FP Regulator bad?

[Jerryl]

Probably off base for this thread but. . .
Provided the ecm or chip can be adjusted accordingly:
If you are out of injector, raise fp IF the pump can supply the volume at the max boost pressure.

 

[Anthony P]

@dennisL, I'll post the flowchart and current draw for the GSS340 in a few minutes - just have to find the spreadsheet, screenshot it and covert to paint so that it can be uploaded.

before you go on the path of a new return line, have to ask what max boost level are you running? do you really need the GSS340M pushing 50 gal/hr at 60 psig or 45 gal/hr at 70 psig?

would the TTA pump with the hot wire feed be sufficient? The Delphi FE0110 is $40 delivered from RockAuto. see it here. the spectra brand pump is $10 less.

 

[Anthony P]

fuel pump history to note: GSS340 was a Ford Mustang pump originally. to allow the pump to fit in the tank on the factory hanger in a G-body with the GM fuel sock strainer, the plastic bottom piece where the fuel sock strainer attaches was machined down. the machined assembly was now the GSS340M. Walbro stopped the added cost of machining plastic when the equivalent F20000169 pumps were introduced in early 2004.

many of us just selected the GSS340M as the need for fuel pressure, as measured at the fuel rail, hit the low 60 psi range. I showed that a few posts ago noting the needed pressure using a TT street chip + 18 psig boost was 62 psig at the rail. the GSS340M also operated at a lower current draw than the GSS307. from the chart below, the difference between the 307 and 340 pumps was about 2 amps at 60 psig fuel pressure with both pumps pushing about 50 gal/hr.

The TTA pump specs from post #58....
the factory stock fuel pump for the '89 TTA was 225 lt/hr or 58 gal/hr as it's stock boost setting was 15 psig. TTA also used the Bosch 237 fpr (44 psig static) over the Bosch 233 fpr (34-37 psig static per service manual, 36psig static per spec)

At the moment, I can't find fuel pressure data about the TTA pump (Spectra SP1115 or Delphi FE0110) with and without a hot wire kit installed.

I'm thinking the TTA pump with a hot wire kit is capable of 62 to 64 psig at the fuel rail. Someone else has to confirm this or post data. As stock, the TTA pump had to push a minimum of 59 psig at the rail; baseline static of 44 + 15 boost = 59. I'm sure there was a few psi safety factor by design.

Back in the 1990s, KenneBell sold the Boost-A-Pump product. it was just a voltage booster via a dial potentiometer to increase voltage to fuel pump that could increase pump output a max of 50%. Today's fuel pump hot wire kit is very similar delivering voltage of maybe 14.4 off the back of the alternator vs the 10 to 12 VDC that might be at the pump via the factory wiring.

Dennis, that's why I'm thinking the TTA pump with hotwire could work if your max boost is in the 16 - 18 range.

I'm also thinking a lot of folks are not knowing of the expected fuel pressure drop once the vac line is re-attached to the regulator. there is so much focus of what the fuel pressure should be set to with vac line off and not what the fuel pressure should drop to once vac line is reconnected to the regulator.

As @pacecarta noted in post #2, "fuel pressure should drop 1psi for 1 psi vac when line connected which if looking at a vac gauge that reads in/hg it should drop pressure half of the vac reading . typical vac at idle sould be around 18 in/hg so drop should be around 9psi also the regulator can only go down as far as the return line will allow , if you have a high flow pump and a hotwire you may not be able to get it lower without improving the return line flow"

For $40 and a little time to drop the tank for install, it might be worth a try the TTA pump before the greater cost and time to create a new "return" line.

OR

there is always the idea to cut-off that return line saginaw fitting and replace with Swagelok fitting and adapter like noted in the earlier links to those modifying the supply line. Swagelok fittings in stainless 20 years ago were approaching $80 each for the process control work I was doing.

 

[Pronto]

This might work:
https://www.discounthydraulichose.com/SS-27305-04-04.html

 

[Anthony P]

Referencing the September 1997 issue of Popular Hot Rodding, which was the beginning of the 3-part series of adding KenneBell bolt-ons to an '86 GN bone stock with 110K miles...

step 1 added a KenneBell Ultimate chip (17 psi boost); used Boost-A-Pump and adjustable fpr to get 54 psi rail pressure at WOT for an air/fuel ratio of 10.98:1

after they added dual muffler exhaust, cold air kit and headers, the noted fuel rail pressure at WOT is up to 56. the claim was 287 hp at this point at the wheels or about 360 at the flexplate using a 20% driveline loss calc.

we install these 255 lt/hr pumps to handle our mods with a TT chip and have more fuel pump capacity if we later choose more performance mods and higher boost levels with added alky kits to stave off detonation.

reference the performance charts on gnttype.org, the GSS340M flowing 50 gal/hr at 60 psi (with 60# injectors) is enough to fuel a 600 HP engine to mid-10 sec ETs.


but if all we are doing is 16-18 psi via that TT chip, why on earth are we giving ourselves these headaches by installing fuel pumps too large for our intentions? So that we can grow into them IF we want more power in the future?

