Fuel pumps - factory and aftermarket
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Fuel pumps - factory and aftermarket
I've been searching all over the site for the last few days, and even wandered over to the RENN sites to do some research... I'm not finding much in the way of answers to my questions, so I'll go with what works - ask you all.
I saw a thread started last year by AMS that looked to be VERY promising on info, but they got side-tracked on another project and have not re-visited the fuel system research - to my knowledge. Hopefully they will pickup where they left off at some point... (hint hint, wink wink)
So, because I simply don't know - I asked the question above on whether you can swap out the factory pump for an upgraded unit - just into the same basket and getting hooked up the same way (with the venturi hoses and all)... Might be a moot point if the X50 or GT2 already has a Bosch 044 pump in it... But then I stumbled across this company: Jay Racing and they have an upgraded/improved version of the 044 that appears to have some pretty good numbers to it (both flow and current draw). Click here for their 044 pump
I'm certainly not trying to reinvent the wheel here, but have wondered if something such as a fuel pump swap could allow us to run more horsepower safely without having to install another pump in another section of the car? I will eventually end up with a dual pump (series or parallel) on my car, but am happy to experiment a little along the way.
Feel free to comment, criticize, or debate... Oh, and if there are some simple answers to my list of questions, that would be nice too.
As always, thanks for your input fellas...
- Does the 996TT have a different pump and/or tank than the X50 and/or GT2?
- Is the factory pump on either setup a Bosch 040 unit?
- When people upgrade their fuel systems with a 2nd pump (inline) do they keep the factory pump as the feeder, or upgrade that unit as well?
- CAN you upgrade the pump in our factory tank/baskets to something better? Say an 044?
I saw a thread started last year by AMS that looked to be VERY promising on info, but they got side-tracked on another project and have not re-visited the fuel system research - to my knowledge. Hopefully they will pickup where they left off at some point... (hint hint, wink wink)
So, because I simply don't know - I asked the question above on whether you can swap out the factory pump for an upgraded unit - just into the same basket and getting hooked up the same way (with the venturi hoses and all)... Might be a moot point if the X50 or GT2 already has a Bosch 044 pump in it... But then I stumbled across this company: Jay Racing and they have an upgraded/improved version of the 044 that appears to have some pretty good numbers to it (both flow and current draw). Click here for their 044 pump
I'm certainly not trying to reinvent the wheel here, but have wondered if something such as a fuel pump swap could allow us to run more horsepower safely without having to install another pump in another section of the car? I will eventually end up with a dual pump (series or parallel) on my car, but am happy to experiment a little along the way.
Feel free to comment, criticize, or debate... Oh, and if there are some simple answers to my list of questions, that would be nice too.
As always, thanks for your input fellas...
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HAHA! No takers yet! Let answer some of your questions first then go deeper...
1 Does the 996TT have a different pump and/or tank than the X50 and/or GT2?
Rumored that it is different never checked because both will be to small for the power level I wanted to make.
2 Is the factory pump on either setup a Bosch 040 unit?
Did not check it out because the pump was not even in my plan so no time wasted on it.
3 When people upgrade their fuel systems with a 2nd pump (inline) do they keep the factory pump as the feeder, or upgrade that unit as well?
Most do. I did and found it did not meet the needs I felt I needed to meet.
4 CAN you upgrade the pump in our factory tank/baskets to something better? Say an 044?
I think someone did that on here. I am not a believer in that octopus pickup setup for big power.
How much power are you looking to make? The fuel system is way overlooked to many bent rods and knock out head gaskets out there.
1 Does the 996TT have a different pump and/or tank than the X50 and/or GT2?
Rumored that it is different never checked because both will be to small for the power level I wanted to make.
2 Is the factory pump on either setup a Bosch 040 unit?
Did not check it out because the pump was not even in my plan so no time wasted on it.
3 When people upgrade their fuel systems with a 2nd pump (inline) do they keep the factory pump as the feeder, or upgrade that unit as well?
Most do. I did and found it did not meet the needs I felt I needed to meet.
4 CAN you upgrade the pump in our factory tank/baskets to something better? Say an 044?
I think someone did that on here. I am not a believer in that octopus pickup setup for big power.
