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EFI Accumulator Question

garyp

Jr. Member
Joined
Mar 13, 2011
Messages
92
Loc.
Germantown
Is this right, or does the return need to go to the tank? I read somewhere that the return could go to the accumulator then to the tank.
IMG_0368.jpg
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
For the accumulator to work right there are 2 loops. one loop from the fuel tank to the accumulator. The other loop is the accumulator to the engine. The accumulator stays full of fuel to keep the engine fed. The fuel tank loop may catch air when the fuel tank is low. the accumulator is there to take that air bubble and send it back to the main tank and keep it out of the engine side fuel loop.

What you have looks about right. The return needs to go to the accumulator for the loops that make up the accumulator work.

Personally I prefer to have the EFI return line merge with the main tank fuel inlet. That keeps all the fuel entering together. With the t-fitting you have there is a mix of fuel going in and fuel going out through the same point. The little added fitting being a dedicated return line back to the main tank. This vents the air bubbles off the accumulator. With the T fitting you have the main tank return de-bubbler sending fuel out of the accumulator at the same time the engine loop is trying to send excess fuel back to the accumulator.
 

fordtrucksrule

Sr. Member
Joined
Feb 11, 2008
Messages
838
I personally don't understand why a lot of people are using a accumulator. Everybody i know who has this setup HAS HAD VAPORLOCK! i personally did a High pressure in tank pump and have NEVER had a issue no vapor lock or anything.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
I can easily see how the above setup could cause vapor lock. Not handling the loop paths correctly.

But I know a lot of people who run an accumulator without issue.

Realistily you don't need an accumulator; IF (and it is a big if) you always keep the intank fuel pickup submerged. Any gulp of air will stall an EFI engine. I had a car that in a left turn on a very low tank of gas would stall. I could tell just how low the gas tank was by how hard I could take the turn before the stall happened. In a Bronco on a trail it isn't handling that will pull fuel away from the pickup, side hills, climbs, decents and even just bouncing around can all do it. If you never run low on fuel, never get into odd angels, never accelerate hard (or brake hard dependng on where the pickup point is in the tank); then you will probably be just fine without an accumulator.
The early EFI factory engines had an accumulator (small one) in the fuel lines. Later (and current) still have an accumulator but it is simply built into the tank.

A proper out of tank accumulator needs 2 inlets and 2 outlets. The inlets don't really matter. One is the supply from the main tank. The other is the return off the EFI regulator. Doesn't really matter how they enter. For the outlets there needs to be 2. And these do matter. One needs to be off the bottom of the accumulator, this feeds the high pressure pump. Coming off the bottom any air bubbles have had a chance to seperate and rise to the top. The top outlet is the return to the main tank. Any air bubble (either sucked up from the main tank or a vapor bubble from heating the fuel in the EFI loop) is sent back to the main tank.
 

00gyrhed

Bronco Guru
Joined
Aug 3, 2006
Messages
2,428
I personally don't understand why a lot of people are using a accumulator. Everybody i know who has this setup HAS HAD VAPORLOCK! i personally did a High pressure in tank pump and have NEVER had a issue no vapor lock or anything.

I am sorry but I have to state this bluntly, because you are going to run people off from a perfectly good way to address certian problems incountered in offroad use. EVERYBODY you know has installed it wrong. Properly installed it will not vapor lock and even poorly installed it certianly has less problems with vapor lock than a STOCK Bronco with the mechanical pump on the engine. However you can't fix stupid and most people dont even understand what it means to suffer from vapor lock and pay no attention to the obviuos causes when they install a system. If you install the right low pressure pump right next to the tank it is practically impossible for it to vapor lock. The only place vapor lock can even ocurr in that system is between the tank and the low pressure pump. PERIOD. If you think it is happening somewhere else you are either wrong or the installation is really screwed up bad. Keep that short line cool and short with no kinks and it just will not vaporlock. (Well it can if the pump is allowed to operate in a certian manner but that is easily fixed.) I run a cheap plastic filter between my pump and tank just to keep the crap out of the pump, and another after my accumulator just to protect the HP pump then a third HP filter right before the injectors to protect them. I live in TX and drive this thing off road for hours on end and even hours in stop and go traffic in 110degree heat. In 15K miles no VL.

