Can you detect a new fuel pump without physically seeing it

[SuperSonic]

As most of you know, removing the fuel tank is no walk in the park. I know when I dynoed the car and even the last dyno I was running the injectors at max capacity making 430 whp. I know the injectors at 440 can't hold that fuel rate. I have since bought 550 cc injectors, just to be on the safe side of having enough fuel. Is there any way of knowing if the fuel pump is oem or if I may have a Walbro. I know when I bought the car, it had the ct super charger, brembos, ct exhaust, headers, even the comptec clutch. There may be a chance the previous owner even added the fuel pump. Is there a way to figure out if the pump isn't oem b4 I drop 600 on a new pump and labor?

 

[ken sampson]

I had 750cc when getting close to 500HP now I run 1000CC for anything over 500HP
Ken

 

[jaffaz32]

Don't hold me to this but a Walbro you will probably hear when you turn the ignition on, on the oem pump i never heard it.

I have a Walbro and i hear it prime as you switch the ignition on. #Becauseracecar haha.

Is there not a access hatch to the pump within the car? I remember seeing one but may had been a different car.

 

[E-Nough Logic]

One Idea, pull the fuel pump supply line, and measure the flow rate? Does the stock fuel pump flow 430whp worth of fuel?

 

[NA1MT]

Why don't you try to contact previous owner?

 

[Briank]

Some fuel pressure measurements may give you a clue if the pump is stock. Are you running any type of voltage doubler, would be unnecessary with a aftermarket pump.

 

[dawk]

Walbro is much louder

 

[NSX-Files]

The Walbro is louder than oem when first turning on the key when it primes for two seconds, but it's not like you can't hear the stock pump if you're listening for it. Perhaps someone near you with a Walbro can let you hear theirs and try to compare. But really the only accurate and safe way to know if your installed pump is up to the task is to do the fuel pressure and volume measurement as described in the shop manual. Honestly, dropping the tank is a bit of a bear, but it's not THAT awful.

 

[SuperSonic]

Thanks guys. I wish the last owner would know. I don't think he even realized the car had brembos at one point. He was a wealthy business owner. He had someone else sell the car for him. Would running a dyno tell me? I mean I am running out of fuel at 7800 rpm in 4th gear. I got the injectors coming Thursday. Can I install them and retune it like that. I mean if I don't run out of fuel I must have another pump. If I do well then it's obvious. I like the idea about the priming sound. I'll ask my buddy with the 02 to let me listen. Also, I am doubling the voltage. I took out the resistor to run the pump full power all the time. I just know Wil said running 390-400 was good. I know 430 is maxing the injectors for sure. That's why I think I might have a fuel pump. 2nd owner got the entire package brembos and all, a fuel pump would fit the bill too.

- - - Updated - - -

Don't hold me to this but a Walbro you will probably hear when you turn the ignition on, on the oem pump i never heard it.

I have a Walbro and i hear it prime as you switch the ignition on. #Becauseracecar haha.

Is there not a access hatch to the pump within the car? I remember seeing one but may had been a different car.

Now that I think of it, when I turn the car on I do hear the whin sound. I can hear the priming sound for about 2 seconds. Hmmmm

 

[NSX-Files]

Now that I think of it, when I turn the car on I do hear the whin sound. I can hear the priming sound for about 2 seconds. Hmmmm

The 2 second part alone is not indicative of an upgraded pump; the 2 seconds is the factory ECU programmed cycle to prime the injectors. The sound is the only difference you might notice between Walbro and OEM pump. That and the difference in volume pumped.

 

[SuperSonic]

Damn.... Cause I was you tubing walbros, and they sound super loud lol. Mine not that loud haha

 

[angus]

You can use a fuel pressure gauge, with the gauge connected you pinch off the return line momentarily while the car is running. You will know right away if it is OEM or a walbro - the OEM pump deadheads at around 80psi - the walbro will do way over 100 like 140 or more.

BE SURE that your fuel line connections are sound before trying this - and have a fire extinguisher handy.

 

[SuperSonic]

Lol Wil. The last thing I need is to catch the car and or house on fire haha. Though that way would work..... I am starting to lean towards it can't be oem. Trying to do calculations a stock fuel pump can barely do the task for a supercharger: it has to use a fpr to bump the psi as well as bypass the resistors to get the max volts it can. The injectors I have now are the 440 Wil. According to the injector calculation sheet on a turbo car with 6 cylinders running 440 should max the injectors at 100% to achieve about 420 whp. I was running 432 at Bisi's and started to drop off at 7800 rpm. The injectors were maxed after I passed 420 whp give or take.