How much power are you looking to make? The fuel system is way overlooked to many bent rods and knock out head gaskets out there.
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HAHA! No takers yet! Let answer some of your questions first then go deeper...
1 Does the 996TT have a different pump and/or tank than the X50 and/or GT2?
Rumored that it is different never checked because both will be to small for the power level I wanted to make.
2 Is the factory pump on either setup a Bosch 040 unit?
Did not check it out because the pump was not even in my plan so no time wasted on it.
3 When people upgrade their fuel systems with a 2nd pump (inline) do they keep the factory pump as the feeder, or upgrade that unit as well?
Most do. I did and found it did not meet the needs I felt I needed to meet.
4 CAN you upgrade the pump in our factory tank/baskets to something better? Say an 044?
I think someone did that on here. I am not a believer in that octopus pickup setup for big power.
How much power are you looking to make? The fuel system is way overlooked to many bent rods and knock out head gaskets out there.
1 Does the 996TT have a different pump and/or tank than the X50 and/or GT2?
Rumored that it is different never checked because both will be to small for the power level I wanted to make.
2 Is the factory pump on either setup a Bosch 040 unit?
Did not check it out because the pump was not even in my plan so no time wasted on it.
3 When people upgrade their fuel systems with a 2nd pump (inline) do they keep the factory pump as the feeder, or upgrade that unit as well?
Most do. I did and found it did not meet the needs I felt I needed to meet.
4 CAN you upgrade the pump in our factory tank/baskets to something better? Say an 044?
I think someone did that on here. I am not a believer in that octopus pickup setup for big power.
How much power are you looking to make? The fuel system is way overlooked to many bent rods and knock out head gaskets out there.
yeah even if you stick an inline pump 044 on the line you are still limited by the intank octopus. Not sure what others have done, but the systems used by Proto and Evoms seem to be able to supply 1000 bhp, so I would say that would work.
My question on this thread would have been, WTF does the GT2RS use. The 996tt/997tt setup is probably at or beyond it's limit at the GT2RS power level and I am sure porsche did something different in that system or I would imagine they did.
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I run one large weldon pump that will supply 2500 hp. fuel delivery is no longer a thought in my mind. But the pump now sits where the front drive use too. If you would like to keep the drive you would need to plumb it into where your spare tire sits.
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any pics of your setup. I like that idea. Did you keep the stock pump as well and Y them together pre rail?
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I'd still really like to know what pump (Bosch?) is in the tank from the factory... and if you can replace just that unit. Seems like putting a stronger (upgraded 044?) pump in the factory basket, with perhaps some upgraded wiring might prove to be a very solid solution for those looking to make 600-700whp??? Maybe I'm way off here...
In a former life when I was a mustang nut, you used to take your factory pumps out of the factory basket and replace them with stronger Walbro units...
Also, I touched on a topic that I meant to include in my initial list of questions... Would we see any benefits from running a thicker gauge power and ground wire to the pump leads? This is another thing that you had to do in the mustangs... I know Ford and Porsche are worlds apart... but the theory behind making power isn't really all that different, yes?
In a former life when I was a mustang nut, you used to take your factory pumps out of the factory basket and replace them with stronger Walbro units...
Also, I touched on a topic that I meant to include in my initial list of questions... Would we see any benefits from running a thicker gauge power and ground wire to the pump leads? This is another thing that you had to do in the mustangs... I know Ford and Porsche are worlds apart... but the theory behind making power isn't really all that different, yes?
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From: Long island NY
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I'd still really like to know what pump (Bosch?) is in the tank from the factory... and if you can replace just that unit. Seems like putting a stronger (upgraded 044?) pump in the factory basket, with perhaps some upgraded wiring might prove to be a very solid solution for those looking to make 600-700whp??? Maybe I'm way off here...
In a former life when I was a mustang nut, you used to take your factory pumps out of the factory basket and replace them with stronger Walbro units...
Also, I touched on a topic that I meant to include in my initial list of questions... Would we see any benefits from running a thicker gauge power and ground wire to the pump leads? This is another thing that you had to do in the mustangs... I know Ford and Porsche are worlds apart... but the theory behind making power isn't really all that different, yes?
