PLEASE READ: Malibu Racing Lives!!

Fuel System Summary

Progress updates on our 4.8L/4L60E Swap into a '79 Malibu.

Moderator: Moderators

Post Reply
User avatar
MalibuRacing
MalibuRacing.com Founder
Posts: 3472
Joined: Mon May 05, 2003 8:04 am
Contact:

Fuel System Summary

Post by MalibuRacing » Fri Oct 29, 2010 1:03 pm

There are MANY options and configurations when it comes to the fuel system. I will not cover all possible fuel system options here, but will cover what we did on our project. I'm not saying that this is the best way (most likely not!), but how we did it. I wanted to maintain the stock appearance and configuration of the fuel system. Because of this, I decided to run an OEM type internal tank pump system. This is good news/bad news. The bad news is the 1978-1983 Malibu is set up for carbureted engines with a mechanical fuel pump. The EFI tanks are designed with different baffle design to prevent starvation to the electric fuel pump. The good news is there is a bolt-in replacement for the Malibu. I chose to get a new replacement fuel tank for a 1987 Monte Carlo with a 4.3L TBI (Throttle Body Injection) engine. This particular tank is setup for EFI, including the correct baffling for the EFI pickup.

Old fuel Tank, note there are only two lines on the sending unit (feed line and vent):
Image


New Fuel Tank, purchased from O'Reilly Auto Parts:
Image

After installing this new tank and driving the car, I have found that I had difficulty filling the fuel tank. It would kick the pump off. That would not be that big of an issue, but it would also spew fuel 2-3 feet out the filler! :shock: . I checked the vent line and made changes to no avail. After some research, I have found this is the case for many (if not all) of the replacement fuel tanks on the market. Apparently there is a design flaw causing ventilation problems during fuel fill-up. There is a fix for this, which would best be done before installing tank. It will require welding on the tank, so you want to do this before putting fuel in the tank. See below for a picture of how to modify the tank (thanks to samh_08 for picture):
Image

For more clarity, the fitting in the filler neck should be a "U" bend with the end facing down toward the tank. See below for my pre-school quality drawing ;) :
Image


Like I said above, I purchased a fuel pump hanger/sending unit from a 1987 Monte Carlo 4.3L TBI. It has an internal fuel pump setup. You cannot use the pump for the TBI, you need to get a high pressure fuel pump. I used a Delco EP241 equivalent, but after reading some more a better pump would be EP381 (E3270 Airtex) = Flow = 50-60 GPH & PSI = 80-90. Of course, if you're building a hot engine combo, you may want to upgrade to an aftermarket pump. Here is a picture of the pickup and fuel pump:
Image


Note that the EFI pump hanger/sending unit has three line connections. They are the main feed line, return line and vent line. I initially considered using the Malibu's steel lines for the feed line and return line, but later decided to run new high pressure fuel hose lines (more on that later). The EFI pump hanger has an unusual fitting on the feed line. Fortunately, there are aftermarket fitting to convert that to AN style fitting. The fitting that I used is an Earl's fitting, part number: 9894DBJERL. The description of the part is: FEMALE 16MM X 1.5 SAGINAW to MALE AN#6. For the return line I used a 5/16" tube to NPT adapter, then a NPT to AN#6 adapter. I purchased this at a local industrial hose and fitting supply company. Both can be bought from Summit or Jegs. The vent line is standard fuel line connected using a clamp. I connected the vent line to the factory 3/8" steel feed line running to the front of the car, and connected a small air filter on the end. I believe it was a Spectre part that looks like a mini-K&N style filter (picture coming). See here for pictures of fittings:
Image

Image


I decided on using high pressure "Push-Lok" style hose for the fuel system. Some may say this is not best hose to use, but I have used it in the past and my father used this for years on his dirt track car without any issues. The simplicity of the push-lok hose is the main reason. Plus, I can get the parts from a local industrial supply company, which makes it very convenient. Below is a few pictures of the routing of the lines:
Out of the top of the fuel tank:
Image


I used an OEM style high pressure (EFI) fuel pump and installed AN fittings on each end. Here is a shot of the main feed line with the filter and the return line:
Image


Main line and return line running along the passenger frame rail. This is the initial running. Don't worry, I later went back and secured the lines using hose brackets every several inches.
Image


Fuel lines coming up the firewall by the heater box:
Image


I had to use AN Fuel rail adapter fittings. Main feed line adapter is Russell 640850. Return line adapter is Russell 640860.
Image


Here, the fuel lines are connected to the fuel rail adapters.
Image


The fuel pump wiring was simple. I connected the ground wire to a chassis location near the tank. The "hot" wire was run to the front of the car and connected to a relay that is activated by the ECM.
Phillip Patterson - MalibuRacing Founder
Father/Son '79 Malibu 4.8 LSx Swap

Only 2 defining forces have ever offered to die for you....Jesus Christ and the American Soldier. One died for your soul, the other for your freedom.

User avatar
hypeboy
Daily Driver
Posts: 40
Joined: Thu Aug 04, 2011 4:29 am

Re: Fuel System Summary

Post by hypeboy » Wed Feb 22, 2012 9:21 pm

I chose to get a new replacement fuel tank for a 1987 Monte Carlo with a 4.3L TBI (Throttle Body Injection) engine. This particular tank is setup for EFI, including the correct baffling for the EFI pickup.

Old fuel Tank, note there are only two lines on the sending unit (feed line and vent):
Image
New Fuel Tank, purchased from O'Reilly autoparts:
Image

I had occasional problems with the fuel tanks, and these problems came in several catagories which are not related to each other. whew but at last you explained it well
thank you very much this helped me a lot.

steve40
Daily Driver
Posts: 30
Joined: Thu Sep 02, 2010 7:41 pm
Location: windsor, ontario

Re: Fuel System Summary

Post by steve40 » Fri Aug 28, 2015 9:47 am

What size and type of pipe did you use to plumb into the filler tube?

Post Reply