Bronco Forum - Full Size Ford Bronco Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
136 Posts
Discussion Starter #1
Hi guy's

I have a 88 5.0 thats been sitting in storage for 4 years. I finally brought it home to work on it. I dropped the fuel tank and cleaned it out. I also put a new fuel pump/sending unit, along with a new fuel filter, and changed all fluids, It also has a new battery..
It turns over great but will not fire up. I disconnected the fuel line after the filter and it will not get fuel there when I turn the ignition to on. Then I disconnected the supply line at the sending unit and i do get fuel.
But the one thing i noticed is the supply line does not go through to the fuel filter, is this right? Does the supply line go straight to the rail? And the return goes through the filter?


Thanks for your time!
 

·
Forward Some Money
Joined
·
5,044 Posts
No, supply goes through the reservoir, high pressure pump, filter, fp regulator, rails. IIRC return goes directly to the tank.
Why would you think the return would go through the filter?
Sounds like you've got things crossed.
 

·
Registered
Joined
·
136 Posts
Discussion Starter #3
I know it sounds like that, but thats how it is for some reason. Im up this morning and i just checked it again to make sure and thats how it is hooked up.
 

·
Super Moderator
Joined
·
26,007 Posts
yo T,
Pressure Fuel Pump, Filter, & Reservoir for '84-89 EFI

NOTE: The frame mounted fuel filter was repositioned to between the fuel pump and engine in February, 1986.
by Steve83

Also by Steve;
"...This is a common problem in all pre-'92 EFI F-series & Broncos. These Ford-style relays (BROWN socket = EEC power; GREEN socket = fuel pump)are notorious for causing intermittent failures in the EEC & fuel pumps. Yesterday, this EEC PWR relay decided to lock on, killing the battery. Today, its contacts are so bad that the truck won't run. So it's about to be TRASH.

See the NEXT caption.

The brown relay is resting on the vacuum cruise servo, and the yellow connector is for the EEC.

If the Fuel Pump relay comes on with the key and stays ON even when the engine isn't running, read this thread..."
http://www.supermotors.net/registry/media/507187


===

Filter; In-Line & Accumulator/Single (Bronco)

Single-Function Reservoir Fuel Flow;

"...Fuel flows in through the larger tank-side supply nipple from the in-tank pump to the inlet check valve, which allows it into the reservoir. As the cup fills, fuel moves up the pickup tube & out the larger engine-side supply nipple. Unused fuel enters the engine-side return nipple, bypasses the blocked-off check valve ('88 revision) and exits the tank-side return nipple. The only fault that would cause a noticeable problem would be for the check valve to stick closed, blocking any fuel from entering the reservoir, but this isn't likely. With the cup removed (have a replacement cup O-ring in-hand before attempting), a sharp pick can be used to pull the valve downward & open. The valve cannot be removed from the reservoir body..."
Source: by Steve83 (Steve, That dirty old truck) http://www.supermotors.net/registry/media/669646

The single-function reservoir (SFR) is used on vehicles with ONE gas tank, like Broncos, vans, & low-trim pickups. The reservoir is always inside the L frame rail beneath the driver's floorpan about 10" behind the frame fuel pump. The 10mm bolt heads are easy to access on the outer face of the frame rail, but some vehicles have a large heat shield that must also be removed...There's not much to the SFR (which is what ALL Broncos of those years have): the '88 version just has the cup & 1 check valve (earlier versions have 2), but it's almost foolproof. Its (meager) function is described in the caption of the 2nd pic..." Steve83 @ http://fullsizebronco.com/forum/showthread.php?p=1778940#post1778940

Single-Function Reservoir O Ring; "The Ford engineering number on the filter is E6TZ-9365-A. A reservoir marked "DO NOT REMOVE CUP" does not contain a filter. For a replacement O-ring for the cup, buy a NAPA 3268 (or equivalent) filter..."
Source: by Steve83

Single-Function Reservoir Overview & pics in 84-89; "The Ford engineering number on the filter is E6TZ-9365-A. A reservoir marked "DO NOT REMOVE CUP" does not contain a filter. For a replacement O-ring for the cup, buy a NAPA 3268 (or equivalent) filter..."
Source: by Steve83 http://www.supermotors.net/vehicles/registry/2742/66025-4

Single-Function Reservoir Testing in 88-89; "...Used on '88-89 Broncos & F-series/E-series/Rangers/others with single tank dual-pump EFI. In this version, the only moving part is the tank-side inlet check valve. The return ports flow freely and are NOT connected to the reservoir. The engine-side supply port is open to the reservoir. To test it, unplug the frame fuel pump, disconnect the engine-side supply (large) line, and cycle the key. If fuel flows out of the reservoir nipple, the reservoir is working normally. If not, disconnect the tank-side supply (large) line, and cycle the key. If fuel flows out of the line, the reservoir check valve is probably stuck, or its internal filter is clogged. A reservoir marked "DO NOT REMOVE CUP" does not contain a filter. For a replacement O-ring for the cup, buy a NAPA 3268 (or equivalent) filter..."
Source: by Steve83 http://www.supermotors.net/registry/media/669585
 

·
Registered
Joined
·
136 Posts
Discussion Starter #7
The reservoir had me confused because the supply line goes in the bottom of the reservoir and out the top. I found the problem, The high pressure pump failed.

thanks for all your help
 

·
Registered
Joined
·
19 Posts
For those with weird fuel pump problems:
I was having an issue with my '86 fuel pumps not pumping, though the fuel pump relay would click. My voltmeter would read the right voltages at the pump plug, and if I hardwired my HP pump directly to 12v, it would work.

I started thinking bad ground, or inertial switch. Tested the switch and ran another ground wire, no luck.

then I started thinking it was a bad connection or high resistance in the 12v path because it is LONG.

The power for the pumps start at the Right Hand apron starter-solenoid-mounted fuse link, then go in the wiring harness all the way to the Left Hand apron to the Fuel Pump Relay (tucked behind the hood mount), then back in the harness to the Right Hand Apron again, through the firewall into the cab for the inertial switch connection, then back to the Right Hand Apron, back in the harness, and over to the Left Hand Apron, where it goes to the final blade connector, then splits to power both in-tank and High Pressure pumps.

First, a little side note. When tracing down the wiring, I found a stray 12v-powered 12-gauge yellow wire tucked into the harness just under the brake vacuum booster. This had just the right length and connection style to connect to the fuel pump circuit, right at the connector before it splits to the two pumps, also right below the booster. Plugging it in resulted in both pumps running, and me being able to run fuel through the lines and back to the tank, as well as checking the pressure at the schrader valve. Its as if this power was there for specifically for fuel pump troubleshooting!

So, Pumps work, and they are well grounded, so that left the LONG power line in question. Testing the inertial switch for resistance, its good (close to 0 ohms). I found a two wire connector on the right fender apron near the heater vent vacuum reservoir (or AC collector? large silver cylinder) that looked like it came from a 1930's lamp, though it was a stock ford connector. In any case, the prongs were all corroded green. I cleaned them up a bit, sprayed some wd40 in there, and plugged/unplugged them about 10 times, and WALA... fuel pumps worked, both with the test jumper, and the ignition.

Hope that helps someone else.
 
1 - 8 of 8 Posts
Top