In a former life when I was a mustang nut, you used to take your factory pumps out of the factory basket and replace them with stronger Walbro units...
Also, I touched on a topic that I meant to include in my initial list of questions... Would we see any benefits from running a thicker gauge power and ground wire to the pump leads? This is another thing that you had to do in the mustangs... I know Ford and Porsche are worlds apart... but the theory behind making power isn't really all that different, yes?
When I was running the stock pump I used the pump power to trigger a relay and used larger wire to run the pump. That should not be overlooked.
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I am not trying to clutter things up, and a larger pump in line may help a bit, but when you suck the venturi pump dry with the larger inline pump what does that do. My thinking is that if that worked it would have been done
here is a good old post by pumalex with excellent pics of the octopus pump:
here is a good old post by pumalex with excellent pics of the octopus pump:
Hey everyone, since I have been struggling with the fuel system these past days because of a leaking fuel hose, I thought I would take some pictures and share it to those who might be interested in understanding how the fuel system works in their car. First I want to thank Kevin at UMW for helping me solve my problem, he probably saved my engine. He also taught me how the system work. You don't get just good parts with him, you get excellent customer service. I will keep sending him some logs from time to time so he can analyse my car and make sure everything is correct.
This is a quick survey of all the parts, if I am wrong somewhere or if something is not well explained, please let me know so I can correct it.
So the fuel pump system is composed of a couple of things. First of all, when you want to change a leaking hose on the fuel system as it often happens, you can not buy only replacement parts from the dealer, you have to buy the whole fuel pump assemble. Only thing that can be purchased separately is the venturi tubes, we'll get to that later.
I have not taken pics of the process on how to remove the fuel pump but it is pretty straight forward and easy. I might take some when I'll install everything back together and add the pictures to this thread.
Now as you can see, with the fuel pump in place, I have a hole in my rubber hose. The outside is looking pretty bad but there is only a tiny hole in the inside layer. My symptoms were slower car and slight hesitation at WOT. With the durametric logs, Kevin was able to diagnose that I was missing fuel pressure. My injectors were showing 100% duty cycle and the AFR would keep raising up. Luckily the ecu pulls timing when this happens, which saved my engine.
Picture of bad hose and fuel pump in place with the fuel sender removed.
To remove the fuel pump assembly, you have to turn it counter-clockwise about 15 deg. Here is a picture of the bracket at the bottom of the fuel pump that holds the assembly in place.
Here are a couple of picture of the fuel pump assembly with the venturi tubes.
Now how does the system work. First you got to know that the fuel pump is in a big plastic tank, called also a surge tank. It is a system that prevents the fuel pump from missing fuel when hard acceleration, braking or long cornering is happening with a lower fuel level in the tank. This prevents fuel starvation and possible blown engine.
The way the fuel tank is made on the 996tt and C4 is a big tank on top of the front differential with two small "pod" going on each side of the differential to add some extra fuel storage. I don't think you have those on the 2wd 911 since there is no diff in the way of the fuel tank.
On this diagram, you can see the pod I am talking about (sorry don't know what other word to use). You can only see one in the picture but there is an other one on the other side we can't see.
Now for the surge tank to get the fuel that is located in the "pods" and the lower part of the fuel tank, the system is using two venturi tubes, one on each side. Since the pump is hanging in the middle of the fuel tank, it has to have a way to get the fuel to the bottom of it. The way the venturi tube is working is pretty simple. Fuel from the fuel pump goes to these tubes and creates a low pressure zone (vacuum) which then sucks fuel and send it in the surge tank. So basically, the fuel pump, on top of sending fuel to the injectors, send fuel to those tubes to create the vacuum to pump the fuel in the surge tank. Pretty weird design and I don't know why they didn't use an other electric pump or something else instead of putting extra stress on the fuel pump but I guess Porsche engineers had good reasons. It seems that one of the fuel pressure failure can be on those venturi tubes, if one fail, all fuel pressure goes to that pipe and back to the fuel tank and you get almost no pressure to the injectors. So it is a good time to inspect them if you remove your fuel pump from the tank.
Here is the end of one of the venturi tube.
