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95 Posts
Discussion Starter #1
I've tried searching, but really not sure what I'm searching for. I'll start by giving a little back story followed by what I've done, then end with my problem so just bear with me.

I bought an 87 bronco with a 5.0 in it back in July. The truck had been parked for 4 years in the street under a tree before I rescued her. It did not run at the time of purchase due to busted exhaust manifolds and dead battery. I took a risk at 500 bucks and trailered her home. I gutted the entire exhaust system and went with pacesetter shorty headers. I replaced the battery, plugs, wires, distributer,coil, ignition module, iac, air filter, and had a new o2 sensor in hand. I trailered it to the muffler shop and had a new y pipe made, and 3" pipe run into a wicked flow (house brand) muffler with dual 2&1/4 inch pipes dumped at the back axle. Trailered it back home and emptied all the old has and refilled it with non ethanol. She fired right up and ran great for 2 weeks. Then the fuel filter stopped up. I replaced it and went on my way. After another couple weeks she started acting up, so I replaced another stopped up filter. (I think we know where this is headed). I ended up draining and pulling the tank. I replaced the sending unit, and inline fuel pump. While I had the tank out I cleaned it and coated the inside. I let it sit for 48hrs so it was good and cured and re-installed everything. It ran like a new truck for 10 minutes until I noticed a vaccum leak at the intake manifold. Got that replaced and she ran great for another 10 minutes.

Now onto my problem. It starts up and idles great. Hell it even runs good until the engine warms up. Then it seems as if the loher I drive it the more Throttle I have to give it to get up to speed. Almost like I've got half the horsepower. The engine sounds good, no hesitation, it just has no power! I am completely at a loss and have no idea where to go next.

I'm sure I left out some parts I've replaced, but I'll get to those later on if needed. Thanks for all the help!

38 Posts
Have you hooked up a fuel pressure gauge to make sure you are getting the correct fuel pressure? This could eliminate a fuel issue and is fairly simple to do,good luck and post up your findings.

95 Posts
Discussion Starter #3
I have not. But speaking of fuel I have replaced the pressure regulator as well.

I called oreillys and they have the pressure test kit to rent. I guess this will be my next plan of attack.

Assuming I have correct pressure everywhere, what else could cause this

Premium Member
23,563 Posts
You still have a cat?

Some years have a fuel reservoir between the tank and high pressure frame pump. Some had filters, some did not.

95 Posts
Discussion Starter #5
Cat's gone. There is the reservoir in the frame, but everything I could find while reading about it says there's no filter in mine. It's a non serviceable item.

Premium Member
23,563 Posts
Maybe someone will pipe in, I can't find it in the search. But many came with a filter.

Super Moderator
26,022 Posts
Single-Function Reservoir;

Single-Function Reservoir Disassembly in an 86; "....More then likely you'll need to remove the transfer case skid plate for more working room BUT you CAN get the bottom part to unscrew if you use the right tool to get it tight enough and have leverage to loosen it PITA that it is. There's probably a lot of built up road grit in and around the threading so use some PB Blaster etc. Think out of the box on this one and get creative with a tool ...but there's no need to remove the top part. The top part (cap) of the reservior has these little spring loaded pressure valves on each side where the lines go to inside to keep the reservior full, the bottom half threads are similar to "pipe" threads so they're tappered for a tight seal so it does take a bit of energy to get it free.....BECAREFULL because it's plastic and if you break any part of it you won't be able to drive the BKO. The O ring can be a PITA also just read above and work at it carefully..." by JKossarides ("The Bronco", Jean ) at FSB

Single-Function Reservoir Disassembly in an 86; "...I found that the only tool I could get to unscrew that damn canister was a rubber lined adjustable oil filter wrench. It was a cheapy wrench that I got at like Kmarts or something. It worked great for this job. Now for the o-ring, lube it in some vaseline an it should stay in place a lot easier. When mine went bad on my old 86, I was getting a lot of hestations, backfires from my lean mixtures. Even had the cops called on me for shooting a gun out the window in a neighborhood..."
Source: by sackman9975 (Scott) at FSB

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) at
Steve's '84-89 Fuel Reservoirs ALBUM

Single-Function Reservoir in 84-89; "...The PN for the filter is given, but you shouldn't actually have a filter in there. It should be an external inline filter further up the frame rail - you only buy the reservoir filter to get the O-ring, and only then if you have some reason to open the reservoir bowl. Unless you're having fuel delivery problems that you've isolated to the reservoir, you should never open it..."

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 (Steve, That dirty old truck) at

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 (Steve, That dirty old truck) at

To permanently eliminate the reservoir, use these Dorman fuel tubes.

