Is 255lph pump in 420a (stock) worth effort??

[Lenn]

I have a pretty much stock 420a + CAI. I like the idea of the 255 pump and mine is losing fuel pressure when loaded anyway. Is there any noticable differences in the cars power if I was to add the 255?? I just dont want to dump too much fuel on a stock internaled engine and blow it up.

 

[totaleclipse_05]

You will not have any problem running a 255lph fuel pump with the stock fuel pressure regulator on a 420a. If you owned a 4G63, the FPR would need to be changed out for a better one. You won't have to worry about dumping too much fuel either with the bigger pump. I would just go with the 255 as it leaves room for a turbo upgrade if you plan on it in the future and is inexpensive (around $100). Keep in mind you will not see any upgrade in power by adding in this fuel pump though.

 

[eclipsers-t]

I just dont want to dump too much fuel on a stock internaled engine and blow it up.

You do not have to worry about blowing a motor up with too much fuel. Only when you lean it out--too much air, which you won't do with a CAI.

Definitely worth it for future modifications...GO Turbo!

 

[dr1665]

[My engine] is losing fuel pressure when loaded anyway.

I'd be curious as to why you're losing fuel pressure. Have you replaced the fuel filter? Re-wired teh stock fuel pump for better performance? Had the injectors cleaned? Let me put it this way, if you were losing pressure at the rail due to a leak in the line under the car, would you consider a bigger fuel pump to "fix" the problem?

It is entirely possible that your fuel pump could be getting tired, but it's been a while since I've heard of anyone talking about how their stocker died. Mine's got over 200,000 miles and almost 11 years of use on it and it's still taking names. If you're going to eventually turbocharge the car, then this is something you'll need at that time, but it seems like it might be a bandaid for another problem to me. There is no reason why I think you should need the Wally at this point.

 

[Lenn]

I just clicked over 100k last night on the odometer. I have had the car serviced by the dealer every 5k miles since I bought it at 50k. I have had this issue with the car breaking up under load in higher gears and accelerating w/o downshift. The dealer cant find/duplicate the problem but they replaced the injectors, replaced the fuel filter and "cleaned all the lines". I put a fuel pressure guage on the car and drove it and watched the needle start to fluctuate when the issue occured. It may not be the fuel pump but more mods were to come on this car once I finish my GSX.

 

[Lenn]

Potentially stupid question- would I see any performance gains or make the fuel pump more nessicary if I was to install a full exhaust or are the stock injectors not capable of flowing anthing more than stock fuel flow and they would need to go, too?

 

[link16]

Until you go turbo or try to compete with Mark, you will not NEED the increased fuel pressure. Keep in mind TOO much fuel can be bad too, you can drown your spark plugs. I did that and I am turbo, I have to go out and get new plugs b/c mine are soaked.

And exhaust will not provide enough of a hp increase to warrent the need of a bigger pump or injectors.

 

[4UH8ERS]

WTF is bieng discussed here? There will be no performance gains from larger injectors or higher fuel pressures from a walbro 255. You would actually lose performance with just larger injectors because you would run rich. If you add more fuel then you need more air to compensate and then you will increase performance. and NO a CAI does not compensate for the more air i was talking about.

 

[dr1665]

The dealer . . . replaced the injectors, replaced the fuel filter and "cleaned all the lines". I put a fuel pressure guage on the car and drove it and watched the needle start to fluctuate when the issue occured.

You didn't mention fuel pressure regulator (FPR). I'm pretty sure the 95 models had some kind of unique (relative) fuel system set up with their own FPR. If the FPR shits the bed on you, you'll run into problems like this. Run a search in the performance/engine or general forums on 2GNT for "fuel pressure regulator" or "FPR" by *subject* and you should get some information right away. (If you just throw "FPR" into the search over there, you'll get thousands of threads about turbo systems and you don't need that info now.)

Potentially stupid question- would I see any performance gains or make the fuel pump more nessicary if I was to install a full exhaust or are the stock injectors not capable of flowing anthing more than stock fuel flow and they would need to go, too?

You have no need of any kind of fuel mods on your car whatsoever. I run fully built on the stock ECU and fuel system without issue. Megasquirt would allow me to make more power on the set up, but you can build pretty much any streetable all motor 2GNT you want and it will still be fine on the stock fuel system.

 

[Lenn]

Thanks, dr1665. I didnt see anything that resembles a FPR under the hood, but I work around Volvos all day long, so I know them better. I will search for that and see what I come up with.
Thanks for all the information from all that responded.

 

[4UH8ERS]

You didn't mention fuel pressure regulator (FPR). I'm pretty sure the 95 models had some kind of unique (relative) fuel system set up with their own FPR. If the FPR shits the bed on you, you'll run into problems like this. Run a

Brian, The 95's FPR is built directly into the fuel rail. He will have to replace the whole fuel rail.

 

[Lenn]

If that is the case (fuel rail replacment), any suggestions on what to test to narrow it down? I know this may move this into the diagnostic thread?

 

[4UH8ERS]

If that is the case (fuel rail replacment), any suggestions on what to test to narrow it down? I know this may move this into the diagnostic thread?

Test the fuel pressure in the feed line at idle and high throttle. Then check the fuel pressure at the fuel rail at idle and high throttle. Chances are your if you losing it in the rail only then its the FPR. You will need a T in order to test the pressure in the line, unless someone else here has another way of doing it.

 

[link16]

If that is the case (fuel rail replacment), any suggestions on what to test to narrow it down? I know this may move this into the diagnostic thread?

Try a Haynes manual, I had to use that for most of my turbo install, It helps but is a bit of a run around. It helped especially when i was working on my fuel system.