LUVTruck.com

I'm having problems with my beloved two-tone (blue & rust) 1978 LUV pickup and I'd greatly appreciate any help, information, advice, counsel,--and at this point, sympathy! I'm also unfortunately not a mechanic.

Problem: it runs for 30 to 60 seconds and then just dies. Pumping the accelerator does not make any difference. But it will immediately crank up again for another 30 to 60 seconds only.

Background: after a tune-up about 3 months ago it was running fine. The tune-up was points, condenser, and distributor cap. Then gradually it started quitting at stop signs and at traffic signal stops. I'd just start it up again and it would run. Then two weeks ago it suddenly quit while I'm driving. I immediately was able to crank it up again and after 30 to 60 seconds it would die again. And so on.

[Full disclosure: this happened the day after I returned from a 320-mile trip. I used the wipers the full time on the return trip. I also discovered that after having added a quart of oil before leaving I'd apparently not put the oil cap back on (duh!) and there was oil blown about in the engine compartment. Whether or not any of this part is relevant I don't know.]

I've done this: Put in a new fuel filter. Put in a new fuel pump. Blown through the fuel line. Unhooked the fuel line from the carburetor, held the hose while someone cranked the engine and observed gas come out. Looked at the wire mesh fuel filter in the carburetor, it seems unclogged. Checked all 6 fuses in the engine compartment, 2 would not blow the horn. I replaced all 6. Hooked up a new Ignition Coil, problem did not change. Installed a new condenser, problem did not change.

Some other weird things are also happening. Sometimes the Seat Belt/Oil/Gen lights come on, sometimes they don't (although they have so far come on every time since I changed the fuses). Sometimes the Radio and Wipers work, sometimes together they don't. The resistor cover on the ignition coil sometimes got very hot, recently it hasn't.

I suspect there may be an electrical aspect to the problem, but just don't know. I got a copy of the wiring diagram (from this site, thank you very much!) and am wondering about, among other things, the fuel pump relay and the solenoids on the carburetor. And reading this bulletin board I see reference to an "electric cut-off" for/to/in the carburetor. Or could it be something completely different, like the wiper motor(s)??

At the same time, it may not be electrical at all, I just don't know. Could it be the carburetor? Air leaks? Other?
---
Does anyone have any ideas?
Where can I get an Owner's Manual? A Shop Manual?
What Haynes Manual(s) do I need?
What Chilton Manual(s) do I need?
Other Manuals?
Websites?
---
Thanks, Charles Lewis, Tallahassee Florida (Sorry, I have no email, I'm doing this at the Public Library.)

Try checking the fuel float level on the carb.Mine would also run for only 30 to 60 seconds.Once I adjusted it ran for more than ten minutes.

_________________
1975 V8 Luv
1980 Bagged Luv

It sounds like the fuel pump is running only when the key is turned to start the truck. It gets just enough time to fill the bowl on the carb, and then it quits. Normal behavior for the pump is to run when cranking it over, but not when the key is just in the on position unless the motor is running. The source of the problem is either the fuel pump relay or what drives that, which I believe is the voltage regulator. (Someone correct me if I'm wrong there.) Try jumping the fuel pump (carefully) from the battery and see if it works that way. If it stays running, you've found the problem.

With some of the other strange light behavior you describe, I wouldn't be surprised if you have some shorts or disconnects in your harness somewhere from some overheated wiring. The previous owner of my 79 did a number on the wiring and cooked the main alternator wire that runs along in the main wiring bundle under the hood. This cooked some other wires and eventually a couple of them crossed. In my case, I had a short of constant power to the source for the reverse light switch on the trans. The symptom? The truck stayed running even when the key was off. It was feeding the whole ignition system backwards through that backup light wiring. Wiring problems can seem almost supernatural at times, but with enough tracing and troubleshooting they can usually be explained and fixed.

Dan brings up a good point, but I would think at idle you'd get enough fuel to keep it running unless the float was just stuck. Seems like that would only be a problem when the fuel demand was higher. You can splash a few drops in the carb and get it to run for a few seconds with no fuel coming in.

