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Alright, last night the truck stopped running...
I checked everything today and the gas goes through all the lines, pump and filter, gets to the carb and allows it to run for a little while(20 seconds at most) and then it just dies... Pumping the gas a LOT keeps it running horribly for a little longer but then it dies just the same.
I don't know what to do really, just looking for suggestions.

I have 2 other hitachi carbs and 1 weber, but the weber is set up for the other side of the engine, not sure if that would be useful.

I already switched to one of the other hitachi carbs and still does the same thing... The other needs bowl cover and gaskets.

Any suggestions would be great, this is my only vehicle and I need it running...

Sounds to me like it's possibly a weak fuel pump, low volume, can't keep p with demand. Or a terribly clogged filter. On mine the electric pumps right down by the tank. Might disconnect line to carb and aim into a clean container, protected skin and eyes of course, and see what kid of volume it kicks out with key turned to 'Run' position. If it's weak then check the fuel filter for blockage.

I replaced the fuel filter and am now using the fuel pump off my parts truck. I have a weber hooked up now and it's still doing the same thing... I did pump into a bottle and found that there was some water in the gas. Put some gas dryer in there and still the same problem. Any other suggestions?

I am new to this site and am in no way a LUV expert but I did have this problem with an old blazer I had one time. I didn't want to beleive there was "enough" water in the line to make it respond that way so I disconnected fuel line from the fuel pump, attached a short piece of fuel line to the pump and put the other end in a gas container I had placed in front of the bumper on the ground. I think I might have even used a whisper of ether to get it to start but after that the engine ran just fine. I siphoned out as much gas as I could out of the fuel tank, FILLED it as full as I could with new gas and a couple bottles of gas dryer (Heet I think) and things were back to normal. This might sound primitive but hey, it worked. Good luck.

Karl

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In life there is the "Way things should be" and then "There's the way they are".

2005 Silverado 3/4T Crew Cab
1981 Luv 2WD
1979 Luv 4x4 Currently going through Open Heart and Cosmetic surgery
1995 Roughneck JetBoat
1981 Luv parts trk

I just had a very similar problem with mine, after it sat for 2 years waiting on a rear differential/axle installation. My truck is a 1980 model 4x4 Mikado, 4spd manual. Once we got the rear end in place, went out for a test drive, and no dice......would run not even a minute, then die just like you cut the switch. I had noticed over the last few months that when I'd start the truck to keep the battery up, it would act like this. I replaced fuel pump, found a bad fuse and replaced that, replaced fuel filter, alternator tested bad, so I replaced it.....still did the same thing. Out comes the manual and we study up on the electrical system. The fuel pump circuit is set up so that initially it has to be in ignition mode to run, that is pump fuel to the carb. Once the motor is running and the key is in the "on" position, the fuel pump continues to run, but if the motor dies, the fuel pump cuts off, even though the key may still be in the on position. What was happening is that when the key was in "ignition" position, the fuel pump was working and filling the bowl of the carb with gasoline, but when the key went back to the "run" position, the fuel pump was cutting off. The engine would run until all the gas in the bowl had run out, and then it would die. After much more trouble-shooting, we found a wire inside the voltage regulator that had broken.....we soldered that back together, and it now runs like a champ. It was a very convoluted way to get to the root of the problem, but I definitely learned a lot about the electrical and fuel systems through the process.

Good luck fixing the problem. Hope this helps.

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1980 LUV Mikado 4x4, 155K, stock

VERY interesting, mootsman, and some first class troubleshooting there! I gotta write that down somewhere...

That gives me hope, because I'm all out of options. Unfortunately, I don't know what or where a voltage regulator is... Can I find a manual or something in pdf format? My truck is a '78 with an '80 engine

thanks guys

EDIT
I found the voltage regulator and everything appears to be connected properly, inside and out... I don't have any other ideas...

Good post mootsman, a good explanation. I bet it was the white/with red stripe wire from the regulator.
Don't ask me how I know.

I would use at least a quart bottle and let fuel pump run until it's at least 1/2 full, to see if flow is strong and constant.

Also I'd drain the tank, because the water is always on the bottom. Then refill with fresh gas, plus some denatured alcohol, like a couple of pints at the least. Alcohol is gas drier, absorbs 50% of its own volume of water.

If you only added gas drier then you never got the water out of fuel lines, could be that's the problem, with water in bottom of float bowl now.

