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Troubleshooting fuel pump (Gen2.5 Montero)
#1101628
06/29/16 05:43 PM
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Joined: Oct 2015
Posts: 13
OP
Need a Spot
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I bought a '99 Montero, not running. It's a long story (isn't it always?), but I'm thinking it's a fuel pump. I'm going through the process to check, but I've never worked on a Montero, and I'm having some trouble finding stuff.
First, the manual says there is a terminal to which you apply power and test the fuel pump. There is a really bad drawing of it, and no description of where this terminal actually is. Best I can tell from the drawing, it should be on the firewall, but I can't find it. Am I looking in the right spot?
Also, I want to test the fuel pump relay. From what I've read it is located behind the inside kick panel on the right side front foot well, in front of the door speaker. I pulled the panel off and found what appears to be an ECU (transmission?), not the relay that I saw in a couple pics. Am I looking in the right spot for this as well?
Any input appreciated.
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: Mudpie]
#1101642
06/30/16 04:05 PM
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Joined: Mar 2005
Posts: 1,006
Body Damage is Cool
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Do you have spark? If no spark then computer may not allow fuel pump to operate. I'd check spark first.
92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: Mudpie]
#1101645
06/30/16 06:41 PM
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Joined: Jan 2000
Posts: 16,227
Web Wheeler
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Did you try to listen for the pump by opening the Fuel filler tube?
That's the first thing I'd do.
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: Mudpie]
#1101669
07/01/16 06:21 PM
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Joined: Oct 2015
Posts: 13
OP
Need a Spot
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Just an FYI, my computer has fried the motherboard, and I haven't got a new one yet. I'm using the computer at the library, and there's a time limit. As such, my ability to search for answers is limited. Sorry in advance if I'm asking something that should be easy to find.
This is where I'm at...
I found the fuel pump test terminal. It was kind of where the drawing in the manual showed it to be, but it was buried in the wiring loom. Applied power to it, and no fuel pump.
Pulled the tank access panel, pulled the plug off the pump and applied power directly and it seems to work. I have no idea how much pressure it's making since the '99 Montero has no Schrader valve on the fuel rail.
Checked for spark, with new plugs. Pulled #1 since it was easiest to get to. There was a spark arcing between #1 and #5 on the coil pack. Pulled the #5 wire off the coil pack and the arcing stopped, but I never got a spark at #1.
I tried reading through the manual online, but due to my time limit I didn't get too far. From what I've read the fuel pump/MFI relay controls both the fuel pump and power to the ECU, so a bad relay would explain my current problem. When I bought it, the previous owners daughter said "it just stopped" when she was driving it.
My current issue is getting to the relay. It's buried in the dash, with no obvious way to get to it. I can see it, but can't even get a finger on it, let alone unbolt or unplug it. Do I have to pull the dash to get to this stupid relay?
Any thoughts appreciated. I wanna go wheelin'...soon!
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: Mudpie]
#1101670
07/01/16 06:57 PM
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Joined: Mar 2005
Posts: 1,006
Body Damage is Cool
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Checked for spark, with new plugs. Pulled #1 since it was easiest to get to. There was a spark arcing between #1 and #5 on the coil pack. Pulled the #5 wire off the coil pack and the arcing stopped, but I never got a spark at #1. Sounds like waste spark system, spark to two plugs whether they need it or not. I don't understand what/why you got, but research waste spark. Did you actually ground the plug with wire attached to see spark?
92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: pcc]
#1101671
07/01/16 08:18 PM
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Joined: Feb 2005
Posts: 1,511
Body Damage is Cool
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As stated above, have you already confirmed that the fuel pump is not working when you turn the key on?
95 Montero SR 3.8 MIVEC, Advance headers, 2 1/2" exhaust, Magnaflow muffler, OME shocks & rear springs, 2" body lift, 3" tank lift, 4.90s, TRE front locker, factory rear locker, Roger Brown Rock Sliderz, 315/75r16 (35") tires, Sport big brakes
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: Mudpie]
#1101683
07/02/16 02:57 AM
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Joined: Oct 2015
Posts: 13
OP
Need a Spot
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Well, I thought I had confirmed. I'm using a crappy test light. I bought a decent meter and checked again and I am getting power to the fuel pump when I crank the motor.
I'm still not getting any spark though. I did ground the plug, and moved the wire to each of the 3 coil packs to check. No spark anywhere.
I had considered just spending the $23 for a new relay when I thought that was the problem. Good thing I can't get to it I suppose or I'd be out 23 bucks. Right now I'm thinking ignition module maybe, but I'm definitely not spending $130 to get one on a hunch. I hate diagnosing by simply throwing money at something.
I'll hit up the library tomorrow and see what I can find for any further testing info, but I'm open to suggestions. As I said, I've never worked on one of these. I'm a Volvo guy. Their little problems and common issues I'm pretty familiar with. The Montero, not at all.
Thanks for the help. I appreciate any input.
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: Mudpie]
#1101684
07/02/16 10:43 AM
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Joined: Mar 2005
Posts: 1,006
Body Damage is Cool
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I did ground the plug, and moved the wire to each of the 3 coil packs to check. No spark anywhere. You'd have to check from the coil pack primary volatge back. I'm not familiar with your system but the basics are the same. Primary voltage switches on/off to coil. The computer switches the voltage, usually by ground switching as positive voltage is constant connection.
92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: Mudpie]
#1101689
07/02/16 09:43 PM
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Joined: Oct 2015
Posts: 13
OP
Need a Spot
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I managed to get the entire electrical section of the factory manual printed out. Hopefully that will have all the procedures for testing. Hard to have confidence though when the factory manual advises in the ignition troubleshooting section to check the coil and distributor.
The vehicle has multiple coils, and no distributor. Great publication Mitsubishi.
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Re: Troubleshooting fuel pump (Gen2.5 Montero)
[Re: Mudpie]
#1101690
07/02/16 10:07 PM
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Joined: Mar 2005
Posts: 1,006
Body Damage is Cool
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Going back to your description of the arc between coil connections. Check for cracks in the coil pack.
92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
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