• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

1986 2.9 Not Running Right


jchris36

New Member
Joined
Aug 21, 2013
Messages
23
Reaction score
0
Points
1
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Explorer
Engine Size
2.9L V6
Transmission
Manual
I've been experiencing this for about 3 months now and I'm really not sure what else to try. I've searched this site many times and read dozens of different threads, and still can't figure out the problem.
The truck runs for about 45 minutes, but will then start to cut out, act like it's choked, and almost die. When it does this it smells like it's running really rich, and will idle really rough, barely running. If I let the truck sit for about 15 minutes it will run well enough to drive again, but still idling really poorly and running really rich with little power and acceleration.
Also, when it's doing this, the fuel pump won't prime correctly. I will turn the key to "run" with the truck off, and I can hear the pump buzzing really loud, but it doesn't shut off.
When the truck is running fine, though, the pump will prime the system and shut off after 1-2 seconds.

I know this is supposedly a common problem, and I've read the TFI thread and tech article, but I changed the TFI, had my old one tested (tested good) and the problem continues.
Before I tried the TFI I replaced the fuel pump in the front tank (truck has dual tanks) and on the rail, I replaced the fuel pump relay, the MAP sensor, and the O2 sensor.

I can't figure this out, and I don't know what to try next. But it's like clockwork, every time I drive it for more than 45 or so miles, it will cut out and want to barely run. If I let it sit overnight, it will run fine.

Anyone got any ideas?
 


RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,291
Reaction score
8,296
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
It reads like two issues, not one
The 45min/45mile issue could be fuel pump failing, I assume either fuel tank suffers this issue so it would have to be high pressure pump issue.

I assume you have changed the fuel filter.

The Dual Pump system(low pressure, high pressure) also has a "reserve canister" located in the frame rail between the 2 pumps, it looks like a canister fuel filter, and is, but it is there so the high pressure pump doesn't run dry when first starting the engine.
Picture in last post here: http://www.therangerstation.com/forums/showthread.php?t=108976
There should also be an inline filter between high pressure pump and engine, but not always.
If high pressure pump sounds louder than normal this reservoir may have reduced volume, clogged up.

The high pressure fuel pump running after 2 seconds and sounding louder than normal does present a problem, the louder part could be because reserve has run dry, and the reason the engine stalled, but that wouldn't cause it to run longer than it should.

The computer controls the fuel pump relay, the one with the GREEN base(BROWN base is EEC relay), this relay's coil gets 12volts when key is on, but the Ground for the coil is the computer(pin22), so relay is computer controlled.
If relay stays closed(fuel pump on) after the 2 seconds then computer is grounding it or there is a shorted wire grounding the coil.
Computer monitors RPMs(from TFI pulses), if RPMs are below 500(approx.) the computer unGrounds the fuel pump relay, this is a safety shut off.
When you first turn on the key the computer turns on(grounds) the fuel pump relay then runs self checks and checks the RPMs, usually this takes about 2 seconds and computer unGrounds the relay if RPMs are less than 500.

You have replaced the GREEN base relay, so that only leaves the wire to computer and the computer itself that is at fault.

On the drivers side of engine bay by the firewall there should be a VIP/OBD connector, have also seen these on passenger side.
This connector has a jumper slot to manually Ground the Fuel Pump relay, it is spliced to the computers pin22 wire.
Look here for which slot in the connector it is: http://www.therangerstation.com/tech_library/OBD_I.shtml

You can use a jumper wire from that slot to ground to activate(close) fuel pump relay, key needs to be on.

But you can also test if that slot is grounded when it shouldn't be.
You need to unplug the fuel pump relay from the GREEN base.
Then connect OHM meter from the slot in VIP connector to Ground
When you turn on the key you should see 0 ohms as the computer Grounds pin22 then after 2 seconds the ohms should go up very high or even show N/C(no connection).
Now wiggle the wires in the engine bay around, see if ohms drop to 0 again showing a short to ground on that wire.


I would also check the Fuel Pressure regulators(FPR) Vacuum Hose, it is on the lower intake and connects to the Fuel Rail and Return fuel line.
Remove the vacuum hose and check it for Fuel or Fuel smell, replace FPR if fuel is present.
 
Last edited:

jchris36

New Member
Joined
Aug 21, 2013
Messages
23
Reaction score
0
Points
1
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Explorer
Engine Size
2.9L V6
Transmission
Manual
It reads like two issues, not one
The 45min/45mile issue could be fuel pump failing, I assume either fuel tank suffers this issue so it would have to be high pressure pump issue.

.....

If high pressure pump sounds louder than normal this reservoir may have reduced volume, clogged up.

Thanks so much for the reply. Really appreciate it. I changed the high pressure pump on the rail, I put in a pump from RockAuto about 2 months ago, but it was loud (probably due to the reservoir that I didn't know about) and the truck wasn't running right still, so I bought a pump with a lifetime warranty from OReilly's and put that in, but same issue, it's still loud and the truck still runs rough after heating up.

