ping" during WOT
- Scan Tool indicates low O2 sensor readings, spark retard during boost, etc.
- Loss of power under boost

Thanks for your reply. Don't know about compression test, but all the spark plugs looked good when I changed them out.....it still had the original ones in it.....Don't know about fuel pressure drops either, but it does not ping....still waiting on a scan tool....It may have lost a little bit of power under boost after I switched from the stock airbox to the 9" cone filter, but I can't be sure as all I have to go off of is the butt dyno at this point, and comparisons to my SRT-8 Charger.......Still not sure what to do since my ultimate concern is the safety of the car and my wallet as well

Overboost
03-07-2007, 04:56 PM
Still not sure what to do since my ultimate concern is the safety of the car and my wallet as well

upgrade the pump....car will thank you. I would rather lighten my wallet by $200 now than by $1000 plus later...

kna4977
03-11-2007, 08:34 PM
upgrade the pump....car will thank you. I would rather lighten my wallet by $200 now than by $1000 plus later...

Agreed, and in the works..............Anyone know if the Walbro 340 will directly bolt in or will I have to do some modifications???????

IL KIM
03-11-2007, 08:49 PM
Direct replacement. You need to throw the pulsator away - you'll figure out what that is when you take the old pump out and see it has an extra part.

kna4977
03-12-2007, 03:50 AM
Great, thanks

IL KIM
03-17-2007, 08:51 PM
So kna4977, share your thoughts on changing out the pump and installing the hot-wire kit - how was it?

kna4977
03-17-2007, 09:29 PM
So kna4977, share your thoughts on changing out the pump and installing the hot-wire kit - how was it?

I did the hot wire last week. No problem there, very easy. The fuel pump installation was a lot easier than I expected. The car I have is a low mileage southern car and has been garage kept its whole life. This helped out greatly as nothing was rusty. Everything was plug and play. Good directions are the most important thing. I had those this time, and it made all the difference versus other projects that I have done in the past without decent directions. Without this forum and doing lots of research (on and off the forum) before doing the job, the results would not have been as good. As with everything, preparation is key.

IL KIM
03-18-2007, 09:44 AM
No problem there, very easy. The fuel pump installation was a lot easier than I expected.

Good for you! Yes, the forum is lot's of help.