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Old 02-20-2017, 11:50 PM   #1
donw1986
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Fuel injection conversion with dual tanks

I am in the process of converting my carbureated 86 to fuel injection and want to keep the dual tanks but not sure how to plumb this, do i need to get two pumps one for each tank inside the tank and a switch to switch from either tank or can you put one pump in line ahead of the selector valve
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Old 02-21-2017, 12:10 AM   #2
bilfman
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Re: Fuel injection conversion with dual tanks

You could use this, easy mode.

http://fitechefi.com/products/40003/
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Old 02-21-2017, 12:41 AM   #3
Nickelcharlie
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Re: Fuel injection conversion with dual tanks

donw1986, I also own a 86 short and would like to add FI to my truck and get rid of the carb. Would you clue us in on what you doing for the change over? Thanks
P.S. thank you bilfman for a very good link!
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Old 02-21-2017, 11:30 AM   #4
donw1986
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Re: Fuel injection conversion with dual tanks

Well i am going to install the msd atomic efi since i live in california, it is the only efi that i can gind that is legal in this state for smog, i havent actually started this project yet but i am gathering parts now
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Old 02-21-2017, 12:37 PM   #5
kdh454
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Re: Fuel injection conversion with dual tanks

Putting a single pump ahead of the selector valve is not ideal. It will be mounted further from the tank than it is designed to operate. The good news is Chevy has already done the hard work for you. Just get a set of 87 tanks, sending units, and the appropriate in-tank pumps (87 R10 pumps do not provide enough pressure). The 87 tanks are externally identical, but have baffles built in to accommodate the pump. You will also need to replace your selector valve with one rated for the higher pressure. I used a selector switch from an 87 and wired it just as the factory did. It is surprisingly easy to do.
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Old 02-21-2017, 03:45 PM   #6
donw1986
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Re: Fuel injection conversion with dual tanks

Ok thanks kdh454, i wasnt to sure if i had to do that but that seems easy enough, just wondering though is it possible to put 87 sending units in my 86 tanks or is there actually a difference in the tanks
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Old 02-21-2017, 03:52 PM   #7
kdh454
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Re: Fuel injection conversion with dual tanks

There is a small baffle (looks kind of like an open box) inside the 87 tank that helps keep from starving the pump. Otherwise, the tanks are the same. I don't know if it is absolutely necessary, but I figured it was not a bad idea to replace my 40 year old tanks while I had them out. I used a Dorman tank from Rock Auto. They were only about $85 each.
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Old 02-21-2017, 04:50 PM   #8
donw1986
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Re: Fuel injection conversion with dual tanks

Ok thanks
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Old 02-21-2017, 08:59 PM   #9
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Re: Fuel injection conversion with dual tanks

I will hopefully be fuel injecting my C10 soon.

I intend to run the factory mechanical pump into a fabricated surge tank, which feeds the high pressure pump. Injectors return to the surge tank, and the tank "overflow" returns to the fuel tank(s) through the tank selector switch.

I haven't done this yet, so my idea is not proven. Watch for the big ball of flame.
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Old 03-10-2017, 09:30 PM   #10
Carl Bill
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Re: Fuel injection conversion with dual tanks

Does anyone know if the 1987 fuel pickup/pump/sending unit assembly will work on 1985 or 86 fuel tanks? I have 2 good 85 tanks. Would like to use the 87 pump units for fuel injection too... but ~$120 for both pump units vs ~$300+ for new tanks... looking were I can save on the budget.

A long ways to go to get a truck built and I haven't even started yet! :|

Thanks in advance for any help.

Carl
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Old 03-10-2017, 09:49 PM   #11
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Re: Fuel injection conversion with dual tanks

Without the baffle thingie in the '87 tank, you run the risk of starving the fuel pump (and engine) any time the fuel sloshes away from the pickup. That kills pumps and can get expensive.
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Old 03-10-2017, 10:07 PM   #12
kdh454
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Re: Fuel injection conversion with dual tanks

You could add a baffle to your tanks. If I remember correctly, they are just open sheet metal "boxes", about 6" square, with a couple holes drilled in the sides, tacked to the bottom of the tank. Anything that helps to contain a small amount of fuel around the pump should work.
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Old 03-10-2017, 10:58 PM   #13
dieseldawg142
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Re: Fuel injection conversion with dual tanks

been running an edelbrock pro-flo in my '85 k30 crew for 16 yrs. it came with a external fuel pump, mounted ahead of the selector. it coughed out last yr after 15 yrs, it's cheap, and easy, just try not to run your tanks under a quarter and you'll be fine. i also replaced the STOCK, 30 yr old switching valve 2 yrs ago with a stock delco 6 port with no issues
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Old 03-10-2017, 11:16 PM   #14
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Re: Fuel injection conversion with dual tanks