That's why I circle back to the possible use of the TTA pump with hot wire kit if we are just using a TT chip or equivalent on the street at 16-18 psi.

 

[Pronto]

In 2003 was able to run the GSS340M in my car without issues with the line off setting of 43. It would drop to 34psi line on. It was one of the earliest mods I did along with the Racetronix hotwire kit. Other mods were a homemade intake pipe, S&B airfilter, Kirbans afr, 160* thermostat, breathers, Hooker catback, test pipe and Thrasher 93 chip. Ran a best of 12.77@103 with 21psi and street tires.
Dennis, with your current changes you were able to get to 36/7. How does the car feel? Any different than before? Is it running too rich? Maybe that's enough to live with. How long have you run that pump? Was the line on pressure always stuck at 40? Did it suddenly happen?

 

[Anthony P]

@Pronto, thanks for sharing your exact results...that you were able to achieve the corresponding pressure drop when the vac line was re-attached.

Now we wait for some more input from the OP. back in post #59 this morning, he noted the following:

"...was able to drill the Return line to #28 (0.1405) without destroying the Saginaw fitting....Now for the bad news - fuel pressure w/vac off = 43 psi, with vac on = 41. I can't begin to describe my disappointment. I was sure this would finally fix the problem."

So even after drilling out the return line saginaw fitting, Dennis reports fuel pressure still won't drop accordingly when the vac line is re-attached to the FPR.

 

[Pronto]

I guess it's possible the line is got a small dent that's not readily visible in it that's restricting flow? If it's not the hard line or fittings then maybe the rubber hose at the tank is kinked?

 

[Jerryl]

Referencing the September 1997 issue of Popular Hot Rodding, which was the beginning of the 3-part series of adding KenneBell bolt-ons to an '86 GN bone stock with 110K miles...
. . . . . .

You are a plethora of solid information.

 

[dennisL]

Sorry guys, I was away for a few days. Let me start with info I should have posted much earlier (or put in my signature).

1987 GN (original owner)
Stock engine, TA49 turbo (adj. wastegate rod), stock intercooler, stock intake with open 4" K&N, stock MAF, flow matched Delphi/Lucas 009 injectors (42.3 lb/hr @ 43.5 psi), adj. FPR (Kirban), Walbro GSS340M pump with hot wire.

Besides being a "plethora of solid information" Anthony guessed right on my current requirements for fuel delivery. My injectors want 43.5 psi and the chip allows 16 - 18 psi max boost. So that's 61.5 psi and with 2 psi margin, I'm at say 64 psi. I installed the Walbro GSS340M pump after having problems getting the 1:1 psi increase with boost using a 4 yr old Walbro 834. This was August 2012. As luck would have it, prior to this I added a fp sensor to the rail and connected it to my PowerLogger. Looking at the old log files shows 37 - 42 psi at idle. This is immediately after the GSS fuel pump was installed. The log files prior to the pump swap show 32-34 psi at idle. So this eliminates the premise that my problem could be a crimped hose/hard line.

And yes, I've had the problem since 2012!! In my defense, I (like many others) was focused on fuel pressure vac off. Forgive me Father for I have sinned. I ignored the vac on pressure but did notice the BLMs were low. The ecm pulled out some fuel and afr was good so "no worries mate".

As Anthony stated earlier, I don't currently need the GSS340M and if going to a 'smaller' pump solves my problem then that certainly is an option. I won't be dropping the tank soon though as its full of Sunoco 94. How about if I make the vent line my return line? Would that be feasible?

As always, thank you for taking the time to help. I appreciate it. There will be free beer at my house when this is fixed.

 

[Pronto]

What pressure are you running right now and what chip do you have?

 

[dennisL]

The pressure at hot idle is set to 43.5 vac off. The chip is my own design. As a temporary fix for the rich idle and normal driving, I have the ecm command less fuel during non-boost conditions and switch to normal (for my injectors) under boost (set to 16-18 lbs). I can change anything the ecm controls, is there something you have in mind?

 

[Pronto]

Just wondering why you don't crank that 49 up some. Your really not even doing much better than a stocker at that psi. I thought if you had a TT chip you might try adjusting the base fuel but you seem to have that done.

 

[Anthony P]

@Jerryl, I'll scan and upload those 3 Popular Hot Rodding articles but may have to wait 'til after SEMA.

