Dual fuel pump wiring question

mnviper · Jul 8, 2009

I'm considering running dual Walbro 255s. Will I need a separate 30amp circuit and relay for the second pump? I'm guessing I can't run them both from the existing circuit and that the MSD voltage booster I currently have will need to go.
Any advice would be appreciated. Thanks.

britospeed · Jul 8, 2009

You're correct. Run a second relay and fuse for the second pump but use the same signal wire to trigger both pumps.

mnviper · Jul 8, 2009

That's what I expected. Thanks for the response.

1TONY1 · Jul 8, 2009

I'm running two 255's. I used the stock wire to turn on my relay. I am picking up power right from the battery and only using one relay for both pumps....large wire to and from the the relay, then split to two wires right before the pumps. No issues with a couple years on this set-up.
I would either move the MSD or not use it. The problem with the MSD BAP is that it has to have the vacuum/boost hose so everyone mounts it up front THEN run the load wires to the rear...doesn't make sense since the pumps and other fuel pump wiring is already in the rear...why add another 10'-15' of wire. I prefer the Kennebell BAP, it uses an electrical signal from a boost sensor....that way it is easy to mount in the rear.

One relay is plenty.
Here are some amp charts: Auto Performance Engineering - Walbro fuel pumps specs

mnviper · Jul 8, 2009

1TONY1 said:
I'm running two 255's.

Thanks for the information Tony. Are you running the stock fuel line with the twin pumps or did you go to something larger?

1TONY1 · Jul 9, 2009

mnviper said:
Thanks for the information Tony. Are you running the stock fuel line with the twin pumps or did you go to something larger?

I am using the stock line for the return which is common. I gutted the metal piece that the stock line goes to. I'm not sure what would replace the stock filter....mine is still there but it would be nice to have a straight hose instead. If you go through the filter maybe put a new one on or back flush the old one off the car (don't ask when I remember this

) . I think RSI had the billet pieces on sale...if they are still on sale I would recommend going that direction. It is a real pain to do what I did...pumps in the stock canister. The braided lines run a foot or so and then Y into a larger line.

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mbccenter · Jul 9, 2009

I ran my return with the stock line then decided to move it off to the side so I was not dumping hot fuel back into the canister.

1TONY1 · Jul 10, 2009

mbccenter said:
I ran my return with the stock line then decided to move it off to the side so I was not dumping hot fuel back into the canister.

How far to the side did you move it ? My pumps are held in the canister but only pick up fuel from outside the canister. The canister also has several large holes in the sides to let fuel flow in/out freely.

1TONY1 · Jul 10, 2009

While we are on the subject...I'll give my yearly spill about the restrictive stock system. It's amazing it will work for our stock hp.....even knowing that it can go a bit higher.

Out of the fuel pump the fuel runs through a hose about 8" long and into this ****** that has an ID of right at 1/8" :omg:

Yes, those running up to 600+ hp are flowing through this small opening :dunno:

The comparison items are:
Ink insert out of a cheapo pen and two pennies side by side.

EllowViper · Jul 10, 2009

No wonder we get get such good mileage.

1TONY1 · Jul 11, 2009

EllowViper said:
No wonder we get get such good mileage.

Excellent point !!!!

Phun70 · Aug 25, 2009

does anyone make a fuel system upgrade kit with the larger pickup?

GTSnake · Aug 25, 2009

EllowViper said:
No wonder we get get such good mileage.

Umm, mileage isn't really a factor of intake diameter.

EllowViper · Aug 25, 2009

..Umm...that was a joke...

Russ M · Aug 25, 2009

Just finished today with my twin 255 setup and we used the factory power to trigger the relay to activate the 2nd pump.

Make sure you DO NOT re use the factory walbro as one of your pumps it has a built in regulator and will cause you nightmares.

Like 1TONY1 we used the factory canister modified to have 2 pumps in it with a -6 line at each pump merging into a -10 at the fuel filter.

It is not a fun job lots of little things that you need to get worked out. But now that I actually did one the next time it should be far easier.

And yes it is amazing what we have for stock fuel systems, and is even more amazing that people try and make more power on the stock system. I would have lost lots of money betting on what kind of hp our factory setup is good for cause my guess would be no more than 200.

james11 · Aug 25, 2009

Mitch (SNAKEBIT) has a dual walbro setup and could probably help you with yours also.

EllowViper · Aug 28, 2009

What kind of regulator are you going with and what PSI are you shooting for? I need to start "schematic-ing" this in my minds eye.

BOTTLEFED · Aug 28, 2009

Thanks for sharing guys.
This is one topic that seems to be lacking on info around here. It is great to see what guys are running for fuel systems so others can learn and discuss what works and what doesn't.

So would you guys recommend running the stock line as a return or not?
When is it enough to just upgrade the stock pump, and when is it time to upgrade the whole system?

