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1992 Explorer. Fuel pump or MAF

AGodlyCanuck

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City, State
Nelson, BC. Canada
Year, Model & Trim Level
1992 Explorer 4dr 4x4 XLT
So, had some. weird shit happen going up a service road. IE. no power going uphill. when giving it the beans, turned down to. go. back. down cos check engine light came on. rough idled, then died.

it would turn over but I wouldn't hear the fuel pump. eventually for it started after beating on the pump from the access under the rear seat.

today I pulled these codes.

565: (O) Canister Purge 1 solenoid/circuit failure - Solenoids

185: (M) Mass Air (MAF) output lower than expected - Fuel control
186: (M) Injector pulse width longer than expected or Mass Air Flow (MAF) lower than expected - Fuel control
542: (O,M) Fuel pump open, bad ground or always on - - Power / Fuel Pump Circuits
 


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AGodlyCanuck

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City, State
Nelson, BC. Canada
Year, Model & Trim Level
1992 Explorer 4dr 4x4 XLT
Fuel pump relay would be my first move, swap it with a known good one, like the blower relay next to it.

Ill have to Google that as I have no idea where that one would be lol
 




LG57

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City, State
Katy Tx
Year, Model & Trim Level
1993 Explorer Sport
Your power distribution box is under the hood. Passenger side just aft of the battery. Lift the lid and you'll see the relays. Under the lid is a diagram of what relay is for what., I think?
 




ddenton749

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City, State
Kennett Square, PA
Year, Model & Trim Level
'93 XLT
So, had some. weird shit happen going up a service road. IE. no power going uphill. when giving it the beans, turned down to. go. back. down cos check engine light came on. rough idled, then died.

it would turn over but I wouldn't hear the fuel pump. eventually for it started after beating on the pump from the access under the rear seat.

today I pulled these codes.

565: (O) Canister Purge 1 solenoid/circuit failure - Solenoids

185: (M) Mass Air (MAF) output lower than expected - Fuel control
186: (M) Injector pulse width longer than expected or Mass Air Flow (MAF) lower than expected - Fuel control
542: (O,M) Fuel pump open, bad ground or always on - - Power / Fuel Pump Circuits

Check the connections at the fuel pump relay and at the fuel pump fuse. It doesn't take much corrosion to stop the fuel pump.
 




AGodlyCanuck

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1992 Explorer 4dr 4x4 XLT
okay, so km going to replace the fuel pump and filter tomorrow.

however there is a new issue..
in the mornings it doesn't want to idle, it will die..
unless I hold the rpms up.
after about 30 seconds of that it will run fine.

how about that?
 




ddenton749

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'93 XLT
okay, so km going to replace the fuel pump and filter tomorrow.

however there is a new issue..
in the mornings it doesn't want to idle, it will die..
unless I hold the rpms up.
after about 30 seconds of that it will run fine.

how about that?

I'm a little confused. Is the car running? I had a 93 explorer for 23 years. I put over 400k miles on it. In all that time I had the fuel pump go bad once. Any other fuel pump issue was related to poor electrical connections at the relay and the fuse. Make sure you check all of those connections before you replace the pump. Use electrical contact cleaner and a small brush.

For the cold engine issue I would look at the engine coolant temperature (ECT) sensor first. Make sure PCM knows that it is seeing a cold engine. If my memory serves me, it will have higher resistance when cold. The resistance will drop as the coolant gets hot. I have heard of people checking them in their kitchen. They remove the sensor measure the resistance when cold then put it in near-boiling water. The resistance should be lower.

Next I would check the Idle Air Control Valve (IACV). It is possible that it is not working at all and the engine is idling on the idle screw. When the engine is warm, unplug the IACV. The idle should drop and it might stall. If that happens the valve is likely good. If the idle doesn't change the valve or the electrical connections are bad.

Do you have a Break Out Box? They are incredibly useful for checking these things.
 




AGodlyCanuck

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1992 Explorer 4dr 4x4 XLT
the vehicle does run, yes.

but which sensor is the ECT.
there's two temp sensors within like 4" of each other.
 




ddenton749

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the vehicle does run, yes.

but which sensor is the ECT.
there's two temp sensors within like 4" of each other.

If the car runs your fuel pump is good.

One sensor is for the temperature gauge. It is the smaller of the two and has one wire. The ECT is almost directly under the throttle body behind the serpentine belt. It has two wires. Use caution when removing the connector. The plastic in these connectors gets old and is easily breakable.
 








ddenton749

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'93 XLT
If I can ask, what made you jump to replace the fuel pump? I mean, if you want to do it, if you have the money and time, or you already have the parts and just want to do it to rule it out, that's fine... I do that sometimes.

AGC: Replacing the fuel pump is an enormous PITA. You have to remove the fuel tank. It is not something you want to do if you don't have to. But...

...If you are going to drop the tank there are a couple of other things you should do while it is out:

1. Replace the steel brake line to the rear brakes. Trust me on this one.
2. Make sure the steel EVAP line isn't rotted. Replace it if necessary.
3. Paint the frame and body behind the tank.

These are things that you can only do with the tank out. These lines run along the frame behind the tank.
 