What at about this and correct me if my logic is wrong: I have the 550 cc injectors now. If I install them then tune it, the tune won't change if I have the oem pump or not. Either way it will have to be tuned for the injectors at idle up to peak boost. If I start to run out of fuel at 7800 rpm then it must be oem pump in which case the car is already tuned for the new injectors so just put a new pump in. If on the other hand it doesn't run dry, well then it is obviously an aftermarket pump. In any event, putting in the injectors now and tuning it will have no effect on if the pump is switched since it's still regulated by the psi and what the injectors are flowing. Only difference would be actually delivering that much fuel correct?

 

[angus]

OK, number one - do this outside. For 2, like I said make sure you have no questionable or loose fuel connection (you should never have that anyway) if you only momentarily pinch the line and you do have a leaky joint it'll allow you to find it - I do this sometimes to find leaks.

You only need to pinch the line for about 1 second to see how high the pressure goes.

If you had a fuel pressure gauge in the car, you would be able to see if your pump was too small since the pressure would drop when you boost up or at high RPM. This is the telltale sign that you need an upgraded pump. No need to over think things.

 

[NSX-Files]

What at about this and correct me if my logic is wrong: I have the 550 cc injectors now. If I install them then tune it, the tune won't change if I have the oem pump or not. Either way it will have to be tuned for the injectors at idle up to peak boost. If I start to run out of fuel at 7800 rpm then it must be oem pump in which case the car is already tuned for the new injectors so just put a new pump in. If on the other hand it doesn't run dry, well then it is obviously an aftermarket pump. In any event, putting in the injectors now and tuning it will have no effect on if the pump is switched since it's still regulated by the psi and what the injectors are flowing. Only difference would be actually delivering that much fuel correct?

I believe your logic might be wrong. If you now have a stock non-adjustable fuel pressure regulator (FPR) and a stock fuel pump, then simply changing the fuel pump from an oem one to a Walbro WILL change the tune. This is because the stock FPR cannot bleed off enough pressure when the Walbro is installed, so your base fuel pressure with a Walbro will be several psi above what the service manual says it should be, and will be delivering more fuel to the injectors than the ECU thinks they are receiving. Your tune would then be off. Now if you currently have an adjustable FPR and a fuel pressure gauge, then maybe you can compensate for this somewhat but the tune would probably still be off after changing the fuel pump component.

Best bet is to have all your fueling components (including the pump, injectors and FPR) decided and in place BEFORE you tune it. If you think you MIGHT need a new fuel pump then I would recommend just do it and give yourself the peace of mind. It's really not that bad a job to drop the tank and swap it out. Then you just tune it once and you're done.

I would suggest as a first step installing a fuel pressure gauge at the fuel filter banjo bolt. Wil's tests sound like a good way to see if you have an aftermarket pump already. Also if you have a way of monitoring the fuel pressure at WOT, then you will see if there is a drop in pressure at high loads. All this can be done without dropping the tank. I have a mechanical gauge on my filter, and also the electronic sender installed there that I wired to my EMS (which transmits all the data via bluetooth to the Digital Logic app on my iPhone). So I can see the fuel pressure inside the car on my iphone, and also see it when it's on the dyno by just looking at the mechanical gauge.

Here's a screen shot from my phone (note the numbers are random because it's not actually paired with the car right now, but you get the idea of what you can monitor - The FUEL PSI is red because the pressure is below what I set for an alarm). I've always thought fuel pressure on a boosted car was right up there in importance. I used to have the AEM digital fuel pressure gauge inside the cabin on my last NSX, this app just makes it easier than having a bunch of gauges in the cabin.

 

[SuperSonic]

Thanks guys. And that is a sweet app. That would be a cool tool to use. So Wil, the gauge from SOS is the one your referring to correct? Just screw onto the banjo and bam. I have a manual to look up the fuel line, but I assume it's off the end of the fuel rail. Thanks for all info. I'll get the gauge b4 the tune to figure it out.

 

[angus]

I believe your logic might be wrong. If you now have a stock non-adjustable fuel pressure regulator (FPR) and a stock fuel pump, then simply changing the fuel pump from an oem one to a Walbro WILL change the tune. This is because the stock FPR cannot bleed off enough pressure when the Walbro is installed, so your base fuel pressure with a Walbro will be several psi above what the service manual says it should be, and will be delivering more fuel to the injectors than the ECU thinks they are receiving. Your tune would then be off. Now if you currently have an adjustable FPR and a fuel pressure gauge, then maybe you can compensate for this somewhat but the tune would probably still be off after changing the fuel pump component.