Okay so if I pull off the reservoir, what am I looking for? Would it just have run dry? It's best to just replace it I'm guessing?
I bought a fuel filter, but couldn't find one in between the high pressure pump and the engine.
I've also pulled the hose off the FPR multiple times and it doesn't smell at all like gas.
 

RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,291
Reaction score
8,296
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
In 1986 some had filters in them some didn't, and had a fuel filter between high pressure pump and engine, which you said yours doesn't.
So you reservoir should have a filter in it, remove the cap and replace the filter with a new one.

Good look here: http://www.therangerstation.com/forums/showthread.php?t=106064

This LMC page shows both types, with filter, shallow, and without filter, deep: http://www.lmctruck.com/icatalog/fr/full.aspx?Page=38#

It shows that is fits 1985-1989 Rangers

I also found Ford part number FOTZ-9K044-A is says it fits 1987 to 1991, that look similar
 

jchris36

New Member
Joined
Aug 21, 2013
Messages
23
Reaction score
0
Points
1
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Explorer
Engine Size
2.9L V6
Transmission
Manual
Okay so I got the canister fuel filter replaced, and that quieted the pump down a lot. Sounds normal now. But the truck still idles awful, and is really rich.

But what's really strange is the pump won't prime, it doesn't shut off. I read through what you commented about testing the computer as well as the relay, and also jumping the OBD port, and I tried to jump the OBD Port with no success, nothing happened, the pump remained on.
But I'm not exactly sure what you meant by port 22 on the computer. I took off the kick panel on the passenger side of the cab, covering the computer, then unbolted the bolt that basically plugs all the wires and pins into the PCM, but even using the wiring diagram in my Chilton I couldn't tell which port was 22... there were 3 rows of pins. I honestly don't really know much about electrical diagrams though, but it showed like there were only going to be two rows coming off the computer in the diagram.
If you could explain what I need to do in simple terms I'd really appreciate it.

But basically if I'm understanding you correctly; when the fuel pump isn't shutting off, it's because of a bad ground coming from the computer? What would a solution be to this? trace the tan wire coming from the computer all the way to the fuel pump relay and see if it's grounding out somewhere?

Thanks
 

adsm08

Senior Master Grease Monkey
Supporting Member
Article Contributor
Ford Technician
TRS 20th Anniversary
Joined
Sep 20, 2009
Messages
34,623
Reaction score
3,613
Points
113
Location
Dillsburg PA
Vehicle Year
1987
Make / Model
Ford
Engine Type
4.0 V6
Engine Size
4.0
Transmission
Manual
2WD / 4WD
4WD
Tire Size
31X10.50X15
Ok, so I read through all of this, I think I retained most of it.

From what I have read you do have an issue with the fuel pump running too much causing the engine to run rich, and you have already replaced the relay. But you are having trouble identifying the correct pin at the computer for testing.

Pin 22 at the PCM connector, if you hold the connector so the two plastic protrusions at the ends face down it is the second pin from the left in the middle row. I like this picture:



I personally would not try to trace or wiggle test that wire, because it's possible to miss the problem. Just overlay it. Cut the wire as close to it's ends as you can and have enough room to splice, then run a new wire.
 

jchris36

New Member
Joined
Aug 21, 2013
Messages
23
Reaction score
0
Points
1
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Explorer
Engine Size
2.9L V6
Transmission
Manual
Thanks so much that picture helps a ton. Okay thanks I will run a wire and see if that causes the relay to shut the pump off. Really appreciate it.
 

jchris36

New Member
Joined
Aug 21, 2013
Messages
23
Reaction score
0
Points
1
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Explorer
Engine Size
2.9L V6
Transmission
Manual
So I cut the wire and ran a new one, but no luck. The relay sometimes clicks but still just stays open and the fuel pump never shuts off when trying to prime. It's really strange, I can hear the relay clicking as if it's trying to close, but just can't. What else controls this relay? I know it's not a bad relay, I replaced it when this started happening.
 

jchris36

New Member
Joined
Aug 21, 2013
Messages
23
Reaction score
0
Points
1
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Explorer
Engine Size
2.9L V6
Transmission
Manual
Okay one idea... The EGR solenoid is making lots of noise, especially after i shut the truck off.. It's takes the solenoid about 15 seconds to stop humming after I kill the engine. Is there a chance that the EGR solenoid or EGR is bad and that the truck is not allowing itself to get any fresh air, and that's why it won't idle?
 

jchris36

New Member
Joined
Aug 21, 2013
Messages
23
Reaction score
0
Points
1
Location
Olympia, WA
Vehicle Year
1993
Make / Model
Explorer
Engine Size
2.9L V6
Transmission
Manual
Any thoughts?
 

Jfpepper

New Member
Joined
May 9, 2015
Messages
4
Reaction score
0
Points
0
Vehicle Year
1987
Make / Model
Ford
Transmission
Manual
do you have any problems driving up hills like the engine starts to feel sluggish and revs high but no power?
 

Sponsored Ad


Sponsored Ad

Staff online

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Truck of The Month


Kirby N.
March Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top