You can see my mods in my sig (6.5# Roe, W/M, BAP, and bolt-ons), I seem to be fine on fuel so far but I will be going to a 10# this winter and continuing the W/M and BAP. Would a bigger pump be necessary if I'm shooting for 700whp?

BOTTLEFED · Aug 28, 2009

EllowViper said:
What kind of regulator are you going with and what PSI are you shooting for? I need to start "schematic-ing" this in my minds eye.

Eric, I think we are in the same boat

paulsgts · Aug 28, 2009

I have 2 255s in my car used stock wiring have had no problems for 3k miles now

1TONY1 · Aug 29, 2009

paulsgts said:
I have 2 255s in my car used stock wiring have had no problems for 3k miles now

It's sooooo easy and cheap to do this with a larger and well fed wire. Why risk it instead of spending an extra $5 bucks ?
Where did you split off the stock wiring for the second pump ?

Two Walbro 255ltr pumps will draw a little over 20 amps depending on pressure. Have you checked the amperage rating of the stock wire ?

1TONY1 · Aug 29, 2009

EllowViper said:
..Umm...that was a joke...

........

Russ M · Aug 29, 2009

BOTTLEFED said:
Thanks for sharing guys.
This is one topic that seems to be lacking on info around here. It is great to see what guys are running for fuel systems so others can learn and discuss what works and what doesn't.

So would you guys recommend running the stock line as a return or not?
Factory feed line as a return is just fine, and you can make it a very clean install if you take the time to find all the adapter fittings from OEM to -6 so everything is plug and play.
When is it enough to just upgrade the stock pump, and when is it time to upgrade the whole system?
There is no point upgrading the stock fuel pump, the work you will have to do just to put in a single pump is close to what the twin pump setup would require.
You can see my mods in my sig (6.5# Roe, W/M, BAP, and bolt-ons), I seem to be fine on fuel so far but I will be going to a 10# this winter and continuing the W/M and BAP. Would a bigger pump be necessary if I'm shooting for 700whp?

The problem with the stock fuel pump is its regulated mechanicaly to 55psi by a mechanism inside the pump. So if you dont go over 55 psi of fuel pressure you should be ok. But if you go higher the pump will start to bleed off fuel and your no longer going to be able to support the power you need.

On my car we ran an AEM universal fuel pressure regulator, its nice and compact fits well right on the end of the passenger side rail.

1TONY1 · Aug 29, 2009

Russ M said:
The problem with the stock fuel pump is its regulated mechanicaly to 55psi by a mechanism inside the pump. So if you dont go over 55 psi of fuel pressure you should be ok. But if you go higher the pump will start to bleed off fuel and your no longer going to be able to support the power you need.

On my car we ran an AEM universal fuel pressure regulator, its nice and compact fits well right on the end of the passenger side rail.

Friendly debate....
Are you sure ? The regulator is the round metal piece that the hose attaches to from the pump seen above the canister with the factory line/connector on it. I don't think the pump itself is regulated but the theory of not being able to go over 55 psi probaly still stands.

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Russ M · Aug 29, 2009

1TONY1,

My car did not have that metal part on the fuel canister. My thoughts on the subject when going into the project was that the regulator was something you could remove which sat on top of the gas tank, as every subject on the viper forums suggests. This is not the case, at least not on my 99 viper.

The only thing that sat on top of the canister was a charcoal canister which we initially thought was the regulator. It turned out to be nothing of the sort, and its a good thing because had we not noticed the regulator inside the factory pump it would have forced us to open everything back up when tuning because with the factory regulator letting go at 55psi tuning would have been impossible.

What initially cought our attention that something was wrong with our theory was that the factory pump has a second ****** on the side of the pump which is used to relieve pressure.

1TONY1 · Aug 29, 2009

Interesting for sure. Good info.
I would like to see some pictures of the pump and canister top. That picture is of my 96 and there was only one ****** on the pump ...hehe...we said *******

Anyway, sounds like there mine be some "year matters" issues as JonB would say.
On mine, I did a test in a bucket with fuel and it wouls fall back out of the metal piece. Wish I had made pictures but what I did was take the guts out of the metal piece so it would return without regulating. I believe someone with my style could make a cheapy system using the stock line as the return and the metal piece will regulate from either direction. Of course all that saves is the price of a real regulator but if you want to stay with stock pressure it might not matter.

Russ M said:
1TONY1,

My car did not have that metal part on the fuel canister. My thoughts on the subject when going into the project was that the regulator was something you could remove which sat on top of the gas tank, as every subject on the viper forums suggests. This is not the case, at least not on my 99 viper.

The only thing that sat on top of the canister was a charcoal canister which we initially thought was the regulator. It turned out to be nothing of the sort, and its a good thing because had we not noticed the regulator inside the factory pump it would have forced us to open everything back up when tuning because with the factory regulator letting go at 55psi tuning would have been impossible.

What initially cought our attention that something was wrong with our theory was that the factory pump has a second ****** on the side of the pump which is used to relieve pressure.

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