Gas to Diesel swap, question on fueling

[idrivea2002golf]

I'm reaching to the forum for recommendations/feedback/thoughts on fueling systems. I've been on the different square body forums looking up the function of the dual tank and the Pollack valve. Seems pretty straight forward. I don't like that it relies on the suction from the engine's mechanical pump for priming, I'd like to have a more proactive fuel supply. For reference truck is a 1981 so I have the 6 port with the motorized valve. I'm currently planning on swapping in a 7.3 idi out of a 90 F350.

Here's where I'm looking for feedback, as I see it I have two options:

Option 1: I keep the existing system as it is (obviously check for functionality and replace anything broken). Use the ON-OFF-ON momentary on the dash for the switching as it already does. In this case I would add an in-line fuel pump (diesel style) between the Pollack valve and the engine's mechanical pump. This would tie into the ignition system. Simplest option but I know these pumps make noise and I don't know if I'm going to want to hear it all the time. Chineseum pumps are 20-30$, Holley or AEM are 200ish.

Option 2: swap the fuel senders I currently have (1981 models) with senders/pumps from 1987+ and basically run two in tank pumps through the Pollack valve. This would require I swap the dash switch which isn't all that difficult. I like that this gives me pump redundancy as the in-line pumps can be fickle. Obviously more up front cost but really not terrible in the grand scope of this build. From my understanding the wiring is the same between the 1981-1986 and 1987+ at the valve, just need to tie in the sending pumps power lines. This also gives me the flow/pressure required for a diesel as I can get the 6.2 in tank pumps. Each pump is about 110$ on rockauto. So similar price to a quality (Holley) inline.

Option 3: something I'm not seeing?

 

[ali_c20]

Thou shalt not put them Ford parts into Chevies. ;D

The 1990 7.3 uses a mechanical fuel pump to feed the injector pump. Using the mechanical fuel pump that is on the engine would be the easiest way. No new sending units, no wiring work on the valve. Replacing a broken mechanical fuel pump is easy, can be done everywhere.
My 0.02$
https://www.rockauto.com/en/catalog/ford,1990,f-350,7.3l+445cid+v8+diesel,1126549,fuel+&+air,fuel+pump,6256

 

[Frankenchevy]

Also, 87+ also have baffled tanks to go with the in tank pump. May not matter, but something to consider.

 

[Broken85]

High Pressure Fuel pump install

Finally updating the powertrain on my 85 K10 Silverado short bed with a BluePrint turn-key, fuel injected 350. I am going to have to upgrade to a high pressure fuel pump obviously but I wanted to check with the group first before I install this. My issue is that I have dual fuel tanks so I...

www.gmsquarebody.com

righteous project I drive. Check out this thread I started. I recently switched over to in tank electric pumps. I think I solved a lot of the questions you have, but maybe not all of them. FYI, the inline pump after the pollak valve did not work. It was not able to pull enough fuel through the pollack with just a siphon because those inline pumps push fuel, and not really pull at all. I had to start all over with in tank electric pumps.

To your other point. Dual redundancy, can’t beat it. So my relay wiring that I also individualized power to each tank as well

 

[idrivea2002golf]

Thou shalt not put them Ford parts into Chevies. ;D

The 1990 7.3 uses a mechanical fuel pump to feed the injector pump. Using the mechanical fuel pump that is on the engine would be the easiest way. No new sending units, no wiring work on the valve. Replacing a broken mechanical fuel pump is easy, can be done everywhere.
My 0.02$
https://www.rockauto.com/en/catalog/ford,1990,f-350,7.3l+445cid+v8+diesel,1126549,fuel+&+air,fuel+pump,6256

Not to split hairs... but TECHNICALLY it's an International Harvester part connected to a ZF part connected to a Borg Warner part. Although I'm going to replace the borq warner part with a New Process part.

Plus, no worse than people putting a Dodge part (6BT) in a square body. Actually, I would argue the 6BT is worse given it is an inline 6, both Chevy and Ford use V configurations.

Silliness aside, the mechanical pump works but it's suction is crap. I'd like to find a more proactive fueling supply especially since switching the pollack valve could possibly introduce air if the unused tank isn't primed.

 

[idrivea2002golf]

High Pressure Fuel pump install

Finally updating the powertrain on my 85 K10 Silverado short bed with a BluePrint turn-key, fuel injected 350. I am going to have to upgrade to a high pressure fuel pump obviously but I wanted to check with the group first before I install this. My issue is that I have dual fuel tanks so I...

www.gmsquarebody.com

righteous project I drive. Check out this thread I started. I recently switched over to in tank electric pumps. I think I solved a lot of the questions you have, but maybe not all of them. FYI, the inline pump after the pollak valve did not work. It was not able to pull enough fuel through the pollack with just a siphon because those inline pumps push fuel, and not really pull at all. I had to start all over with in tank electric pumps.