I used a Holley Hydramat in my stock tank, very easy to adapt to your stock sending unit. No need for baffles or spending extra money on '87 tanks!
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Old 03-10-2017, 11:32 PM   #15
Carl Bill
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Re: Fuel injection conversion with dual tanks

Quote:
Originally Posted by Nick_R_23 View Post
I used a Holley Hydramat in my stock tank, very easy to adapt to your stock sending unit. No need for baffles or spending extra money on '87 tanks!
I already need to buy new sending unit assemblies... mainly for gas gauges. Will the Holley work well with the dual tank valve? How much for a pair? The 87 assemblies with the pumps are around $60 each.

I am looking at the FiTech Go Street (400hp), and may also use their recommended sump.

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Old 03-10-2017, 11:36 PM   #16
Carl Bill
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Re: Fuel injection conversion with dual tanks

Quote:
Originally Posted by Nick_R_23 View Post
I used a Holley Hydramat in my stock tank, very easy to adapt to your stock sending unit. No need for baffles or spending extra money on '87 tanks!
Wow... never mind. I just looked at the Hydromat... a pick up - not a pump. kinda pricey on Summit. I can see how that would solve the problem... but for the prices they are asking... I can buy 2 - 87 tanks with pump/sending unit assemblies cheaper. Unless I am missing something? :|
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Old 03-11-2017, 09:20 AM   #17
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Re: Fuel injection conversion with dual tanks

I suggest keeping it as much as GM designed for 1987 for the ease of replacement parts down the road should you have to replace anything. Besides, having an updated system but appearing completely stock is always a more appealing aspect to it should you sell the truck later on.
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Old 03-11-2017, 04:59 PM   #18
hatzie
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Re: Fuel injection conversion with dual tanks

1987 tanks with 1987 senders and in-tank pumps.
Change the dash switch to the 1987-1991 fuel valve switch that you should already be using on your 1981-1986 NL2 dual tank valve.

The fuel pump power wires are wyed into the green valve motor wires on the 1987-1991 systems. You need to be sure the fuel pump recieving positive from the tank switch is the one with a clear fuel path to the engine through the valve.
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Old 03-11-2017, 05:10 PM   #19
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Re: Fuel injection conversion with dual tanks

I've got complete dual tank LSx harness kits w/65 psi switchover valve if you decide to go with an all new setup. The dash switch triggers the LH or RH pumps and is a switched IGN control setup. If you're wiring is all in good shape you may not need a complete stand alone kit but I have them if you need one.
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Old 08-10-2017, 12:10 AM   #20
pointbreak
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Re: Fuel injection conversion with dual tanks

Curious about this, I have a 1976 Silverado with dual tanks I'd like to convert to Efi. I'm looking at the mad atomic. Can the 87 stuff be used in my tanks as well. Just to get it to snuff to install the higher rated switch, the newer in tank pumps and such?
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Old 08-10-2017, 07:51 AM   #21
homemade87
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Re: Fuel injection conversion with dual tanks

Quote:
Originally Posted by Carl Bill View Post
Does anyone know if the 1987 fuel pickup/pump/sending unit assembly will work on 1985 or 86 fuel tanks? I have 2 good 85 tanks. Would like to use the 87 pump units for fuel injection too... but ~$120 for both pump units vs ~$300+ for new tanks... looking were I can save on the budget.

A long ways to go to get a truck built and I haven't even started yet! :|

Thanks in advance for any help.

Carl
Just to answer some questions about this in this thread . Short answer is yes . But there is some things to consider . I put a 87 sender in my 82 tank when I converted to the 87 tbi . The baffle is there for only when the gas level gets low to keep the gas around the fuel pump when inertia ( braking , cornering , ect ) try's to moves the fuel away from the pump . I went into this knowing the problem so I never let the fuel get below 1/4 tank and run it like this for 15 years . Once in a while I let the fuel get a little low and have to brake hard at a light and it would stumble a little . Never a good idea to run elect fuel pump low anyway . This is how it stays cool .

The carb is forgiving for this because it stores it own fuel and if the pick up is uncovered for a second you would never know it . The fuel F/I uses pressure to supply the fuel directly so if you uncover the pickup the pressure will immediately drop and interrupt the fuel supply to the engine .

If you are one of those that run your fuel to the end or only put $10.00 in at a time you are going to have trouble . If you sell your truck and the next guy does not know what going on they are going to have trouble .

In the end its best to use the baffle tank . I have since converted my 82 to a ls2 with a new 87 tank . I only have one tank .

Just something to think about .

Answer to Carls question is yes . The sending units will fit .
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