See this caption:
"ISSUE: Ford Motor Company of Canada, Limited (Ford) has determined that certain 1986, 1987, 1988 and 1989 model F-150/250/350 Trucks and Broncos sold in specific areas of Canada where severe winter weather is experienced contain a fuel tube that may develop a leak.
by Steve83 (Steve, That dirty old truck)
Technical Instructions: The new stainless steel reinforced Teflon� fuel line replaces both the short "jumper" fuel line from the high-pressure frame-mounted fuel pump to the filter, and the long fuel line from the filter to the fuel rail on the engine. The existing In-Line Fuel Filter will be removed and discarded. A canister-type Fuel Filter will be added to the existing fuel reservoir on the frame rail behind the high pressure pump.
NOTE: The frame mounted fuel filter was repositioned to between the fuel pump and engine during 1986 model year production. This was incorporated in February, 1986.
by Steve83 (Steve, That dirty old truck)
Fuel System Pressure Relief

EFI Engines
CAUTION: Fuel supply lines on 4.9L EFI, 5.0L EFI, 5.8L EFI and 7.5L EFI engines will remain pressurized for some period of time after the engine is shut off. This pressure must be relieved before servicing of the fuel system.

Before opening the fuel system on vehicles with EFI engines, relieve fuel pressure as follows:
1. Locate and disconnect the electrical connection to either the fuel pump relay, the inertia switch or the in-line high pressure fuel pump.
2. Crank engine for approximately ten seconds.
NOTE: Engine may start and run for a short time. If so, crank engine an additional five seconds after engine stalls.
3. Connect the electrical connector that was disconnected in Step 1.
4. Disconnect battery ground cable.
5. Raise vehicle on hoist. Refer to the appropriate model year Volume F, Pre-Delivery Shop Manual, Section 50-04, Hoisting and Jacking.

Canister-Type Fuel Filter Installation

CAUTION: If the fuel filter canister is being serviced with the rear of the truck higher than the front, or if the tank is pressurized, fuel leakage or siphoning from the tank fuel lines could occur. To prevent this condition, maintain the vehicle front end at or above the level of the rear of vehicle. Also, relieve tank pressure by loosening the fuel fill cap. Cap should be retightened after pressure is relieved. If vehicle is warm, install the fuel filter before the pressure rebuilds.
1. Remove the reservoir shield on 4 x 4 vehicles by removing either three or four screws (depending on vehicle). On 4 x 4 vehicles it may be necessary to disconnect the rear of the front driveshaft to allow for tool clearance.
NOTE: To maintain driveshaft balance, mark the rear slip yoke in relation to the transfer case yoke for correct positioning during reinstallation. Then remove the nuts and U-bolts (bolts for F350 transfer case) that connect the front driveshaft to the rear slip yoke of the transfer case.
2. Unscrew the lower canister of the reservoir using a flexible strap type oil filter wrench, and slide canister out from frame rail.
NOTE: Fuel canister will be full of fuel.
3. Empty fuel from the fuel canister. Remove and discard the O-ring.
4. Remove the stand pipe from the reservoir by pulling it down sharply. Discard the stand pipe.
5. Install grommet (supplied with filter) into top of filter cartridge, then install the fuel filter cartridge into fuel canister.
6. Position new O-ring so that it is seated in the O-ring groove of the canister.
7. While keeping canister level, so as not to dislodge O-ring, position canister to bottom of reservoir housing and tighten loosely by hand. It may be necessary to loosen reservoir-to-frame mounting bolts to access the canister. Using a flexible strap type oil filter wrench, complete filter canister tightening by turning canister about one-sixth of a turn past initial O-ring compression.
NOTE: The rubber grommet on the filter will automatically seat on the piloted stud of the upper housing as the canister is tightened.
REMINDER: If reservoir-to-frame mounting bolts were loosened in above step, re-tighten.