Can you see the fuel level thru the float bowl sightglass? If you can see it before you start the truck and it dissapears after its running its most likely what 800xl is going at. When you tested the pump, did it blast fuel out of the line or was it a lame, steady flow? This could indicate that your new pump is failing. I had a new pump go out in 2 months. If you have stong ,solid fuel flow. Try and slave in a new wire to the pump that has an alligator clip that you can connect directly to the battery. (This is a temporary fix to find out if the truck will drive down the road). If it works, you can focus on the stock wiring/relay. You could wire a switch to the dash and run it that way but i dont recommend it. You could end up leaving the pump on an run the battery down( i had mine wired direct thru a switch and i ran the battery down too many times).

_________________
Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

I have had some wires that were burned up and i ended up replacing them .Its a bit of a job tracing it out. However the intrusment panel comes out easy and is held in place with a few wing nuts. You can get a Haynes manuel from there website or there are used ones often on Ebay.
I think yours is a Series 8. But the Manuel covers all the series.

Im no luv expert, but would have to agree at checking first everything feul pump related. Electrical problems are usually more sporatic, or just shut down period. the relays gave me trouble and had to replace them both, until I ripped all the wiring out.

have fun.

I've had a couple of fuel pumps go out and the usual symptom for me was the truck running ok until you got on it a bit and then it would die off intermittantly. Either accelerating through the gears would do it or running highway speeds it would conk when the motor was pulling more fuel than the pump could match. I would think unless it was just putting out a little trickle that it could keep up with a truck at idle.

Around here they switch to "oxygenated" fuel in the fall and that always seemed to be when I would have pump problems. My theory was the older pumps used rubber that did not hold up to methanol additives in the gas, but I didn't lose enough of them to really be sure.

There is also some danger in leaving the pump on with the truck off. If the float valve leaked a little it would overflow the carb and fill the motor with gas. Assuming there wasn't an explosion, cranking over a motor with a cylinder full of liquid is not a good thing either. Any way you look it, bad news. You could wire it to something run off the ignition so that it wouldn't run without the key turned but you could still have problems if you left the truck running and the motor died.

Anyone know more about the whole engine speed sensor/fuel pump relay/voltage reg relationship? I keep meaning to get an alternator with integrated regulator but I hesitate because I don't want to stare at the wiring diagram that long. That might be a good solution to this problem as well, assuming you can rework things so all those relays function like they should.

That needle and seat is notorious for getting a little bit of trash stuck in it, and flooding it out. Mine used to do the same thing. Take it out, and clean it up, and see if that helps you.

here is something to look at.since your getting your gen,seat belt lites along with this problem. there is one thing that connects them all . your ignition switch. if it goes bad you will get the lite readings just like you typically do when you first start your truck. normally they shut off in a few seconds. but with the switch bad they could come back on if its giving a false reading.as for starting and shuting off the bad switch can cause that to.when in start mode there is an extra circuit to the coil to boost voltage to ease start up. after start up when you release the switch its supposed to switch to its normal circuit. if the switch is bad it might be not allowing it to switch accordingly. my 2 pennies worth later

well that last one was me it didn`t log me on again oh well

_________________
don`t have the luv no more but I still like em.72 el camino,
00 & 06 silverado one 4x4, turboed vw sandrail,99 banshee, 06 raptor 700, 02 polaris trailblazer.

i had the same problem with my 78 a while back so my dad and i rebuilt the carb and put it on and it still did it so we just keeped starting it and eventually after about an hour of playing with the screws and an tyming and just stuff like that it finally started. i think one of the jets was still clogged and couln'g flow. it happened to me 1 more time after that and i just hooked our air compreior up to the fuel line and blew into it towards and through the carb and that fixed and havent had a problem since

_________________
1980 4x4 header stock motor lifted 4 1/2 in. in the rear and 3 1/2 in the front

Check the field connection in the alternator. If the field isn't hooked up or the wire is broken the fuel pump will not run. I have had this happen too. I ended up putting a one wire delco on the truck ( tired of fixing the Hitachi). I had to short the two field wires together, with an oil pressure switch made for that purpose. Don't just connect the two wires together, if you have a wreak the pump will continue to run, possibly fueling a fire! So do it right the first time, get the switch. Be safe!!!!