I had a camaro in tank pump in my 350 TPI Jeep. I could run it to down to like 1/2" of fuel on the street but offroad was another issue. Off camber and even up long hills with an 1/4 of a tank or less it would starve in short order. I installed a 2" deep sump with another 4" baffle around it and the return dumping deep down into the sump into the sump. On the street you could actually empty the tank but I still had to keep at least 1/4 tank in it off road in certian conditions. In long off camber runs to the passenger side it would still starve for fuel. A properly installed accumulator system with external pumps WILL fix that. I made my accumulator and it holds 3/4 gallon of fuel. It is baffeled internally and the HPO pumps pulls right out of the bottom. I can and have run the entire system down to nothing under just about ANY operating condition other than upside down. As long as I am right side up and there is any fuel on the accumulator the engne runs without a hiccup. The LP pump can loose suction and pick it up over and over again but the 3/4gallon tank just doesn't ever empty no mater what I am doing, at some point I will hit level ground and the 3/4 gallon tank is suddenly fuel again. Problem is if you dont listen for the low pressure pump loosing suctiona and then picking it back up you do not know you are running out of gas until the thing just flat runs out of fuel.

On the street without question I would probably always run an in tank pump. They last longer because they stay cooler in the fuel, generally are much quiter, and there is one less pump to die. But off road unless you can get that pump in a deep baffled sump you have to will have to keep a higher level of fuel in the tank and that can severely limit your range, especially since broncos dont have a lot of large tank options.

If I have a 1/2 tank or more I can actully pump through a dead low presure pump by pinching the return from the accumulator to the tank.

So if he wants to offroad it he is better off with the accumulator system or be willing to accept the fact that if he gets into really offroading the thing he needs to keep more fuel in his tank.
 

00gyrhed

Bronco Guru
Joined
Aug 3, 2006
Messages
2,428
Exactly,

I can easily see how the above setup could cause vapor lock. Not handling the loop paths correctly.

But I know a lot of people who run an accumulator without issue.

Realistily you don't need an accumulator; IF (and it is a big if) you always keep the intank fuel pickup submerged. Any gulp of air will stall an EFI engine. I had a car that in a left turn on a very low tank of gas would stall. I could tell just how low the gas tank was by how hard I could take the turn before the stall happened. In a Bronco on a trail it isn't handling that will pull fuel away from the pickup, side hills, climbs, decents and even just bouncing around can all do it. If you never run low on fuel, never get into odd angels, never accelerate hard (or brake hard dependng on where the pickup point is in the tank); then you will probably be just fine without an accumulator.
The early EFI factory engines had an accumulator (small one) in the fuel lines. Later (and current) still have an accumulator but it is simply built into the tank.

A proper out of tank accumulator needs 2 inlets and 2 outlets. The inlets don't really matter. One is the supply from the main tank. The other is the return off the EFI regulator. Doesn't really matter how they enter. For the outlets there needs to be 2. And these do matter. One needs to be off the bottom of the accumulator, this feeds the high pressure pump. Coming off the bottom any air bubbles have had a chance to seperate and rise to the top. The top outlet is the return to the main tank. Any air bubble (either sucked up from the main tank or a vapor bubble from heating the fuel in the EFI loop) is sent back to the main tank.

