Walbro 307 cant' keep up withstock turbo??

[squeeze87]

Hi all,
I'm running 42.5 009's with a MaxEffort setup. Steve said to set the fp at 46 line off. I have been having trouble with KR on the race gas setting since I installed this. Granted I'm running 30° timing which a stock turbo should handle, and running Torco 112 straight and 20 lbs of boost. I installed a hood mounted FP gauge, and that pump will only produce 62 lbs of pressure at WOT! I should have 66 if 1 lb per lb of boost is correct. The pump is hotwired too. Has anyone ever seen 65-70 lbs out of a 307 or a 340 for that matter?? If this is all the fuel pressure I can produce, I can't even upgrade the turbo! I think walbro is full of SHI* with their specs. What do you guys think? Not enough voltage or crappy pump? I did check the voltage at the pump at idle and it was 14 volts, I have no clue what it is at WOT. Thanks!

 

[UNGN]

What kind of fuel pressure regulator? Is the AFPR and the pump both new? Did you get rid of the pulsator and necked down area when installing the pump?

 

[Steve Wood]

replaced the fuel filter?

 

[squeeze87]

Thanks for helping,
Yeah everything is less than a year old. I bought the AFPR as well as the pump from ANS in Chicago. I'm not sure on the brand, It's billet unpainted aluminum if that helps, If it's important, I can find out. No pulsator and I trimmed off the smaller part of the tube it fit on. I also asked ANS if they shimmed the pump relief spring and they said they did, but they also said the 307 will support 500hp.

 

[squeeze87]

whoops, i was typing while you posted Steve, Yes on the fuel filter, new last spring.

 

[c&cgn]

Originally posted by squeeze87
whoops, i was typing while you posted Steve, Yes on the fuel filter, new last spring.

If you mean last spring, as in a year ago I would change it again. It may not be your problem but you should change the fuel filter at the beginning of every season IMO. Fuel is one thing our cars can't do without.

 

[RealFastV6]

Is it a billet topped stocker? Or a full billet one?

 

[REDS HOT AIR]

WITH THE PUMP RUNNING CLAMP OFF THE RETURN LINE DOWN BY THE FRAME AND SEE IF IT JUST RELIEVES THERE OR IF YOUR ACUALLY USING MORE FUEL THAN IT CAN PUMP.

 

[Steve Wood]

Unless the 307 is a bad unit, it should easily pump enough fuel.

Red had a good suggestion for clamping off the line to see if the pump will put out the pressure...there is one problem with it, by itself, there is no real fuel demand at that point so you are testing pressure, not volume. Check the fuel pressure to see if it goes to about 70# when you do this...

To complete the equation, you need to test flow. Hook a hose on the end of the fuel rail and stick it in a gallon container...touch the fp test lead to terminal on the back of the alternator..probably need a longer wire to make the jump....

It should fill the gallon jug in less than one minute.


You might also check the voltage at the tank while the engine is running to make sure your voltage is good. Sometimes the problem lies in a lousy ground even tho the hot wire is in place. ]

 

[squeeze87]

Well, I clamped off the return line and it pegged the FP gage so I guess that's OK. Then I checked flow and the pump will fill a 1 gal jug in 44sec. But when I took it out for a ride today it still wont make over 60-62 lbs at WOT. I guess i will try to get some scanmaster voltage readings at WOT and see what they are. At idle, there is almost 14 volts at the pump. Steve Y recommended a volt booster or having an adjustable voltage regulator put in my alternator, so I might try that. Steve W, where are the grounds I should check? Thanks

 

[azgn]

could you have a leak in the vacuum line to the regulator?

 

[Steve Wood]

The voltage seems okay...does the scantool logged voltage remain high thru out the run?

Altho I think it is okay, check that there is a ground from the tank to the sheet metal, not the frame. Then check the sheetmetal ground by the battery.

Check the hose connections from the tank to the fuel lines and make sure one is not kinked.

 

[c&cgn]

Have you checked out your boost gauge? Maybe it is not accurate. I have seen and/or heard of plenty of aftermarket boost gauges that were off by 2+ psi. Any idea what your O2's are @ WOT? You could be excessively rich and not know it and the pump be perfectly fine.

 

[Racetronix]

Testing the pump should be done at W.O.T. operating pressure.
If you are running 46PSI static + 20lbs boost then you should be testing the pump @ 66PSI of FP.

As stated in my previous postings, the GSS307 is not recommended for TB applications as the bypass is set to open too low and the motor armature is not as efficient / powerful as the GSS340. The GSS307 will draw more current at a given FP that the GSS340. Assuming the vendor modified the GSS307 bypass one would have to ask what pressure was the bypass set at? Walbro engineering states that “this adjustment is very sensitive and not an exact science.” “Modified pumps are not covered under Walbro's 1 year warranty.” There is only a $10.00 difference between the GSS307 and GSS340.

What type of hotwire harness do you have?
Where does it interface to?
What is the gauge of the wire used?
What is the voltage drop / difference between the supply and pump end while operating at 66PSI FP?
What is the fuel flow at 66PSI

To determine the fuel flow you would have to run the pump at vehicle WOT voltage (this can vary from car to car. An external power supply / charger can be used if available), Set the regulator at 66PSI and run its return line into a bucket. The car would not be running at this time. This will give you a better idea of what your fuel pump volume is under WOT conditions. This is not exact however it is more accurate than running a line from your Schrader valve into a bucket.

Jack
Racetronix

 

[squeeze87]

I'm using a Caspars hot wire kit and I dont have all the specs such as wire gage, but its hooked from the alternator and plugs on between the pump and the factory harness. I am going to check for vacuum leaks in the regulator line. Jack from racetronics, I couldnt find just a walbro340 on your site, do you have a link to that page. I WILL see 66 lbs of pressure or know the reason why before I'm done!! Thanks

 

[Steve Y]

I have a new 340 . I also have a new AC filter.
Checked all the lines carefully for kinks.
With the fuel delivery equal to 38 pound injectors at full PW in 3rd gear and using 2 glycerin filled gauges....first one then the other cuz I did not believe the first one......the best I can get is 64 PSI with static pressure of 46 and 26psi boost.
Alternator puts out 15 v under a load.
I can live with this cuz I have alcohol injection, but I wasted my money on that damn pump it appears, cuz it is not any better than the one I took out.
I did have a leaking hose to the regulator at one time a few years ago so I knew enough to also check that.
Steve

 

[Racetronix]

Steve Y,

There is obviously something missing from the picture there as the GSS340 should have no trouble producing your required pressure.

Do you have a hotwire kit in there?
What type / brand of regulator do you have?

Jack
Racetronix

 

[jetmech]

Is your vacuum line to the reg. collapsing, it may be too soft. But is the vacuum line still in vacuum when wot . Just trying to help. I remember my vac line collapsed at idle one time and used a stronger line.

 

[Steve Y]

I have an Applied regulator and can turn it up over 70.
Also I have # 10 wires going back off the alternator through a relay. I checked the voltage at the tank and there is almost 1 volt drop, which is normal I think.
I dunno.
Steve

 

[Racetronix]

Steve,

That voltage drop seems a bit high for 10Ga wire???
Do you have an ammeter to see what your pump is drawing?
Did you solder all your connections?
Perhaps you need to upgrade some of your body grounds?
Where did you place your test leads to come up with this comparative voltage loss?

Jack
Racetronix