_________________
1980 4X4 LUV

Thank you one and all! Because of work I won't be able to get back to working on it until Friday morning. The first thing I'm going to do is connect the fuel pump directly to the battery and see what happens (thank you 800xl!). If that doesn't do it, then I'll try some of the other suggestions. I will report back sometime Saturday 3/1/2003 on my progress or non-progress, as the case may be. In the meantime....
---
First, I have a 1972 LUV Shop Manual and a 1978 LUV. Anybody want to trade a '78 manual for a '72 manual, even-steven? The '72 is used, of course, but it's all there and quite usable.
---
DAN: Can you take a stab at telling me what a fuel float level looks like and where it is? I don't have a background in this, but I'm willing to do my homework.
---
800XL: In addition to your hot-wiring the fuel pump, thank you for your comments about wiring. I've long suspected I have a sporadic electrical problem. I suspect the wiper motor(s), but don't really know, it well might be something entirely different.

And if it can be done, after this is over, I'd like also to replace the generator with an alternator.
---
BLUE MEANIE: Can you take a stab at telling me what a float bowl sightglass and where it is? I've had the air cover off, didn't really go any further--scared I'd mess something up--except to check the filter where the fuel enters the carburetor. I didn't see anything that I would call a sightglass, but again, I have no idea what it might look like.

To check the new pump here's what I did: I hooked a 4-foot hose up to the fuel pump on the output side, put the hose into a bucket, set the bucket near the open door, sat in the cab and cranked the engine. The gas, once it started coming out, came out in what I would call a steady flow. I have no experience to know what you mean by a "strong, solid" flow or by a "blast". The flow that did come out seemed adequate to me.

One time I cranked it for close to 45 seconds to see if it would cut off. It didn't. But because the fuel flow didn't go to the carburetor the engine never started.

I guess the next logical step here is to get a transparent hose and start the engine and watch the fuel flow. In fact, now that I think of it, this seems a reasonable thing to do.
---
ZANE: Thank you!
---
77SSLUV: You're saying your fuel pump relay (and voltage regulator?) gave you trouble and the root cause was wiring problems?
---
DRUMMERFORHIRE: Can you take a stab at telling where the needle and seat are and what they look like. How do you take it out. "Clean it up" means what, wiping it off, or more?
---
RACELIFE (Guest): I took the ignition switch out and checked the connections with an ohmmeter, using a diagram from my '72 manual. At this level--resistance, some or none--it checked out OK. Anyway I can check further?
---
THEluvMAN: Thank you! I might have to go that route.
---
RICK SMITH: Thank you! Will check this out. Remember, though, I still have a generator, not an alternator.
===
Also: One person looking at the carburetor when the engine died said the butterfly valve wasn't opening. Elsewhere in this website I saw a reference to an electric cut-off on/to the carburetor. Any thoughts about this, anyone?
---
I'm not on the Internet, I'm doing this from our County Library. I'll check in again tomorrow, Thursday 2/27/2003, early evening, EST. Again, thank you, one and all. CL

my relays were bad, and i got a couple from a donor luv that was layin around. I dont remember too much about what happened. I was tracin electrical lines and they seemed like a probable culprit. replaced them both and vouala!

I had forgotten about the older LUVs having a generator, I got rid of my last pre-76 LUV quite a while back so I forget about some of the differences on those older trucks. Come to think of it, some of the 75 and older trucks I've seen had a manual fuel pump, stuck on the right side of the engine. If thats the case all this help we're giving for electrical problems might not mean a whole lot.

Rick Smith: I'd like to hear some details about the one wire alternator swap if you have time. Please post more or email me. I've been thinking of going that route myself but didn't want to stare at the wiring diagram long enough to figure it out yet. That stock regulator seems to be tied into a lot of stuff so I wondered what the best way of bypassing all of it would be. On my 79 the heater fan and the fuel pump both cut out if the motor stops. Replacing the hitachi is high on my list of want-to-do's. I'd like to get a few more amps and a one wire alternator is cheaper than replacing the Hitachi and the reg.

Im sure rick will get back to you, but i have the set up and its a piece of cake. just a little jumper from one terminal to another.

