1999 FUSO FG USA model. 4d34t engine. Owned for 14 years. Has been extremely reliable. Had been sitting in storage for about 9 months (not unusual) and I tried to start it. Took longer than normal to start and won't rev up once started. (it will rev up to maybe 15-1600 rpms in neutral) Lots of diesel rattle and check engine light on. I tried 6 or 8 times. One time I held the starter engaged for longer than normal and it seemed to run right for 2-3 seconds before reverting to its non-revving condition. Exhaust is light gray as normal. No evidence of blockage of intake air. (but there is a butterfly in the intake manifold operated by vacuum whose role I don't understand). Turbo spins freely. How does the ignition key system stop the engine when it's turned to off? I have a suspicion it might be a problem in that system, maybe limiting fuel flow. I assume that system is electrical and a fault in that might trigger the check engine light? There is an emergency engine-off cable pull on the truck but I assume that is completely separate from the keyed system. I can see no evidence of broken or disconnected wires anywhere. I don't have a scanner to check the code on the check engine system. Most of the engine is mechanical so there must be a limited number of conditions which would set off the check engine light. That's one of the reasons why I think it might be in keyed on/off system.
99 FG Starts, runs rough, won't rev up
- Thread starter kerry
- Start date
SkiFreak
Crazy Person
You should be able to access the error code/s by using the blink code method on the dash.
That will give you a much better starting point, opposed to making assumptions.
If only I know how to access that blink code. Do you know? I know there's an access point for a scanner in the passenger kick well somewhere (I've seen it once) and I did read years ago that blink codes can be initiated but I don't think I've ever read how to initiate them.
Does anyone know if this is the correct procedure to get blink codes on a 1999 FG USA model? https://www.fcarusa.com/TechSupport/FAQ/mitsubishi-fuso-accessing-diagnostic-trouble-codes
Got the diagnostic code figured out. On right hand side there's a large panel with the windshield washer fluid container on the back side. Release its latch and it will drop down exposing the blower motor. To the right and bottom of the blower motor is the diagnostic connector. Associated with it are two other connectors. One labeled Memory Clear and the other a single wire in a round connector labeled Diagnostic Check. Disconnect that one and the code will flash. It's flashing 1 1 2. Not exactly sure what that means but it apparently doesn't correlate directly to trouble code 112. I am looking at a manual which suggest 1 1 flashes correlates with trouble code 191-193 which indicates a fuel pressure problem. I'm going to search further but if it really is a fuel pressure code then that does suggest that my initial diagnosis of a problem with the fuel shut off solenoid could be correct. I haven't identified the shut off solenoid conclusively but there is an electrical component on the back of the IP directly above the manual lever shut off mechanism so I suspect that this the shut off solenoid. Although oddly, it has a large bundle of wires going to it. I would have expected only a couple of wires to a solenoid.
Made some progress. The wires coming from that electrical device in the back top the IP above the manual shut off lever split into two connectors (actually visible in the photo if you look closely). One bundle has about 8 wires and the other three. I'm making a guess that the three wire connector controls the fuel shut off solenoid and the larger bundle provides data to the ECM. So I disconnected the 3 wire bundle at the connector about a foot from the IP. With the key on I'm only getting 5.36 volts coming to that connector. I'm assuming it should be getting 12+ volts. (if you know otherwise or know of some aspect of the ECM which operates at 5.36 volts let me know). Now it's not starting at all, I presume as a result of not getting any fuel. No idea at the moment what is causing that voltage drop, if indeed it should be at 12 volts. Maybe dirty connectors in the ignition switch. Starter is getting 12.57 volts and operates well. It's also not clear to me why, if that connector/wires does control the fuel shut off solenoid, it has 3 wires and not just 2 wires. Most solenoids I'm familiar with use just two wires.
soaringpotato
New member
Can you take a picture of your injection pump?
SkiFreak
Crazy Person
Before spending any money on replacement parts, take a step back and do some basic checks.
Some simple fault finding should be the first place to start.
You mentioned that the truck has been sitting for an extended period, therefore there is a possibility that there may be some corrosion or sticky parts.
As has been mentioned on this forum many times before, Fusos have issues if the grounds are not making good contact. Start by undoing all of the earth contacts and cleaning them.
Another possibility is that you have a sticky solenoid on your injector pump, or a poor electrical connection to the solenoid. Check all of the plugs and enure that there is no corrosion.
There is a small strainer in the fuel line that connects to the injector pump. This has been known to cause fuel starvation issues. Make sure it is clean. (look in your manual to find its location)
Some simple fault finding should be the first place to start.
You mentioned that the truck has been sitting for an extended period, therefore there is a possibility that there may be some corrosion or sticky parts.
As has been mentioned on this forum many times before, Fusos have issues if the grounds are not making good contact. Start by undoing all of the earth contacts and cleaning them.
Another possibility is that you have a sticky solenoid on your injector pump, or a poor electrical connection to the solenoid. Check all of the plugs and enure that there is no corrosion.
There is a small strainer in the fuel line that connects to the injector pump. This has been known to cause fuel starvation issues. Make sure it is clean. (look in your manual to find its location)
Looks like I may have figured out the three wires. The solenoid likely uses two magnets, a high power, high amperage magnet to engage the solenoid and a lower power lower amperage magnet to hold it open. At least that appears to be the kind of system a Cummins diesel uses.—-edit. This is incorrect
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My pump looks identical to the picture I posted above.
soaringpotato
New member
Are you looking for help to troubleshoot the issue? Those pictures are meaningless. Let's look at your injection pump. Snap some photos and upload. Otherwise it's very difficult to help out a fellow Fuso owner.
I'm fairly sure the fuel is flowing adequately as I unscrewed the primer pump and tried pumping and it's firm. It also leaked some fuel when I unscrewed it so I know it has fuel up to that point. I also know the chassis to engine ground appears to be fine since I measured voltage to the starter terminal and to the solenoid connection (at least what I'm taking to be the solenoid connection) and I'm getting 12 volts at the starter but only 5 on the solenoid connector. I think there may be a relay in the system somewhere to power the solenoid. I need to find it and check it. It's not impossible that a rabbit or rodent chewed a wire somewhere. My daughter's car was parked in a storage area a few miles from the truck and it had wires eaten by a rabbit. I did a quick scan of the wiring harness and saw no rodent damage but I may not have looked closely enough.
I don't follow. Why are they meaningless. The truck is 10 miles away and I took pictures of various parts but not the whole pump. The whole pump pictured above is identical to mine. There are other pictures of other kinds of pumps used on the 4d34t engine that are not identical to mine. The one pictures above is identical in all the details.