Truck looses power while driving

[driggers.a]

So in the past week or my truck has inherited this problem where occasionally the truck will sputter out and loose power. About 50% of the time it shuts of completely, the other 50% it will come back to life without having to turn the key to start her up. If I have to crank the engine over to turn the car back on she'll usually throw a nasty back fire too, lights stay on when the engine dies too. I thought it may have been a vacuum issue so I checked for that, found a minor one, that's been solved now and it still occurs. Other than that the engine runs great.

 

Any ideas? Ignition timing? Something loose? Or am I looking at a fuel issue?

 

Oh, 1976 620 w/ L20

[izzo]

Were you on a hill or getting on it?

[MicroMachinery]

Give it a tune up: Plugs, Wires, Cap, Rotor, Condenser, Fuel Filter, Air Filter. Always start with the simple stuff.

 

It's good practice to begin diagnosis with a tune-up. It's generally inexpensive, and that way you have a good starting point for finding the problem.

[driggers.a]

Were you on a hill or getting on it?

 

Its more when getting on it, hasn't happened during light throttle yet.

 

 

Give it a tune up: Plugs, Wires, Cap, Rotor, Condenser, Fuel Filter, Air Filter. Always start with the simple stuff.

 

It's good practice to begin diagnosis with a tune-up. It's generally inexpensive, and that way you have a good starting point for finding the problem.

 

In the last 5k I've got new cap and rotor, fuel filter, oil filter, air filter, plugs, water pump, coolant hoses.

 

I have a feeling one of my connections on my coil or something is loose, IIRC when my engine died one time my tach wasn't reading any RPM when my car was definitely still in gear and moving. Didn't really process that until now :sleep:

[.sunlover]

what fuel pump are you running, and do you have a fuel regulator in place? I puke out in my l20 after lots of acceleration and am almost sure it's because my cheap electric fuel pump can't keep up with my carb with the fuel regulator i'm running. The coil might be a separate issue, or your coil might be dying under load, but they usually either work or they don't. almost free to change your coil lead wire, you might check that first. First check voltage with the key on, should be close to what your battery has, if low, change wire, check again, if still low, clean leads from, ign switch, change if still low. if seems okay, as datsunmike has suggested regarding fuel, shut it off when it's doing this, pull over and check how much fuel is in your float bowl. Then you'll know what the problem is.

[.sunlover]

should say to clean wire to the ignition switch before changing it, and clean terminals before you change you coil wire.

[datzenmike]

Check/replace the points. Check the rest of the ignition system for anything loose.

 

Next time it quits stop immediately and check the fuel level in the glass in the front of the carb. Is it at the line or not.

 

If not replace the fuel filter again. Cut the old one open and see what plugger it up.fr

[.sunlover]

Check/replace the points. Check the rest of the ignition system for anything loose.

 

Next time it quits stop immediately and check the fuel level in the glass in the front of the carb. Is it at the line or not.

 

If not replace the fuel filter again. Cut the old one open and see what plugger it up.fr

 

Haha, called it :) (the middle) I'm in tune with your baddassedness :)

[banzai510(hainz)]

if you sghut the key off and the truck stays running it could be a volt reg. But this might nnot be your specific issue.

 

Lights will stay on as the swithc is ON unless battery is dead.

 

Unless you put a different coil in there and its getting hot or bypass the ballast reisitor with a point coil that could be it.Or a fuel issue.

Next time this happens gently wack where the gas goes into the carb. the needle valave could be sticky not letting gas in.

 

Is this a stock carb?

 

Be honest I would do a valve lash ck as I remember you just got his vehicle.

 

As for tune up stuff I have bought a set in 7/8 years. But when it comes to points I always ck the point gap. and make sure noting is touching inside that could ground the points out. Loose screw holding the wire to condensore.

[metalmonkey47]

I had the EXACT same symptoms when I was having sediment from the tank work it's way past the filter into the float bowl of my Weber. I gradually would loose more and more power under any load until eventually, the truck was missfiring and refused to move.

 

 

 

If you have a Weber, cleaning the carb is as easy as 6 screws and a C-clip on the choke arm. You can generally get away with using the old gasket, but I would prefer to throw in a new one at the same time.

 

If you have the stock carb, good luck! I hate those little buggers.

 

 

While you're at it, might as well do a good tune up.

[daverino]

check diverter / abv valve

[tomyboy]

I've had the same problem in the past.

Make sure all fuel lines are tight.

They will suck air. Worst when under a load.

Would idle forever.

Keep it simple.