@dennisL, you have about 20 HP gained via the TA-49 over a stock turbo at the street 16 - 18 boost levels. the 49 breathes better and charge temp is lower than stock turbo at these levels. No real gains over a stock turbo until you're running greater than 20 - 22 psi boost levels. The limiter on the stock turbo is the turbine wheel; it's done at about 20 psi boost. 1 psi boost = about 10 HP. 20 psi boost vs 14 stock is 60 HP. A good running stock engine at 14 psi boost makes about 290 HP @ flexplate so about 230 HP at the wheels. At 20 psi boost, you're making about 360 bHP. (informational...) At this level, stock injectors, stock intercooler, stock turbo are all maxed out.
On the other end of the stock turbo, the compressor wheel is capable of a lot more. FWIW here is the compressor map for the stock TB0348.


On pump gas alone, I would ease slowly to boost levels greater than 18, if at all. PowerLogger will show if detonation is starting to rear its ugly head. Still running the original stock valve springs? May want to swap over to the Comp 980's as the stockers will be fluttering at high rpm and you're making more power over stock.

Before you entertain modifying the fuel lines, I'd suggest trying a lower capacity pump. I noted earlier the TTA pump. check out the specs on RockAuto here (Delphi FE0110). TTA's were 15 psi boost stock using the Bosch 237 fpr. That pump is rated at 58 psi at 12 VDC flowing 22 gal/hr - it was fine for the stock TTA. ADD the hot wire kit and the pump will flow some more. What voltage does your hot wire setup provide at the pump?

In my files, I also have a note about one of GM's most common fuel pump, the Delphi FE0114 pump. On RockAuto here. The FE0114 is the fuel pump for the Syclone and Typhoon, '92-'96 Vette and a bunch of trucks. It's between the TTA pump and the GSS340M. It might work a little better than the TTA pump & the hot wire kit. it runs at 62 psi and is supposed to flow 35 gal/hr. Syclone & Typhoons used Bosch 237 fpr as well. the PDF below is an article discussing GM's two most popular fuel pumps.

if you get a pump from RockAuto, here is a code for 5% off 9450149189787743. type the #'s in the "how did you hear about us" box in the cart.

 

[dennisL]

In 1998 when I swapped the stock turbo with a TA49, I wanted just 'a bump up' from stock. The GN was my daily driver and I was commuting 110 miles a day.

As for the fuel pump I'm not opposed to using a smaller one. I just want to provide the fuel required for the Lucas 009 injectors at 16 - 18 psi boost and fix my vac-on fuel pressure problem. I looked at the Delphi FE0114 specs and it shows "average flow 35 gal/hr at 14V" which appears to much less than my current Walbro GSS340M. Since I have the hot wire and upgraded harness at the pump, I don't think voltage will be an issue. We'll see .....

 

[Pronto]

Some people can run the dw300 pump without modding the return line too. The qc on the lines must have been low if there is that much variation between all the people that have replaced the stock pumps.

 

[dennisL]

Some people can run the dw300 pump without modding the return line too. The qc on the lines must have been low if there is that much variation between all the people that have replaced the stock pumps.

I was thinking the same thing which is why my return line was suspect. However I can't see any kinks, I enlarged the opening and blew air through it 3 times - made no difference.

It certainly appears that the frame mounted return line is the problem because I first disconnected the hose at rear axle and ran it to a gas can. Pressure still high. Then disconnected return below the engine and ran return down-pipe to a gas can. Pressure now low (where it should be).

I agree with Anthony that a smaller pump should work fine with my setup but I'm concerned about doing that, then finding the vac on pressure is still too high. In other words, is high volume flow the root cause of my problem or is it the return line. If others can use the same pump with a stock return line why can't I?

 

[Anthony P]

running out of ideas...thinking of some sort of pipe cleaner to pass thru the length of that 1/4 return line. maybe 16 gauge solid copper wire could be pushed thru the bends as a pipe cleaner? from the front and from the back to get thru the entire length. maybe it could dislodge something. then reattach the lines at the crossmember (run the engine or use a jumper wire to your fuel pump hot wire to run the pump) and use some gas to flush the line to a clean container at the rear. use a fine paint strainer to filter the flushed gas to see if any foreign material was dislodged.

 

[Pronto]

The "pipe cleaner" idea is probably worth a try. If you don't want to go through the hassle of dropping the tank maybe it's time to try eliminating the fitting. If that doesn't solve the issue just run a 3/8" line or AN6 line and forget about it. Plenty of guys have run a new line. Eric from TT used to sell the DW300 and flat out said you have to replace the return line with a AN6 line. He doesn't mention that with the 255lph he sells now. It's probably the pump Anthony is talking about. Personally I would stay with the pump you have and work around the return line, but that's just me.

 

[1BUICKTtype]

can someone make a line kit to eliminate the restriction? I'd like to keep the original metal return line if thats not the problem and a fitting or restriction is the real culprit. otherwise, does anybody make a AN6 return line kit? I know Racetronix has one but they sell it in their full fuel line kit which includes a 8AN feed which i definitely dont need that. I tried calling to see if they would sell just the AN6 return line to me but they haven't returned my call yet