1987 Fuel Sender Conversion for LSx Swap
 

Here is how I set up my fuel system for my current LSx Swap on my '85 GMC. I will be using a return style system. The engine is from a 2000 5.3 from a GMC truck. The engine is stock except for headers and a cold air intake.

I bought a new '87 tank and sender from Spectra Premium from Amazon.com.
Tank, 16gal (SWB) PN GM11B
Sender, Driver side tank: #FG05M -OR- Passenger side tank: #FG05N

For the pump I purchased a Bosch #69225 (same as an ACDelco EP381) from Rockauto.com. The kit includes clamps, fuel line, isolator, wiring pigtail and clamps for install.

I also purchased a new Strainer, Spectra Premium #STR01 (required for Fuel Pump Warranty) from Rockauto.com. I did not know the sender kit had one already with it...oh well, it was just a couple of bucks, now I have a spare...

The fittings I used are:
Jegs 3/8” tube to -6 Male AN Fitting (#100551)
Earl’s 5/16” tube to -6 Male AN Fitting (#165056)
I used one Earl’s and one Jegs because of cost, I saved a few bucks & Jegs did not have the 5/16” fitting (the Earl’s 3/8” tube to -6 Male AN Fitting is PN#165006, if you have to have both fittings the same brand). I got these thru Amazon.com.

Here are pictures of the components:
Sender:
http://i266.photobucket.com/albums/i...psvhxkp6mp.jpg

http://i266.photobucket.com/albums/i...ps3u9jsdez.jpg

Fuel Pump, Strainer, and Fittings:
http://i266.photobucket.com/albums/i...pspajz2wut.jpg

Re: 1987 Fuel Sender Conversion for LSx Swap
 

First step in the conversion is to modify the tubes on the top of the sender for the -6 AN adapter fittings. The small bulge on the end of the 3/8" line and the 5/16" line need to be removed.

Cut them off as close to the bulge as possible, but the OD of the line must not be enlarged or the fitting's ferrule will not fit correctly. Deburr both the inside and outside of the lines once they are cut off.

http://i266.photobucket.com/albums/i...ps3ls6keir.jpg

Here is the Jeg's Fitting (for the 3/8" line) taken apart.

http://i266.photobucket.com/albums/i...ps64xxxbl2.jpg

Slide the red part of the fitting over the end of the 3/8" line followed by the brass ferrule. Screw the blue part of the fitting into the red part and tighten per mfg's directions to crushe the ferrule and make the seal on the tube.

Here is the assembled fitting on the sender:

http://i266.photobucket.com/albums/i...ps7wl4erh4.jpg

Now, repeat for the 5/16" line. The Earl's fitting is a little different shape on the tube end, I needed to bend the support tab on the top of the sender down off the tube before putting on the fitting. Once the fitting was on and tight, I bent the support back up and around the tube.

Here is the completed fittings on the top of the sender:

http://i266.photobucket.com/albums/i...ps9rflgfuu.jpg

Leave the center tube (1/4" diameter) alone. Use a regular hose and hose clamp to route a vent tube up and out of the way on this tube of the sender.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Next is the install of the pump on to the bottom of the sender. My pump kit had all the parts needed to attach the pump as did the sender kit I purchased. I used the hose and clamps from the sender kit. The clamps in that kit are the "fuel injection" style clamps as opposed to regular worm gear clamps that came with the pump. Slide the black rubber sleeve over the pump and place the black rubber cushsion on the base of the sender. Slide the hose and clamps on to the pump, then install the hose to the tube of the sender and seat the pick up end of the pump in the cushsion at the base of the sender. Tighten the clamps. Press the strainer onto the pump thru the hole in the base of the sending unit. Connect the wire pig tails for the pump motor.

Here is the pump installed on the sending unit:

http://i266.photobucket.com/albums/i...psfihoawzh.jpg

Completed pump and sending unit:

http://i266.photobucket.com/albums/i...psita9k9lg.jpg

From here, just intall the pump into the tank with the new o-ring and lock ring that came with the sender (or the tank). Both had them...

Connect your hoses to the supply and return fittings and the vent hose. Install the tank in the factory location.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

I thought I read on the mfg's website that those tube to AN fittings were not for high pressure applications. I believe they were only rated at 35 psi or something like that. That's the sole reason I did not go with those. They look good though. I'll post some pics up of my fuel sender set up.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Here is the spec's straight from the manufacure's web site for the Earl's fitting:

https://holley.com/products/Plumbing...ts/AT165056ERL

It is rated for 250 psi.