[datsun mechanic]

i don't know all the details of your truck but if you suspect fuel,,,,,,,, i would put on fuel pump gauge 2.5 to 3.5...... carefully blow out fuel line to tank if you know how............always replace f filter................can also ck fuel volume according to you manual............drive with out gas cap test

[Jovan Munoz]

So in the past week or my truck has inherited this problem where occasionally the truck will sputter out and loose power. About 50% of the time it shuts of completely, the other 50% it will come back to life without having to turn the key to start her up. If I have to crank the engine over to turn the car back on she'll usually throw a nasty back fire too, lights stay on when the engine dies too. I thought it may have been a vacuum issue so I checked for that, found a minor one, that's been solved now and it still occurs. Other than that the engine runs great.

 

Any ideas? Ignition timing? Something loose? Or am I looking at a fuel issue?

 

Oh, 1976 620 w/ L20

 

Check the coil, my truck would also loose power when driving or even when i was at a stop light. I changed the coil and problem solved

[kneesamo]

My votes for a sticky needle valve.

[DattoDime70]

So in the past week or my truck has inherited this problem where occasionally the truck will sputter out and loose power. About 50% of the time it shuts of completely, the other 50% it will come back to life without having to turn the key to start her up. If I have to crank the engine over to turn the car back on she'll usually throw a nasty back fire too, lights stay on when the engine dies too. I thought it may have been a vacuum issue so I checked for that, found a minor one, that's been solved now and it still occurs. Other than that the engine runs great.

 

Any ideas? Ignition timing? Something loose? Or am I looking at a fuel issue?

 

Oh, 1976 620 w/ L20

I've gotten the same problems on my 70 510 with l16,Weber 2bbl and matchbox ei dizzy,I've replaced the fuel lines,filters, fuel pump,dizzy cap and rotor, and a new ei coil from a 200sx(wired right) and I still can't figure it out and it's still doing it! How did you fix the problem :(

[datzenmike]

I've gotten the same problems on my 70 510 with l16,Weber 2bbl and matchbox ei dizzy,I've replaced the fuel lines,filters, fuel pump,dizzy cap and rotor, and a new ei coil from a 200sx(wired right) and I still can't figure it out and it's still doing it! How did you fix the problem :(

 

Next time it quits get the clutch in and shut off ASAP and pull over. Look at the sight glass on the front of the carb. If empty you have a fuel delivery problem. Could be anything between the carb and the tank. If it has fuel is it over full, flooded?? Could be improper float level, sticking needle valve, sunken float, sticking float. If at normal level look elsewhere like the ignition.

[DattoDime70]

Next time it quits get the clutch in and shut off ASAP and pull over. Look at the sight glass on the front of the carb. If empty you have a fuel delivery problem. Could be anything between the carb and the tank. If it has fuel is it over full, flooded?? Could be improper float level, sticking needle valve, sunken float, sticking float. If at normal level look elsewhere like the ignition.

I've done that and it is at normal level.

[datzenmike]

Is the matchbox facing the front? or towards the back? If to the back it can overheat.

 

Is the dizzy grounded with a separate ground wire to the head or block?

[DattoDime70]

Next time it quits get the clutch in and shut off ASAP and pull over. Look at the sight glass on the front of the carb. If empty you have a fuel delivery problem. Could be anything between the carb and the tank. If it has fuel is it over full, flooded?? Could be improper float level, sticking needle valve, sunken float, sticking float. If at normal level look elsewhere like the ignition.

I've tuned the Carb too

[DattoDime70]

Is the matchbox facing the front? or towards the back? If to the back it can overheat.

 

Is the dizzy grounded with a separate ground wire to the head or block?

the module is facing the engine.

I've use that screw next to the vacuum to ground a 16g wire to the left side of the engine bay in the fender.

[Kingman]

Identical issue to what I was having a while back. I thought the truck kept running out of gas, but then when I wiggled the wires going to the coil in the harness it would fire back up. Some corroded wiring and a loose connection were the issue, fixed that and it's been golden since. Now when it dies like that it really is out of gas haha.

[banzai510(hainz)]

If matchbox installed on a POINT ignition vehicle !!!!!!!!!!!!

One must wire it up like a Pertronix where you still use the point coil(1.6 ohms) and ballast resisitor1.6ohms)

B to blk/wht

C to - side coil

 

Or wire it with a EI coil like a 79 200sx or MSD Blaster 2

 

NO BALLAST!!!!!!!!!!!!!

 

blk/wht ON wire (usually the blk/blu(or HOTSTART) can be shorted with the blk/wht to the +side coil.

 

B + side coil(shorted to above so 3 wires are at the + side coil

C - side coil

 

 

If one removes the ballst resisitor and leaves the Point coil installed on a matchbox the coil will get HOT.

FEEL it next time this happens.

[driggers.a]

Sorry for my absence, have been busy with school and work.

 

I went through all the ignition connections and cleaned all of 'em up. Replaced the intake, exhaust, carb gaskets as well, she runs much better. Also had a u-joint making some noise, so I rebuilt the drive shaft. Went down to a 3.889:1 gear in the rear, much better cruising on the freeway. :cool:

[datsun mechanic]

.........try remove gas cap then test drive(closed system trouble???)