To remove the venturi tube from the fuel pump assembly (which you have to do in tank before removing the fuel pump assembly) you just remove the two flexible fuel line on top and unclip the plastic block by the back of the surge tank (took me a while to figure out how to remove those pipes)
Here is a shot of the back of the surge tank where you can see the two holes for the clips of the venturi tubes. (sorry about the workbench mess)
Now here is a picture of the fuel pump assembly with some lines to see where fuel goes.
The big white piece is the surge tank. In the middle (black circle) is the fuel pump itself. The red line is the fuel pressure hose going to the injectors.
The blue line is the fuel return hose from the fuel rail (After the fpr)
The green line seems to come from the fuel filler neck probably to fill the surge tank first when you fill up with gas (not sure on that one)
The yellow line is the fuel coming from the fuel pump and going to the venturi tubes. You can see there are two, fuel splits up in two but can't see it in the pic.
The orange line is the fuel picked up in the "pods" and going back to the surge tank after the venturi did it's thing.
On my car it was the rubber 180 deg hose that failed but it seems like usually it is the flexible nylon hose that fails so if your car has some years and some mileage, it will eventually fail, might has well inspect it or just change it in a preventive manner. It is expensive and I didn't want to try some cheaper replacement part just by buying some in-tank fuel hose but I guess it could be done. If someone had good success with a custom fix, please share you experience as I find it kind of stupid to replace the whole fuel pump assembly only to change some hose that will eventually fail again anyway. If tuners are reading, maybe making a tougher system would be a good thing to sell. I just have to fix my car quick to be able to hit the track in a week, it couldn't have happened in a worst time. At least I found the problem before I hit the track…
If you find anything wrong in my text, please let me know. Hope this will be of some interest to some people. Happy Porsching.
This is a quick survey of all the parts, if I am wrong somewhere or if something is not well explained, please let me know so I can correct it.
So the fuel pump system is composed of a couple of things. First of all, when you want to change a leaking hose on the fuel system as it often happens, you can not buy only replacement parts from the dealer, you have to buy the whole fuel pump assemble. Only thing that can be purchased separately is the venturi tubes, we'll get to that later.
I have not taken pics of the process on how to remove the fuel pump but it is pretty straight forward and easy. I might take some when I'll install everything back together and add the pictures to this thread.
Now as you can see, with the fuel pump in place, I have a hole in my rubber hose. The outside is looking pretty bad but there is only a tiny hole in the inside layer. My symptoms were slower car and slight hesitation at WOT. With the durametric logs, Kevin was able to diagnose that I was missing fuel pressure. My injectors were showing 100% duty cycle and the AFR would keep raising up. Luckily the ecu pulls timing when this happens, which saved my engine.
Picture of bad hose and fuel pump in place with the fuel sender removed.
To remove the fuel pump assembly, you have to turn it counter-clockwise about 15 deg. Here is a picture of the bracket at the bottom of the fuel pump that holds the assembly in place.
Here are a couple of picture of the fuel pump assembly with the venturi tubes.
Now how does the system work. First you got to know that the fuel pump is in a big plastic tank, called also a surge tank. It is a system that prevents the fuel pump from missing fuel when hard acceleration, braking or long cornering is happening with a lower fuel level in the tank. This prevents fuel starvation and possible blown engine.
The way the fuel tank is made on the 996tt and C4 is a big tank on top of the front differential with two small "pod" going on each side of the differential to add some extra fuel storage. I don't think you have those on the 2wd 911 since there is no diff in the way of the fuel tank.
On this diagram, you can see the pod I am talking about (sorry don't know what other word to use). You can only see one in the picture but there is an other one on the other side we can't see.
Now for the surge tank to get the fuel that is located in the "pods" and the lower part of the fuel tank, the system is using two venturi tubes, one on each side. Since the pump is hanging in the middle of the fuel tank, it has to have a way to get the fuel to the bottom of it. The way the venturi tube is working is pretty simple. Fuel from the fuel pump goes to these tubes and creates a low pressure zone (vacuum) which then sucks fuel and send it in the surge tank. So basically, the fuel pump, on top of sending fuel to the injectors, send fuel to those tubes to create the vacuum to pump the fuel in the surge tank. Pretty weird design and I don't know why they didn't use an other electric pump or something else instead of putting extra stress on the fuel pump but I guess Porsche engineers had good reasons. It seems that one of the fuel pressure failure can be on those venturi tubes, if one fail, all fuel pressure goes to that pipe and back to the fuel tank and you get almost no pressure to the injectors. So it is a good time to inspect them if you remove your fuel pump from the tank.