It's been raining and overcast here (Tallahassee, Florida) for the last several days, including today, but this last Sunday afternoon it cleared up a little for about 3 hours so I went out and hot-wired the fuel pump to the battery, routing the wires through the cab and connecting/unconnecting them with alligator clips. Cranked it up and, Oh Joy!, it ran and ran and ran. I cut it off after about 20 minutes. And so my problem is definitely electrical instead of carburetor.

But wait.... Monday morning it cranked up but with a little hesitation before turning over. But it started. Then driving, the GEN light came on--and stayed on, on, on. Monday afternoon I barely got it started, the GEN light stayed on--and then after a good hour or so, it went out! And at the same time so did the Temp gage and the Fuel gage! Hmmm.... Well, looking in the Haynes manual I got Monday, looking at a "typical" wiring diagram, I see that these three things all run first through the fuse box. So I checked the fuses that I just put in new last week--all good! Hmmm.

I parked it on top of a hill last night and started it this morning by coasting downhill and putting it into gear, the GEN light and gages are back! So after thinking about it a while, all the time keeping it running, I went to my neighborhood Advanced Discount Auto Parts store and first had my battery checked--47% charge, bad--and then my alternator--defective. Hmmm. [I forgot, I put an alternator in 2 or 3 years back, it went straight in with no wiring change or problem.] Anyhow, tomorrow I go Wal-Mart and pro-rate replace the battery, I've got 2 years remaining on the warranty, and then back to ADAP for the new alternator that should be in then from their warehouse--life-time warranty, no charge, no pun.

Now to the nub: these battery and alternator problems cropped up immediately after I hot-wired the fuel pump. So did the hot-wiring cause these problems, or were they there all along and part of my electric fuel pump problems? Hmmm...
---
The Haynes manual has helped of course, but by and large the authors presuppose a background body of knowledge that I just don't have. So, can anyone out there tell me specifically how to check a voltage regulator with a multimeter? The specs the manual gives for an ignition coil are for up to Series 4. Are the specs the same for Series 8? And the manual does not even mention the fuel pump relay--anyone know how to check it? From the wiring diagram I got from this site (thank you again!), I'm presuming it's the one with five prongs (next to one with four prongs), but I'm really not 100% sure.
---
So far I can't even find a fuel pump relay. I've tried ADAP, the NAPA store, two Chevrolet dealers, several Independent parts houses, and a junkyard that used to have two LUVs but no longer does. I've two more independents here and possibly a junkyard far in the next county to try tomorrow, but if anyone has any thoughts, I'd greatly appreciate them.
---
One other thing I'm going to do that I picked up from this site is to remove the fuses and check/clean all the connections underneath the fuse box.
---
I know I wax prolix, but what the heck, it's good therapy, organizes my thoughts, and I'm sure happy to find a community out there! Thank you again for your help. And I'd sure welcome any comments/hints/suggestions on any of this.
===
About the hills. Some, perhaps many, of you may think of Florida as flat. Well, that's south of here and south of here has gone to hell and good riddance too! Up here in North Florida we have hills, ravines, caverns, bat caves, even a waterfall or two. In fact the Red Hills Horse Trials start here in Tallahassee in a few days.

And so I'm sure thankful I live on my neighborhood hill when I have the car problems I have!
---
Cordially, cl.

Im an electrician, but house type wiring- not cars. I can tell you, though, that when you have opens and shorts, the sky is the limit for weird crap to happen. A lot of it depends on how good of shape the wiring is in and if somone has hacked at it.

I couldnt find a relay new anywhere. I had to get one from the junk yard. Ive heard a lot of fuel pumps get rewired off the fuse block on a circuit that comes on when the key is in the running position. This is easily checked with a tester. You could possibly use you tounge if needed.

this is one reason i rewired my crap with Painless.......

have fun..

Did you disconnect the stock fuel pump wire from the pump before connecting the jumper wire to the pump? If its still connected, it may be sending electricity back thru the wire to the relay and causing all of the wiring problems. Im not sure cause i haven't looked too hard at the wiring diagram of your truck. It might be a possibility because the 3 relays on the fenderwell could be tied together in someway.

_________________
Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.