If you have changed carbs then that eliminates mechanical carb issues, except for water residue in bowl. Check all vacuum lines closely looking for cracks. Outside chance it could be the coil, too. Inspect ignition under cap and check points gap also, and look for carbon tracks inside of cap.

Status Report:

Ok, so basically this is what I know.
NOT carb problem
When the key is in the RUN position, fuel pump IS NOT ON
When the key is in the START position, fueld pump IS ON
I have tried two differnet ignition
I'm pretty sure there is no more water in the system...
I've inspected the voltage regulator and everything seems fine, I might buy a new one anyway
I'm going to put the original carb back on

Another Status Report:

I was testing power on the line to the fuel pump just to be certain that nothing was happening and found that there is indeed power through the line when the key is in the START position but there is not power when the key is in the RUN position... so, would that point to voltage regulator? I'm depending on you guys right now because I have no knowledge of such things and can only guess. I could try and find a cheap mechanic but I'm pretty pressed for cash right now...

Thanks guys
Here's my number if you have an epiphany or something: 541-337-2357
My name is Caleb

The fuel pump gets power when the key is at START, but when the key is at RUN the fuel pump only gets power with the motor running. If the motor stops spinning the fuel pump will not have power. If you can get the motor to stay running long enough to test and find there is still no power to the fuel pump then it could be the alternator, voltage regulator, or the fuel pump relay. You can fill the carb bowl up with fuel and it should run long enough to get power to the pump tested.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Like what 800xl says. Once the engine is running and the alternator starts charging, it closes a relay inside the voltage regulator, which then sends power to the fuel pump relay ( which is under the cover on on the passenger side fender), this then powers the fuel pump. If engine stops fuel pump stops.
BTW all this is mandated for safety in case of an accident.

Alright, I bought a new voltage regulator and now it runs! I ran it down the street a bit and it died on me, I was still clipping along so I just let the clutch out and it came right back to life. If it still dies, would that indicate a possible problem with the alt? I have another that I know works... Maybe I should just get a charging system test, I think les schwab does them. Anyway, I think the voltage regulator was definitely the main problem.

Thanks for all your help

fuel pump is powered by a relay under a metal cover on passengers side. It is notorius for failing. It is powered by the alternator. They are not available but autozone has one that will work. Wiring is different. search my name for wiring info.

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1980 Luv 4X4
another 1980 luv 4x4

so...i lied, truck still wont stay running, apparently that was just a random time that it worked.
I don't really have a ton of money right now, so im gonna describe exactly what happens and see if anybody can verify that it's the relay (or anything else).

* I start the engine now and it starts right away most of the time, sometimes I have to try 2 or 3 times before it starts.
* It stays running as long as it's sitting still (on flat ground)
* It dies randomly while driving, it's obviously a fuel shortage issue.
* sometimes flooring it will keep it running (even if i'm going 10mph)
* It seems like blockage in the line somewhere...but it would have to be something floating in the tank that randomly clogs the line because there is nothing in the actual lines.

So, relay or clog? Also, the relay cover screws are rusted like crazy... I might have to grind them off

Just a susgestion to check out your problem, at its cheep if not free.

On the passenger side of your firewall there are a couple of multi wire plugs going to the back of the truck. I would try splicing a wire from a toggle switch (fused of corse) and drive around to see if it acts up. If not you know you have a relay or wire problem. I will link you to the wiring diagram.
http://www.luvtruck.com/PDF/Series8.pdf

This is from a 78, not sure of your year. Go down to the second page of the diagram and look for the wiper moter, right above that is the connection. On terminal #1 is a black/yellow and a red wire going into the connector and it leaves the connector as a black/red wire, splice into that one.

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Certified pilots, looking down on people since 1903.

Correct me if I'm wrong, but don't relays only go fully bad? I didn't think they could go periodically bad, or partially bad...

They do go bad intermitently, I have seen it too many times.

_________________
Certified pilots, looking down on people since 1903.

Some random thoughts:

Just because it allows engine to run occassionally that doesn't mean the carb is okay. A sticking or misadjusted float will cause exactly what you describe, because float bowl may only fill enough to allow a short period of operation.

Just because fuel pump does pump some fuel doesn't mean it pumps enough fuel to supply the engine under load. Also a clogged fuel filter may allow enough fuel to pass into carb bowel but not enough to run the engine.

A clogged fuel line might allow just enough fuel through to fill bowl slowly but not enough to supply engine under load.

You'll have to trace/test all the electrical related to fuel anyway, to insure reliable operation, so that's the other place to look.