To your other point. Dual redundancy, can’t beat it. So my relay wiring that I also individualized power to each tank as well

Red3833's post with the diagrams and explanation of using the sniper output is kind of the swap I was thinking about doing.

I appreciate the feedback on the inline. My biggest concern, especially since I'm going to be dealing with a diesel, is having the inline pump not have enough suction.

I think I'm going to do the dual in tank setup.

 

[AuroraGirl]

Red3833's post with the diagrams and explanation of using the sniper output is kind of the swap I was thinking about doing.

I appreciate the feedback on the inline. My biggest concern, especially since I'm going to be dealing with a diesel, is having the inline pump not have enough suction.

I think I'm going to do the dual in tank setup.

if you use the original fuel pump on the engine, you should use the ford pollack valve, since it was designed to suck diesel through the valve when not running
vs the pollack on these trucks was intended to support fuel being pushed through it

 

[AuroraGirl]

Strictly Diesel - Selectable Restriction?

Selectable Restriction?

www.strictlydiesel.com

 

[ali_c20]

Not to split hairs... but TECHNICALLY it's an International Harvester part connected to a ZF part connected to a Borg Warner part. Although I'm going to replace the borq warner part with a New Process part.

Plus, no worse than people putting a Dodge part (6BT) in a square body. Actually, I would argue the 6BT is worse given it is an inline 6, both Chevy and Ford use V configurations.

Silliness aside, the mechanical pump works but it's suction is crap. I'd like to find a more proactive fueling supply especially since switching the pollack valve could possibly introduce air if the unused tank isn't primed.

When you rip it out of a Ford truck it's a ford part ;D
The dual intake pump setup is the best solution imo.

 

[idrivea2002golf]

When you rip it out of a Ford truck it's a ford part ;D

I'm leaning toward to the dual. Doesn't seem any more expensive than a quality inline. And I have the bed off so access to replace them is just as easy.

 

[Grit dog]

if you use the original fuel pump on the engine, you should use the ford pollack valve, since it was designed to suck diesel through the valve when not running
vs the pollack on these trucks was intended to support fuel being pushed through it

^This doesn’t make sense to me. First, a 1981 Chevy has fuel being pulled thru the tank valve. Like every other truck before efi. Second, it doesn’t matter to the pollack valve anyway. Push or pull.
Also, practically, there’s no reason imo an original Chevy valve would be restrictive anyway. If it’ll pull enough gas thru for sub 5mpg full throttle pulls on a gas engine, it will work for something that needs less fuel like an old diesel. Unless you think viscosity is a problem. But it’s not since GM also had diesels using the same valve.

 

[AuroraGirl]

^This doesn’t make sense to me. First, a 1981 Chevy has fuel being pulled thru the tank valve. Like every other truck before efi. Second, it doesn’t matter to the pollack valve anyway. Push or pull.
Also, practically, there’s no reason imo an original Chevy valve would be restrictive anyway. If it’ll pull enough gas thru for sub 5mpg full throttle pulls on a gas engine, it will work for something that needs less fuel like an old diesel. Unless you think viscosity is a problem. But it’s not since GM also had diesels using the same valve.

I dont know what to tell you, im just guessing that an otherwise identical valve would be different, and its only for diesel. I can be wrong, but maybe theres something exposed to the fuel that would corrode with diesel but not gas.
Assuming this isnt a concern, The reason I brought up pressure has to do with fords diesel is pushing fuel from the tank
But gms diesel is pulling diesel from the tank. Am I right on this? I dont know either detroits or powerstroke (as opposed to IDI)


and as I re-read, I realize now that he said IDI not powerstroke, so both are pulling.

he wants to, however, push through.
I think I brought up the pollack from ford because their powerstrokes push through that pollak with like 60psi, And I have 0 idea if the gas one used by GM is going to do that safely. The TBI pump in the tank isnt pushing 60psi , so it wouldnt have been a consideration. And unless I am mistaken, the detroit is pulling fuel from the engine? I dont know what kinds of pressures he needs from the tank to get IDI happy, but an ancillary concern was the possibility of the valve not being fully one way or the other. But a fresh valve, tank with baffling, and good fuel lines shouldnt have any issue?

maybe get poly tanks to reduce metal accumulation possibilty

 

[Grit dog]

^Im not an expert on IDI engines either. And never will be but from all the other diesels I’ve been around and worked on, they only need minimal positive pressure to the injection pump so not a big concern about fuel pressure upstream of the IP.
This is half supposition since idk idi lol.

Pretty sure one could run a low pressure electric pump just downstream of the tank valve quite reliably. Have had that setup with a cheesy little pump feeding the K20 and it works. That would be the simplest and least intrusive if one doesn’t need to replace a pile of parts in the first place (tanks, senders, valve etc)

 

[Burban]

Haven't seen it mentioned, but on a dual tank setup, how do you handle the return?

AFAIK any diesel is going to need a return line, how does it know which tank to return to.