Here is the end of one of the venturi tube.
To remove the venturi tube from the fuel pump assembly (which you have to do in tank before removing the fuel pump assembly) you just remove the two flexible fuel line on top and unclip the plastic block by the back of the surge tank (took me a while to figure out how to remove those pipes)
Here is a shot of the back of the surge tank where you can see the two holes for the clips of the venturi tubes. (sorry about the workbench mess)
Now here is a picture of the fuel pump assembly with some lines to see where fuel goes.
The big white piece is the surge tank. In the middle (black circle) is the fuel pump itself. The red line is the fuel pressure hose going to the injectors.
The blue line is the fuel return hose from the fuel rail (After the fpr)
The green line seems to come from the fuel filler neck probably to fill the surge tank first when you fill up with gas (not sure on that one)
The yellow line is the fuel coming from the fuel pump and going to the venturi tubes. You can see there are two, fuel splits up in two but can't see it in the pic.
The orange line is the fuel picked up in the "pods" and going back to the surge tank after the venturi did it's thing.
On my car it was the rubber 180 deg hose that failed but it seems like usually it is the flexible nylon hose that fails so if your car has some years and some mileage, it will eventually fail, might has well inspect it or just change it in a preventive manner. It is expensive and I didn't want to try some cheaper replacement part just by buying some in-tank fuel hose but I guess it could be done. If someone had good success with a custom fix, please share you experience as I find it kind of stupid to replace the whole fuel pump assembly only to change some hose that will eventually fail again anyway. If tuners are reading, maybe making a tougher system would be a good thing to sell. I just have to fix my car quick to be able to hit the track in a week, it couldn't have happened in a worst time. At least I found the problem before I hit the track…
If you find anything wrong in my text, please let me know. Hope this will be of some interest to some people. Happy Porsching.
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Yep, I read that thread on my quest for knowledge... Guy did a great job diving right into it! 
There are still a LOT of guys out there who are making good power (Markski for instance) with just the 044 pump (maybe changing out the in-tank pump too - i can't tell for sure)... Just wondering what else you can do to fortify the setup on a street car... not some 1000whp 60-130 monster...
There are still a LOT of guys out there who are making good power (Markski for instance) with just the 044 pump (maybe changing out the in-tank pump too - i can't tell for sure)... Just wondering what else you can do to fortify the setup on a street car... not some 1000whp 60-130 monster...
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I am not trying to clutter things up, and a larger pump in line may help a bit, but when you suck the venturi pump dry with the larger inline pump what does that do. My thinking is that if that worked it would have been done
here is a good old post by pumalex with excellent pics of the octopus pump:
here is a good old post by pumalex with excellent pics of the octopus pump:
Prche951, Exactly what I had thought.. When I pulled that monster out I was in shock that someone actually spent the time to make that monster work. The engineering hours must be crazy. But it does work for the job it was made for with a good safety factor, many cars making 200+ crank hp more then stock all day long..
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Prche951, Exactly what I had thought.. When I pulled that monster out I was in shock that someone actually spent the time to make that monster work. The engineering hours must be crazy. But it does work for the job it was made for with a good safety factor, many cars making 200+ crank hp more then stock all day long..
Good to know. Why they went through all that engineering is beyond me. I am pretty sure the stocker is a 40 not an 044 so replacing the the stocker would give a little help.
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Tough crowd... Has anyone replaced the factory pump with an 040 or 044?
Here's a couple of questions for you Tim... 1st, where are the pics? 2nd, what did you do for a pickup with your single big-*** pump? Do you have to keep the tank above a certain level with that setup?
Here's a couple of questions for you Tim... 1st, where are the pics?
2nd, what did you do for a pickup with your single big-*** pump? Do you have to keep the tank above a certain level with that setup?