Fuel Line Replacement:
CAUTION: Fuel lines may still contain fuel. Use caution when disconnecting.
1. Remove the three bolts holding the fuel filter bracket to the frame. Retain one bolt for subsequent use.
2. Disconnect "Push Connect" fitting at the high pressure pump outlet nipple by removing hairpin clip and twisting the line while pulling on it.
3. Using a 16 mm wrench for the fitting and a 14 mm wrench (on the boss of the fuel pump) for backup, unscrew outlet nipple from the front of the high pressure fuel pump. Discard nipple and copper sealing washer.
4. Install new copper washer (E6TZ-9374-A) on the new fuel pump nipple (E6TZ-9416-A). Screw this new nipple into the pump. Torque to 12-16 Nm (9-12 lb-ft), while keeping a 14 mm wrench (on the boss of the fuel pump) for backup.
5. Select the appropriate new fuel line as per Parts Ordering Information.
6. Remove red shipping plug on fuel pump outlet connector of the fuel line if present. Leave white shipping plug on for protection. Install the end of the fuel line with the small bell-shaped connector to the new fuel pump outlet nipple. Push on to nipple until distinct click is heard or felt. Pull on line to test for and confirm retention. Engage the retainer clip to line and nipple by firmly pushing down on the clip.
NOTE: If fuel line removal is required use tool T90T-9550-B to release connector.
7. Route fuel line forward inside frame rail, following routing of fuel return line. Install clip N800558-S100 to retain fuel lines, by bolting to lower front bolt hole in frame, that was previously used for the fuel filter bracket. Use bolt from Step 1 and nut N620480-S100. Torque to 8-12 Nm (6-9 lbs. ft.) Ensure fuel line is pressed against frame rail web to clear automatic transmission shift linkage.
8. Disconnect the fuel supply line at the engine fuel rail as follows:
a) lift the tethered retaining clip off the coupling connection. Move it aside, leaving it hanging by its tether.
b) disconnect the fuel line spring lock coupling, using the proper special service tool.
9. 5.0L or 4.9L engines equipped vehicles. Remove the complete fuel supply line, filter and jumper fuel line as an assembly. Mutilate and scrap.
10. 5.8L or 7.5L engine equipped vehicles. Use a pair of diagonal side cutters to cut both ends of the fuel supply line flush with the foil insulation wrapping. This leaves the wrapped section of the original supply line in place, which is not to be disturbed. Use caution to avoid damaging fuel return line. Mutilate and scrap the ends of fuel lines, fuel filter and bracket and "jumper" fuel line.
11. Remove white shipping cap and connect fuel line to engine fuel rail. Install retainer clip previously removed in Step 8.
12. (5.0L or 4.9L) Strap new fuel line to existing fuel return line using tie straps 95874-S at 8" (20cm) intervals. Cut off excess tie strap length.
13. (5.8L or 7.5L) Strap new fuel line to existing fuel line insulation bundle. Locate tie straps 95874-S at 8" (20 cm) intervals. Ensure heat shield is installed as shown. Use additional strap to secure fuel line to shield. Cut off excess tie strap length. Slight excess fuel line length is allowed to form a "hump" at the upper end of the fuel line near the engine.
14. Lower vehicle.
15. Reconnect battery ground cable.
16. Cycle ignition key to "ON" position 5 times at 2 second intervals to prime the fuel system. Inspect reservoir, pump nipple and fuel line connections for leaks (correct as required).
17. Start engine and reinspect the fuel system for leaks. (Correct as required).
18. (4 X 4 only) Reinstall fuel reservoir shield. Torque attaching bolts to 16-20 Nm (12-15 lb-ft).
19. (4 x 4 only) Reinstall driveshaft, if removed, making sure markings on rear slip yoke and transfer casing yoke line up so as to maintain driveshaft balance.
20. Mutilate and scrap all removed parts.

This Recall Supersedes and Replaces Safety Recall 88S57

Recall Time Limitation
Parts Return
LABOR TIME: Install new fuel line from the high-pressure frame-mounted fuel pump to the engine and install filter in frame mounted reservoir 1.5 Hrs.
Administrative allowance 0.1 Hrs.
by Steve83 (Steve, That dirty old truck)

Single-Function Reservoir Parts Break-Out Diagram in 84-89

Premium Member
9,999 Posts
You should be able to "pull codes" from the vehicle computer, self test connectors should be on the right inside fender liner behind the battery area, mine are Red & Tan in color. Your 87 should be a 2 digit fault code system.

You have two ways to pull codes, buy a battery operated Ford Code Reader with diagnostic book which has all the fault code numbers and explanations, available on Amazon for $24.99 OR use a paper clip and "pulse codes" a bit more of a PITA but will get it done.

Loss of power could be bad wires or plugs BUT a loss of power can also be an exhaust leak some where in the emissions system so if you have the Thermactor Air Injection cross over tube bolted to the back of the cylinder heads go directly to the "check valve" threaded into the top of the tube where they rust or burn thru form heat and moisture over time. If you get a code:44 air injection system fault, more then likely that's the culprit the valve runs around $20.00 at most auto stores or try = Pollution Control Industry which has a wide variety of emissions products....

Also do a visual inspection of ALL plastic and rubber vaccum lines which can also trigger an exhaust leak affecting performance. I replaced all my old brittle lines with a kit you can buy from all the difference in performance.

My 86 has two fuel filters, one forward ahead of the elec.fuel pump on the frame rail and the other is further back on the frame rail under the transfer skid plate referred to as a "reservoir" which has a hockey puck style filter inside and the kit and O ring costs around $ some Broncos have two fuel filters with a reservoir which does not need servicing so make sure you know which one you have.....any issues with my reservoir top/cap which has spring loaded stems and tiny o'rings the vehicle won't run as fuel will not travel any farther up to the rail.

There is one other possibility which could be your ECT sensor = engine cooling temp sensor located in a hex riser threaded into the lower intake manifold is a fule manager at cold start so any issues with that could result in a no engine start.

If it's just about idle then check and clean your IAC = idle air control valve located on the right side of the throttle body. When the engine is up to normal temp unplug it and if the RPMS drop then you're good to go OR unbolt it fom the TB but leaving it connected to the harness, turn the key to RUN only and watch for movement extra pair of hands would be lol...

You can test fuel pressure with a guage on the FPR = fuel pressure regulator located on the fuel rail drivers side, 37 psi engine cranking only and 40 psi engine running with the vaccum line disconnected..

Good Luck ~ :thumbup
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