Best bet is to have all your fueling components (including the pump, injectors and FPR) decided and in place BEFORE you tune it. If you think you MIGHT need a new fuel pump then I would recommend just do it and give yourself the peace of mind. It's really not that bad a job to drop the tank and swap it out. Then you just tune it once and you're done.

I would suggest as a first step installing a fuel pressure gauge at the fuel filter banjo bolt. Wil's tests sound like a good way to see if you have an aftermarket pump already. Also if you have a way of monitoring the fuel pressure at WOT, then you will see if there is a drop in pressure at high loads. All this can be done without dropping the tank. I have a mechanical gauge on my filter, and also the electronic sender installed there that I wired to my EMS (which transmits all the data via bluetooth to the Digital Logic app on my iPhone). So I can see the fuel pressure inside the car on my iphone, and also see it when it's on the dyno by just looking at the mechanical gauge.

Here's a screen shot from my phone (note the numbers are random because it's not actually paired with the car right now, but you get the idea of what you can monitor - The FUEL PSI is red because the pressure is below what I set for an alarm). I've always thought fuel pressure on a boosted car was right up there in importance. I used to have the AEM digital fuel pressure gauge inside the cabin on my last NSX, this app just makes it easier than having a bunch of gauges in the cabin.

I agree fully.

 

[E-Nough Logic]

I believe your logic might be wrong. If you now have a stock non-adjustable fuel pressure regulator (FPR) and a stock fuel pump, then simply changing the fuel pump from an oem one to a Walbro WILL change the tune. This is because the stock FPR cannot bleed off enough pressure when the Walbro is installed, so your base fuel pressure with a Walbro will be several psi above what the service manual says it should be, and will be delivering more fuel to the injectors than the ECU thinks they are receiving. Your tune would then be off. Now if you currently have an adjustable FPR and a fuel pressure gauge, then maybe you can compensate for this somewhat but the tune would probably still be off after changing the fuel pump component.

Best bet is to have all your fueling components (including the pump, injectors and FPR) decided and in place BEFORE you tune it. If you think you MIGHT need a new fuel pump then I would recommend just do it and give yourself the peace of mind. It's really not that bad a job to drop the tank and swap it out. Then you just tune it once and you're done.

I would suggest as a first step installing a fuel pressure gauge at the fuel filter banjo bolt. Wil's tests sound like a good way to see if you have an aftermarket pump already. Also if you have a way of monitoring the fuel pressure at WOT, then you will see if there is a drop in pressure at high loads. All this can be done without dropping the tank. I have a mechanical gauge on my filter, and also the electronic sender installed there that I wired to my EMS (which transmits all the data via bluetooth to the Digital Logic app on my iPhone). So I can see the fuel pressure inside the car on my iphone, and also see it when it's on the dyno by just looking at the mechanical gauge.

Here's a screen shot from my phone (note the numbers are random because it's not actually paired with the car right now, but you get the idea of what you can monitor - The FUEL PSI is red because the pressure is below what I set for an alarm). I've always thought fuel pressure on a boosted car was right up there in importance. I used to have the AEM digital fuel pressure gauge inside the cabin on my last NSX, this app just makes it easier than having a bunch of gauges in the cabin.

Wow that is a nice gauge setup. Wonder where you can get one of those....? lol.

Are you mapping boost pressure against fuel pressure using the advanced warning system? IE 2 conditions, boost pressure > 10psi & fuel pressure < 50psi? Having fuel pressure wired up to your AEM EMS is a VERY useful tool, very undervalued in the tuning community.

 

[LMR]

Why don't you just check the bolts for the fuel tank, it will be easy to see if they have been removed before. If not then you still have the OEM pump in. If they have been removed then most likely it's been replace with an aftermarket pump.

 

[NSX-Files]

Wow that is a nice gauge setup. Wonder where you can get one of those....? lol.

Are you mapping boost pressure against fuel pressure using the advanced warning system? IE 2 conditions, boost pressure > 10psi & fuel pressure < 50psi? Having fuel pressure wired up to your AEM EMS is a VERY useful tool, very undervalued in the tuning community.

Honestly, I have not taken the time to set up advanced warnings although I'm sure it's probably pretty easy and would be awesome to have. It's a great device and app, glad you developed it!