AGodlyCanuck

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1992 Explorer 4dr 4x4 XLT
If I can ask, what made you jump to replace the fuel pump? I mean, if you want to do it, if you have the money and time, or you already have the parts and just want to do it to rule it out, that's fine... I do that sometimes.

when it was stuck up the back road I would try to crank it over and I couldn't hear the fuel pump and only would crank over after I beat it with a screwdriver
(there's an access under the seat)
 




AGodlyCanuck

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1992 Explorer 4dr 4x4 XLT
If the car runs your fuel pump is good.

One sensor is for the temperature gauge. It is the smaller of the two and has one wire. The ECT is almost directly under the throttle body behind the serpentine belt. It has two wires. Use caution when removing the connector. The plastic in these connectors gets old and is easily breakable.

you think that sensor would cause it to idle poorly and die?
I also did consider the IAC valve
 




ddenton749

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you think that sensor would cause it to idle poorly and die?
I also did consider the IAC valve

The ECT can cause the poor idle condition when cold. The engine doesn't see a cold engine so it doesn't increase the fuel ratio. When it gets warm the engine doesn't need rich fuel. Without the ECT the PCM will stay in open-loop mode. It will use look-up tables to set the air-fuel ratios instead of using actual readings (closed-loop). This will result in lower fuel economy and possibly performance issues.

Still, check your IACV. A non-functioning valve can cause the same issue when cold. It won't increase the air flow into the manifold to raise the idle speed when cold. The bad IACV can cause poor idle because it is not adjusting the bypass air around the throttle plate to control idle speed. There is an adjusting screw on the throttle just like a carburetor had. It is for when the PCM see serious enough problems to go into failure mode (limp-home mode). Disconnect the IACV while the engine is idling hot. The RPM's should drop and it might stall. If it doesn't, the IACV is not working. Check the connections first before you replace it. If you do replace it, buy the Motorcraft part, not the aftermarket. Sometimes the IACV will get dirty and clogged, especially if you have a lot of oil in your intake manifold and throttle body. (Common problem) You can try removing the IACV and cleaning it with throttle body cleaner. Make sure the passages in the intake are clean.

Another common problem is a dirty MAF, especially if you have the heavy oil condition I mentioned above. Remove the MAF from the MAF body and clean it using MAF cleaner. You will likely need the special tool to remove the tamper-proof screws. Clean the wires carefully and make sure the passages aren't clogged.

One more thing: Check the plastic tube between the MAF and the throttle body. They tend to crack in the accordion area causing vacuum leaks.
 




AGodlyCanuck

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1992 Explorer 4dr 4x4 XLT
after work I took a video of the startup.
except this time it didn't stall out and die, it almost did. I put it in drive and idled it against the curb to add a load and still didn't stall. So yeah, I'll check that sensor tomorrow, check the IAC valve but I'm also wondering if it's a vaccum leak somewhere.


this morning when it started it was 2°c (35°f)
after work it was 12°c (53°f)

 




Kain316

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91 explorer xlt 4x4
I would just replace the temp sensor and sender. It's about 20 bucks. You're going to be right there anyway do remove the IAC and take it apart. Clean it very carefully with carb cleaner and a scotchbrite after cleaning the brass needs to be cleared using a paper towel and rubbing alcohol. Put everything back as you found it. Side note be very careful taking apart the IAC
 




Mr. Alligator

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it would turn over but I wouldn't hear the fuel pump. eventually for it started after beating on the pump from the access under the rear seat.

Do you have an access panel for your fuel pump???
 








AGodlyCanuck

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1992 Explorer 4dr 4x4 XLT

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AGodlyCanuck

Well-Known Member
Joined
June 13, 2018
Messages
191
Reaction score
67
City, State
Nelson, BC. Canada
Year, Model & Trim Level
1992 Explorer 4dr 4x4 XLT
The ECT can cause the poor idle condition when cold. The engine doesn't see a cold engine so it doesn't increase the fuel ratio. When it gets warm the engine doesn't need rich fuel. Without the ECT the PCM will stay in open-loop mode. It will use look-up tables to set the air-fuel ratios instead of using actual readings (closed-loop). This will result in lower fuel economy and possibly performance issues.

Still, check your IACV. A non-functioning valve can cause the same issue when cold. It won't increase the air flow into the manifold to raise the idle speed when cold. The bad IACV can cause poor idle because it is not adjusting the bypass air around the throttle plate to control idle speed. There is an adjusting screw on the throttle just like a carburetor had. It is for when the PCM see serious enough problems to go into failure mode (limp-home mode). Disconnect the IACV while the engine is idling hot. The RPM's should drop and it might stall. If it doesn't, the IACV is not working. Check the connections first before you replace it. If you do replace it, buy the Motorcraft part, not the aftermarket. Sometimes the IACV will get dirty and clogged, especially if you have a lot of oil in your intake manifold and throttle body. (Common problem) You can try removing the IACV and cleaning it with throttle body cleaner. Make sure the passages in the intake are clean.

Another common problem is a dirty MAF, especially if you have the heavy oil condition I mentioned above. Remove the MAF from the MAF body and clean it using MAF cleaner. You will likely need the special tool to remove the tamper-proof screws. Clean the wires carefully and make sure the passages aren't clogged.

One more thing: Check the plastic tube between the MAF and the throttle body. They tend to crack in the accordion area causing vacuum leaks.

the ECT and MAF have been replaced.

and here's the IACV

 

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