In my opinion the LS fuel system is not really high pressure. It only runs at about 58 psi. Yes, that is higher than carbed fuel systems, but many other systems operate a much higher pressures than that and use the AN/tube adapters.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

I've must have been looking at these....nice write-up btw.

http://www.summitracing.com/parts/ea...6erl/overview/

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Nice write-up. Were you planning on using the same tubing to AN adapters for the stock fuel line and running a short section of FI hose / braided line between the two or were you doing something different?

Re: 1987 Fuel Sender Conversion for LSx Swap
 

This was before it went in

http://i1341.photobucket.com/albums/...psf0lcdvuw.jpg

Re: 1987 Fuel Sender Conversion for LSx Swap
 

LS-K - That looks good. Probably the same amount of work as mine too. What's funny to me, is the part number you linked to Summit is the same part number on the Holley (Earl's) web site that lists them for 250 psi.

NorCalAnthony - They make a specific adapter fitting for the GM fuel lines on the rail. Between the tank and the rails I will be using braided line.

Here is the part numbers for the fuel rail adapter fittings:
Supply Line: http://www.summitracing.com/parts/rus-644120/overview/
Return Line: http://www.summitracing.com/parts/rus-644110/overview/

I used the black ones. 644123 (Supply) & 644113 (Return)

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Sweet write up. I have a fresh 5.7 I should put in my truck, it's been put up in storage for awhile now I need to put it to use.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Everything is just plug and play as far as the pump to sender goes? And then the two wires coming from top of the sending unit which I assume is a ground and a switched 12v?

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Yes sir the pump just almost falls into place. There are 3 wires coming out of the connector at the top of the sender. Black is to Ground, Gray is the Power to the Pump and the Purple is the sender to the gage.

**(I might have the Gray and the Purple switched. I will check and repost to confirm.)**

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Ok cool those are the same ones I've seen a few other people use. Out of curiosity, why didn't you use those on the sending unit instead of the compression style? I think the compression style looks like a more solid connection but wasn't sure if there was anything more to it than that...

Re: 1987 Fuel Sender Conversion for LSx Swap
 

the sender has a different style of bead form on the end of the hard line. It is more of a bulge to hold a hose on with clamps. The LS rail has a squared lip/ring form that is further from the end of the line. I don't think they make an adapter for the type of bead form on the sending unit. Atleast I have never seen one...

Compare the 2nd picture in post #1 of the tubes on the sender to the tubes on the LS fuel rail and you will see the differences I am trying to explain.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

This should be a sticky. Great information for LSx swappers.

My question is, do you really need to convert the return line into a high pressure line?

Re: 1987 Fuel Sender Conversion for LSx Swap
 

My truck already has the spectra GM11B tank. It does not have any baffle inside. Are you sure this tank is for EFI?

Re: 1987 Fuel Sender Conversion for LSx Swap
 

The spectra GM11C might be the 16 gallon EFI tank?

Re: 1987 Fuel Sender Conversion for LSx Swap
 

I basically did the same thing expect i used an 87 suburban tank with ep381 pump, you dont need baffles , as long as you dont run it low low on fuel. My fittings havent leaked any T all

Re: 1987 Fuel Sender Conversion for LSx Swap
 

I used the GM11B tank, it does not have a baffle in it, but I have not had any issues with it when the level gets low. I am not 100% sure that the GM11C has a baffle in it either. In a search I did this morning, the GM11C does come up as the tank for a 1987 R10 with TBI...

Re: 1987 Fuel Sender Conversion for LSx Swap
 

I converted mine to -6 AN for the simple reason that I was reusing some existing -6 AN lines for my fuel system. I am not sure what the actual pressure is in the return line (but should not be over 60psi), but on MY return style rails, I could only find the adapter for a -6 AN and it is just simple to change over the sending unit to -6AN fitting.

Most push lock hose and fittings are rated to at least 200psi and that could be a simple hose to make up with -6 JIC fittings (same as -6 AN fittings) that don't even use hose clamps. Having the -6 AN male to 5/16" tube fitting on the sending unit is just extra safety against a hose and clamp leaking.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

GM11C should have a baffle in it. GM1C (the 20 gallon EFI tank) definitely does, here is a photo of my new Spectra Premium, pn GM1C:

http://foamypirate.com/img/88chevy/l...m/image010.jpg

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Nice suburban tank. How many gallon is it?? I found a 1991 40 gallon suburban tank on rock auto I was thinking of trying.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

thank you for doing this thread. ill be using this info real soon

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Nice write up! your procedure and write up are almost exactly what i had envisioned in my head. it is very nice to see actual photos tho.

