720 Running Super Weak

[Mmoony]

Hey y’all, wanted to get some advice on where to start with my 720. Runs super weak, really slow acceleration and feels like it’s maxing out around 60mph. Gets decent mpg at around 18 or so. Also starting in the morning is a pain. Cranks and cranks, fires, sputters, dies. Repeat. Throw it in gear, dies, restart, repeat. Pull out onto the road, sputters and dies. You get it. 
 

Had the head gasket done about a year ago. Just put a manual choke on the carb since the electric choke quit working, although it the choke doesn’t seem to make a difference. My mechanic friend said my timing chain is loose and only one of my ignition coils is firing. There are also a few vacuum leaks I’m pretty sure. Where would you guys start? Any other things I should check? 

[datzenmike]

Replace the 10 amp fuse on the far left side of the fuse box. This will get your exhaust side plugs firing. This will likely fix all your problems as the timing should be at about 5 degrees with both plugs firing. Two plugs means the combustion happens faster so no need for much ignition advance. With only one plug working per cylinder the burn time is a lot longer and would need to be closer to 12 degrees. Effectively, with single plug it's like the timing is retarded by 6 degrees.

 

It should go faster than 60 I would think so just for the heck of it, replace the fuel filter between the tank and the pump. The electric pump is on the outside of the frame just forward of the rear right tire. They are under $5 and even if it doesn't help it's likely due to be changed anyway.

 

 

[720_Jeff]

Not sure if all auto parts stores carry the in-pump filter.  Part 16404-28530

 

Fuel Pump - 1985 Nissan 720 Pickup (nissanpartsdeal.com)

[Thomas Perkins]

Take the fuel line off the carb and put in a mason jar and have someone turn over the engine and see how much gas goes in the jar.Could be bad fuel filter,bad fuel pump.Could be bad ignition coils.Take wires out of coils and see what the inside of coil look's like.Check the condition of the plugs.Maybe bad oil rings.Mine went bad in 2009 and I got a new Jasper engine.Maybe time for a Weber.My coil 5 years ago.