I was typing my novel when you psoted. :)
 

fordtrucksrule

Sr. Member
Joined
Feb 11, 2008
Messages
838
I am going to have to apologize. I wasn't trying to bash anyone. I am just ignorant against the accumulator. In my opinion i just don't see how they will work good i guess in some setups. I see a 1 issue i would be concerned about witch is location of the accumulator getting heat soaked by the heat under the hood
 
OP
OP
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garyp

Jr. Member
Joined
Mar 13, 2011
Messages
92
Loc.
Germantown
Yes this accumulator thing is a pita, but without an efi type tank, I believe the best way to go. I would think that with 5-7 psi in the acu. and whatever pressure from the return, and no resistance at the tank, there would be constant flow back to the tank. Thanks again for all the advice.
 

jw0747

Contributor
Bronco Guru
Joined
Nov 22, 2006
Messages
2,434
Loc.
San Antonio, TX
seen many efi equipped Broncos including mine and have never once seen an accumulator in the return line. some have them on the supply side but many have removed them. they are good on the supply side if you run your fuel tank almost dry while driving but IMHO you don't need one anywhere. total waste. put a rope on yours and use it for a boat anchor.
 

BUCKNBRONK

Sr. Member
Joined
Jun 30, 2011
Messages
521
Loc.
fresno
seen many efi equipped Broncos including mine and have never once seen an accumulator in the return line. some have them on the supply side but many have removed them. they are good on the supply side if you run your fuel tank almost dry while driving but IMHO you don't need one anywhere. total waste. put a rope on yours and use it for a boat anchor.

yep- waist of time imho. just a fad. ford never had one, in tank, frame mount fuel pumps it makes no diff if ur out of fuel ur out. a accumulator will not help it, only mask's problems with inadequate/improperly set up fuel systems. I have one sitting in my shop for 10 years after I got told I was going to need one, never installed it after I tried to find a suitable mount location and realized that it was more trouble than it was worth. Heres a idea, keep fuel in your tank when u go off road- problem solved. I have sat at 45+- deg angles for 30+ min. and never had a problem. EfI tank , frame mount pump, 3/8 lines in /out- no shirt, no shoes, no problems.
 

bmc69

Contributor
Bronco Guru
Joined
Jun 11, 2004
Messages
11,851
I personally don't understand why a lot of people are using a accumulator. Everybody i know who has this setup HAS HAD VAPORLOCK! i personally did a High pressure in tank pump and have NEVER had a issue no vapor lock or anything.

Funny...adding the accumulator setup to my righ CURED its vapor locking problems. ;D

But I do agree an in-tank setup should never have a varpor lock problem; its just that all my rigs use external pumps.
 

kholding

Bronco Guru
Joined
Sep 6, 2010
Messages
2,209
Loc.
Las Vegas, NV
I just bought the BC EFI fuel tank with the "in-tank pump", should I still install an accumulator? I think I am almost more confused now?
 

chuzie

Bronco Guru
Joined
Jul 21, 2006
Messages
2,697
I think Chuck builds his tanks special so the pickup is never uncovered. So no need for an accumulator
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
I just bought the BC EFI fuel tank with the "in-tank pump", should I still install an accumulator? I think I am almost more confused now?

Should not need one. The accumulator is for running carb style fuel tanks. Carburators are fairly imune to an air bubble in the fuel line. The fuel bowls are the accumulator.

As for saying ford never had one on the frame, lie. I can think of a couple. The '87 BroncoII I had used one. I ended up getting to know too many details of that truck in the second 100k I owned it. Drivers frame rail about under the drivers seat. Small, maybe 2" across and 2" tall. But it had one. 4 fuel line connections. We also have an older (late 80's) super duty at work with a 351 in it. it has one too. These are the early days of EFI, many parts were still compatable with carburated setups. Most of the fuel systems are left over designs of the carburated predecessors that had additions to make the EFI work. These are the EFI setups that were factory equipped with 2 fuel pumps. The '91 F150 we recently got is newer and has only in-tank pumps. By this time the fuel systems were being better adapted and strayed quite a bit from the old carburator days.
 

chuzie

Bronco Guru
Joined
Jul 21, 2006
Messages
2,697
I had one of those old Ford accumulators from an 80's F-Series truck. It worked well with the exception that there was nothing to top it off on the return side. The other two nipples were for the return but it never dumped to the accumulator. I upgraded to BC's accumulator recently and like it but only because I have a LP pump on the frame.
 
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