Walbro fuel pump question.

[bishir]

I've had my GN for about 3 weeks. I'm starting to figure out that these cars had issue with fuel starvation. First of all, where is the stock fuel pump located? Is it in the fuel tank? If so, what are the steps of removal? Another thing, can someone tell me more about a Walbro fuel pump? That seems to be the popular choice. I believe I saw one on ebay that included all of the wiring and require no splices. That's the kind of setup I'd be interested in. Does the Walbro install in tank, or is it outside? Is it a plug and play operation, or does it require an entire day or weekend in the garage? Any info would be extremely helpful and appreciated.

Thanks,

James

 

[DynamicGN]

The walbro 340 or 307 are in-tank fuel pumps, the fuel pump brings good instructions...I suggest you hotwire it to the alternator for more volts. Racetronix sells an excellent plug and play hotwire kit for it.

 

[Snorman]

The fuel pump in these cars is a standard high pressure EFI in-tank pump. Drop the tank, remove the pump assembly, put in the new pump, and reverse for install. A pump and hotwire kit is a 2-4 hour job.
The kit you see on eBay is most likely the Racetronix kit. It is truly "plug and play" with no splicing, cutting or soldering required.
S.

 

[bishir]

Thanks for the reply guys. The Racetronix "plug and play" is indeed what I'm interested in. What is the difference between the 307 and 340? I'm not planning on a 11 sec car, but I would like a nice almost stock streeter. Would one of these pumps be overkill for my application?

Thanks,

James

 

[UNGN]

The 340 can flow more at high pressure (high boost) than the 307, but both work good and neither are "overkill" for even a stock car. A fuel pump upgrade should be considered mandatory, even if you were to buy one of those 100 mile GN's on E-bay. The stock pump is simply inadequate when the boost is raised much above stock.

 

[bishir]

Thanks for your response! Is there a way to tell if the stock pump isn't doing it's job? I have a scanmaster and my fuel readings are near 800 most of the time. The instructions recommended at least 760 IIRC.

Thanks,

James

 

[Snorman]

Higher O2 mV's mean the car is richer. You're safe at over 800, I think the range people shoot for is 750-770. Admittedly, I'm not yet an expert on all the ranges that the SM measures.
These cars have a constant return fuel system. Installing a bigger (higher volume) pump won't effect anything. Excess fuel not dropped at the rails will simply return to the tank. In any case, the Walbro 340's are hardly considered overkill in any car.
A few giveaways for dying pump are increased noise level and inability to hold pressure under boost.
Upgrading a pump is such an inexpensive mod, it's one of the first things to do.
S.

 

[black heat]

On dropping the fuel tank:

Get someone to help you (when doing it the first time).

1. Run fuel down to near empty (weight problem)

2. Disconnect battery-lessens fire hazzard.

3. Raise car (jacks) for easier access to undo the two straps
that are attached just fwd of the tank.

4. You'll have to get on your back for this, it will be time
consuming, just like someone said-two or more hours.

5. Some guys just bring the tank down on their stomach,
others use a jack (with board) to bring the tank down.
I did it both ways, not too much fun.

6. Reverse the procedure to bring it back in place.



7. Good luck!!

 

[GNANIMO]

James,

Get a FP gauge. Know what your static FP is and start from there.. For every # of boost your FP should increase 1# as well.

Example you are running 40# on the FP (vacuum line on) and you are boosting 15# you should be hitting 55# of FP at MAX boost.

If you are not the pump is not able to keep up with the boost you are pushing.. this will mean a lean state.. which could mean boom!

The Racetronix kit is a nice kit, I just installed mine last week.

 

[bishir]

Okay, I don't think I'd like a fuel pressure gauge that mounts on the hood, but I would be willing to buy and install a rail mounted gauge. If I do, how would I be able to read the fuel pressue at boost?

Thanks for the informative post,

James

 

[Snorman]

Postons (and I'm sure some of the other vendors) sells a FP gauge kit that can rail mount and also has a length of braided hose with the correct fittings on it to extend the gauge to the windshield. You can tape it to the base of the windshield for tuning purposes, then remove the line and mount it back to the rail.
Also, some people use a bracket so the that gauge isn't mounted to the hood. Rather, the bracket bolts underneath the hood near the cowl and loops around 180* for a mounting point for the gauge cup.
S.