What fuel line are you using? i know you said it was braided but do you have a source and part number? i shop almost exclusively at JEGS for the simple reason they have free shipping and are usually a buck or two less than summit.

What fuel tank switching unit (under cab) are you using? source?

I am installing all this in a pre-FI truck so i gotta make harnesses from the sending units to power source. I am hunting up detailed info on the HOT WIRE 'kit'. this looks like no fun at all!

I am planning to use the corvette filter/regulator on my swap for simplicity reasons. I am planning (if it will actually work) to use aftermarket fuel rails so i can have a single fuel line from the reg to the rail to keep things less clustered. but i dunno yet if the aftermarket fuel rails are compatible with the truck intake manifolds. I think the aluminum intakes manifolds sure look cool, but my wallet doesnt think than the expense of the intake manifold for the use of cheap fuel rails is worth it.

-Izzy

Re: 1987 Fuel Sender Conversion for LSx Swap
 

I got my hose and fittings from Jegs. I used their house brand braided hose and AN fittings. All -6 stuff.

My went into a pre-FI truck too, but only with a single tank. Can't help you there...As for the wiring, I used the stock wire for the Fuel Level gauge that ran down to the tank. I ran the fuel pump power wire from a relay on the fender well and followed the sender wire from the fuse block plug on the firewall down to the tank/sender. Simple.

Hope that helps. My son just swapped pumps to a Walbro 400, did not have to change anything except the base that supports the pump. Had to cut that off and use a hose clamp to secure it to the hanger rod. Getting ready for Turbo upgrade.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

I used AN fittings also but I silver soldered steel AN fittings to both ends of the fuel system, 87 pick up tank and return fuel system

Re: 1987 Fuel Sender Conversion for LSx Swap
 

for you guys that used the 87 sending unit will any gauge work with it? I did this on my 75 blazer I need to replace the gauge but wasn't sure if I could just keep the 75 gauge or do I need to get a 87 gauge

Re: 1987 Fuel Sender Conversion for LSx Swap
 

I am not 100% sure, but it should. I think that the 87 and 75 gauges use the same resistance range. I know that my 84 gauge worked with the 87 sender....

Re: 1987 Fuel Sender Conversion for LSx Swap
 

The 87 sender worked n my 78 also, the old one was busted for 20 years !

Re: 1987 Fuel Sender Conversion for LSx Swap
 

so you were ok running a 78 gauge to a 87 sender? classic parts is having a 10% off sale I'm going to order a new gauge save me like $5 or $6 :)

Re: 1987 Fuel Sender Conversion for LSx Swap
 

The Gm fuel gauges were all 0-90ohm till mid 1990s you shoud not have any problems with the fuel gauge

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Well I haven't run out of gas yet!!

I no longer have to put gas in the truck every 100 miles

The LS gets better mileage, but now I do not have a speedometer, I like the fuel gauge better!

Re: 1987 Fuel Sender Conversion for LSx Swap
 

LOL same boat but ive been using a GPS app on my phone. thanx for the help

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Bringing back an old tread! Great write up. This will help me alot. Question: You are using the corvette style filter w/ return that you can mount near the tank. I'm swapping a truck 5.3 with the return already on the truck intake.

Would I just use a regular filter that is not a return style? and run two long fuel lines from the intake? Since the truck intake has a regulator built in along with return.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

this will definitely help me as well. Aggie91 did you ever find out if the purple went to the gauge and grey went to power or vise versa?

Re: 1987 Fuel Sender Conversion for LSx Swap
 

This was set up for the return style lines on the intake. I did not use the corvette style return filter.

I just ran two -6 lines from the tank up to the rails. One for supply and one for return. That set up worked with a pump upgrade to a Walbro 400 style pump and made over 515 ft lbs of torque before blowing a head gasket...:lol:

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Gray is power to the pump.

Purple is the sender wire to the gauge.

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Cool. Thank you! Did you cut the plug off and solder wires?

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Grey to the wire going to the fuel pump relay and purple to the fuel gauge?

Sorry meant to put that in the other post...

Re: 1987 Fuel Sender Conversion for LSx Swap
 

Yes.

For the plug, I got the matting connector and pins and put that together on the wires going back up front to the cab area.