87 dually with 350 TPI

[dually]

Was wondering if anyone has the answer to the "dual" fuel tank switching valve from a "throttle body" to the TPI unit. I'm sure it will not hold the pressure of the TPI fuel pumps or will it? If not how does one get around this nad still swap from tank to tank and still have the fuel gauge work also. THnk you fopr any info.
Dually

[76stepsidechevy]

Im sure theres a switching valve out there that can handle the pressure if the stock one can't. I think gm had done away with dual tanks by the time they had port injection on the trucks but I think the f*rds still had dual tanks well into the high pressure efi years.

I just installed a holley tbi setup and they listed part numbers for a switching valve for a dual tank setup. I know its still only 15 lbs of pressure but they have kits out now that run high pressure pumps. I would immagine those kits have provisions for a dual tank setup too.

[rs72z]

Rock auto sells one that can take 70psi.

[Maxzillian]

What I ended up doing on my truck was mounting a spin-on fuel filter to the radiator support in the engine bay. The filter head was modified so that the outlet had a pickup tube that protruded down to the bottom of the filter.

Using a 2 port mechanical pump, I draw fuel through the stock lines and circulate fuel through this filter. I then mounted an electric pump to the inner fender (no idea if this will survive the summer heat) that sucks fuel from the pickup tube and provides high pressure fuel to the fuel rail. The return of the fuel rail dumps back to the filter inlet.

The nice thing is that this filter serves as a small surge tank since the truck was an 85 and has no internal tank baffles. It also allowed me to retain the stock selector valve and plumbing. The only real downside is that without any isolators to mount the pump, it is audible from inside the cab of the truck (I'll fix this in the future).

[Desert1957]

Is there a reason you do not have any faith in the "87 TBI Fuel Valve" that comes on these trucks? Just curious?

Desert

[rs72z]

He's running too injection Wichita required more fuel pressure. The stock changeover valve is only rated at about 15-20the psi, I believe.
Posted via Mobile Device

[Desert1957]

Originally Posted by rs72z

He's running too injection Wichita required more fuel pressure. The stock changeover valve is only rated at about 15-20the psi, I believe.
Posted via Mobile Device

Oh, my bad. here is another option. Keep the stock change over valve and use this Holley kit with the pump upstream from the change over valve.



Desert

[rs72z]

Originally Posted by Desert1957

Oh, my bad. here is another option. Keep the stock change over valve and use this Holley kit with the pump upstream from the change over valve.


Sorry for the spelling stupid auto correct.

Desert

Posted via Mobile Device

[Desert1957]

Whats with the stupid line you posted inside my quote? I did not say anything about being "Stupid" to anyone?????????

[rfmaster]

Originally Posted by Desert1957

Whats with the stupid line you posted inside my quote? I did not say anything about being "Stupid" to anyone?????????

He was referring to autocorrect function common in most mobile devices being not 'very bright' = 'stupid'. There is no reference to anything of substance being stupid in your post. Words can hurt if taken out of context LOL.

//RF

[wyattglock]

Originally Posted by rfmaster

He was referring to autocorrect function common in most mobile devices being not 'very bright' = 'stupid'. There is no reference to anything of substance being stupid in your post. Words can hurt if taken out of context LOL.

//RF

You can say that again! I think he meant TPI injection, not too injection.

[dually]

Thank you all for your help. I am useing the Holley 12-914 Fuel Pumps rated at 255 LPH @60 PSI. As Desert1957 said I don't think the stock PSI rateing will hold up to the 60PSI of the Holley pumps. IF anyone has tried the combo I will moitor this forum now and again. RS 72 Z may have something and I will call Rock Auto this week to see. AGAIN That you all for the help and I hope maybe this has helped othersd too.
DUALLY

[dually]

I forgot to say that I don't think the stock pumps @ 13 to 18 PSI will keep up with a "frame" mounted fuel pump. I don't think the volume is there for that. I remember when I did auto repair in the dealerships that Ford uses that combo but I can't remember what there specs on the tank pump to the Hi pressure pump was. YEA I know I fell down once and worked for ford BUT I STILL drove a CHEVY to work :-)
Dually

[rfmaster]

Originally Posted by dually

I forgot to say that I don't think the stock pumps @ 13 to 18 PSI will keep up with a "frame" mounted fuel pump. I don't think the volume is there for that. I remember when I did auto repair in the dealerships that Ford uses that combo but I can't remember what there specs on the tank pump to the Hi pressure pump was. YEA I know I fell down once and worked for ford BUT I STILL drove a CHEVY to work :-)
Dually

That is not entirely correct. Third gen camaros and Vettes used in tank fuel pump (FP) to feed 40 to 50 PSI at the injector rail. In fact in tank FP is preferred for several reasons. High pressure FP do not lift fuel very well and instead are better at pushing it. This is why Ford used two pumps - a lift pump and a secondary higher pressure pump. Between the two there should be a fuel filter acting as a fuel accumulator (VW and Cady used this setup) for high pressure FP to draw from.
In tank FP is cooled by the gasoline and frame rail mounted units only have convectional cooling. Frame rail mounted pumps tend to be noisier (boy do I know this).

As for your project - the 6 port fuel switches marketed by Pollak 42-159 are rated for 60 PSI - which is just enough for your TPI dual tank system.
http://pollak.thomasnet.com/Asset/IS-41_b.pdf

//RF

[rs72z]

Originally Posted by Desert1957

Whats with the stupid line you posted inside my quote? I did not say anything about being "Stupid" to anyone?????????

Sorry about that. Thats why i try not to post from my phone.

[DirtyLarry]

Well, here is my .02 on this topic. Fuel pressure through the switch valve isn’t so much the problem it is the small 5/16 return port that will cause you issues.

I originally tried to use the factory GM style Pollak dual tank switch valve on my 8.1L when I first installed it back in 2008. At the time I was running the engine on a Dephi MEFI-4 ECM which basically runs the engine just like a larger TPI engine (speed density calculations, batch fired the injectors, TPI 43 psi fuel pressure, etc). The problem was the fuel pressure at the engine fuel rail was over 100 psi at idle with the switch valve in place. Once I popped the return line off at the switch valve and allowed the return fuel to pour straight into a bucket the fuel pressure went back to normal (43 PSI) at the fuel rail. I figured, okay there was just something wrong with my valve so I got a new Pollak switch valve from my local GM dealer and would up with the same result. The best I can figure is the little 5/16 return port in the switch valve is too restrictive. If you notice most of the newer higher pressure EFI vehicles have a larger 3/8 fuel return line, not a 5/16 return line.

At the time I could not find a different brand or type of switch valve with a larger return port so I ended up adding a diesel transfer pump to move fuel from the RH tank (now storage tank) to the LH tank when needed. This is kind of a hassle but it works great. I currently have no fuel lines going to my switch valve but I do have it hooked up so I can flip the switch to see how much fuel is in the “storage” tank.